Shale gas: It is not so scattered by hydraulic soles, like his little. Frequining or hydraulic fracturing: technology, history, equipment What is oil production by the method of frequency
British researchers analyzed the method of hydraulic reservoir (GPA, the method of intensifying the work of oil and gas wells) in terms of its safety for the environment, economics and society. As a result, the hydraulic fracturing method was placed on the seventh place in the ranking of nine energy sources. Perhaps such a study will be carried out in America - in the only country in the world, where the GPA method is now considered to be one of the main ones.
Low security
The fracturing of the reservoir is an ambiguous process, during which water, sand and high-pressure chemicals are fed into the reservoir, as a result of which cracks that facilitate oil and / or gas production appear.
To assess the consequences of using the hydraulic fracturing method in the UK, a group of scientists from Manchester University amounted to a rating of energy sources (among them coal, wind, sunlight), evaluating the safety of their use in terms of environment, economics and society. The hydropower method, scientists placed on the seventh position of the rating.
Scientists report that in order for the hydraulic fracturing method to be as safe as wind and the sun energy, it is necessary to reduce its negative impact on the environment intensively 329 times.
The researchers amounted to various forecasts for the future and determined that the situation in which 1, not 8 percent of the electricity developed in the UK, will be accounted for, is more favorable.
Frequining in context
Scientists say that most of the research related to the hydraulic method is aimed at studying its environmental impact. These studies are mainly held in the United States. British specialists argue that the socio-economic aspect is not sufficiently studied. They call their research project with the first work, which addresses the impact of the GPA method on the environment, the economy and society.
"This allows us to evaluate the safety of the method of using the method as a whole, without paying all the attention to only one aspect like transportation, noise or pollution of water, which is actively discussed today when studying shale gas," said the Independent Professor of the University of Adiz Azapadzhik.
In some states, the PRT method is prohibited, and at the moment America is the only country using it on a large scale. Perhaps the British study will encounter American professionals to conduct their own analysis. If in America the safety of the hydraulic fracturing method will be as low as low, then policies can apply to the use of less dangerous energy sources.
In the modern branch of oil production, the fracturing of the formation (GPP) is an effective method of impact on the bottomhole of the well. This method is necessary to increase productive returns from the oil or gas field, the degree of absorption of discharge varieties of wells, as well as in the framework of work on groundwater isolation. The process of hydraulic rupture of the reservoir itself includes the creation of new cracks and an increase in the already existing ones that run in the bottomroom breed. The exposure to cracks occurs by adjusting the pressure of the fluid supplied to the well. As a result of the hydraulic reservoir from the well, it becomes possible to produce valuable resources located at a remote distance from the barrel.
From the history of the appearance of hydraulic injections
Developments to increase the productivity of oil production from finished wells were carried out in the States at the end of the XIXVEK: Then the method of stimulation was tested by an explosion of nitroglycerin, which broke solid rocks and allowed to receive valuable resources from there. In the same period, tests were carried out on the development of a bottomhole zone with the help of acid, and the latter method was actively distributed in the 30s of the last century.
During the use of acid to stimulate well productivity, it was found that the increase in pressure can lead to the breaks of the formation. From this, the development of the idea of \u200b\u200bthe hydraulic injection of the breeds began, and the first attempt was made in 1947. Despite the failure, the researchers continued to develop the method, and their work was crowned with success two years later. In the 50s, the states in the States increasingly began to develop using the method of hydraulic breaks of the formation, and by the last third of the XXVEK, the number of such operations exceeded a million only in America itself.
The hydraulic rupture of the formation as a methodology for developing wells began to be used in the USSR: the first attempts were marked in 1959. After that, there was a period of extrusion of the popularity of this method, because in Siberia, wells began to develop wells, which, without additional manipulations, ensured uninterrupted oil and gas production in the necessary volumes. Since the end of the 80s, the methodology has again received distribution, when the previous deposits ceased to give the same number of valuable resources, but they could not yet be considered completely exhausted. Currently, the method of hydraulic rupture of the formation is applied throughout Russia, as well as in other states.
Varieties of hydraulic breaks
In the modern field of resource development, two types of hydraulic rupture are distinguished:
- Propant hydraulic fracture. At the same time, a special material for crushing is applied. During the procedure, proppant is poured inside so that the cracks created from pressure are not connected back. Such a kind of method is well suited for sandstones, aleurolite and other terrigenous breeds. The hydraulic gap with the propant is used most often.
- Hydrogenation of the reservoir with the use of acid. Such a method is more acceptable for carbonate rocks, and cracks that are obtained by combining the increase in pressure and adding a destructive fluid, do not need additional consolidation, as in the first case. The main difference between the acid hydraulic break from the usual treatment of the same acid consists in the amount of material and the degree of pressure.
Regardless of the type of processing, the success of the UGP is depends on a number of factors. First of all, the object for the implementation of the method must be selected taking into account its features, types of formations, as well as depth and intensity of development. The choice of technology depends on the conditions in which the well is located. With proper use, the efficiency of oil production in the processed well becomes much higher.
The process of conducting a hydraulic reservoir
The hydroxide of the reservoir is advisable for wells with a low productive ability, which occurs due to the natural density of the layers or with a decrease in the quality of filtration after opening the next layer.
The processing process takes several stages:
- Study of the well, during which its ability to absorb, pressure resistance and other parameters are determined.
- Cleaning well. For this, drainage pumps are used and the trunk is washed so that the filtering properties in the bottom-up region are sufficient for further work. Also, the well can be treated with hydrochloric acid so that the conditions for forming cracks from the rupture were optimal.
- Descent into the well of pipes for supplying fluid into a slaughter. The casing is equipped with a packer and hydraulic in order for the pressure does not deform the pipe. The mouth is equipped with a head for connecting the equipment, which is necessary for the injection of washing fluid.
- Hydrogen itself is performed by injection of fluid until cracks appear in the reservoir. Immediately after hydraulic impact, you need to download fluid at high speed.
- The mouth is overlapped, the well does not touch until the pressure decreases.
- Flushing well after hydraulic rupture and mastering.
With a small depth, the fracturing of the reservoir can be carried out without tubing tubes or without a fuse. In the first situation, the discharge is made by casing pipes, and in the second it can be organized and along the ring around them. This technique allows you to minimize the loss in pressure indicators if the process uses a very thick consistency fluid. In addition, for some wells, a multistage gap is carried out, in which different layers receive cracks, due to which their permeability increases much.
To determine the location of the cracks themselves, the radioactive logging method is used. This technology makes it possible to find out where the gaps are located, with the introduction of ordinary and charged sand.
The "shale revolution" obviously seriously seizes the minds of politicians and businessmen of the whole world. The palm of the championship in this area holds Americans, but, apparently, there is a possibility that the rest of the world will soon join them. Of course, there are states where it is practically no mining of shale gas - in Russia, for example, to this undertaking the main percentage of political and business elites relates rather skeptical. The case is not so much in the factor of economic profitability. The most important circumstance that may affect the prospects for such an industry like mining of shale gas, the consequences for ecology. Today we will explore this aspect.
What is shale gas?
But for a start - a small theoretical excursion. What is a shale mineral mineral, which is mined from a special type of minerals - the main method, with which the mining of shale gas is being carried out, the consequences of which we are today, guided by the positions of experts, we will study - Frequin, or hydraulic fracturing. It works like this. In the earth's depths, a pipe is introduced into the almost horizontal position, and one of its branches is displayed on the surface.
In the process of fakeing in the gas storage, the pressure is injected, which contributes to the outlet of the shale gas upwards, where it is going. The greatest popularity of the production of mentioned minerals acquired in North America. According to the estimates of a number of experts, revenue growth in this industry in the US market over the past few years amounted to several hundred percent. However, unconditional economic success in the aspect of the development of new ways of production of "blue fuel" can be accompanied by huge problems associated with mining gas. They are worn, as we have already said, environmental character.
Harm of ecology
What the United States and other energy powers should, in the opinion of experts, to pay special attention, working in such a sphere as mining of shale gas, is the consequences for ecology. The main threat to the environment is the main method of extracting minerals from the depths of the Earth. We are talking about the Frequin itself. He, as we have already said, is a flow in the globe of water (under very large pressure). Such an impact can have a pronounced negative impact on the environment.
Reagents in action
Technological features of frenching is not the only character. The current mining methods of shale gas involve the use of several hundred species of chemically active, and in the potential of toxic, substances. What can it mean? The fact is that the development of appropriate deposits requires the use of large amounts of fresh water. Its density is usually less than the one that is characteristic of underground waters. And therefore, light layers of liquid, one way or another, can over time climb the surface and reach the mixing zone with drinking sources. At the same time, they are likely to contain toxic impurities.
Moreover, an option is possible, in which light water will return to the surface of contaminated non-chemical, but quite natural, but still harmful to human health and ecology substances that may be kept in the depths of earthly subsoil. An indication point: It is known that it is planned to produce shale gas in Ukraine, in the Carpathian area. However, experts of one of the scientific centers conducted a study during which it turned out: layers of land in those regions that are supposed to contain shale gas are characterized by an increased maintenance of metals - nickel, barium, uranium.
Occasion technology
By the way, a number of experts from Ukraine calls to pay attention not so much on the problems of shale gas production in the aspect of the use of harmful substances, how many technologies used in the gas gasovics used. Representatives of the Scientific Environment of Ukraine in one of their reports on the ecological topics put forward appropriate theses. What is their essence? The findings of scientists, in general, are reduced to the fact that the mining of shale gas in Ukraine can cause significant damage to the fertility of soils. The fact is that with those technologies that are involved for the insulation of harmful substances, some materials will be located under arable ground. Accordingly, to grow something over them, in the upper layers of the soil, will be problematic.
Ukrainian subsoil
There are also concerns in the environment of Ukrainian experts about the possible spending of drinking water reserves that can be a strategically significant resource. At the same time, already in 2010, when the shale revolution was only gaining momentum, the Ukrainian authorities issued licenses for reconnaissance work on shale gas to companies in Exxonmobil and Shell. In 2012, drilling of search wells in the Kharkiv region was carried out.
It could testify, experts believe that the interest of the Ukrainian authorities in the development of "shale" prospects are likely to reduce the dependence on the supply of blue fuel from the Russian Federation. But now it is not known, analysts consider what further prospects of work in this direction (due to famous political events) are considered.
Problem Frequin
Continuing the reasoning about the shortcomings of technologies of shale gas, it is also possible to pay attention to other remarkable theses. In particular, in fakeing, some substances can be used, they are activated as a break fluid. At the same time, their frequent use can lead to a significant deterioration in the degree of permeability of rocks for water flows. In order to avoid this, gas can use water in which soluble chemical derivatives are used close in composition to cellulose. And they carry a serious threat to human health.
Salt and radiation
There were precedents when the presence of chemicals in waters in the area of \u200b\u200bshale wells was recorded by scientists not only in the estimated aspect, but also in practice. After analyzing the water flowing into the sewage treatment plant in Pennsylvania, the experts found much higher than normal, the level of salts - chlorides, bromide. Some of the substances found in water can react with atmospheric gases - for example, ozone, resulting in toxic products. Also in some depth layers located in areas where shale gas is mined, the Americans have discovered radium. Which, respectively, radioactive. Apart from salts and radium, in waters that are concentrated in areas where the main method of shale gas production is applied (Frequin), scientists have discovered various kinds of benzene, toluene.
Legal Lazake
Some lawyers note that the harm of the ecology inflicted by the American gas-producing companies "shale" profile has hardly a lawful nature. The fact is that in 2005, a legal act was adopted in the United States, according to which the Frequining method, or the fracturing of the formation was derived from under the monitoring of the Agency for Environmental Protection. This agency, in particular, has ensured that American businessmen act in accordance with the prescriptions of the law on the protection of drinking water.
However, with the adoption of a new legal act, the US enterprise has received the opportunity to act outside the agency control zone. It became possible, experts, extraction of shale oil and gas in the immediate vicinity of underground drinking water sources. And it despite the fact that the agency in one of his research came to the conclusion that the sources continue to pollute, and not so much in the process of frenching, as many time after the completion of the work. Analysts believe that the law was not adopted without political pressure.
European Freedom
A number of experts focuses on the fact that not only Americans, but also Europeans do not want to understand what is dangerous than the mining of shale gas in the potential. In particular, the European Commission, developing sources of law in various fields of EU economy, did not even create a separate law regulating environmental issues in this industry. The agency was limited to, emphasize analysts, just a publication of the recommendation, in fact, without anything obliging energy companies.
At the same time, according to expert comments, Europeans are not too much strive for the early start of work on the extraction of blue fuel in practice. It is possible that all those discussions in the EU, which are associated with the "shale" subject - only political speculation. And in fact, Europeans, in principle, are not going to master gas production by the unconventional method. At least in the near future.
Complaints without satisfaction
There is information that in those areas of the United States, where the mining of shale gas is going, the consequences of an environmental nature have already made itself felt - and not only at the level of industrial research, but also in the environment of ordinary citizens. Americans living next to wells where frenching is applied, began to notice that the water from the crane has greatly lost in quality. They are trying to protest against shale gas mining in their locality. However, their possibilities are believed to be experts are incomparable with the resources of energy corporations. The business scheme is implemented quite simple. In case of claims from citizens, they form honeying ecologists. In accordance with these documents, drinking water must be in perfect order. If residents do not suit these papers, then gasoviki, as reported in a number of sources, pay them in the pre-trial procedure for compensation instead of the signing of contracts for non-disclosure of information about such transactions. As a result, the citizen loses the right to report something to the press.
The verdict is not burdens
If the lawsuits are still initiated, then decisions made not in favor of energy companies are not in fact very burdensome for gas. In particular, according to some of them, the corporations undertake to supply drinking water from environmentally friendly sources at their own expense or to install cleaning equipment for them. But if in the first case the victims of the inhabitants, in principle, can be satisfied, then in the second - as experts believe - there may be a special reason for optimism, since some can still be seen through the filters.
The authorities decide
In the expert environment, there is an opinion that interest in the shale in the United States, as well as in many other countries of the world, is more political. This, in particular, may indicate the fact that many gas corporations are supported by the Government - especially in such aspects as tax breaks. The economic consistency of the "shale revolution" experts are assessed ambiguously.
Drinking water factor
Above, we said that Ukrainian experts questioned the prospects for mining of shale gas in their own country, largely due to the factors that frekeening technology may require spending a large amount of drinking water. It must be said that specialists from other states express such concerns. The fact is that without shale gas is already observed in many regions of the planet. And it is likely that such a situation will soon be observed in developed countries. A "shale revolution", understandable, will only contribute to the acceleration of this process.
Ambiguous slate
It is believed that mining of shale gas in Russia and other countries is not mastered at all or at least not happening in this pace, as in America, just because the factors considered by us. This is, first of all, the risks of environmental pollution toxic, and sometimes radioactive, connections that have a place to be with french. Also, this is the probability of depletion of drinking water reserves, which may soon even become a resource, according to the degree of importance not inferior to blue fuel. Of course, the economic component is also taken into account - there are no consensus among scientists on the profitability of shale deposits.
Currently, hard-to-recovery stocks are widely involved. oilDeaded to low-permeable, weakly referred, inhomogeneous and dissected manifiers.
One of the effective methods of increasing well productivity, revealing such layers and increasing the pace of selection oil Of these, the hydraulic rupture of the formation (GPP). Hydraulic gap can be defined as a mechanical method of impact on the productive reservoir, in which the breed is broken through the planes of minimum strength due to the exposure to the pressure reservoir created by injection into the fluid reservoir. The fluids by which the energy required for the break is transmitted from the surface at the bottom of the well, called the break fluids.
After breaking under the influence of fluid pressure, the crack increases, its connection arises with the system of natural cracks, not opened well, and with high permeability zones; Thus, the area of \u200b\u200bthe reservoir is expanding, drained well. In formed cracks, the granular material is transported by granular material fixing cracks in the disclosed state after removal of overpressure.
As a result, the production of discharge wells producing or the injection of injection wells increases, due to the reduction of hydraulic resistances in the bottomhole zone and increase the filtration surface of the well, and also increases the final oilverter Due to the acquisition for the development of weakly drainaged zones and propelurs.
The hydraulic fracturing method has many technological solutions caused by the peculiarities of a particular processing object and the target achieved. GDP technologies differ primarily on the volume of injection of technological fluids and pans and, accordingly, in size of the cracked
The most widespread was obtained by local focus as an effective means of exposure to the well zone. In this case, it is sufficient to create cracks with a length of 10 ... 20 m with injection of dozens of cubic meters of liquid and units of tons of proppant. In this case, the flow of wells increases by 2.3 times.
In recent years, the technologies for creating cracks have been developing intensively in medium and high-permeable formations, which reduces the resistance of the bottomhole zone and increase the efficient radius of the well.
Conducting the hydraulic crash to the formation of extended cracks leads to an increase in not only the permeability of the bottomhole zone, but also the coverage of the reservoir by influence, involvement in the development of additional reserves oil and increase oil recovery generally. It is possible to reduce the current waterproofing of the production. The optimal length of the fastened crack with the permeability of the formation 0.01 ... 0.05 μm2 is usually 40 ... 60 m, and the download volume is from tens to hundreds of cubic meters of liquid and from units to tens of tons of proppant.
Along with this, selective hydraulic fracturing is applied, which allows to involve into development and increase the productivity of low-permeable layers.
To engage in industrial development gas Ultra-lower leaks (less than 10 MKM 2) in the USA, Canada and a number of Western European countries successfully apply the technology of massive in the same time create cracks with a length of 1000 m and more with download from hundreds to thousands of cubic meters of liquid and from hundreds to thousands of proppant.
Experience in the use of hydraulic reservoir abroad
For the first time B. oil Practice Hydraulic gap was produced in 1947 in the United States. The technology and theoretical ideas about the process of hydraulic fracturing were described in J. Clark in 1948. After which this technology quickly gained widespread. By the end of 1955, more than 100,000 hydraulic fractures were conducted in the United States as theoretical knowledge of the process and improvement of technical specifications. equipment, Liquids of breaking and crushing materials The success of operations reached 90%. By 1968, more than a million operations were produced in the world. In the United States, the maximum of operations to stimulate wells by the hydraulic fracturing method was noted in 1955 - approximately 4500 GPP / month, by 1972 the number of operations decreased to 1000 GPP / month, and by 1990 it was already stabilized at the level of 1500 operations / month.
The technology of UGPs is primarily based on knowledge of the mechanism of the occurrence and propagation of cracks, which allows you to predict the geometry of cracks and optimize its parameters. The first sufficiently simple models that determine the link between the pressure fluid pressure, plastic deformation of the rock and the resulting length and disclosure of the crack, were responsible for the needs of practice until the operations of the PSU did not require the investment of large funds. The introduction and massive hydraulic hydraulic hydraulic hydraulic fracturing fluids led to the need to create more advanced two and three-dimensional models allowing more reliably to predict the results of processing currently in fishing practice. Growing the crack and the flow of fluid in it in two mutually perpendicular directions.
The most important factor in the success of the GPP procedure is the quality of the break and proppant fluid. The main purpose of the break fluid is the transmission from the surface at the bottom of the energy well, necessary for the disclosure of the crack, and transportation of the proppant along the entire crack. The main characteristics of the system "Liquid break - proppant" are:
Rheological properties of "clean" fluid and liquid containing proppant;
The infiltration properties of the fluid that determine its leakage into the reservoir during the hydraulic displeasure and when the proppant is transferred along the crack;
The fluid ability to ensure the transfer of proppant to the ends of the crack in suspension without its premature deposition;
The possibility of light and fast removal of the break fluid to ensure minimal pollution of the packaging of the proppant and the surrounding reservoir;
Compatibility of a break fluid with various additives provided by technology, possible impurities and reservoir liquids;
Physical properties of proppant.
The technological fluids of the hydraulic fluid must have a sufficient dynamic viscosity to create high conductivity cracks due to their large disclosure and efficient filling proppant; have low filtration leaks to obtain cracks of the required dimensions at minimum fluid costs; ensure the minimum decrease in the permeability of the zone of the reservoir in contact with the break fluid; provide low fusion pressure losses in pipes; To have sufficient thermal stability and high shear stability for the processed formation, i.e. stability of the structure of the liquid during the shift; Easy to endure from the reservoir and cracks of the hydraulic time after processing; be technological in preparation and storage in commercial conditions; have low corrosion activity; be environmentally friendly and safe in use; Have a relatively low cost.
The first gap fluids were on oil The basis, however, since the end of the 50s, it began to use water-based liquids, the most common of which are guar resin and hydroxypropylguar. Currently, in the United States, more than 70% of all hydraulic PPPs are produced using these liquids. Geli oil The basis is used in 5% of cases, compressed foam gas Apply in 25% of all hydraulic fractures. To increase the efficiency of the hydraulic dispenser, various additives are added in the break fluid, it is mainly anti-filtration agents and friction reduction agents.
Failures when conducting hydraulic in low-permeable gas The formations are often due to the slow removal of the break fluid and blocking the crack. As a result, the initial flow rate gas After the hydraulic fracturing, it may be 80% lower than the time established after time, since the increase in the well flow rate occurs extremely slowly as the crack is cleansed - within weeks and months. In such plates, the use of a mixture of hydrocarbon fluid breakdown and liquefied carbon dioxide or liquefied CO was especially relevant; With the addition of nitrogen. Carbon dioxide is introduced into the reservoir in the liquefied state, and is carried out as gas. This allows you to speed up the removal of fluid break from the formation and prevent such negative effects, the most pronounced in low-permeable gas collectors like blocking cracks with a gap liquid, impairment of phase permeability for gas near cracks, change in capillary pressure and wettability of rock, etc. The low viscosity of such rupture fluids is compensated for in carrying out the operations of a hydraulic fracture.
Modern materials used to secure cracks in the open state - proppants - can be divided into two types - quartz sands and synthetic proppants of medium and high strength. The physical characteristics of proppants that affect the conductivity of the crack include such parameters as strength, the size of the granules and the particle size distribution composition, the quality (the presence of impurities, solubility in acids), the shape of the granules (sphericality and roundness) and the density.
The first and most widely used material for fastening cracks are sands whose density is approximately 2.65 g / cm 2. Sands are commonly used in the hydraulic fracturing of the formation, in which the compression voltage does not exceed 40 MPa. Medium Urgent are ceramic proppants with a density of 2.7 ... 3.3 g / cm 3 used at a compression voltage up to 69 MPa. Heavy-duty proppants, such as sintered bauxite and zirconium oxide, are used at a compression voltage up to 100 MPa, the density of these materials is 3.2 ... 3.8 g / cm 3. The use of heavy-duty proppants is limited to their high cost.
In addition, the so-called superelock is used in the USA - quartz sand, the grains of which are coated with special resins that increase the strength and preventing the removal of particles of the cooled proppitate from the crack. The superpection density is 2.55 g / cm. 3. Synthetic residal proppants are also produced and used.
The strength is the main criterion in the selection of proppants for specific reservoir conditions in order to ensure the long-term conductivity of the crack at the depth of the reservoir. In deep wells, the minimum voltage -Gorizontal, so predominantly vertical cracks are formed. With a depth, the minimum horizontal voltage increases approximately 19 MPa / km. Therefore, in depth, the proppants have the following applications: quartz sands - up to 2500 m; proppants of high strength - up to 3500 m; High strength proppants - over 3500 m.
Studies of recent years, conducted in the United States, showed that the use of proppants of average strength is cost-effective and at depths of less than 2500 m, since increased costs due to their higher compared to the quartz value of value overlap winnings in additional oil production Due to the creation of a high-conducting proppant packaging in a crack.
Most often apply proppants with dimensions of granules 0.425 ... 0.85 mm (20/40 mesh), less often 0.85 ... 1.7 mm (12/20 mesh), 0.85 ... 1,18 mm (16/20 mesh), 0.212 ... 0.425 mm (40/70 mesh). The choice of the desired grain grains is determined by a whole complex of factors. The larger the granules, the greater permeability, the packaging of the proppant in the crack is possessed. However, the use of a large fraction proppant is associated with additional problems when it is transferred along the crack. The strength of the proppant is reduced with an increase in the size of the granules. In addition, in weak-controlled reservoirs, it is preferable to use the proppant of a smaller fraction, since, due to the removal of particles, the packaging of coarse-grained proppant is gradually clogged and its permeability decreases.
From the roundness and sphericity of the granules of proppant depends on the density of its packing in the crack, its resistance, as well as the degree of destruction of the pellets under the action of mountain pressure. The proppant density determines the transfer and position of the proppant along the crack. High density proppants are harder to maintain in suspension in the break fluid when they are transported along the crack. Filling the crack with a proppant high density can be achieved in two ways - using high-viscosity liquids, which transport proppant along the length of the crack with its minimum precipitation, or the use of low-viscosity liquids at an elevated pace of their injection. In recent years, foreign firms began to produce lightweight proppants characterized by a reduced density.
Due to the large variety of leaving fluids and proppants existing on the US market, American oil The Institute (API) has developed standard techniques for determining the properties of these materials (API RP39; PRUD "Homme, 1984, 1985, 1986 - for gap fluids, and the RP60 API for proppants).
Currently, in the United States has accumulated a vast experience in carrying out hydraulic fracturing, while all increasing attention is paid to the preparation of each operation. The most important element of such preparation is the collection and analysis of primary information. The data necessary for the preparation of the hydraulic fracturing can be divided into three groups:
Geological and physical properties of the formation (permeability, porosity, saturation, reservoir pressure, position gas phone and water contacts, petrography breeds);
Characteristics of geometry and fracturing orientation (minimum horizontal voltage, Jung module, viscosity and density of break fluid, Poisson coefficient, breed compressibility, etc.);
Properties of break and proppant fluid. The main sources of information are geological, geophysical and petrophysical studies, laboratory analysis of core, as well as the results of the commercial experiment, which consists in carrying out micro and mini-hydraulic persons.
In recent years, the technology of an integrated approach to the design of hydraulic fracturing is developed, which is based on many factors, such as the conductivity of the reservoir, the system for the placement of wells, the mechanics of the crack, the characteristics of the break and proppant fluid, technological and economic restrictions. In general, the water optimization procedure should include the following elements:
The calculation of the amount of break and proppant fluid necessary to create the crack of the required size and conductivity;
Technique to determine the optimal parameters of the discharge, taking into account the characteristics of proppant and technological restrictions;
A complex algorithm that allows you to optimize the geometric parameters and the conductivity of the crack, taking into account the productivity of the reservoir and the system for the placement of wells, ensuring the balance between the filtering characteristics of the formation and cracks, and based on the criteria for maximizing profits from the processing of the well.
The creation of optimal GPT technology implies compliance with the following criteria:
Ensuring optimizing the reserves of the deposit;
Maximization of the proppant penetration depth in a crack:
Optimization of the discharge parameters of the break and proppant fluid;
Minimization of the cost of processing;
Maximizing profits by receiving additional oil and gas. In accordance with these criteria, the following stages of optimization of the hydraulic fracturing on the facility can be distinguished:
1. Selection of wells for processing, taking into account the existing or projected development system, providing maximization oil production and gas When minimizing costs.
2. Determination of the optimal geometry of the crack - length and conductivity, taking into account the permeability of the formation, the wells arrangement system, well remoteness from gas- or water impact contact.
3. Selecting a crack propagation model based on the analysis of the mechanical properties of rock, voltage distribution in the formation and preliminary experiments.
4. Selection of proppant with appropriate strength properties, calculation of the volume and concentration of proppant necessary to obtain a crack with specified properties.
5. Selection of a break fluid with suitable rheological properties, taking into account the characteristics of the formation, proppant and geometry of the crack.
6. Calculation of the required amount of break fluid and determining the optimal parameters of injection, taking into account the characteristics of the fluid and proppant, as well as technological restrictions.
7. Calculation of the economic efficiency of the PRT.
Joint efforts of the American gas Research Institute (GRI) and the largest petroleum and gas US companies (Mobil Oil Co., Amoco Production Co., Schiumberger, etc.) developed a new technological complex, which includes mobile equipment GRI for testing and controlling the quality of the SGP operation, the GRI unit for the study of rheology, a three-dimensional computer program for "design" FRACPRO cracks, devices for determining the stress profile in the reservoir and microseismic techniques for determining the height and azimuth of the crack.
The use of a new technology allows you to choose a break fluid and proppant, the most corresponding to specific conditions, and control the distribution and disclosure of the crack, the transportation of the proppant in suspension along the entire crack, the successful completion of the operation. Knowledge of the stress profile in the formation allows not only to determine the pressure of the hydraulic, but also to predict the geometry of the crack. With a high difference in voltages in the collector and in impermeable barriers, the crack applies to a large length and less height than in the layer with a minor difference of these stresses. Accounting for all information in the three-dimensional model allows you to quickly and reliably predict geometry and filtration characteristics of the crack. Approbation of new hydraulic technology in six gas US deposits (in PcShas, Wyoming and Colorado) showed its high efficiency for low-permeable collectors.
In some cases, the hydraulic gap occurs at significantly lower pressures than the initial stresses in the formation. The cooler of the formation as a result of injection into the discharge wells of cold water, significantly different from the temperature from the plastic, leads to a decrease in elastic stresses and hydraulic discontinuities in discharge wells during bottomholes used in the factory. Studies conducted at the Pradho Bay (USA) field showed that shells of cracks that appeared in this way fluctuates within 6 ... 60 m. Currently, it is generally recognized that in injection wells with a large contrast for the temperature of the formation and injected water occurs. Hydraulic gap.
When carrying out a hydraulic fracturing in inclined wells, the direction of which deviates from the rupture plane, problems arise related to the formation of several cracks from different perforation intervals and with the curvature of the crack near the well. To create a single flat crack in such wells, a special technology is used based on the restriction of the number of perforations, determining their size, quantity and orientation relative to the directions of the main stresses in the formation.
In recent years, technologies for the use of hydraulic fracturing in horizontal wells are being developed. The orientation of the crack in relation to the axis of the well is determined by the direction of the horizontal trunk with respect to the azimuth of the minimum main voltage in the formation. If the horizontal barrel is parallel with the direction of the minimum main voltage, then the transverse cracks are formed during the hydraulic. Developed technologies for creating several cracks in one horizontal well. In this case, the number of cracks is determined taking into account technological and economic constraints and is usually 3 .-. 4.
The first commercial experiment on the creation of several cracks in the inclined well was carried out by Mobil in the 60s. Hydraulic B. petroleum Horizontal wells were carried out at the fields in the Danish part of the North Sea. On the gas The field in the North Sea (Netherlands) in the layer with permeability of 1-10 -3 μm 2 in the horizontal well created two transverse cracks.
The largest project is implemented on gas The Zolingen field in the North Sea (Germany), characterized by ultra-low permeability (10-6... 10-4 μm2), the average porosity of 10 ... 12% and the average thickness of the layer is about 100 m. In a horizontal barrel with a length of 600 m, four The transverse cracks, the poludin of each of which is about 100 m. The peak flow rate of the well was 700 thousand m 3 / day, the well is currently working with an average flow rate of 500 thousand m 3 / day.
If the horizontal portion of the well is parallel with the direction of the maximum horizontal voltage, the hydraulic crack will be longitudented with respect to the axis of the well. The longitudinal crack can not give a significant increase in the flow rate of the horizontal well, but the horizontal well with a longitudinal crack itself can be considered as a crack of very high conductivity. Considering that the conduct of conductivity is the determining factor in increasing the flow rate with cracks in the middle and high-phase reservoirs, when developing such reservoirs, it is possible to use hydraulic fracturing in horizontal wells to form longitudinal cracks. Experienced work to determine the efficiency of longitudinal cracks, conducted at the Kuparoquar River (Alaska) field in four horizontal wells, showed that productivity increased by an average of 71%, and costs of 37%. In all cases, the choice between the design of vertical wells with hydraulic fractures, horizontal wells or horizontal wells with hydraulic fracturing is carried out on the basis of assessing the economic efficiency of this or that technology.
The pulse hydraulic technology allows you to create a somewhat radially divergent cracks in the well, which can be effectively used to overcome the skin effect in the bottom-up zone, especially in medium and high-permeable plants.
Hydrogenation of medium and high-permeable formations is one of the most intensively developing wells currently developing wells. In high-permeable formations, the main factor in the increase in the flow rate due to hydraulic fracturing is a crack width, unlike low-permeable formation, where such a factor is its length. To create short wide cracks used
the proppant precipitation technology at the end of the crack (TSO-TIP Screen Out), which consists in jelting the proppant primarily by the end of the crack by gradually increase its concentration in the working fluid during processing. The precipitation of proppant at the end of the crack prevents its growth in length. A further injection of a propapant carrier liquid leads to an increase in crack width, which reaches 2.5 cm, whereas with the usual GPP, the crack width is 2 ... 3 mm. As a result, the effective conductivity of the crack (the product of permeability and width) is 300 ... 3000 μm 2m. To prevent the removal of proppant during the subsequent operating The wells TSO technology is usually combined either using a pitted proppant, which is collapsing and has resistance to viscous friction during miningOr with gravel package, when proppant is kept in a crack using a filter (FRAC and-Pack). The same technology is used to prevent the crack germination to oil Contact. TSO technology is successfully applied at the Pradho Bay (USA) field, in the Gulf of Mexico, Indonesia, the North Sea.
Creating short wide cracks in wells that reveal medium and high-permeable layers gives good results with a significant deterioration in collector properties in the bottomhole zone as a means of increasing the efficient well radius; in multidimensional sand collectors, where the vertical crack ensures the continuous connection of thin sandy splay with the perforation zone; in collectors with migration of the smallest particles, where, by reducing the flow rate near the wellbore, sand is prevented; in gas Formation to reduce negative effects associated with flow turbulization near the well. To date, more than 1 million successful hydraulic hydraulic hydraulic hydraulic hydraulic hydraulic fracturing was carried out in the United States; more than 40% of the wells foundation were processed, resulting in 30% of reserves oil and gas Translated from off-balanced to industrial. In North America increase oil production As a result, the use of hydraulic fracturing was about 1.5 billion m 3.
In the late 70s, the creation of new solid synthetic proppants began the rise in the field of hydroelectric fracture on gas and petroleum Deposses of Western Europe, timed to busy sandstones and limestone, located at large depths. By the first half of the 80s, the second peak period is confined in carrying out the operations of the hydraulic fracture in the world, when the number of treatments per month reached 4800 and was directed mainly to dense gas Collectors. In Europe, the main regions where massive hydraulic hydraulic hydraulic hydroelectric power gries are focused on the fields of Germany, the Netherlands and the United Kingdom in the North Sea, and on the coast of Germany, the Netherlands and Yugoslavia. Local hydraulic is also carried out on Norwegian fields of the North Sea, in France, Italy, Austria and in Eastern Europe.
The largest work on the conduct of massive hydraulic power gries were taken in Germany in gas-bearing The layers located at a depth of 3000 ... 6000 m at a temperature of 120 ... 180 ° C. Mortar and high-strength artificial were used mainly here in the period 1976-1985. In Germany, several dozen massacked hydraulic fracturing was carried out. The proppant consumption was in most cases about 100 in third cases - 200 T / SLE., And when carrying out the largest operations, it reached 400 ... 650 T / SLE. The length of cracks varied from 100 to 550 m, the height from 10 to 115 m. In most cases, the operations were successful and led to an increase in the flow rate of 3 ... 10 times. Failures during individual hydraulic fracturing were associated mainly with a high water content in the reservoir.
Fastening cracks hydraulic in oil-containing films, unlike gas-containingIt was carried out mainly using sand, since the depth of these reservoirs is only 700 ... 2500 m, only in some cases medium proppants were used. On the petroleum Fields of Germany and the Netherlands, the proppant consumption was 20 ... 70 t / SLE., And in the Vienna Austria, the optimal proppant consumption was only 6 ... 12 T / SLE. Successfully processed both old and new mining wells with good insulation of adjacent intervals.
Gas The UK deposits in the North Sea provide about 90% of the country's demand in gaza and retain the dominant role in gas supply until the end of the century. Proppant consumption at GPP gas-bearing Sandstones located at the depths of 2700.-. 3000 m, was 100 ... 250 T / SLE. . Moreover, first, the cracks were fixed either by sand or medium or high-strength synthetic proppant, then from the beginning of the 80s, the technology of serial injection into the crack of proppants differing in both fractional composition and other properties was distributed. According to this technology, 100 ... 200 tons of sand with a 20/40 mesh grain size, then 25 ... 75 tons of medium propulsion proppant with grain-size 20/40 or 16/20, was first injected. In some cases, a threefractionial method was successfully used with a sequential injection of proppants 20/40, 16/20 and 12/20 or 40/60, 20/40 and 12/20.
The most common variant of the two-forming hydraulic dispenser was in the injection of the main volume of sand or the medium propulsion proppant of type 20/40 followed by the injection of medium-sized or high-strength proppant type 16/20 or 12/20 in the amount of 10 ... 40% of the total volume. There are various modifications of this technology, in particular, good results gives an initial injection into the fracture of fine-grained sand type 40/70 or even 100 mesh, then the main amount of sand or proppant type 20/40, and the termination of the crack is a solid coarse-grained proppant 16/20 or 12 / twenty. The advantages of this technology are as follows:
Fastening the crack with high-strength proppant in the vicinity of the well, where the compression voltage is highest;
Reducing the cost of the operation, since ceramic proppants in 2 ... 4 times more expensive sand;
The creation of the greatest conductivity of the crack in the neighborhood of the slaughter, where the filtration rate of the fluid is maximum;
Preventing the removal of the proppant in the well, provided by a special selection of the difference in grains of the main and terminating the crack of proppants, in which smaller grains are delayed on the border between proppants;
Blocking by fine-grained sands of natural microcracks that are branched off from the main, as well as the end of the crack in the formation, which reduces the loss of the break fluid and improves the conductivity of the crack.
Propapants injected into different crack areas may differ not only by fractional composition, but also by density. In Yugoslavia, the technology of massive hydraulic hydraulic fracturing was found when a light medium proppant is injected first in a crack, and then a heavy better high-speed proppant.
Light proppant longer maintained in suspension in the transporting liquid, therefore it can be delivered to a longer distance along the wings of the crack. The injection of a heavier high-quality proppant in the final phase of a hydraulic grinding step allows on the one hand to provide compression resistance in the highest voltage area near the slaughter, and on the other hand, to reduce the risk of operation in the final stage, as the light propitual pant is already delivered to the crack. Macesed hydroelectric power gries, held in Yugoslavia,. They are among the largest in Europe, since 100 ... 200 tons of light proppant were injured in the first stage in the crack, and on the second - about 200 ... 450 tons are heavier. Thus, the total amount of proppant was 300 ... 650 tons.
As a result oil The crisis of 1986, the volume of work on the fees was significantly reduced, but after stabilization of prices for oil In 1987 - 1990 An increasing number of deposits is planned for carrying out the reservoir, while high attention began to optimize the technologies of the hydraulic fracture, the effective selection of crack parameters and proppant. The highest activity for conducting and planning hydroelectric fractures in Western Europe is celebrated in the North Sea on gas deposits in the British sector and in non-tent-carrying chalk sediments in the Norwegian sector.
The significance of the technology of hydraulic fracturing for the fields of Western Europe is proved by the fact that prey Third stock gas Here it is possible and economically justified only with the hydraulic place of the formation. For comparison - in the USA 30 ... 35% of hydrocarbon reserves can be extracted only with the use of hydroelectric power gries.
The specificity of the development of marine deposits determines the higher cost of operations to stimulate wells, therefore, to ensure higher reliability in 1989-1990. It was decided to complete the use of sand use as a split material on British fields in the North Sea. Especially durable and widely used sand as a proprietary material in Yugoslavia, Turkey, Eastern Europe and the USSR, where there was one equipment For the hydraulic power plant, there was no sufficient capacity for the production of expensive synthetic proppants. So, in Yugoslavia and Turkey, the medium-step proppant was used only for completing the crack, and the main volume was filled with sand. However, in recent years, in connection with the creation of joint ventures, expanding the sale of proppants by Western manufacturers, direct consumers, the development of their own production, the situation changes. In China, hydraulic PPPs are carried out with injection of the bauxite proppant of its own production in volume up to 120 tons. It is shown that even the low concentration of bauxite provides better conductivity of cracks than the higher sand concentration. There are extensive prospects for the use of hydraulic power plants in the fields of North Africa, India, Pakistan, Brazil, Argentina, Venezuela, Peru. At the deposits of the Middle East and Venezuela, dedicated to carbonate collectors, the main technology should become an acid hydroelectric power grump. It should be noted that in most countries of the third world, natural sand is used as a precipulating material, the use of synthetic proppants is envisaged only in Algeria and in Brazil.
In domestic oil production The hydraulic fracturing began to apply from 1952 the total number of hydraulic fracturing in the USSR in the peak period 1958-1962. Exposed 1500 operations per year, and in 1959 reached 3000 operations that had high technical and economic indicators. By the same time, theoretical and fishery and experimental studies on the study of the mechanism of hydraulic and its influence on the flow of wells are related. In the subsequent period, the number of hydraulic power gries decreased and stabilized at about 100 operations per year. The main CPU centers were focused on the fields of the Krasnodar Territory, the Volga-Ural region, Tataria (Romashkin and Tuymazine fields), Bashkiria, Kuibyshev Region, Chechen-Ingushetia, Turkmenistan, Azerbaijan, Dagestan, Ukraine and Siberia.
Hydrogen was carried out mainly to master the discharge wells in the introduction of intra-circuits and in some cases petroleum wells. In addition, the hydraulic break method was used to isolate the tributaries of the flooded water in wells with monolithic formations; In this case, the horizontal fracture of the hydraulic crash, created in a predetermined interval, was used as a waterproofing screen. The massive hydraulic survey in the USSR was not carried out. With the equipment of fishery, more powerful water injection equipment, the need for a wide range of hydraulic fractures in the injection wells disappeared, and after entering into the development of large high-tech deposits of Western Siberia, the interest in the hydraulic fracturing in the industry has practically disappeared. As a result, from the beginning of the 70s to the end of the 80s in the domestic oil production The hydraulic size on an industrial scale was not applied.
The revival of the domestic hydraulic fracturing began in the late 1980s due to a significant change in stock structure oil and gas .
Until recently, only natural sand was used as proppant in Russia in the amount of up to 130 t / SKV "And in most cases, 20 ... 50 t / SK was injured. Due to the relatively small depth of the occurrence of the processed formations, there was no need to apply synthetic high-quality proppants. Until the end of the 80s, during the conduct of a hydraulic system, it was used mainly domestic or Romanian equipmentIn some cases - American.
There are now broad potential opportunities for the implementation of large-scale operations for the implementation of low-permeable hydraulic gas-bearing Floors at the fields of Siberia (depth - 2000 ... 4000 m), Stavropol (2000 ... 3000 m) and Krasnodar (3000 ... 4000 m) edges. Saratov (2000 m). Orenburg (3000 ... 4000 m) and Astrakhan (Karachaganak deposit (4000 ... 5000 m)) regions.
IN oil production Russia pays great attention to the prospects for the use of the PGP method. This is primarily due to the growth trend in stock structure oil Shares in low-permeable collectors. More than 40% of the reserves of the industry is in collectors with permeability of less than 5-10-2 μm2, of which about 80% of which is Western Siberia. By 2000, the growth of such stocks in the industry is expected to 70%. Intensification of the development of low productive deposits oil It can be carried out in two ways - a seal of well grid requiring a significant increase in capital investments and increasing costs oilor an increase in the flow rate of each well, i.e. intensification of use as stocks oilAnd wells themselves.
World experience oil production It shows that one of the effective methods of intensifying the development of low-permeable collectors is the hydraulic method. High-conducting fractures of the hydraulic dispenser allow to increase well productivity in 2 ... 3 times, and the use of hydraulic fracturing system as an element of the development system, i.e., the creation of a hydrodynamic system of wells with fractures of the hydraulic, gives an increase in the pace of recovery reserves, raising nefteverters Due to the involvement in the active development of weakly registered zones and propellars and increase the coverage of the factory, and also allows you to enter into the development of deposits with a potential flow rate of 2 ... 3 times lower than the level of profitable mining, therefore, translate part of the off-balanced reserves in "industrial. Increased wells after a hydraulic fracture is determined by the ratio of the reservoir and cracks and the dimensions of the latter, and the well productivity coefficient does not increase indefinitely with increasing crack length, there is a limit length of length, excess of which practically does not lead to The growth of the flow rate of the fluid. For example, when the layer permeability is about 10-2 μm2, the extreme half is approximately 50 m. Considering the increase in wells of wells as a result of the creation of fractures of the hydraulic, when designing a development using a hydraulic fracture, a rare well grid can be planned.
For the period 1988-1995 In Western Siberia, more than 1600 hydraulic operations were conducted. The total number of development objects covered by GPA exceeded 70. For a number of GDP objects, it became an integral part of the development and is carried out at 50 ... 80% of the fond of mining wells. Thanks to the hydraulic fracturing in many places, it was possible to achieve a profitable level of rebate oil. The increase in flow rates was an average of 3.5 when hesitation on various objects from 1 to 15. The success of the FLP exceeds 90%. The overwhelming number of well-operations was carried out by specialized joint ventures on foreign technologies and in overseas equipment. Currently, the volume of hydraulic fracturing in Western Siberia has reached a level of 500 well-operations per year. The share of hydraulic fracturing in low-permeable collectors (Jurassic sediments, Achimov-Skye package) is 53% of all operations.
Over the years have accumulated certain experience in conducting and evaluating the effectiveness of hydraulic fracturing in various geological and physical conditions. The extensive experience of the reservoir was accumulated in JSC "Yuganskneftegaz". Analysis of the effectiveness of more than 700 hydraulic fracturing conducted by the SP "Yuganskfrakmaster" in 1989-1994. On 22 layers 17 deposits JSC "Yuganskneftegaz" showed the following.
The main objects of the use of hydraulic techniques were deposited with low-permeable collectors: 77% of all treatments were carried out on objects with layers permeability less than 5-10-2 μm2 of which 51% of them are 10-2 μm2 and 45% - less than 5-10 μm2.
First of all, the hydraulic fracturing was carried out on a low-efficient well foundation: on inactive wells - 24% of the total work, on low-riveted wells with a fluid flow rate of less than 5 tons - 38% and less than 10 tons / day - 75%. On anhydrous and low-water (less than 5%), the wells foundation accounts for 76% of all GPAs. On average, for the period of generalization for all treatments as a result of hydraulic fracturing, the flow rate of the fluid was increased from 8.3 to 31.4 tons / day, and oil - from 7.2 to 25.3 t / sut, i.e. 3.5 times with an increase in flooding by 6.2%. As a result, additional oil mining Due to the PSA, about 6 million tons were about 6 million tons for 5 years. The most successful results were obtained during hydraulic fracturing in neturfaces with large neftensaturated The thickness (Achimov pack and layers of the B1 of the Prirazlogo field), where the flow rate of the fluid increased from 3.5 ... 6.7 to 34 tons / day with an increase in the waterticity of only 5 ... 6%.
The experience of the hydroxidation of intermittent reservoirs represented mainly by individual lenses of the collector, was obtained in the LUKOIL-Kogalymneftegaz TPP in the Misthima deposit. The intermittent zone pads are opened by two adjacent wells at an average distance of 500 m only in 24% of cases. The main task of regulating the diabetic field development system is the involvement of the intermittent zone of the reservoir 1 and accelerates the pace of reserves. For this purpose, at the deposit in 1992-1994. Performed by the joint venture "Katkoneft" 154 GPA. The success of the treatments was 98%. At the same time, on the processed wells, a fivefold increase in the flow rate was obtained on average. Volume additionally mined oil amounted to 1.6 million tons. The expected average duration of the technological effect is 2.5 years. At the same time additional prey Due to the PSA, one well should be 16 thousand tons. According to SiblingInp, by the beginning of 1997, 422 SGP operations were already on the field, the success of which was 96%, the volume was further mined oil - 4.8 million tons, the average increase in flow rate - 6.5 times. The average ratio of the flow rate of fluid after a hydraulic fluid relative to the maximum flow rate reached before the hydraulic and characterizing the potential well capabilities was 3.1.
At the TPP deposits "LUKOIL-LANGEPASNEFTEGAZ" during 1994-1996. 316 hydraulic operations of the hydraulic operations were conducted, in 1997 - inventory 202 hydraulic. Processing is carried out by their own forces and JV Katkoneft. Additional oil mining Amounted about 1.6 million tons, the average increase in the flow rate of -7.7 t / day on the well.
In 1993, industrial work began on the field of hydraulic fracturing on the fields of OJSC Novyabskneftegaz, during the year 36 operations were conducted. The total production of hydraulic fracturing by the end of 1997 amounted to 436 operations. The hydraulic fracture was usually carried out in low-riveted well-water wells located on areas with degraded filtration and capacitive properties. After GRP Debit oil increased by an average of 7.7 times, liquid - 10 times. As a result of the hydraulic fracturing in 70.4% of cases, the waterproof increased by an average of 2% to the GPP to 25% after treatment. The success of the treatments is high enough and average is 87%. Additional oil mining From the production of hydraulic fracturing at Novyabskneftegaz, by the end of 1997 exceeded 1 million tons. The company Dowell Schiumberger is one of the world's leading intensification of wells. Therefore, great interest is its work on hydraulic fracturing on Russian deposits. This company has prepared a draft of the first Soviet-Canadian experiment on the conduct of massive hydraulic hydraulic fracturing at the Saliam deposit. For example, on one of the wells in a layer with permeability of 10 ^ μm ^ was designed a fury to half 120 m at a complete height of 36.6 m. After the summer in 1988, a hydraulic fusion in the Bazhenovskaya retinue began to focate with a flow rate of 33 m / day 17 days dropped to 18 m ^ / day. Before GRP, the influx was "undeveloping", i.e. The level of fluid in the well did not rise to her mouth.
In 1994, Dowell Schiumberger held several dozen hydraulic fracturing on Novo Purpean, Tarasovsky and Harampursk deposits of Purneftegaz JSC. In the period until 01.10.95, 120 hydraulic persons were held at the Purneftegaz fields. The average daily flow rate of the processed wells was 25.6 tons / day. Since the beginning of the introduction of hydraulic fracturing, 222.7 thousand tons were produced oil. Data on recesses of wells in approximately a year after the SGP: in the second half of 1994, 17 operations were conducted at the Purneftegaz fields; Middle Boat oil Before the GRP was 3.8 t / sut, and in September 1995. -31.3 T / day. According to some wells, a decrease in watering is noted. The introduction of GPU made it possible to stabilize the falling oil production on NGDU "Tarasovskneft".
Analysis of the results of the introduction of hydraulic fracturing in the deposits of Western Siberia shows that this method is usually used in single selected mining wells. The generally accepted approach to the evaluation of the efficiency of the hydraulic is to analyze the speakers oil production Only processed wells. At the same time, the bases are accepted for the PRP, and the additional prey calculated as the difference between the actual and basic production For this well. When making a decision on the conduct of hydraulic fracturing in the well, the effectiveness of this event is often not considered, taking into account the entire formation system and the alignment of mining and discharge wells. Apparently, the negative consequences of the use of hydraulic fracturing, noted by some authors, are associated with this. So, for example, according to the estimates, the use of this method in some sections of the Mamontovsky field caused a decrease nefteverters Due to the more intense growth in the distribution of some of the processed and especially surrounding wells. The analysis of the technology of hydraulic in the fields of OJSC Surgutneftegaz showed that often failures are associated with an irrational choice of processing parameters, when the pumping rate and volumes of technological fluids and proppant are determined without taking into account factors such as the optimal length and width of the fixed crack calculated for these conditions; The pressure of the rupture of clay screens separating the productive reservoir from the above and underlying gas- and water-saturated formation. As a result, potential GPP capabilities are reduced as a means of increasing mining, increase the waterproof production.
Experience of the acid hydraulic break layer is available on Astrakhan gas condensate The field, the productive deposits of which are characterized by the presence of dense porous fractured limestones with low permeability (0.1 ... 5.0) and porosity 7 ... 14. UGP use is complicated by large depths operational Wells (4100 m) and high bottomhole temperatures (110 ° C). In the process operating Wells occurred the formation of local depression funnels and reducing the reservoir pressure in some cases to 55 MPa from the initial 61 MPa. The consequence of these phenomena can be a condensate loss in the bottomhole zone, incomplete removal of fluid from wellbores, and the like. To improve the filtering characteristics of the bottomhole zone of low-code wells, massaged acidic treatments with injection parameters close to hydroelectric power plants are periodically carried out. Such operations make it possible to reduce work depression by 25 ... 50% of the initial, slow down the growth rate of depression funnels and the rate of decrease in the mouth and bottomhole pressure.
The hydraulic rupture of the formation on the Astrakhan field is carried out using a special equipment Frakmaster firms. Technology of work, as a rule, was as follows. Originally determined the method of well injection of methanol or condensate. Then, with the aim of aligning the pickup profile and creating conditions for processing with acidic composition of less permeable areas and connecting to the operation of the reservoir throughout its thickness, the gel was injected. A mixture of hydrochloric acid with methanol or hydrophobic acid emulsion ("hydrochloric acid in a hydrocarbon medium" was used as an active reactive fluid reactive liquid. When conducting an interval hydraulic hydraulic hydraulic hydraulic hydroelectric pump, collectation of high-pressure zones or perforation channels was carried out either by gel or with a diameter with a diameter of 22.5 mm together with gel. The PPP moment was recorded on an indicator chart on a sharp increase and the subsequent drop in pressure with simultaneous growth of pickup. It is possible that already existing cracks have revealed on some wells, since the fact of the hydraulic diagram has not been noted, and the pressure corresponded to the gradient of the crack disclosure pressure gradient. Practice of hydraulic fracturing on Astrakhan gas condensate The field showed its high efficiency, provided that the wells and technological processing parameters are correct. A significant increase in the flow rate was obtained even in cases where several acid treatments were carried out on the well to hydraulic, the latter were unsuccessful.
The highest efficiency of the hydraulic fracturing can be achieved when designing its application as an element of a system of development, taking into account the system for placing wells and an assessment of their mutual influence in various combinations of processing mining and discharge wells. The effect of the hydraulic hydraulic fracturing is manifested in the work of individual wells, so it is necessary to consider not only the increase in the flow rate of each well due to the hydraulic displeasure, but also the effect of the mutual location of the wells, the specific distribution of the inhomogeneity of the reservoir, the energy capabilities of the object, etc. This analysis is possible only on the basis of three-dimensional mathematical modeling. The process of developing a section of a formation or an object as a whole using an adequate geological-fishing model that detects the features of the geological heterogeneity of the object. With the help of a computer model of the development process using a hydraulic fracture, it is possible to estimate the feasibility of the hydraulic fracturing in injection wells, the effect of hydraulic oil and Ottoman and the rate of development of the object of development, identify the need for repeated processes, etc. In the industrial implementation of the hydraulic implementation of the hydraulic implementation, it is necessary to prepare a project document in which the GPA technology would be justified, linked to the development system of the deposit as a whole. When carrying out a hydraulic system, it is necessary to provide a complex of commercial research on the priority wells to determine the location, direction and conductivity of the crack, which will allow adjustment to the GPP technology taking into account the characteristics of each specific object. A systematic author's supervision is needed for the introduction of hydraulic fracturing, which will allow to take operational measures to increase its effectiveness.
The factors defining the success of the hydraulic fracturing are the correct selection of the object for conducting operations, the use of hydraulic technology, optimal for these conditions, and competent selection of wells for processing.
Basic concepts about the method of hydraulic layer break
Definition. A hydraulic rupture is called a process in which the fluid pressure acts directly on the formation of the formation up to its destruction and the occurrence of the crack. The continuing effect of fluid pressure is expanding the crack deep from the break point. In the injected liquid, the split material is added, for example, sand, ceramic balls or agglomerated bauxite. The purpose of this material is to keep the created crack in the disclosed state after resetting the fluid pressure. This creates a new, more spacious dwarf channel. The channel combines existing natural cracks and creates an additional area of \u200b\u200bthe drainage of the well. The fluid transmitting pressure on the formation breed is called a break fluid.
Tasks solved with hydraulic
In the hydraulic break, the following tasks must be solved:
A) Creating a Crack
B) holding cracks in uncovered condition
C) removal of break fluid
D) raising reservoir productivity
Creating a crack
The crack is created by downloading the liquids of the suitable composition into the reservoir at the speed of its absorption by the reservoir. The fluid pressure increases until the internal stresses in the breed are surpassed. A crack is formed in the breed.
Crack hold in uncovered condition
As soon as the development of the crack began, the crushing material is added to the liquid - proppant (usually sand), carried by a liquid into a crack. After the process of hydraulic and pressure relief, proppant holds the crack open and, therefore, permeable for reservoir liquids.
Removal of fluid break
Before you start production From the well, you should remove the break fluid. The degree of complexity of its removal depends on the nature of the fluid used, the pressure in the reservoir and the relative permeability of the layer on the break fluid. The removal of the break fluid is very important, since, lowering relative permeability, it can create obstacles on the path of fluid inflows.
Enhance the productivity of the formation
Prior to the design of the process, it is necessary to analyze its economic feasibility.
Purpose of hydraulic rupture
Holding the hydraulic persecution has two main goals:
one). Increase the productivity of the reservoir by increasing the efficient radius of the drainage of the well. In the formation with relatively low permeability, the hydraulic is the best way to increase productivity.
2). Create a channel of the inflow in the attractive zone of disturbed permeability.
Disruption of the permeability of the productive reservoir is an important concept for understanding, since the type and scale of the rupture process is designed to correct this violation. If it is possible to create a crack passing through a zone, filled with proppant, and lead the pressure drop to the normal size of the hydrodynamic pressure gradient, then the well productivity will increase.
Disrupting the permeability of the productive reservoir. Usually, the violation of the permeability of the productive reservoir is identified with the "skin damage", then - there is a violation of the permeability of the bottomhole zone. However, this value can not always be determined through measurements or calculation of the "skin". The skin is usually taken - the factor (the coefficient that determines the degree of violation of the collector properties of the formation) is zero to indicate that there is no violation of the permeability of the layer, but it actually does not mean that there is no damage. For example, acid treatment may penetrate enough into the reservoir on a plot of several meters at the top of the 20-meter perforation interval so that the studies of a positive skin be detected during the studies. However, at the same time, the positive part of the interval can be partially clogged with mechanical impurities or drill solution. Genuine potential productivity of this well may be many times more than its performance when measured by zero skins.
The permeability of the reservoir may be violated as a result of the impact of physical or chemical factors or their joint action: the magnitude of the pore of the solution, changes in the wetting of the formation due to the invasion of water from an extraneous source. An ordinary water barrier caused by excessive absorption of fluid is a kind of permeability impairment. A similar result causes an invasion of plastic water from another zone or from another sector of the collector.
Here are some forms of disruption of the permeability of the formation:
one). Invasion in the formation of particles drill Solid.
2). The invasion of the filtrate reservoir drill Solid.
3). The invasion of the cement filtrate reservoir.
four). The discrepancy of perforations in size, the number and depth of the penetration of the holes.
five). Destruction of perforation and sealing mother breed.
6) Mehpromes in the ending fluid or liquid of stuff penetrating the reservoir or scoring perforation.
7). Invasion in the formation of liquids of finishing or stitching.
eight). Blood clogs with natural clays.
nine). Deposits of asphaltenes or paraffins in a formation or perforation.
10). Salts in plast or perforations.
11). Education or injection of emulsion into the reservoir.
12). Pacing acids or solvents with mehprosies or deposits of mehpromes in the formation.
All this can lead to a decrease in productivity, and in severe cases - to full cessation mining From the well. Some types of stimulation influence can help.
The effect of impaired permeability on well productivity. Most of the types of permeability impairment reduces the initial permeability of the formation. The effect of this decrease in productivity depends on the depth of damage to the zone surrounding the trunk.
If, for example, there is a decrease in permeability by 50% in a layer with a thickness of 5 cm, then this will lead to a decrease in productivity by only 14%. If the decrease in permeability covered the 30-centimeter layer, productivity drops by 40%. The decrease of 75% permeability in the 30-centimeter thicker will lead to a loss of productivity in 64%. Therefore, the well, which should give 100 cubic meters per day, but the permeability of the formation within a radius of 30 cm from the trunk is only 25% of the initial mining, oil will be only 36 m3 / day.
To study the effect of reservoir damage to productivity, the models of the formation can be used (both mathematical and physical laboratory models). It is important to remember that to minimize the depth and severity of the damage to the layer do not need to regret the effort.
Low permeability. Initially, the hydraulic survey was introduced as an economic improvement gas mining From reservoir with relatively low pressure. In low-permeable (up to 10 mD), the formations are created high - permeable channel (100 - 1000 Darcy) of the inflow. These are provided by large areas of drainage, in which a slow feeding of hydrocarbons from a layer with very low permeability is carried out. Thus, all the reservoir energy is used as much as possible. A significant impact on the expected results of hydroprases of various types and sizes has the bearing capacity of the formation fluid.
The direction of the crack crack.
The rupture crack can be oriented in a horizontal or vertical direction. The type of gap that can happen in specific conditions depends on the voltage in the formation. The gap occurs in the direction perpendicular to the smallest voltage.
Vertical gap. Most wells occur vertical gaps. The rupture crack forms two wings oriented at an angle of 180 ° to each other.
Vertical break
Horizontal gap. The horizontal gap occurs in the well, if the horizontal voltage is greater than the vertical voltages.
Horizontal break
Fluid rupture
The most important part of the design of the hydraulic is the selection of fluid break. The following factors should be considered:
Compatible with reservoir and reservoir liquids.
1) impellation of the permeability of the formation
When conducting the hydraulic, the liquid is absorbed in the zone adjacent to the surface of the crack. Because of the increased saturation with the fluid of the invasion zone, the relative permeability of the formation fluid is reduced. If the permeability of the plastic fluid is low, and on the fluid rupture is even lower, it can lead to a complete blocking of the inflow. In addition, the reservoir can be bubbly clays, which swell at contact with the break fluid and reduce permeability.
2) violation of the permeability of sandy traffic jam
The permeability of the sandy tube, as well as the fluid intrusion zones, can be impaired as a result of saturation with liquid. The flow of a crack can also be limited to the presence in the sandy tube of residual after the exposure of mehpromes or polymers.
3) reservoir liquids
Many liquids are prone to the formation of emulsions or to sedimentation. In order to avoid risk, when choosing proper chemical components, laboratory tests should be carried out.
Cost.
The variation in value for various gap fluids is very different. The most cheap water, while methanol and acids are quite expensive. It should also be considered the cost of the gel-forming component. In any case, it is necessary to compare the benefits of formation of the formation with appropriate liquids and chemicals with their cost (Table 11).
Table 11.
Comparative cost of various liquids (US dollars)
|
Name of break fluid |
Cost 1 cubic meters |
Cost 1 cubic meters. gel-forming component |
Cost in sum |
|
Water thickened |
66,00 |
66.00 |
|
|
Polymersion water |
126,00 |
126,00 |
|
|
Thickened reformat |
250,00 |
94,00 |
344,00 |
|
Two-phase fluid |
50,00 |
66,00 |
116,00 |
|
Methanol + CO2. |
350,00 |
150,00 |
500,00 |
|
Polymershidden methanol |
400,00 |
210,00 |
610,00 |
|
Liquid CO2. |
300,00 |
300,00 |
|
|
15% Acid |
380,00 |
200,00 |
580,00 |
|
Acid 28% |
750,00 |
250,00 |
1000,00 |
Types of liquids
Water based liquids. Water based break fluids today in most treatments. Although it was not so in the first years of hydraulic persons when liquids on oil The basis was used in fact on all processings. This type of fluid has a number of vacations over liquid on oil Based.
1. Water based liquids is more economical. Basic component - water is much cheaper than oil, condensate, methanol and acid.
2. Water based liquids give a greater hydrostatic effect than oil, gas and methanol.
3. These fluids are non-flammable; Therefore, they do not explode.
4. Water based water is easily accessible.
5. This type of fluid is easier controlled and thicken.
Linear break fluids. The need to thicken water to help transport the crushing material (proppant), reduce the loss of fluid, and increase the width of the crack was obvious for early chosenses. The first thickener of the water was starch. In the early 1960s, a replacement was found - guar glue is a polymer thickener. It is used in our time. Other linear gels are also used as a break fluid: hydroxypropyl, hydroxyethylcellulose, carboxymethyl, xanthan and in some, rare cases of polyacrylamide.
Connecting break fluids. For the first time were used in the late 1960s, when much attention was paid to hydraulic fracturing. The development of this type of fluid solved many problems that occur when it was necessary to pump linear gels in deep wells with high temperatures. The connecting reaction is such that the molecular weight of the base polymer largely increases the various polymer molecules into the structure together. The first connecting liquid was guar glue. A typical connecting gel at the end of the 1960s consisted of a 9586 g / m3 guar coordinator with borite antimony. The antimony Wednesday was with a relative-visible pH indicator in a break fluid. Boric Wednesday was with a high pH. There were also many other liquids of this type, such as aluminum, on a chromium, copper basis, and manganese. Additionally, in the late 1960s, the beginning of the 1970s began to use a CMC-based (carboxyl methyl cellulose) and some types of hydroxycyluetulose-based compound, although the latter was expensive. With the development of hydroxypropyl guar and carboxymethylhydroxyethyl cellulose polymers, a new generation of coordinates was also developed. The polymer venerer molecules tend to increase the thermal stability of the base polymer. This is theorests that this temperature stability comes from a decrease in the thermal instability of the molecule as a result of its most homogeneous nature and some protectedness from hydrolysis, oxidation or other depolymerization reactions that can happen. The compound polymers, although they increase the apparent viscosity of the fluid to several orders, do not necessarily cause friction at a pressure increasing to some degree during injection operations. These systems have recently been replaced by slowing down disorders.
Slowing consecutive systems. Decent attention of its development in the 1980s, when they were used as a break fluid with a controlled compound time, or a delayed connection reaction. The connection time is defined as the time to ensure the basic fluid to have a homogeneous structure. Obviously, the connection time is the time needed to achieve a very large increase in viscosity and the formation of a homogeneous liquid. A significant amount of research was carried out to understand the importance of using liquid constructive systems. These studies have shown that slowing down the consecutive systems show the best supersaturation of the opposite, they give a greater viscosity, and increase the thermal stability in the fluid. The process of these systems is reduced friction when downloading. As a result of this, slowing downstream systems are used more than ordinary remedy systems. The main advantage of the use of consecutive systems over linear liquids is described below:
1. They can reach the viscosity is much higher when the GEL compared to the gel load.
2. The system is most effective in terms of controlling fluid loss.
3. Content systems have better thermal stability.
4.Ceated systems are more efficient in price for foot polymer.
Liquid on oil Based. The simplest on oil The basis of the gap of the gap is possible today, this is a product of aluminum phosphate reaction and a basic, typical aluminate of soda. This connection reaction that converts the created salt, which gives viscosity in diesel fuels or holds back to a highly gravitational crude system. Aluminum phosphate gel improves more raw oil and increases thermal stability.
Aluminum phosphate can be used to create a fluid with increased stability to high temperatures and good capacity for proppant transport for use in wells with high temperatures: more than 127 ° C. The main disadvantage of the use of liquids on oil the basis is a fire hazard. Also it should be noted that the preparation of liquids on oil Based requires large technical and high-quality control. Preparation of water based liquid significantly facilitates the process.
Liquid on alcohol basis. Methanol and isopropanol were used as components of a water-based liquid and a liquid on an acid-based basis, or, in some cases, like salt liquids, breaking throughout the years. Alcohol, which reduces the surface tension of water, was essential to remove water obstacles. In fluids, the alcohol rupture was widely used as a temperature stabilizer, as it acts as an oxygen holder. Polymers raised the ability to thicken pure methanol and propanol. These polymers including hydroxypropylcellulose and Idroxypropilguar, replaced. Guar resin raises viscosity by 25% higher than methanol and isopropanol, but also gives a precipitate. In the formations that are sensitive to water, hydrocarbonate liquids are more preferable than liquid based liquids.
Emulsion break fluids. This type of break fluid was used for many years even some of the first gap fluids on oil based, were externally petroleum Emulsions. They have many drawbacks and they are used in a very narrow spectrum, because extremely high friction pressure is the result of viscosity inherent in them and due to lack of friction reduction. These gap fluids were invented in the mid-1970s. Cost efficiency oil emulsion implies that oil Can be mined back and sold. These emulsions were very popular when raw oil And condensate cost $ 19 - $ 31 per m3. Use of type emulsions " oil in water "was essentially reduced with increasing prices for oil.
Also in world practice, the following types of gap fluids are known:
Pen-based liquids, gap fluids where nitrogen and carbon dioxide is used gas dissolved in water.
Rheology of liquids
The rheological properties of liquids include properties describing the flow of liquids, absorbing them, carrying the ability, etc. , for example, viscosity. The viscosity of the break fluid into a very large degree affects how the fluid is absorbed by the breed of the formation: the thick liquid is lost less than hopeless. Below is the classification of rupture fluids.
1) Newtonian liquids. In such liquids, a linear relationship between the shear voltage and the shift rate is observed. Examples: Water, unguarded raw oil, Reformed.
2) Nengeton liquids. Bingamas - the simplest species of Nengeton liquids. As in Newtonian liquids, there is a linear relationship between the shear voltage and the shift speed. However, to excite the flow of these liquids, some, not infinitely small shift voltage is required. Example: foam.
Calculation of viscosity in the crack of the rectangular section:
E \u003d P + 5,79x10-3 XQ / HW2 (Sortipauz)
where P-plastic viscosity (centipoise)
Q-consumption when downloading (m3 / min)
H-Height of the Crack (m)
W-width of the crack (mm)
3) liquids submitted by the power law. Such liquids appears "apparent" viscosity, which changes together with a change in flow rate (shift rate). "Apparent" viscosity decreases with increasing shift rate.
4) Supercritical fluids. When using a high CO2 burst liquids (hydroelectric mixture of methanol and CO2, GPP liquid CO2), the gap occurs at a pressure, and often and temperatures that are higher than the critical parameters for CO2. In this range, the density and viscosity increases, the fluid rheology becomes difficult to describe.
Viscosity measurement.
Usually, viscosity measurement is carried out using a rotary viscometer Fan and Funnel Marsh.
Shift rate with standard revolutions of the viscometer (Table 12).
Table 12.
|
Viscometer turnover |
Shift rate |
|
1022 |
Control of liquid filterness
The magnitude of the efficiency of the break fluid shows how the volume of the fluid is stroked with a form with respect to the amount of liquid that creates a crack. For example, if the effectiveness of the liquid is 0.65, this means that 35% of the liquid is lost, and only 65% \u200b\u200bof the fluid form the volume of the break. It can be said simplified that the lower the loss of fluid, the higher its effectiveness. However, it should be remembered that although excessive filtering is undesirable, there will be no use from low absorption, if not adding a sufficient amount of proppant to the liquid for proper cracking. Lower fluid leak will also not give a crack quickly and allow proppant to fall out of a weighted state.
For the quantitative characteristic of fluid loss, the coefficient of filtractivity is used, in which the formation breed, fluid properties and break fluid parameters are taken into account.
The carrying capacity of the liquid on proppanta.
The carrier ability for proppanta is the function of supplying the pump, viscosity, the ending of sand and friction on the surface of the crack crack. During the hydraulic, the proppant acts both vertical and horizontal components of the velocity vector. The horizontal component is usually much more vertical, more thanks to which the proppant moves along with the liquid. As soon as the pump work stops, the proppant will settle until the crack is closer.
Polymerous liquids have a very large viscosity and form with a proppant almost an ideal suspension, which allows you to fill the entire crack volume with the proppant. In lowland systems, for example, in liquid CO2, turbulent thinness is used to obtain suspension particles of proppant.
Friction.
When conducting a hydraulic time to half the power of mechanisms focused on the site, can be spent on overcoming friction in the NKT. Some fluids show more friction strength than others. In addition, friction is higher than less pipe diameter. Accounting for friction of fluid and consumption requirements when designing the hydraulic displeasure is no less important than a pressure limit or compatibility with a formation. Based on information on a large amount of hydraulic, pressure graphics were drawn up, which will help when designing the energy needs of the process.
Safety.
When choosing a break fluid, in addition to the danger of high pressure present at any hydraulic fracturing, the fire hazard and fluid toxicity should also be taken into account.
Removal and determination of the amount of fluid.
Return of well by production After hydraulic, it requires careful planning. If the pressure on the bottom of the well is not enough for the well to start to produce itself, gasify Liquid by creating additional znergia and lowered static pressure. Some gap fluids, like liquid CO2 or foam, are removed very quickly and with the definition of their volume.
Proprietary materials (proppants)
The crushing is performed in order to maintain the permeability created by hydraulic. The crack permeability depends on a number of interrelated factors:
1) type, size and uniformity of proppant;
2) the degree of its destruction or deformation;
3) the quantities and method of moving proppant.
Some of the most common sizes of proppants:
Table 13.
Properties of precipitation agents
1) dimensions and homogeneity
With a decrease in the limit dimensions of the material particles, the load increases, which it can resist, which contributes to the resistance of the permeability to the crack filled with proppant.
At zero stress of closure, the permeability of the ceramic proppant 20/40. One of the reasons for this is more orntered, compared with sand, sphericality of ceramic particles.
A significant content of small particles (dust) in the sand can significantly reduce the permeability of the crack crack. For example, if 20% of particles of the proppant 20/40 passes through Sieve 40, the permeability will decrease 5 times.
The permeability of sand 10/16 is about 50% higher than the permeability of the sand 10 - 20.
American Oil Institute (API RP 56).
2) Strength
With an increase in cracking voltage or horizontal voltage in the skeleton of the formation breed, a significant decrease in the permeability of proppants occurs. As can be seen from the graphs of the long-term permeability of proppants, at a stress of closure of 60 MPa, the permeability of the proppant 20/40 "carboprop" is significantly higher than that of conventional sand. When the closure voltage is higher than that of conventional sand. With a closure voltage of about 32 MPa, the particle size curves for all conventional sands quickly fall. The strength of sandy grains varies depending on the place of origin of the sand and the limit dimensions of the particles.
3) thermochemical stability
All applied proppants should be, if possible, are chemically inert. They must resist aggressive liquids and high temperatures.
4) Cost
The cheapest proppant is sand. High strength proppants, such as agglomerated bauxite or resin-coated sand, are much more expensive. Assessment of their applicability should be done on the basis of an individual economic analysis on this well.
Permeability test.
When choosing the necessary types and sizes of proppant, it is very important to determine its permeability. Before testing proppants, radial filtering cameras were used. However, some fundamental difficulties are related to the currents that are incorruptible Darcy law and very low, not measurable, pressure drops did not allow to obtain reliable test results. The imperfection of radial chambers led to the development of linear filtration cameras.
Long-term permeability.
The fundamental disadvantage of ANI techniques is that it gives results only on short-term permeability. At the fishery it was found that the forecast prey Very rarely corresponded to the actual one. There are many reasons for that, but the main reason was too optimistic data on short-term permeability used in predicting.
Types of proppants.
The first material that was used to hold the crack in the opened state was a silly sand. As technology develops, it became clear that some of the types of sand better than others.
In addition, artificial proppants were created, suitable for use where natural sands are unsuitable.
1) Ceramic proppants
There are two types of ceramic proppants: agglomerated bauxite and proppants of intermediate strength. The permeability of the latter is close to the permeability of the agglomerated bauxite, the density is lower than that of the bauxite, but slightly higher than in the sand.
The agglomerated bauxite is a high-strength proppant, developed by the company "EXson Production Risech". It makes it from high-quality imported bauxite ores. The manufacturing process involves grinding ore into very fine particles, transformation of primary ore into spherical particles of the desired size and firing them into the furnace at a sufficiently high temperature causing the agglomeration process. The final product usually contains 85% Al2O3. The remaining 15% is oxides iron, titanium and silicon. The specific density of its 3.65 compared with the density of the sand is 2.65. Agglomerated bauxites are used mainly in deep (deeper than 3,500 m) wells.
2) Intermediate density ceramics
These proppants differ from agglomerated bauxite, first of all, their composition. The content of aluminum oxide in them is lower, the silicon content is higher, and the specific density is 3.15. At pressures up to 80 MPa in permeability, they are close to agglomerated bauxite. Therefore, in most cases, due to lower cost, they replace bauxites.
3) low density ceramics
These proppants are manufactured in the same way as other ceramics. The main difference is the composition. They contain 49% Al2O3, 45% SiO2, 2% TiO2 and traces of other oxides. The density of these proppants is 2.72, then they are the most common proppants of whitewash their price, density strength close to sand density.
Calculation of the hydraulic rupture
Make a plan for the reservoir of the formation, select the working fluids and evaluate the process indicators for sealing conditions:
Operating Well (Table 14), deposits.
Table 14.
|
INDICATOR |
Designation |
Value |
DIMENSION |
|
Depth of well |
2100 |
||
|
Diameter in lot |
0,25 |
||
|
Remove the thickness of the layer |
13,5 |
||
|
Average permeability |
9,8*10-8 |
||
|
Module of elasticity of breeds |
2*1010 |
PA |
|
|
Poisson's ratio |
0,25 |
||
|
Average density of breeds over the productive horizon |
2385,2 |
kg / m3. |
|
|
Liquid density rupture |
kg / m3. |
||
|
Liquid viscosity break |
Pass |
||
|
Sand concentration |
1200 |
kg / m3. |
|
|
Package pace |
1,2*10-2 |
m3 / S. |
1. Mountain pressure component:
RGV \u003d RGL \u003d 2385.6 * 9.81 * 2100 * 10-6 \u003d 46.75 MPa
2.Gorizontal Mountain Pressure:
RG \u003d RGV * N / (1-N) \u003d 46.75 * 0.25 / (1-0.25) \u003d 15.58 MPa
In such conditions, under the hydraulic fracturing, it is possible to expect the formation of a vertical crack.
We will we project the hydraulic fluid hydraulic. As a fluid of break and fluid, we use a thickened thickened oil With additive asphalt, density and viscosity are given in the table. Sand assignment (cm in Table 4.), We will plan the injection of approximately 5 tons of quartz sand of the fraction of 0.8-1.2 mm, the download pace (data in Table 4.), which is much more than minimally permissible when creating vertical cracks .
Under the hydraulic grinding, the fluid is continuously injected in a volume of 7.6 m3, which is simultaneously a break fluid.
To determine the parameters of cracks, we use formulas arising from the simplified method of Yu.P. Zheltov.
3. Consider pressure on the bottom of the well at the end of the hydraulic:
RZAB / RG * (RZAB / RG-1) 3 \u003d 5,25E2 * Q * m / ((1-N2) 2 * Rg2 * VZh) \u200b\u200b\u003d 5.25 * (2 * 1010) 2 * 12 * 10-3 * 0.2 / (1-0.252) 2 * (15,58 * 106) 3 * 7,6) \u003d 2 * 10-4
RZAB \u003d 49.4 * 106 \u003d 49.4 MPa
4. Determine the length of the crack:
l \u003d (VZE / (5.6 (1-N2) H (RZAB-RG))) 1/2 \u003d (7,6 * 2 * 1010 / (5.6 * (1-0.252) * 13,5 * (49.4 - 15,58) * 106)) 1/2 \u003d 31.7 m
5. Determined width (disclosure) of cracks:
w \u003d 4 (1-N2) * L * (RZAB-RG) / E \u003d 4 * (1-0.252) * 31.7 * (49.4-15,58) * 106/1010 \u003d 0.0158 m \u003d 1.58 cm
6. Determine the spread of a cracking fluid in a crack:
L1 \u003d 0.9 * L \u003d 0.9 * 31.7 \u003d 28.5 m
7. Determined the residual width of the crack, taking the porosity of the sand after its closure M \u003d 0.2:
W1 \u003d WNO / (1-M) \u003d 1.58 * 0,107 / (1-0.3) \u003d 0.73 cm
8. Determined crack permeability of such a width:
KT \u003d W21 / 12 \u003d 0.00732 / 12 \u003d 4.44 * 10-6 m2
The hydraulic silence will be carried out through a NKT with an inner diameter D \u003d 0.076 m, isolating the productive reservoir with a hydraulic anchor.
We define the parameters of the PPE.
1. Frozen pressure on the movement of the nuclear power fluid.
RG \u003d RN (1-NO) + Rps * NO \u003d 930 * (1-0,324) + 2500 * 0,324 \u003d 1439 kg / m3
The number of Reynolds
RE \u003d 4QRI / (Pdmzh) \u003d 4 * 12 * 10-3 * 1439 / (3,14 * 0.062 * 0.56) \u003d 516.9
Coefficient of hydraulic resistance
L \u003d 64 / RE \u003d 64 / 633.7 \u003d 0.124
According to Yu.V. Iztov, if there is sand in the liquid at re\u003e 200, the early turbulization of the flow occurs, and the friction loss at RE \u003d 516.9 and NO \u003d 0.324 increases by 1.52 times:
16Q2L 1.52 * 0,124 * 16 * (12 * 10-3) 2 * 2100 * 1439
RT \u003d 1,52L¾¾¾ RG \u003d ¾¾¾¾¾¾¾¾¾¾¾¾¾¾R \u003d 26 MPa
2P2D5 2 * 3,142 * 0,0765
2. The examination that needs to be created at the mouth at GPP:
Ru \u003d Rzab-Rzhgl + RT \u003d 49.4-1439 * 9,81 * 2100 * 10-6 + 26 \u003d 45.9 MPa
3. The use of hydraulic fluids into the well is pumped with pump units 4in-700 (Table 15.)
14,6
The required number of pumping units:
N \u003d RUQ / (RAQAKTS) +1 \u003d 45.9 * 12 / (29 * 14,6 * 0.8) + 1 \u003d 3
Where the operating pressure of the unit;
QA- supply of the unit at this pressure
kTS - the coefficient of the technical condition of the unit depending on the service life of KTS \u003d 0.5 - 0.8
4. Fluid supplies for sealer-portimizer:
VP \u003d 0.785 * D2L \u003d 0.785 * 0.0762 * 2100 \u003d 9.52 m3
5. Durability hydraulic:
t \u003d (VP + VP) / QA \u003d (7,6 + 6.37) / (14.6 * 10-3 * 60) \u003d 19.5 min.
Technique and technology of hydraulic layer break
GPP technology includes the following operations: Wasp well; descent to a well high-strength NKT with a packer and anchor at the bottom end; strapping and crimping on the determination of the injection of the well injection of fluid; Downloading on the tubing in the reservoir of fluid-break, fluid-sand and sealing fluid; Dismantling equipment And the start of the well to work.
According to technological schemes, the conduct is distinguished by a single, directional (interval) and multiple PPP.
With a single hydraulic pressure under the pressure of the injected liquid, all the reservoirs are opened at the same time, when directed - only the selected reservoir or splay (interval), having, for example, understated productivity, and at repeated hydraulic hydraulic hydraulic hydraulic hydraulic fracturing.
The design of the GPA technology is mainly reduced to the following. With regard to specific conditions, they choose the process diagram of the process, working fluids and the proplisting agent. With a single GDP, based on experience, 5-10 tons of sand take. The concentration of sand in the carrier is determined depending on its holding ability. When using water, it is 40-50kg / m3. Then, by the number and concentration of sand, the amount of fluid-podfoster is calculated. On the basis of experimental data, 5-10m3 leaving fluids are usually used. The volume of the sealing fluid is equal to the volume of the casing and pipes, which are injected into the layer of fluid-sand.
The minimum fluid injection flow should be at least 2 m3 / min and can be estimated during the formation of vertical and horizontal cracks, respectively, according to the formulas:
.
where qgor - min. expenses, l / s; h - the thickness of the layer, see; Wovert, woven - the width of the vert. and mountains. cracks, see; μ - fluid viscosity, MPa x C; RT - radius of horiz. Cracks, see
The pressure of the forage of the reservoir is installed by experience or ouens by the formula:
RGP \u003d PR + SR
where RGRP - Zab. layer break pressure; PR \u003d HRPG - mining pressure; SR - the strength of the breed of the formation on the break in conditions of comprehensive compression; H - the depth of the reservoir; RP is the average density of the overlying rocks equal to 2200-2600 kg / m3, an average of 2300 kg / m3; G - Acceleration of free fall.
Discharge pressure at the mouth of the well:
RU \u003d RGRP + ΔRTr - PC
where Δrtr -Photers of friction pressure in the pipes; PC is the hydrostatic pressure of the fluid column in the well.
If the pressure pressure of the RU is greater than the permissible mouthpiece of the Rudop, then an anchor packer is installed on the roof of the productive reservoir. The permissible pressure of the RUDO is taken as the largest of two pressures calculated by the lame formula and using the Yakovlev-Shumilov formula.
In sedimentary rocks, submerctic cracks are usually formed, the length of which reaches the first tens of meters, and the disclosure is a few mm, less and see the GPP causes an increase in the flow rate of 1.5-2 times or more. To increase the efficiency of hydraulic fracturing in carbonate rocks it is combined with acid treatment of rocks. The discharge pressure is poorly amenable to theoretical prediction, since it depends on many reasons: stresses in the breed, its strength, already existing fracture, the angle of inclination of the formation, etc. Usually, overpressure is selected empirically and ranges from 0.1 to 1.5 (an average of about 0.8) hydrostatic.
For the hydraulic fracturing, the well is appropriately equipped. High-performance pumps can be connected to her mouth, capable of developing the necessary overpressure. Pump-compressor pipes are lowered inside casing pipes, equipped At the bottom of the packer (Fig. 1). The annulpled space of the casing above the grip interval should be securely cemented.
In compliance with all technological requirements and favorable conditions for hydraulic conditions, its effect is undoubted.
Special units and technical means used in GPP
The system of hydraulic is the preparation of appropriate reagents as a liquid of hydraulic and subsequent injection of it into the productive zone with low flow and high pressure in order to separate the rock to form a crack as a result of hydraulic exposure. First of all, pure liquid (buffer) is pumped into the well to initiate cracks and its promotion in the reservoir. After that, the suspension continues to develop the crack.
The preparation of hydraulic hydraulic fracturing is produced on the borehole, immediately before downloading it into the reservoir. The hydraulic preparation system of hydraulic fracturing includes: sandbridge, capacity with oil or diesel fuel, mixing unit (blender). The system's blockage has a 1.5-fold storage margin.
Before the start of the power plant, equipment And the binding is pressed on working pressure. Control directly in PPP (pump units) is carried out through a computer center, which has automatic protection against possible accidents (impulse gusts). In the event of an accident, the computer center automatically turns off the pumps, the check valves of the strapping close the reverse flow of the fluid at the well and before each pumping units. Pressure reset is performed in a vacuum installation included in the kit. equipment SNP and constantly included in the strapping. The same vacuum installation collects the residues of liquid bones in the strapping and pumps after the hydraulic pumps, in order to exclude the straits on the soil when the lines are dismantled. Resetting pressure from the annular space is made in the CA-320 capacitance, constantly connected to the mouth of the well through the crosslinor of the fountain reinforcement.
For the production of hydraulic fracturing, the following technique is used (on the example of the field of deposits in question):
1. KRAZ-250 CA
2. Ural-4320 fire truck
3. Kenword Peskovoz
4. Kenvord Chem.Four.
5. Kenvord Blender
6. Kenvord Pumping
7. Kenvord Cement Aggregate
8. Kenvord-pipes
9. Ford-350 Laboratory
10. UAZ-3962 Sanitary van
11. K-700 Vacuum Installation
Kenwordd technique equipped Special filters catching emissions.
Underground equipmentused for hydraulic fracturing.
The wellness of the well is produced by a special salt solution, which is prepared on a mortar node.
The technology used eliminates the solution to the surface of the soil and the nearest reservoirs. In the preparation of the well to the hydraulic fracture to eliminate possible emissions of the fuel fluid and well products, the mouth is equipped with preventor installations "Nydril".
When preparing for a hydraulic hydroelectric power plant to download the fluid in the well, the column of the tubing with a diameter of 89 mm is descended. The annulus space (casing and tubing 89 mm) is sealed with a packer installed in the GPP area. The packer installation is checked with crimping space with water on the operating pressure of the casing through the Central As-320.
The mouth of the well for carrying out a hydraulic fracturing is equipped with two "Hamera" valves (working and duplicating).
Liquid break and split agents.
For hydraulic, it is best to use a liquid that does not contain the aqueous phase. The technology should use diesel engines, but more often finds oil (as a more affordable and relatively cheap product) with gelation activator and destructor, as well as the paw in the friction. The ratio of special additives depends on the temperature of the object (reservoir) of the subsequent processing. Thus, the ROG-4 system is used for high (more than 80 ° C) temperature conditions, ROG-5, respectively for low. Each of the specified modes of fluid, depending on the temperature of the medium, has optimal rheological properties. A certain permanent system of measuring the parameters of fluid and regulating its values \u200b\u200bwith special additives defined on the basis of computer calculations carried out on the well is used. The structured liquid is optimal for the transfer of the fixing material, and it almost does not interact with the rock and the saturated fluids. The absence in its composition of the aqueous phase eliminates the possibility (when the gel destruction) of the negative effect on the nature of the saturation of the reservoir environment. The physical properties of the fluid are characterized by the following indicators: Density - 0.85 t / m3, viscosity - 90 MPa.s, Consistency coefficient - 0.3. To secure the crack, high-strength is pumped (withstands the pressure of at least 70 MPa) artificial thermal product (propant) of aluminosilicate composition. The material used is almost one size (20/40 mesh), the grains are quite perfect, round, average sphericity coefficient of 0.9. It provides high filtration capacity (about 200 Darcy) even with the most dense packaging and external pressure of 50 MPa.
Criteria for selection of wells for hydraulic fracturing.
For hydraulic fracturing, preference is given to wells that satisfy the following criteria below. The latter in the complex allow you to provide intensification with high probability oil production. Depending on the initial permeability of the formation and the state of the bottomhole zone of the well, the criteria are grouped in two following positions.
1. Low-permeable collectors (GPP provides an increase in the filtering surface), the following criteria must be observed.
1.1. Effective multiple thickness of at least 5 m;
1.2. Lack of wells in wells gas of gas caps, as well as injected or aluminum water;
1.3. Productive reservoir subjected to hydraulic fracturing is separated from other permeable layers with impenetrable sections, more than 8-10m thick;
1.4. The remoteness of the well from GNA and BNC should exceed the distance between the mining wells;
1.5. Accumulated selection oil from the well should not exceed 20% of the specific reserves;
1.6. dismemberment of the productive interval (subjected to hydraulic) - not more than 3-5;
1.7. The well must be technically proper as condition operating The columns and the grip of the cement stone with a column and rock should be satisfactory in the range above and below the filter by 50m
1.8. Fold permeability not more than 0.03 μm2 when viscosity oil In reservoir conditions, no more than 5 MPa.s.
2. Hydraulic reservoir gap in medium and low permeability collectors for intensification oil production Due to the elimination of elevated filtration resistances in the bottomhole zone.
2.1. the initial productivity of the well is significantly lower than the productivity of the surrounding wells;
2.2. the presence of a skin effect on the KVD;
2.3. Water products, wells should not exceed 20%;
2.4. Well productivity should be lower or slightly different from the design and basic.
As follows from the above, the criteria reduced to carry out a versatile preliminary expert assessment of each well with technical, technological and geological and field positions.
With their strict performance with a high probability, the technological success of the FGP operations and the corresponding receipt of additional oil production. The realizable volume of the latter certainly must compensate for the material costs for the CPU.
Technology conducting a hydraulic power plant.
On the example of the deposits of Tomskneft JSC, consider the technology of the hydraulic power plant.
The technology of the process is as follows. Parister is held operating The columns are 15-20 meters above the roof of perforation interval, the packer interval is selected according to the MLM diagram.
The wellness of the well is equipped with au-700 au-700. The burglar space is pressed for a pressure of 15 MPa in order to check the tightness of the packer. In the future, during the process, the pressure on the outer space at the pressure test level in order to reduce the load on rubber cuffs generated by subpaucert pressure during the process.
8 pumping units are used for hydraulic hydraulic units, and 6 of them are occupied on the process, 2 work in idle mode.
The discharge of the emulsion is performed at a discontinuity pressure at the overall productivity of the aggregates of 1.8 m3 / min. A pinning material with a concentration of 150 kg / m3 is supplied to the flow of the injected fluid, which gradually increases and in the last 20 minutes is 500 kg / m3. The sand is pre-roasted in the Pesmark mixers of the USP-50 and is fed to the suction pipe of the 4An-700 Central Asia-320 unit. After the cessation of the sand supply, the sealing fluid is downloaded 20 m3 at a temperature of 2.4 m3 / min.
The valve on the buffer closes after the process, the wellness of the well is equipped with a pressure gauge and the pressure drop curve is removed on it, the interpretation of which allows you to determine the radius of the crack.
Springmers and the AC-820 and An-700 assemblies are used from the technique, which allow you to lift the pressure at the wellhead to 45-60 MPa. However, at pressures of 60 MPa, the AN-700 aggregates were operated on the limit of their capabilities, i.e. With significant depths and a dense productive reservoir, technical limitations occur in pressures, and accordingly the flow rate of the liquid.
Upon reaching the above values, the reservoirs usually occurs. The specified pressure range was predetermined by the difference in lithologic-physical, and mainly the strength characteristics of the formation and stresses in the breed. Therefore, the Cracked Created Cracked are oriented in the vertical direction.
According to domestic technology, a special composite liquid is used to carry out the termination of the fracture of the material, where in ammoniated aqueous solution of calcium nitrate (ArNX), which is 55-65% of the total fluid volume (about 100 m3), 30-43% was added oil and 1.5-3.0% emulsifier. The type of emulsifier used, in turn, depended on the outdoor temperature.
The ARNN polyemulsion is characterized by elevated physical characteristics: density 1.18-1.24 t / m3, viscosity - 120-150 MPa.s, Consistency coefficient - 0.8. Increased viscosity and consistency of the fluid were provided to ensure the transfer of sand used in order to fix the crack, the volume of which is constant and is about 20 tons. The maximum concentration of sand in the liquid reached 500 kg / m3. For better disclosure of cracks and exclusion of sand fallout at the bottom of the well, high pumping speed was required, which was technically feasible at a level only 2.4 m3 / min.
As a propruting agent, imported quartz sand was used.
The use of domestic technology during the hydraulic hydraulic technology did not give satisfactory results, so currently at the Frakmaster Services ICP in the field of hydraulic services, and using more perfect techniques.
Foreign technology for downloading is used special pump equipment: Ejector plunger horizontal pumps Three-cylinder pumps with a replaceable hydraulic part (from 3 "to 71/2,"), which develop pressure up to 100 MPa and consumption 2.5 m3 / min.
Theoretical (confirmed experimental) dependences of the geometric sizes of the crack are established: the length x height (extension area), the width of viscosity, the amount of injected fluid, pressure and injection pace. Their rather complicated relationship is reflected and solved at the computer modeling level both before work on the well and in the process.
The pumps are provided by a high flow rate of fluid flow 5.5 m3 / min and with a relatively small density of the propax (1.6 t / m3) in the process of operation, a sufficiently high (up to 1000 kg / m3) is maintained (up to 1000 kg / m3).
After a certain estimated time, as a transition (under the action of the destructor), from a gel condition in a more movable liquid, the injected fluid post is removed from the crack.
From the foregoing it follows that the used joint ventures "Wah Frakmaster services" and specialized for hydrogenated fracturing fluids, fixing material, as well as techniques and technology in many indicators are beneficial to the domestic. This in the aggregate provides more than the initial and accumulated increase. oil production. The following main factors are seen as preferential:
The absence of a hydraulic phase in the liquid;
High filtering properties of the fixing material provided by the sphericity of grains and homogeneity of the fraction;
Technological and technical ability to carry out hydraulic fracturing with the installed length and width of cracks. It is theoretically established that at low temperaments of injection of hydraulic hydraulic fluid (about 2.5 m3 / min) are formed long (up to 300 m) cracks. For the formation of relatively short and wide cracks, twice the highest pace of injection of fluid is needed. The presence of long cracks, as is known, can contribute to undesirable premature breakthroughs of the injected waters.
In addition to the above, it is also a significant difference in the order of operations when starting the well to work. So, immediately after the hydraulic fracturing on foreign technology, the well is carried out on the expulsion of the various fittings in the increasing sequence of their diameters: 2, 4, 8 mm; This ensures a smooth increase in depression in the bottomhole zone, accompanied by the removal of the hydraulic fluid, strengthening the mountain pressure of the propax in a crack and connecting the development object. As follows from the foregoing, in the entire process of the work of hydraulic fracturing, the aqueous phase is not introduced in the entire process of the hydroelectric zone, which is favored by movement and extracting oil phases.
Another method is carried out hydroelectric technology. Immediately after the hydraulic fracture, the well was joined by salt solutions, followed by a breakdown of the packer and the climb of the NKT. Then goes down the pump equipment And begins exploitation Well. Thus, according to domestic technology, the whole process from the beginning of the hydraulic fracturing to the subsequent start-up of the well to work is almost permanently accompanied by the presence in the bottomhole zone and the fracture of the aqueous phase.
It is well known for a negative impact on the productivity of the federation of wells, and the degree of this effect is proportional to the time of exposure to fluid on the layer zone. In the area under consideration, saline solution is used and, depending on the magnitude of the reservoir pressure in the well area, the density usually fluctuates about 1.18 t / m3 (mineralization - 300 g / l).
In fishing practice, the solution is not properly filtered, therefore, a lot of foreign substances of sandy-clay composition is injected into the well. Their content is so great that it is often the cause of the failure of the pumping equipment. From here it is easy to present the degree of coloring the permeable concerns in the perforation interval, the fracture of the hydraulic and inevitable decline due to this well productivity.
Evaluation of the technological efficiency of the hydraulic effect
In accordance with the currently adopted classification of modern methods of increase nefteverters Fluors hydraulic refers to a group of physical methods.
Technological efficiency of applying increase methods nefteverters Characterized:
Additional oil production Due to the increase nefteverters reservoir;
Current additional oil production due to the intensification of the selection of fluid from the reservoir;
Reduction in the volume of the volume of the water. Additionally mined oil For the set period of time, it is determined by an arithmetic difference between actual wells with hydraulic fracturing and settlement production without a hydraulic power plant (basic prey).
When counting oil production Over the past period, the main task is only in the correct definition of the basic oil production.
One of the methods is the chattering of technological indicators of development, based on physically meaningful mathematical models. In this case, a sufficiently reliable adaptation of the calculated indicators to the actual is possible in the presence of source physical parameters and long history operating. With reliable adaptation, the method allows you to determine changes mining For groups of wells, deposits and especially attractive the possibility of quantitative assessment of interference (interference) wells. The accuracy of the results depends on both the reliability and completeness of the source information and the possibilities of the mathematical model.
With regard to the estimated estimates, then, based on the specific situation, it is necessary to note the following. The wells with hydraulic fracturing dispersed almost throughout the large field. Creating a settlement model of objects Even in separate areas is associated with a huge amount of work and the involvement of powerful computing equipment. In addition, to date on wells there are very scanty geological and physical and geological and fishing information, some of which is subject to change in the process operating Wells, in time. As a result, the adaptation of the estimated model and to obtain reliable forecast technological indicators of development makes it difficult. It seems that the results are most acceptable or suffer from the smallest error for relative estimates of well-influence, i.e. their interference.
In conclusion, it can be noted that the GPU allows you to solve the following tasks:
1) an increase in productivity (pickup) well in the presence of contamination of the bottomhole zone or the small permeability of the collector;
2) expansion of the interval of inflow (absorption) in the multidimensional structure of the object;
3) intensification of the inflow oil, for example, using granular magnesium; insulation of water flow; Regulation of the profile of the pickup, etc.
A group of researchers came to the conclusion that Frequin can affect the low weight of the child born within three kilometers from the zone of its use.
What is Frequin?
If you are aware of the most discussed apocalyptic scenarios, which are based on the anthropogenic factor, then surely you know about the possible depletion of our planet's resources and immersion of mankind in chaos anarchy. Despite the fairly long-term prospects for such developments, the limited resources required for comfortable, and it is really necessary to emphasize this word. However, in addition to a dozen directions for searching for a comprehensive solution to this problem, on the invention of the perpetual motor to the development of resource extraction projects on other planets, there are a couple of simplified solutions: find new sources or pretty shake old.
If the first option, in principle, can be accompanied by the construction of infrastructure around a new object containing minerals, then the second really causes concern. One of the methods that is particularly popular today in the fuel and energy industry is frequin.
Frequin, or a hydraulic rupture of the reservoir implies, as follows from the name, hard, but the most effective (from an economic point of view) the method of development has already exhausted deposits. The basis of Frequining technologies is the use of a whole range of chemical reagents, which, when interacting, cause the formation of high-legisled cracks to roll out the latest oil and gas residues in the hard-to-reach plastics of the Earth.
Data collection
This barbaric technique has already gained bad fame, but the laws of certain countries, including the United States, allow its use. Although individual states are trying to prohibit the application of fakeing on their territory to stop greedy to the company's money, it is required to assemble an indisputable set of evidence of its negative environmental impact and public health.
In particular, the study published in Science Advance contributes to this struggle. The team of researchers from Princeton, Cambridge and other US universities found that Frequing has a direct impact on the health of pregnant women. Their work has shown that children born within three kilometers from the resource mining zone by the method of breaking the layer, 25% are more at risk to be born low weight.
In the course of the study, the recording of the birth of more than 1 million children from 2004 to 2013 was studied. Moreover, the marital status of each mother, its place of residence, race and education was additionally studied for the purity of the study.
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