Hard-to-recover oil reserves (TIZ) are reserves of deposits (fields, development objects) or parts of a deposit that are characterized by relatively unfavorable geological conditions for oil occurrence and (or) its physical properties for extraction. The extraction of HPE requires increased costs of material, money, labor, non-traditional technologies, special non-serial equipment and scarce reagents and materials.
Other hard-to-recover oil reserves (namely: high-viscosity oil; oil from reservoirs with an initial low oil saturation; oil with a high saturation pressure close to the initial reservoir pressure and a minimum flowing pressure significantly lower than saturation pressure; gas oil underlain by bottom water; finally, oils of small oil reservoirs with poorly defined boundaries) require the design of complex combined oil recovery processes: an adaptive development system, selective injection of a displacing agent, a combination of stationarity and non-stationarity of injection, alternating injection, advanced waterflooding, polymer flooding, gas flooding, and also heat carrier injection ; using deep perforation, hydraulic fracturing, various combinations of vertical, shallow and horizontal wells, as well as tree wells, various combinations of oil reservoirs into production facilities.
The increase in hard-to-recover oil reserves in the country makes the problem of creating and applying new efficient technologies for the corresponding geological and physical conditions, using more advanced methods for their modeling and development, especially relevant.
The development of hard-to-recover oil reserves by horizontal well systems makes it possible to reduce the number of wells required for the development of reserves by 2-3 times.
Most deposits contain hard-to-recover oil reserves (unfavorable geological conditions of oil occurrence or its properties), the extraction of which requires increased costs of material and financial resources, labor, non-traditional technologies, special non-serial equipment and scarce reagents and materials.
In order to intensify the development of hard-to-recover oil reserves from intermediate layers of the coal-bearing strata of the Novokhazinskaya area in NGDU Yuzharlanneft in 1984, impact centers were organized at the IX production site. The technology of this type of flooding consisted in the fact that water intakes were arranged for the selection of mineralized formation water from the aquifer of the C-VI formation. This water is currently pumped into injection wells by an electric centrifugal pump.
In reservoirs with hard-to-recover oil reserves, an extremely complex oil displacement mechanism is observed, associated with the simultaneous influence of many factors, such as capillary phenomena, viscous forces, phase transitions in combination with layered heterogeneity.
The development of objects with hard-to-recover oil reserves, of course, affects the technical and economic indicators of development.
Although the role and importance of hard-to-recover oil reserves in the overall balance of oil production in the country will increase in the future, the absolute levels of oil production in the foreseeable future will still be determined by highly productive flooded deposits, the development of which is carried out using flooding methods in various modifications and combinations.
There are billions of tons of hard-to-recover oil reserves in Russia, already explored, but not yet brought into industrial development.
In connection with the increase in the share of hard-to-recover oil reserves in the country, the problem of improving the efficiency of well operation in the fields of non-Newtonian (abnormally viscous) oils is of particular relevance. During the development of such fields, the operation of wells is complicated by the manifestation of anomalies in the viscosity and mobility of oil, the formation of asphalt, resin and paraffin deposits, increased corrosive aggressiveness of well products and is accompanied by a significant decrease in the productivity of producing and injectivity of injection wells. The success of solving this problem largely depends on the development and implementation of new chemical reagents and compositions of process fluids in all oil production processes, without exception, from the opening of a productive reservoir to conservation or liquidation of wells. Work in this direction has been carried out for a number of years at the Department of Development and Operation of Oil and Gas Fields of the Ufa State Petroleum Technological University under the guidance and with the direct participation of the author of the report.
Stepnoozerskoye field shows the feasibility of putting hard-to-recover oil reserves into active development through the use of the latest drilling equipment and technology, development systems, intensification of oil production and the use of methods for enhanced oil recovery.
The extraction of residual or newly introduced hard-to-recover oil reserves is associated with significant complications in the processes of reservoir development, construction and operation of wells.
In recent years, the share of hard-to-recover oil reserves, concentrated in low-permeability shale terrigenous reservoirs, during the development of which the permeability decreases even more, and the filtration characteristics of productive formations deteriorate. The deterioration of the filtration properties of the bottomhole formation zone (BFZ) is caused by the precipitation of various reaction products after the injection of chemical reagents, an increase in the water saturation of rocks and a decrease in phase permeability for oil. Therefore, one of the main tasks in oil production from these reservoirs is the restoration and improvement of the filtration characteristics of the bottomhole zone.
Currently, in the development of hard-to-recover oil reserves, the efforts of scientists are aimed at creating technologies that provide an increase in the final production of oil reserves by improving the coverage of the reservoir, which is confirmed by the following data.

Increasing the efficiency of development of deposits with hard-to-recover oil reserves (TRIZ) is currently of paramount importance for the oil industry due to the depletion of active reserves in highly productive fields and the decline in production from them.
Russia has huge hard-to-recover oil reserves. In fairness, the state should give these oil reserves for development to those who have effective technology. Undoubtedly, there should be some economic tax incentives at the initial stage. However, only tax incentives cannot turn an inefficient technology into an effective one, because the difference in productivity between unproductive and medium-productive reservoirs is too large. For example, the productivity of unproductive reservoirs is 10 to 30 times lower than the minimum economically viable productivity; and the maximum tax benefits can compensate for a 2-fold decrease in productivity, respectively, a 5- to 15-fold decrease in productivity will remain uncompensated.
It is shown that a significant intensification of the production of hard-to-recover oil reserves is possible only with the use of new technological and technical means, namely the creation of rigid autonomous waterflooding systems with differentiated water injection pressures, using special designs of injection wells made of high-quality steel, separate water conduits, small BKNS.
Interesting: what do we mean by hard-to-recover oil reserves. Probably, physically these oil reserves are quite recoverable1, but economically they are not recoverable, because the economic costs of their extraction exceed the economic proceeds from their sale, because their extraction is economically unprofitable. Even if taxes on the sale of this oil are completely abolished, then, given the share of such taxes, it is possible to double the market price of oil for a subsoil user. Of course, when developing hard-to-recover oil reserves, certain tax incentives are necessary, especially in the initial, most risky period of development. But tax incentives are not a radical remedy, even the complete abolition of taxes and costs for the sale of produced oil does not solve the problem. More effective is another ideological direction - it is necessary to create a fundamentally new technology and reduce the cost of extracting this oil by three to five times or more.
The problem of designing the development of oil fields with hard-to-recover oil reserves, namely, oil reservoirs of low and ultra-low productivity, is the need for fairly accurate calculations. It is known that the inaccuracy of calculations has to be compensated by reserving part of the calculated capacity. And the greater the inaccuracy, the more the design performance decreases, in order to ensure the required 90% reliability of design indicators. But the estimated productivity of oil reservoirs of low and ultra-low productivity is already extremely small, on the verge of or beyond economic profitability, so there is nowhere to reduce it - it cannot be significantly reduced. Therefore, the calculations must be carried out with the greatest possible accuracy.
With this technology, secondary objects with hard-to-recover oil reserves are not developed.
But in order to solve this problem and bring hard-to-recover oil reserves into effective industrial development, it is necessary to propose not just a new system, not just a set of new methods, but such a system and such a complex that would provide the necessary economic profitability and could later be used by many others. oil companies.
One of the most important characteristics that determines the areal or local nature of the impact on the reservoir can be taken as a classification feature for technologies for the development of hard-to-recover oil reserves. In the first case, the impact covers a significant part of the deposit. In the second case, the bottom-hole formation zone is treated.
One of the elements of a highly efficient integrated technology for the development of hard-to-recover oil reserves, developed by specialists from JSC Tatneft and TatNIPIneft, is the widespread use of horizontal and branching horizontal wells. 146 horizontal wells have been drilled in Tatarstan, 122 of them have been developed, operated or put into operation. The average oil flow rate of horizontal wells is 6 5 tons / day, which exceeds the flow rate of the surrounding vertical wells by 2 times. Horizontal wells produced a total of 748 thousand tons of oil.
The Stepnoozerskoye oil field is one of the objects with hard-to-recover oil reserves. Commercial oil-bearing capacity was revealed in deposits of the Carboniferous system. Specific in the structure of the Lower Carboniferous deposits is the wide development of erosion incisions of both areal and channel types.
So, in our opinion, the criterion for identifying hard-to-recover oil reserves in a separate oil reservoir should be the average oil productivity index of wells drilled into this reservoir.
Specializes in the field of improving technologies for involving hard-to-recover oil reserves in the development in order to increase the oil recovery factor.
The innovative system for developing oil fields with hard-to-recover oil reserves presented here, proposed by AO RITEK, provides for a comprehensive optimization of the oil production process. This system is constantly being improved taking into account the achievements of science and technology and is practically implemented at the oil fields of AO RITEK in Tatarstan and Western Siberia.
The innovative system for developing oil fields with hard-to-recover oil reserves presented here, proposed by AO RITEK, provides for a comprehensive optimization of the oil production process.
In highly productive fields, there are layers and interlayers containing hard-to-recover oil reserves.

The Russian Innovative Fuel and Energy Company (RITEK) is developing hard-to-recover oil reserves and thereby solving the most important problem of the Russian and world level. The fact is that in Russia and all over the world, huge oil reserves have been discovered, amounting to many hundreds of millions of tons, in layers of low and ultra-low productivity. Moreover, these reserves were discovered a long time ago, 20 - 30 or more years ago, but were not put into development, because with standard, commonly used development systems, this is economically unprofitable, economically ruinous even for rich companies and the state.
The collection also deals with the problems of technical and economic evaluation of the effectiveness of the development of hard-to-recover oil reserves at the stage of designing and implementing impact technologies.
Thus, it is justified here: as a criterion for identifying hard-to-recover oil reserves, the minimum average oil productivity factor for wells drilled into the considered oil reservoir should be used.
Further, at least briefly, it is necessary to list the technologies we proposed for the development of hard-to-recover oil reserves, but hard-to-recover ones not on the basis of the extremely low productivity of the reservoirs, but on other grounds.
Currently, serious attention is paid to involvement in the active development of hard-to-recover oil reserves. At all fields, the tasks of intensification are being solved, and in some cases, scientific and production support for the development of Lower Carboniferous and Devonian oil deposits with carbonate reservoirs.
The book highlights the main features of the geological structure of oil deposits with hard-to-recover oil reserves of Bashkortostan, presents the results of experimental, pilot-industrial and field work to improve the technologies for developing these deposits.
According to the authors' estimates,721 in carbonate reservoirs in the fields of the Perm Pri-Urayye, hard-to-recover oil reserves by 1988 amounted to 3 4 of the remaining balance reserves.
Works carried out by AOZT Tatnefteotdacha to enhance oil recovery from reservoirs involve hard-to-recover oil reserves. The need to use special technologies and measures requires significant costs. Due to its specificity, the use of EOR technologies has a costly mechanism. The work is carried out on the edge of cost. The cost of oil production with their use is approximately 15 times higher than the cost of oil produced without the use of EOR methods.
According to the estimates of the authors721, in carbonate reservoirs in the fields of the Perm Urals, hard-to-recover oil reserves amounted to 3/4 of the remaining balance reserves by 1988.
The collection presents studies on solving some problems of field development with hard-to-recover oil reserves.
In order to increase the efficiency of the development of oil fields and especially objects with hard-to-recover oil reserves, it is necessary to significantly improve the use of the drilled well stock. In this matter, great hope is placed on the Decree of the Government of the Russian Federation of November 1, 1999 No. 1213 On measures to put into operation idle control and mothballed wells in oil fields and Decree of the Cabinet of Ministers of the Republic of Belarus of February 15, 2000 No. 38 On measures on the commissioning of idle control and mothballed wells at the oil fields of the Republic of Belarus, exempting organizations engaged in oil and gas production on the territory of the Republic of Bashkortostan from regular payments for oil and gas production and deductions for the reproduction of the mineral resource base in relation to oil and gas , produced from put into operation idle, control wells and wells that were in conservation as of January 1, 1999, with the exception of new wells awaiting development after drilling.
Compounded drilling fluid is intended for drilling and penetrating productive horizons with hard-to-recover oil reserves, represented by interbedding of sandy-silty-clayey rocks in the carbonate layer.
The strategic task of achieving the world technological level is being solved, which will ensure the effective development of hard-to-recover oil reserves, the growth of new highly productive reserves, the minimization of production costs, and the expansion of participation in international projects.
Change in the share of additionally drilled wells and oil production from them along the D0 and Ai horizons of the Romashkinskoye field.
This can be explained by the fact that they are drilled mainly for the purpose of extracting hard-to-recover oil reserves.
This is the reason for the need to create more advanced methods of influencing deposits with hard-to-recover oil reserves.
The technology of using a fibrous-dispersed system is a new promising means of increasing oil recovery in heterogeneous reservoirs with hard-to-recover oil reserves / / NTZh Oilfield business.
Table 5.3 gives a quantitative (expressed as a percentage of recoverable reserves) estimate of hard-to-recover oil reserves for these fields. An analysis of the features of the geological structure of oil deposits shows that the deposits are distinguished by a complex geological structure and are characterized by a wide range of values ​​of geological and physical parameters. Table 5.3 shows that most of the formations contain a significant amount of hard-to-recover oil reserves. This is explained by the fact that oil deposits are characterized by high zonal, lenticular and layer-by-layer heterogeneity of reservoirs. Analysis of the development of these fields shows that predominantly highly permeable interlayers and reservoir sections are being produced.

Industrial oil and gas production has been going on for more than a century. Not surprisingly, the most easily accessible hydrocarbon reserves were initially involved in the development. Now they are becoming less and less, and the probability of discovering a new giant field, comparable to such as Samotlor, Al-Ghawar or Prudhoe Bay, is almost zero. At least, in the current century, nothing of the kind has yet been found. Whether you like it or not, you have to develop deposits of hard-to-recover oil.

Hard-to-recover reserves can be divided into two groups. One includes deposits with low reservoir permeability (tight sandstones, shales, Bazhenov formation). At the same time, the oil extracted from such deposits is quite comparable in its characteristics to the oil from traditional fields. The other group includes deposits of heavy and high-viscosity oil (natural bitumen, oil sands).

Attempts to extract oil from low-permeability reservoirs by traditional methods lead to the following effect - at first, the well gives a good flow of oil, which ends very quickly. Oil is extracted only from a small area adjacent to the perforated section of the well, so vertical drilling in such fields is inefficient. It is possible to increase the productivity of a well by increasing the area of ​​contact with an oil-saturated formation. This is achieved by drilling wells with a large horizontal section and performing several dozen hydraulic fracturing operations at once. The so-called "shale oil" is extracted in a similar way.

When extracting natural bitumen or extra-viscous oil, hydraulic fracturing will not help. Methods for extracting such raw materials depend on the depth of the oil-saturated rocks. If the depth is small and amounts to tens of meters, then open-pit mining is used. When oil occurs at a depth of hundreds of meters, mines are built to extract it. In Canada, the oil sands of Alberta are developed in this way; in Russia, the Yaregskoye field can serve as an example. The rock extracted by the excavator is crushed, mixed with hot water and fed into the separator, which separates the oil from the sand. The viscosity of the resulting oil is so high that it cannot be pumped through the pipeline in its original form. To reduce viscosity, oil is mixed with a process solvent, usually gasoline or diesel fuel is used.

If the rock cannot be extracted to the surface, steam heating is carried out underground. The steam gravity treatment technology used by Tatneft at the Ashelchinskoye field is based on the use of a pair of horizontal wells. Steam is injected into one of them, oil is taken from the other. Steam for injection into the well is produced at a specially built boiler house. At deep occurrence, the efficiency of the method decreases due to the fact that the steam temperature decreases markedly on the way to the reservoir. The method of steam-gas stimulation developed by RITEK, which provides for the production of steam directly in the reservoir, is deprived of this disadvantage. The steam generator is installed directly in the face, it is supplied with reagents that interact with the release of heat. The reaction produces nitrogen, carbon dioxide and water. The dissolution of carbon dioxide in oil further reduces its viscosity.

Gas companies are experiencing similar problems. Cenomanian deposits are the most convenient for development. Cenomanian reservoirs usually have high permeability, which allows them to be exploited by traditional vertical wells. Cenomanian gas is “dry”, it consists of 97-99% methane and therefore requires minimal effort to prepare before being delivered to the transport system.

The depletion of Cenomanian deposits is forcing gas companies to turn to hard-to-recover gas reserves. The Turonian stage is characterized by low reservoir permeability, so vertical wells are ineffective. Nevertheless, 85-95% of Turonian gas consists of methane, which makes it possible to manage with relatively inexpensive methods of its preparation in the field.

The situation is worse with gas extracted from the Valanginian stage and Achimov deposits. Here lies the "fat gas", in addition to methane containing ethane, propane and other hydrocarbons. Before gas is supplied to the transport system, they must be separated from methane, and this requires complex and expensive equipment.

For one field, gas deposits can be identified in different tiers. For example, at the Zapolyarnoye field, gas occurs in Turonian, Cenomanian, Neocomian, and Jurassic deposits. As a rule, the most accessible Cenomanian stage is first involved in prey. At the famous Urengoyskoye field, the first Cenomanian gas was obtained in April 1978, Valanginian gas - in January 1985, and Gazprom began to exploit the Achimov deposits only in 2009.

We are grateful to the organizers of the VIII International Industrial and Economic Forum "Unification strategy: Solving urgent problems of the oil and gas and petrochemical complexes at the present stage", which took place on November 19-20, 2015 at the Russian State University. Gubkin for the opportunity to present a new technology for the extraction of hard-to-recover oil reserves of the Bazhenov formation, called Technology No. 5 of the KVKR.

The technology was developed jointly by New Technologies and KOMPOMASH-TEK. At the moment, the implementation of the project has already begun in cooperation with the Gazprom Neft company with scientific participation and support from the Russian State University of Oil and Gas. I. M. Gubkina, Moscow State University. M. V. Lomonosov, and in particular, the Faculty of Chemistry of Moscow State University and the Oil and Gas Center of Moscow State University.

SLIDE No. 1. Bazhen's problem.
The Bazhenov Formation is often compared to North American oil shale plays such as Bakken/Three Forks and Eagle Ford. But they are similar only externally.
In contrast to the North American oil-bearing shale plays, the productive formations of Bazhen are more plastic, more heterogeneous and, most importantly, less powerful.
Thus, at Bakken/Three Forks or at Eagle Ford, the formed drained volume, as a rule, ranges from 30-40 million m 3 . At Bazhen this figure is almost 10 times lower: 3-4 million m 3 .
The amount of tight oil in such a relatively small drainable volume is not enough to overcome the break-even point when producing only the tight oil itself.
That is why, according to industry experts, the cost-effective development of Bazhen is possible only if an additional hydrocarbon resource, kerogen, is involved in the active development. And this, in turn, means that the Bazhen PP must be heated ...

SLIDE № 2. The main problem of modern thermal methods of enhanced oil recovery (EOR).
The main problem of modern thermal methods of enhanced oil recovery (EOR) is the lack of technologies that allow delivering a high-temperature working agent to great depths. So, for example, in the case of using high-quality and very expensive thermal cases of class “E” (0.006>λ≥0.002 W/m°C; P<20 МПа и Т<350°C) ТМУН могут быть использованы на глубине до 1400 метров. Более бюджетные термокэйсы класса “B” (0.06>λ≥0.04 W/m°C; R<40 МПа и Т<400°C) позволяют доставлять рабочий агент на глубину 1500 метров, но с увеличенными тепловыми транспортными потерями.
The Technological Complex of Technology No. 5 of KVKR uses unique tubing with TIP (0.0408 W/m°C) developed by CJSC KOMPOMASH-TEK (Russia), which, due to a lower linear weight, can be used at a depth of up to 3500 meters. But their private use also does not solve the logistical problem, since when the working agent is delivered to the bottom of the well, located at a depth of 3000 meters, the temperature of the working agent, due to inevitable thermal transport losses, decreases by 70 - 80 ° C.
Thus, the working agent delivered to the bottom of the well, for example, to a depth of 3000 meters, must be reheated and also the pressure loss of the working agent due to friction must be compensated. Moreover, it is desirable to heat the working agent to a higher temperature (480°C) compared to the temperature it had on the surface part of the well (450°C) prior to the start of the process of its transportation to the bottom of the well.

SLIDE number 3. Problem solving.
In Technology No. 5 of KVKR, this fundamental problem of modern thermal EOR is solved by organizing an exothermic oxidation reaction (ERO) of organic compounds in SC-water in the presence of an oxidizing agent at the bottom of the well, in its under-packer volume. Specifically, methanol is used as the organic compound, and hydrogen peroxide or air is used as the oxidizing agent. As a result of the exothermic reaction of methanol oxidation in SC-water in the presence of, for example, hydrogen peroxide, CO 2 is formed, with which the working agent is additionally enriched, and H 2 O, and heat is released, which is spent (a) on reheating the working agent and, accordingly , (b) to increase its pressure to the thermobaric values ​​specified by the technology.

SLIDE № 4. Traditional thermal EOR and In-situ retorting. Technology No. 5 KVKR - technology of the Concept of in-situ retorting.
Existing thermal EOR methods can be divided into two groups: a) traditional HOR and b) thermal methods In-situ retorting concepts, including thermochemical methods.
Traditional thermal EOR use as a working agent, mainly wet steam, the use of which can only temporarily change the viscosity and density of heavy hydrocarbons.
The difference between the thermal methods of the concept of in-situ retorting and the traditional approach is that as a result of the use of a high-temperature working agent in the form of supercritical water or superheated steam with a high degree of superheat, an irreversible decrease in the viscosity and density of heavy hydrocarbons occurs. They are molecularly modified in the reservoir and already upgraded, lighter hydrocarbons are extracted to the surface.
The concept of in situ retorting is very often referred to as the in situ refinery concept and some pre-treatment of hydrocarbons in the reservoir becomes part of the production process.
The downstream becomes part of the upstream.
If we talk only about hydrocarbons, then the use of such an approach on the Bazhenov formation will allow:

To further improve the quality of low-permeability oil;

Convert (liquefy and/or molecularly change) bitumen into lighter hydrocarbon fractions;

And the MAIN THING is to carry out in-situ generation of synthetic hydrocarbons from kerogen due to its hydropyrolysis.

SLIDE No. 5. Formula of Technology No. 5 KVKR.
If we talk, in general, about the potential of Technology No. 5 of the KVKR, then it allows:
(1) to the extent necessary
(2) to form and deliver to the reservoir a working agent having (a) the most effective compositional composition and (b) the required thermobaric characteristics; while, at the same time,
(3) increase reservoir permeability and reenergize it,
(4) generate synthetic hydrocarbons (SHC) from kerogen and
(5) improve the oil quality of tight rocks and molecularly modify the bitumen, and in this way
(6) stimulate the production of (a) improved quality tight oil and (b) synthetic hydrocarbons generated within the reservoir by withdrawing them through a zone with increased permeability.
In the most general form, when a working agent in the form of supercritical water (T = 480°C and P up to 45 MPa) is introduced into the reservoir, three interconnected and conditionally separated processes are carried out in the reservoir:
- reenergization of the productive formation;
- increase in reservoir permeability;
- a process aimed at reducing the degree of molecular blocking of nanofluid-conducting channels by large hydrocarbon molecules due to fragmentation into smaller molecules.
For example, large asphaltene molecules, reaching 30 nanometers in diameter, can block macrofluidic channels (more than 50 nanometers thick), not to mention fluidic channels at the micro (up to 5 nanometers) and mesolevels (from 5 to 50 nanometers).

SLIDE No. 6. The mechanism for increasing the oil recovery factor of Technology No. 5 KVKR.
The predicted oil recovery factor of Technology No. 5 KVKR is from 40 to 50%.
The predicted achievement of such a high oil recovery factor would not have been possible without ensuring a) reenergization of the productive formation - increasing the in-situ pressure to the maximum possible: 45 MPa, b) increasing its permeability, c) reducing the degree of molecular blocking of nanofluid-conducting channels, and, finally, d) the selection of hydrocarbons in a well through areas of a productive formation with a modified increased permeability.
The processes mentioned above are at the same time unconditional success factors for the economically efficient development of the Bazhenov Formation using cyclic thermochemical treatment.

SLIDE No. 7. The structure of Technology No. 5 KVKR.
This diagram shows the structure of Technology No. 5 of the KVKR.

SLAD No. 8. Commentary on structural blocks.
Block "Intralayer retorting":
40 years of work of the world's leading R&D structures. Hundreds of studies. Tens of hundreds of laboratory studies. Successful pilot projects of SHELL and EXXON MOBIL. Fundamental research is generally completed. Applied research dominates.
Block "Chemical reactions":
The exothermic reaction of the oxidation of organic compounds in supercritical water in the presence of an oxidizing agent is a proven and well-studied chemical reaction.
Block "Technological complex":
There are no technical and technological obstacles to the implementation of the Project "Technology No. 5 KVKR".
Block "Mathematical modeling":
We have started creating a reservoir model and in-situ complex processes - "virtual core / reservoir", FIB-SEM, lattice Boltzmann method (LBM), etc.

SLIDE № 9. I. In-situ retorting - significant basic applied provisions.
The most significant basic provisions of the Concept of in-situ retorting are presented in the Table on Slide No. 9.

SLIDE № 10. II. Chemical reactions.
Slide 10 presents the results of three studies to determine the heat release (kJ/mol) during the exothermic oxidation of methanol in supercritical water. The studies were carried out by specialists from the Massachusetts Institute of Technology (USA), the University of Hiroshima (Japan) and the Sandia National Laboratory (USA).
Also on the slide are photographs of the explosive and prolonged oxidation of propanol in supercritical water in the presence of an oxidizer with the formation of a flame at a fuel concentration of more than 16%.
Technology No. 5 KVKR uses the process of safe flameless long-term oxidation of methanol in supercritical water in the presence of an oxidizing agent at a methanol concentration of not more than 5%. The duration of the oxidation process is 5-6 seconds.

Slide number 11. III. Technological complex Technologies No. 5 KVKR.
Technological complex No. 5 KVKR consists of:
Ground supercritical water generator (Т=450°C and Р 45 MPa);
APG treatment plants;
tubing with heat-insulating coating (up to 3500 meters);
Heat-resistant downhole packer capable of operating at a temperature of 700°C and a pressure of 70 MPa; And
Heat-resistant annular packer capable of operating at temperatures of 700°C and pressures up to 100 MPa.

SLIDE No. 12. Exclusivity of Technology No. 5 KVKR.
The exclusivity of the potential of Technology No. 5 KVKR lies in its ability to:

1. Generate a working agent that has the most effective composition for the in situ generation of synthetic hydrocarbons from kerogen.

2. It is cost-effective to deliver a working agent with the above compositional composition and the required thermobaric characteristics to a productive formation located at a depth of 2500 to 3500 meters.

3. Increase up to 5 times the permeability of the productive formation and create a volumetric and integrated in-situ fluid-conducting system.

4. Re-energize the productive formation - create a powerful pressure regime for the selection of hydrocarbons.

5. Rational extraction of hydrocarbon resources. So, for example, the predicted cumulative oil production from one well with a drained volume of rock equal to 4 million m 3 (Bazhen) is equal to or greater than the predicted cumulative oil production from one well with a drained volume of 40 million m 3 (Bakken/Three Forks) .

6. Ensure highly efficient oil production from Bazhen without a preliminary multi-stage hydraulic fracturing (MSHF).

7. Technology No. 5 KVKR, despite its youth, is characterized by a high degree of technical and technological maturity, as it is combinatorially formed from several mature technologies that have long been well mastered by the Russian industry.

8. Due to the intensive method of oil extraction, the period of field development to almost complete depletion is reduced by several times, and energy costs, maintenance and operation of the field are accordingly reduced.

The invention relates to the field of oil and gas industry and will find application in the production of hard-to-recover oil reserves mainly for carbonate reservoirs of heterogeneously saturated layered formations. Provides an increase in the efficiency of the method due to the impact on the formation by swabbing, taking into account the conditions in the well. The essence of the invention: the method provides for the installation of a mast for swabbing before starting work in each well on its column flange using a bolted connection, choosing its height of at least 3-4 meters. After completion of work in each well from among those scheduled for swabbing, depending on the results obtained, they are sequentially grouped. Wells in which an increase in production rate or its restoration are obtained are operated in the same mode, i.e. mechanically using a deep well pump. Wells in which a high flow rate is obtained only with swabbing in comparison with artificial lift are operated in the swabbing mode. Wells in which no positive results have been obtained in increasing the flow rate are operated using a swab by alternating cycles of product accumulation and its pumping out of the well. 1 z.p. f-ly, 2 ill.

The invention relates to the field of oil and gas industry and will find application in the production of hard-to-recover oil reserves, mainly for carbonate reservoirs of heterogeneously saturated layered formations.

Known "Method of periodic operation of a marginal well with a deep-well pumping unit", which consists in alternating cycles of fluid accumulation and its pumping, equipped with a sump. At the same time, the minimum allowable bottomhole pressure and the corresponding annular pressure are first determined, taking into account the drawdown value on the formation, corresponding to the maximum allowable well productivity and the formation safety condition. In the processes of accumulation and pumping of liquid from the well, the value of the annular pressure is controlled. When its value increases during the accumulation process and decreases during the pumping process, gas is bled from the annulus, respectively, or gas is pumped into this space to maintain the annulus pressure at a certain level and restore, in both cases, the value of the selected, working drawdown on the formation.

The method for certain wells with low-viscosity oil can play a positive role and get an increase in production.

However, its use is limited by the fact that it does not take into account the viscosity of the reservoir oil. As is known, oil fields with hard-to-recover oil reserves are characterized by a high content of asphalt-resinous substances, as well as paraffin. They not only clog the well filter, but also the downhole pump, which necessitates frequent treatments by thermochemical methods, which is associated with additional tripping operations to remove the pump.

In addition, to implement the method, it is necessary to lay a gas pipeline, which is also economically unprofitable - it increases the cost of oil production.

A device for oil production is known, in the description of the patent of which a description is given of the method of oil production by influencing the reservoir by swabbing using an installation that includes a drive with a drum for cable, with which a piston ( swab) with the possibility of passing through itself the well fluid and lifting it to the surface, and diverting it to the collection point during its reciprocating motion.

The method involves instead of traditional downhole pumps, lowered on rods or on a geophysical cable of a centrifugal pump, to use a piston pump of the swab type.

The known method of the technical essence is closer to the proposed one and can be taken as a prototype.

The disadvantage of the known method is that the transfer of all numerous wells to oil production by swabbing is not economically feasible without taking into account the geological and technical condition of the well and its hard-to-recover oil reserves. This is due to the fact that the dismantling of surface equipment, the lifting of underground equipment from the well, as well as the installation of the swabbing plant - all these operations take a lot of time and labor. In addition, long-term downtime of the well reduces the rate of oil production, worsens the production capabilities of the well due to irreversible processes occurring in the bottomhole formation zone in terms of deterioration of the reservoir properties of the formation, and its restoration is also associated with a large expenditure of time, material resources and labor, attraction of technical means.

The objective of the present invention is to eliminate the above disadvantages of the prototype.

The problem is solved by the described method, including the impact on the reservoir by swabbing in order to increase oil production or restore the flow rate of marginal wells.

What is new is that before starting work in each well, the mast of the swabbing unit is mounted on the column flange of the well using a bolted connection, choosing its height of at least 3-4 meters, and after completion of work in each well from among those scheduled for swabbing, depending on the results obtained, they are sequentially grouped: into wells in which an increase in production rate or its restoration is obtained - they are operated in the same mode, i.e. artificial lift using a downhole pump and for wells in which a high flow rate was obtained only during swabbing in comparison with artificial lift, they continue to be operated in the swabbing mode, and in those wells in which positive results were not obtained in increasing the flow rate, they are operated using a swab by alternating cycles of accumulation of products of its pumping from the well.

Another difference is also the fact that before running into the well, the swabs are provided with check valves that work to close from the side of the wellhead.

The presented drawings explain the essence of the invention, where figure 1 shows a General view of the installation for the extraction of hard-to-recover oil reserves by the proposed method in operation, in partial section; figure 2 - section along a-a figure 1.

The installation for the implementation of the proposed method contains a mast made of welded tubular structures, to the uprights 1 of which the bases 2 and 3 are rigidly fixed, the upper and lower, respectively, made in the form of a disk with a central hole for the rope 4. On the upper base 2 with the help of lugs 5 is installed upper guide roller 6. The lower base 3 with the lower guide roller 7 is fixed to the column flange 8 by means of a bolted connection. The lower roller cheeks 9 by means of a bolt 10 is connected to the bracket 11 of the lower base with the possibility of rotation in the vertical direction. The bracket is connected with the bolt 12 to the plate 13, which is connected by bolts 14 and 15 and spacers 16 to the lower base 3 of the mast with the possibility of horizontal rotation. Thus, the lower roller is installed with the possibility of orientation relative to the drum with rope 4 of the winch, which also includes a gearbox and an electric motor (the winch is not shown). Reliable stability of the mast is provided by couplers 17.

The method is carried out in the following sequence.

First, the number of wells in a given oil field to be swabbed is determined. There can be dozens, hundreds or more of such wells awaiting stimulation, including those that have been put into circulation, depending on whether the given oil field is large or small.

Before starting work in the well, a mast with a height of at least 3-4 m, the swabbing installation described above, is mounted using a bolted connection on the column flange of the well (see figure 1), and the bottom of the swab is provided with a check valve operating to close from the wellhead . The winch of the installation is equipped with a control unit with a two-cycle program and setting for the optimal mode of operation (the control unit is not shown). Then the rope 4 is passed through the lower and upper guide rollers 6 and 7 and its end is fixed to the swab with the load (the swab is not shown). Then the drum is released from the brake and it begins to rotate, unwinding the rope, and thereby lowering the swab into the tubing string 18 under its own weight. If necessary, to accelerate the descent, the swab is supplied with a load. When the swab reaches the static level of the well liquid, its valve opens and the liquid begins to flow into the cavity of the tubing string. As the swab moves to the required depth according to a given program, the liquid present in the well fills the cavity of the tubing string. Further, according to the program of the control unit, the winch electric motor is turned on, the winch gearbox starts to rotate the drum in the opposite direction - the swab is lifted. When the swab is moved upwards, the valve closes under the weight of the liquid and the liquid above the swab flows through the discharge pipe 19 of the wellhead fitting into the liquid-transporting line or container. After the swab reaches the upper lifting point, the control unit program switches off the electric motor. The swab, under its own weight and load, again begins to move down, and the cycle is repeated by stimulation of the well formation, the duration of which sometimes lasts up to a month or more.

As the work in one well is completed, swabbing operations can be carried out in parallel and in several wells; by mechanized method using downhole pumps, and for wells in which a high flow rate was obtained only during swabbing in comparison with the mechanized method of production - they continue to be operated in the swabbing mode, and in those wells in which positive results were not obtained in changing the flow rate in the direction of increasing , they are operated using a swab by alternating cycles of product accumulation and its pumping out of the well.

Upon completion of work in all planned wells of this oil field, they then proceed to other or similar work in parallel.

The technical and economic advantage of the invention is as follows.

The use of the invention in the oil fields provides optimization of the development of oil reservoirs, reducing the cost of time and materials due to other expensive types of reservoir stimulation to stimulate them, as well as reducing labor costs.

Sources of information

1. Pat. RF No. 2193648, 7 E 21 V 43/00, BI No. 33, 2002

2. Pat. RF No. 2172391, 7 E 21 B 43/00, BI No. 23, 2001 (prototype).

1. A method of extracting hard-to-recover oil reserves by influencing a productive formation by swabbing in order to increase oil production or restore the flow rate of marginal wells, characterized in that before starting work in each well, the mast of the swabbing unit is mounted on the well column flange using a bolted connection, selecting it a height of at least 3-4 m, and after completion of work in each well from among those scheduled for swabbing, depending on the results obtained, they are sequentially grouped: for wells in which an increase in production rate or its restoration has been obtained, they are operated in the same mode, those. artificial lift, using a downhole pump, and for wells in which a high flow rate was obtained only with swabbing compared to artificial lift, they continue to be operated in the swabbing mode, and wells in which positive results were not obtained in increasing the flow rate, operated with the use of a swab by alternating cycles of accumulation of products of its pumping from the well.

2. The method according to claim 1, characterized in that before running the swabs into the well, they are provided with check valves operating to close from the side of the wellhead.

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The invention relates to gas and oil wells and is intended mainly for use at the stage of operation of said wells to increase the flow of fluid from a reservoir.