RU2540715C1 - Development method of multiple-zone oil deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method involves lowering of a pipe string with a filter below a well liquid level, extraction of the production from the well, separation of oil and water in the well shaft, water pumping to another formation, and lifting of oil to the surface. A filter represents an annular tube; an internal tube has a hydrophobic surface with a degree of hydrophobic properties of at least 99%, with capillary holes with a diameter of not more than 2 mm and density of at least 50 holes per metre. The lower part of the internal tube allows no water passage. The external tube has a hydrophilic surface with a degree of hydrophilic properties of at least 99%, with capillary holes with a diameter of not more than 2 mm and density of at least 50 holes per metre. In the lower part of the filter there installed is a packer between a casing string and the external tube for sealing of this space, and between the external and internal tubes of the filter there left in the lower part is space for liquid passage. Liquid penetrates into the space between the internal and the external tubes of the filter, where it is filtered through the capillary holes, thus being separated into oil and water.

EFFECT: improving efficient separation of oil and water in a well shaft; improving efficiency of water flooding and increasing oil recovery of a deposit.

2 dwg

Description

The invention relates to the oil industry and can find application in the development of multilayer oil deposits, the layers of which coincide structurally, with the selection of products from the lower layer and pumping water into the upper layer.

There is a method of operating a high-water well oil well, which includes separate, thanks to a packer installed between the strata, pumping oil from the reservoir to the surface with preliminary gravitational separation of the products in the well into oil and water and pumping the separated water into the receiving reservoir. Above the packer installed above the reservoir, a pump is placed on the pipe string communicated with an inlet with a sub-packer space, and with an outlet through a radial hole in a pipe string with an over-packer space, and pipes of a smaller diameter are placed under the radial holes from the conditions of gravitational separation of products into oil and water while the separated oil is lifted along the annulus and the pipe string with the possibility of regulating its flow rate at the mouth, and water, controlling its amount, is pumped along the annulus space to the receiving reservoir due to the pressure of the liquid column in the well and the excess pressure generated by the pump, the interval of the receiving formation being reported as a separate tube with wellhead measuring equipment, based on the readings of which control the quality of the water pumped into the receiving formation. Additionally, the emulsion in the production of the formation before injection into the annulus is separated into oil and water by a separator (RF patent 2394153, CL E21B 43/00, publ. 10.07.2010).

Closest to the technical essence of the proposed method is a method of operating a well, which consists in the fact that the well is supplied from bottom to top with a string of tubing with a packer at the end, a deep pump, a commutator, two concentrically arranged outer and inner tubing tubing columns, nozzles with holes on the outer tubing string, the well is separated by a packer above the reservoir, the reservoir products are fed by the downhole pump in a cyclic mode “p supply-stop ”from the reservoir through the tubing string, through the switch, the annulus between the inner and outer tubing strings, the nozzle and nozzle openings into the annulus between the production well and the outer tubing string, create and maintain in the upper part of the well a pressure of not less than the degassing pressure of oil and not more than the permissible pressure on the production casing; the formation of products for oil and water, regulate the completeness of the separation of the half-cycle operation of the deep-well pump “stop” and the distance between the switch and nozzles with holes, direct oil to the oil line, supply water through the switch to the inner column of the tubing and through the pipeline to the discharge borehole by pumping water and / or through the annulus between the production string and the outer tubing string and tubing string with a packer in the reservoir above the packer with downhole pumping of water (RF patent No. 2490436, cl. E21B 43/12, E21B 43/38, publ. 08/20/2013 - prototype).

A common disadvantage of the known methods is the insufficiently effective separation of oil and water, the complexity of the design, excessive rise to the surface of the water. The methods also do not allow the efficient use of shared water in order to maintain reservoir pressure by flooding, which leads to low oil recovery in the development of deposits with two or more layers that are structurally identical.

The proposed invention solves the problem of increasing the efficiency of separation of oil and water in the wellbore, increasing the efficiency of water flooding and, as a result, increasing the oil recovery of the reservoir.

The problem is solved in that in the method of developing a multilayer oil reservoir, which includes lowering a pipe string with a filter below the liquid level in the well into the well of the producing well, taking products from the formation, separating oil and water in the well, pumping water into another formation, raising oil to the surface, according to the invention, the filter is a pipe in a pipe, the inner pipe has a hydrophobic surface with a degree of hydrophobicity of at least 99%, capillary holes with a diameter of not more than 2 mm and a density of at least 50 holes / m, and the lower part of the inner pipe does not allow water to pass, the outer pipe has a hydrophilic surface with a degree of hydrophilicity of at least 99%, capillary holes with a diameter of not more than 2 mm and a density of not less than 50 holes / m, and a packer is installed between the casing in the bottom of the filter and an outer pipe to seal this space, and between the outer and inner pipes of the filter at the bottom, leave space for the passage of fluid, moving from the reservoir through the wellbore, the fluid enters the gap between the inner and outer pipes of the filter, where it is filtered through capillary holes, separating into oil, which, getting into the inner pipe and then into the pipe string, is pumped to the surface by the pump, and water, which gets through the outer pipe into the annulus with the casing pumped into the upper layer.

SUMMARY OF THE INVENTION

The oil recovery of an oil deposit is significantly affected by the system of maintaining reservoir pressure by water flooding. One of the ways to increase it is to use production wells for simultaneous fluid production in one formation and water injection in another. At the same time, no water pipes are brought to the well, but separation in the well of the selected fluid from the lower reservoir into oil and water is used. Water is used for injection into the upper layer in the same well. Thus, increase the efficiency of the waterflooding system of the reservoir, consisting of at least two reservoirs. In the absence of flooding in the deposits, this method is used to dispose of water in the upper layer. However, existing technical solutions do not fully allow these tasks to be completed. The proposed invention solves the problem of increasing the efficiency of separation of oil and water in the wellbore, increasing the efficiency of water flooding and, as a result, increasing the oil recovery of the reservoir. The problem is solved as follows.

Figure 1 presents a schematic illustration of a plot of oil deposits with two layers, opened by a well. Figure 2 shows a schematic illustration of a section of a section of an oil deposit perpendicular to the wellbore. Designations: 1 - lower reservoir, where fluid is taken from, 2 - upper reservoir, where water is pumped, 3 - not the reservoir, 4 - production well, 5 - casing, 6 - cement ring, 7 - perforations, 8 - column pipes, 9 - filter, 10 - inner pipe of filter 9 with hydrophobic coating, 11 - outer pipe of filter 9 with hydrophilic coating, 12 - packer between casing 5 and outer pipe 11 of filter 9, 13 - space between outer 11 and inner 10 pipes filter 9, 14 - pump for lifting well products (oil) and the surface 15 - Pump for water injection into the upper layer, 16 - a packer for sealing the space between the casing 5 and the pipe string above the upper reservoir 8 2.

The method is implemented as follows.

The oil reservoir area, represented by the lower 1 and upper 2 reservoirs (Fig. 1), with a terrigenous or carbonate type of reservoir and separated by a non-reservoir 3, is opened by a well 4. A well 4 is cased by a column 5, cemented by a cement ring 6 and reopened by perforation 7 into productive formations 1 and 2. Either the productive part of formations 1 and / or 2 may have an open trunk.

Filter 9 is lowered into the wellbore 4 between the upper 2 and lower 1 layers on the pipe string 8. The filter 9 is a pipe in a pipe and has the following structure (Figs. 1, 2): the inner pipe 10 has a hydrophobic surface with a degree of hydrophobicity of at least 99%, with capillary holes with a diameter of not more than 2 mm and a density of at least 50 holes / m, and the lower part of the inner pipe 10 does not allow water to pass. The outer pipe 11 has a hydrophilic surface with a degree of hydrophilicity of at least 99%, capillary holes with a diameter of not more than 2 mm and a density of not less than 50 holes / m, and a packer 12 is installed in the lower part of the filter 9 between the casing 5 and the outer pipe 11 for sealing given space. Between the outer 11 and inner 10 pipes of the filter 9 in the lower part leave a space 13 for the passage of fluid.

These extreme values were identified by studies that showed that in the vast majority of cases, with these parameters, depression in the wellbore allows water to penetrate through the surface of the outer pipe 11 with holes with a hydrophilic coating, and oil through the surface of the inner pipe 10 with holes with a hydrophobic coating . In this case, oil does not penetrate through the surface with holes with a hydrophilic coating, and water does not penetrate through the surface with holes with a hydrophobic coating.

Moving from the reservoir 1 along the borehole 4, the fluid enters the space 13 between the inner 10 and outer 11 of the filter pipes 9. Here, the fluid is filtered through the capillary holes of the pipes 10 and 11, being separated into oil and water. Water, falling into the inner pipe 10 and then into the pipe string 8, rises to the surface with the pump 14. Oil falling through the outer pipe 11 into the annulus with the casing 5, the pump 15 is pumped into the upper layer 2.

Above formation 2, it is possible to install a packer 16 to prevent corrosion of the casing 5. In this case, the packer 16 must have a sealed hole for the passage of the cable of the pump 15.

Injection of water from the lower layer to the upper must be carried out with the compatibility of their formation water, in order to avoid the loss of salts. Or add reagents against the loss of salts (in this case, the packer 16 is not installed).

Similar operations are carried out in other wells. Thus, a development system is created in which the production wells of the lower formation 1 are simultaneously injection wells of the upper formation 2.

Development is carried out until the full economically viable development of deposits.

The result of the implementation of this method is to increase the efficiency of separation of oil and water in the wellbore, increase the efficiency of water flooding and, as a result, increase the oil recovery of the reservoir.

An example of a specific implementation of the method

The oil reservoir area, represented by the lower 1 and upper 2 productive formations (Fig. 1), with a terrigenous type of reservoir and separated by a clay layer of non-reservoir 3, is opened by a vertical well 4. Formation 1 with an effective oil-saturated thickness of 6 m lies at a depth of 1650 m, the reservoir 2 with an effective oil saturated thickness of 5 m lies at a depth of 1610 m.

Well 4 is cased with a column 5 with a diameter of 168 mm, cemented with a cement ring 6 and re-opened by perforation 7 in the productive formations 1 and 2.

Preliminary studies of the compatibility of formation waters of both layers showed the possibility of their mutual use for the purpose of maintaining reservoir pressure.

Filter 9 is lowered into the wellbore 4 between the upper 2 and lower 1 layers on a tubing string 8 with a diameter of 60 mm. Filter 9 is a pipe in a pipe and has the following structure (Figs. 1, 2, 3): inner pipe 10 with a diameter of 60 mm has a hydrophobic surface with a degree of hydrophobicity of 99% (product of the company "Quartz", brand K1-ZGF; the surface is obtained by diluting this product with hydrocarbon-based paint, applying to the surface and subsequent drying), capillary holes with a diameter of 2 mm and density 50 holes / m Rich lower portion of the inner tube 10 does not allow water to pass. Outer pipe 11 with a diameter of 102 mm has a hydrophilic surface with a degree of hydrophilicity of 99% (product of the company "Quartz", brand K1-ZFS; the surface is obtained by diluting this product with water-based paint, applying to the surface and subsequent drying), capillary holes with a diameter of 2 mm and a density of 50 holes / m, and in the lower part of the filter 9, a packer 12 is installed between the casing 5 and the outer pipe 11 to seal this space. Between the outer 11 and inner 10 pipes of the filter 9 in the lower part leave a space 13 for the passage of fluid.

Above the formation 2, a packer 16 is installed with a sealed hole for the passage of the cable of the pump 15.

The well is put into operation. Moving from the reservoir 1 along the borehole 4, the fluid enters the space 13 between the inner 10 and outer 11 of the filter pipes 9. Here, the fluid is filtered through the capillary holes of the pipes 10 and 11, being separated into oil and water. Water, falling into the inner pipe 10 and then into the pipe string 8, rises to the surface with the pump 14. Oil falling through the outer pipe 11 into the annulus with the casing 5, the pump 15 is pumped into the upper layer 2.

Similar operations are carried out in other wells. Thus, a development system is created in which the production wells of the lower formation 1 are simultaneously injection wells of the upper formation 2.

Development is carried out until the full economically viable development of deposits.

As a result, during the development of the reservoir, which was limited by the watering of production wells to 98%, a total of 148.5 thousand tons of oil was produced from one element, which includes one production well and, correspondingly, the same injection well in each formation (including 90 , 2 thousand tons - from the lower layer 1, 58.3 thousand tons - from the upper layer 2 due to water injection) over 35 years of development, the oil recovery ratio (CIN) was 0.312. According to the prototype, ceteris paribus, 130.4 thousand tons of oil was produced (including 85.8 thousand tons - from the lower layer 1, 44.6 thousand tons - from the upper layer 2 due to water injection) for 30 years of development, CIN amounted to 0.274. According to the prototype, the well was flooded to 98% 5 years earlier than by the proposed method. The increase in recovery factor by the proposed method is -0.038.

The proposed method allows to increase the CIN.

The application of the proposed method will solve the problem of increasing the efficiency of oil and water separation in the wellbore, increasing the efficiency of water flooding and, as a result, increasing the oil recovery of the reservoir.

Claims (1)

A method of developing a multilayer oil reservoir, including lowering a pipe string with a filter below the liquid level in the well into the well of the producing well, taking products from the formation, separating oil and water in the well, pumping water into another formation, raising the oil to the surface, characterized in that the filter is a pipe in a pipe, the inner pipe has a hydrophobic surface with a degree of hydrophobicity of at least 99%, capillary holes with a diameter of not more than 2 mm and a density of at least 50 holes / m, the lower part of the inner pipe would not allow water to pass, the outer pipe has a hydrophilic surface with a degree of hydrophilicity of at least 99%, capillary holes with a diameter of not more than 2 mm and a density of at least 50 holes / m, and a packer is installed between the casing and the outer pipe in the lower part of the filter sealing of this space, and between the outer and inner pipes of the filter at the bottom, leave space for the passage of fluid, moving from the reservoir along the wellbore, the fluid enters the space between the inner and filter pipes, where it is filtered through capillary holes, separating into oil, which, getting into the inner pipe and then into the pipe string, is pumped to the surface by the pump, and water, which, falling through the outer pipe into the annular space with the casing, is pumped into upper layer.

Images