RU2265715C2 - Method for identification of oil replenishment zone in oil bed and method for above process intensification - Google Patents

Abstract

FIELD: oil production industry, particularly enhanced recovery methods for hydrocarbons obtaining.

SUBSTANCE: method of oil bed development in mode of depletion drive by productive well drilling and operation or in mode of bed pressure maintaining on the base of productive and injection wells drilling and operation involves performing three-dimensional seismic investigations to detect three-dimensional natural microcrack system tracing; plotting field development map indicating well outputs and volumes of accumulated oil; analyzing carbon (¹⁴C) and tritium (³H) isotope concentration in oil samples extracted from production wells; plotting lines characterized by constant concentration thereof; performing complex analysis of the obtained information to identify possible oil inflow area; subsequently developing the fields with deactivation of injection wells in above area and near it; producing oil from production wells along with possible pressure reduction in oil inflow area, wherein above pressure reduction is conditioned by process reasons and technological limits.

EFFECT: oil inflow intensification.

2 cl

Description

The present invention relates to the field of oil and gas industry, namely, to identify the zone of replenishment of oil deposits and the intensification of this process, when conditions are created for the implementation of the corresponding idea of the Galactocentric paradigm.

A consequence of the Galactocentric paradigm created in our country is the renewability of oil resources in the developed oil deposits for a typical time of about 100 years as a result of the global geochemical cycle of water and carbon (see Barenbaum A.A. Galaxy, Solar System. Earth. Edition. GEOS, 2002, p. 355-336). An example of the Shebelinsky gas condensate field confirms such estimates. Therefore, the task arises, on the one hand, of identifying a replenishment zone, and on the other hand, creating conditions conducive to this process.

There is a known method-analogue of the development of an oil deposit, including drilling and operating production and injection wells, the construction of so-called development maps, where circles are drawn at the location of each well, the areas of which on a scale reflect the current flow rates or accumulated volumes of oil produced (see Muslim R. Kh., Abdulmazitov R.G., Ivanov A.I., Suleymanov E.I., Khisamov R.B. Geological structure and development of the Bavlinsky oil field.

This method is intended to identify areas of increased productivity of wells in an oil field, but is not applicable for the purposes of the present invention, aimed at identifying a replenishment zone and creating conditions for intensifying this process.

The fulfillment of the task is achieved by the fact that in the method of identifying the zone of replenishment of oil reserves and the intensification of this process, including the development of oil deposits in the mode of depletion of reservoir energy by drilling and operating production wells or in the mode of maintaining reservoir energy based on drilling and operation of production and injection wells in which a system of natural macrocracks is detected according to 3D seismic data, construction of development maps is carried out with reflection of flow rates wells and accumulated volumes of produced oil, analyze oil samples from producing wells for the content of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ N), build maps of the isoconcentrate of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ N), perform a comprehensive analysis of this information and on its basis identify possible zones of replenishment of oil reserves, while the intensification of replenishment of oil reserves in the course of its further development is carried out with the exception of the functioning of injection wells in the identified th zone and its environment, and the extraction of oil from producing wells is carried out with a decrease in reservoir pressure in the replenishment zone, as well as the fact that

- after shutdown of injection wells and oil production with a decrease in reservoir pressure, the analyzes of oil samples from production wells for the content of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ N) are repeated and the dynamics of the productivity of the replenishment zone for oil deposits is monitored by them.

The method is as follows.

Before or during the development of the oil field, 3D seismic work is carried out, on the basis of which a system of macrocracks, as well as their lateral and deep tracing, are identified.

Based on field data on current production rates and accumulated volumes of oil produced in wells, two types of development maps are constructed. On some, in the form of circles on a scale, the current flow rates of the wells are noted. On others, accumulated oil production for each well is likewise noted. Wells with the largest circles serve as indicators of possible zones of replenishment of oil reserves.

Wellhead oil sampling is performed for all wells and an analysis of the selected samples for the content of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ H) is carried out. These two “markers” were chosen because the half-life of the carbon isotope ¹⁴ C is 5730 years, and tritium ³ H is 12.4 years. Their presence in oil speaks of its young age, in spite of the age of millions of years, as is still believed.

Based on the results of these analyzes, maps of the concentration of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ H) are built.

Based on a comparison of these five maps, an oil replenishment zone is identified.

Further development of the oil reservoir is carried out with the exception of the injection of water or another working agent into the identified replenishment zone. Oil production from wells confined to the identified zone and its surroundings is carried out in such a way as to reduce reservoir pressure in the considered zone to the minimum acceptable value from a technological point of view. For example, up to the saturation pressure of oil with gas. The creation of an increased depression between the deep replenishment zone and the developed sections of the oil reservoir will provide an intensification of the process of inflow of deep oil. After the identification of the zone of replenishment of oil reserves and the intensification of oil inflows, analysis of oil samples continues to assess the dynamics of oil inflows.

Implementation example.

The cited source provides examples of building development maps. This is a widespread practice of geological and field analysis of the development status of an oil reservoir. However, the goals of constructing such maps according to the invention are changing. They are now intended not only to assess the development of oil reserves in different zones, but also to identify a potential zone of replenishment of oil reserves.

3D seismic is implemented today in almost every oil field being developed or put into development. Such a proven and effective method for studying the oil reservoir allows us to identify a network of tectonic disturbances, i.e. future locations for identifying an oil replenishment zone.

The authors are aware of at least one case where a ¹⁴ C radioactive carbon isotope was found in oil sample analyzes (see JMPeter, P. Peltonen, SDScott. ¹⁴ C ages of hydrothermal petroleum and carbonate in Guaymas Basin, Gulf of California; Implications for oil generation, expulsion, and migration. GEOLOGY, v 19. p. 253-256. March 1991). As for the analysis of oil samples for tritium content, they were carried out in our country in connection with nuclear explosions in oil deposits (see Barenbaum A.A., Zakirov S.N. Galactocentric paradigm and its consequences for the theory and practice of oil field development and gas. Oil industry, 3/2002, cc.32-34). Analysis of oil samples for the presence of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ N) allows you to build maps of isoconcentrate, as well as to identify areas of replenishment of oil deposits.

The integration of these methods allows you to identify potentially possible areas of replenishment of reserves as "workers".

The identification of the desired zones can be complicated by the overcompensation of oil withdrawals taking place in a number of oil deposits by water injection. The created excess reservoir pressure, of course, prevents the possibility of oil inflows, and therefore, complicates the identification procedure.

In such cases, in potential replenishment zones, the process of lowering the reservoir pressure below the initial one is carried out. To do this, stop pumping water into the surrounding areas, as well as intensify the selection of oil from the corresponding wells. Then the role of isotope analysis increases markedly.

In the case of overcompensation by injection selection and the absence of a replenishment zone, reservoir pressure is reduced below the initial pressure over the entire productivity area so that the zone manifests itself.

Further development of the oil reservoir, after identifying the replenishment zone, continues in such a way that formation pressure in this zone is as low as possible. This facilitates the flow of deep oil. Subsequent analyzes of oil samples for the content of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ H) make it possible to control and evaluate the dynamics of the productivity of the identified zone of replenishment of oil reserves.

Thus, according to the Galactocentric paradigm, the time has come to revise the views on the formation of oil, the formation of oil deposits and to accept the idea of renewable oil resources. There are real methods that allow, based on a comprehensive analysis, to identify replenishment zones of oil deposits. After its establishment, the strategy for the further development of the reservoir with the aim of intensifying the process of replenishing oil resources becomes clear.

Claims (2)

1. The method of identifying the zone of replenishment of oil reserves and the intensification of this process, including the development of oil deposits in the mode of depletion of reservoir energy by drilling and operating production wells or in the mode of maintaining reservoir energy based on drilling and operation of production and injection wells, in which a system of natural macrocracks according to 3D seismic data, construct development maps with reflection of well flow rates and accumulated volumes of oil produced, analyzer cosiness of oil samples from producing wells for the content of carbon isotopes ( ¹⁴ C) and tritium ( ³ N), maps of isotope concentrates of carbon ( ¹⁴ C) and tritium ( ³ N) are built, a comprehensive analysis of this information is performed, and based on it, possible replenishment zones are identified oil reserves, while further development is carried out with the exception of the functioning of injection wells in the identified zone and its environment, and oil extraction from production wells is carried out with a decrease in reservoir pressure in the replenishment zone. 2. The method according to claim 1, characterized in that after shutting off the injection wells and oil production with a decrease in reservoir pressure, the analyzes of oil samples from production wells for the content of radioactive isotopes of carbon ( ¹⁴ C) and tritium ( ³ N) are repeated and the dynamics is monitored productivity of the zone of replenishment of oil reserves.