RU2540714C1 - Oil deposit development method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method involves lowering to a shaft of a production well below a liquid level of a pipe string with pumps, as well as with filters installed on pipe ends, recovery of the product from the lower productive formation, separation of oil and water in the well shaft, water pumping to the upper formation, and oil lifting to the surface. Into the well there lowered are two filters below the upper formation, each on an individual pipe string. Filters represent pipes with capillary holes with a diameter of not more than 2 mm and density of at least 50 holes per metre. With that, one filter on the pipe string has a hydrophobic surface with a degree of hydrophobic properties of at least 99%, and the other filter on the other pipe string has a hydrophilic surface with a degree of hydrophilic properties of at least 99%. The upper formation is cut off from above and from below with packers so that no liquid can flow via an annular space from the lower formation to the upper formation, and the pipe string with a filter with a hydrophilic surface is perforated opposite the upper formation. Liquid is filtered through the capillary holes of the filters, thus being separated into oil and water.

EFFECT: reduction of water flooding of the recovered product and increase of oil recovery of a productive formation.

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Description

The invention relates to the oil industry and can find application in the development of oil deposits with two or more layers, which coincide in structural terms, 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. In addition, 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 ЕВВ 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. Е21В 43/12, Е21В 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 method also does 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 an oil reservoir, which includes lowering the pipe string with pumps and filters installed at the pipe ends into the wellbore below the fluid level, selecting products from the lower reservoir, separating oil and water in the wellbore, injecting water in the upper layer, the rise of oil to the surface, according to the invention, two filters are lowered into the well below the upper layer, each on a separate pipe string, the filters are pipes with capillary holes with a diameter of not more than 2 mm and a density of at least 50 holes / m, moreover, one filter on the pipe string has a hydrophobic surface with a degree of hydrophobicity of at least 99%, and the other filter on the other pipe string has a hydrophilic surface with a degree of hydrophilicity of at least 99%, the upper layer is cut off above and below the packers, so that the liquid cannot flow into the upper layer along the annulus from the lower layer; opposite the upper layer, the pipe string with a filter with a hydrophilic surface is perforated, moving from the lower productive layer about the wellbore, the liquid is filtered through the capillary openings of the filters, separating into oil, which, getting through the filter with a hydrophobic surface into the pipe string, is pumped to the surface by the pump, and water, which, through the filter with the hydrophilic surface, into the other pipe string is pumped into the upper layer through perforations in the pipe string opposite the given 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, they 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. 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, 9 - pipe strings, 10 - a filter with a hydrophobic surface, 11 - a filter with a hydrophilic surface, 12 - a pump for lifting well (oil) products to the surface, 13 - a pump for pumping water into the upper formation 1, 14 - packers between the casing 5 and pipe columns 8 and 9, 15 - perforation holes in the pipe string 9 opposite upper layer 2, 16 - packer in the pipe string 9.

The method is implemented as follows.

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

Filters 10 and 11 are lowered into the borehole 4 between the upper 2 and lower 1 layers on the pipe columns 8 and 9, respectively. Also, the pumps 12 and 13 are lowered into the pipe columns 8 and 9 above the filters.

Filters 10 and 11 (figures 1, 2) are pipes with capillary holes with a diameter of not more than 2 mm and a density of at least 50 holes / m. The filter 11 on the pipe string 9 has a hydrophilic surface with a degree of hydrophilicity of at least 99%. The filter 10 on the pipe string 8 has a hydrophobic surface with a degree of hydrophobicity of at least 99%. These surfaces are obtained by applying stable formulations (hydrophilic or hydrophobic), or the filters are made from appropriate materials.

These extreme values were identified by studies that showed that in the vast majority of cases, with such parameters, depression in the wellbore allows water to penetrate through the surface of the filter 11 with holes with a hydrophilic coating, and oil through the surface of the filter 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.

The upper layer 2 is cut off from above and from below by packers 14, so that liquid cannot flow into the upper layer 2 along the annulus from the lower layer 1.

Opposite the upper layer 2, the pipe string 9 with the hydrophilic surface of the filter 11 is perforated 15.

Moving from the lower reservoir 1 along the borehole 4, the fluid is filtered through the capillary holes of the filters 10 and 11, being divided into oil, which, getting through the filter 10 with a hydrophobic surface into the pipe string 8, pump 12 rises to the surface, and water, which getting through the filter 11 with a hydrophilic surface into the pipe string 9, the pump 13 is pumped into the upper layer 2.

Above the formation 2, it is possible to install the packer 16 in the pipe string 9 to prevent corrosion. In this case, the packer 16 must have a sealed hole for the passage of the cable of the pump 13.

Water injection from the lower layer 1 to the upper 2 should be carried out only if their formation water is compatible, 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 the sterrigene type of the reservoir and separated by the clay layer of not the reservoir 3, is opened by a vertical well 4. Formation 1 with an effective oil-saturated thickness of 8 m lies at a depth of 1690 m, formation 2 with an effective oil saturated thickness of 6 m lies at a depth of 1635 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.

Filters 10 and 11 are lowered into the borehole 4 between the upper 2 and lower 1 layers on the tubing strings 8 and 9 with a diameter of 60 mm, respectively. Also, pumps 12 and 13 are lowered into the tubing strings 8 and 9 above the filters.

Filters 10 and 11 (figures 1, 2) are pipes with capillary holes with a diameter of not more than 2 mm and a density of at least 50 holes / m. The filter 11 on the pipe string 9 has a hydrophilic surface with a degree of hydrophilicity of at least 99%. The filter 10 on the pipe string 8 has a hydrophobic surface with a degree of hydrophobicity of at least 99%. These surfaces are obtained by applying stable formulations: hydrophilic (product of the company "Quartz" brand K-3SF) or hydrophobic (the product of the company "Quartz" brand K1-3GF). To do this, dilute the hydrophilic powder with water-based paint, apply it to the surface and wait for drying, similarly act with a hydrophobic powder, which is diluted in a hydrocarbon-based paint.

The upper layer 2 is cut off from above and from below by packers 14, so that liquid cannot flow into the upper layer 2 along the annulus from the lower layer 1.

Opposite the upper layer 2, the pipe string 9 with the hydrophilic surface of the filter 11 is perforated 15.

Above the formation 2, a packer 16 is installed in the pipe string 9, which has a sealed hole for the passage of the pump cable 13.

The well is put into operation. Moving from the lower reservoir 1 along the borehole 4, the fluid is filtered through the capillary holes of the filters 10 and 11, being divided into oil, which, getting through the filter 10 with a hydrophobic surface into the pipe string 8, pump 12 rises to the surface, and water, which getting through the filter 11 with a hydrophilic surface into the pipe string 9, the pump 13 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 159.1 thousand tons of oil were produced from one element, including one production well and, accordingly, the same injection well in each formation (including 96 , 5 thousand tons - from the lower layer 1, 62.6 thousand tons - from the upper layer 2 due to water injection) over 34 years of development, the oil recovery ratio (CIN) was 0.313. According to the prototype, ceteris paribus, 139.8 thousand tons of oil was produced (including 89.5 thousand tons - from the lower layer 1, 50.3 thousand tons - from the upper layer 2 due to water injection) for 29 years of development, CIN amounted to 0.275. 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 an oil reservoir, including lowering pipe columns with pumps and filters installed at the ends of the pipes into the wellbore, taking products from the lower reservoir, separating oil and water in the wellbore, injecting water into the upper reservoir, raising oil on the surface, characterized in that two filters are lowered into the well below the upper layer, each on a separate pipe string, the filters are pipes with capillary holes with a diameter of not more than 2 mm and a density of not less than 50 TV / m, and one filter on the pipe string has a hydrophobic surface with a degree of hydrophobicity of at least 99%, and another filter on the other pipe string has a hydrophilic surface with a degree of hydrophilicity of at least 99%, the upper layer is cut off from the top and bottom by packers, so that along the annulus from the lower reservoir, the fluid cannot flow into the upper reservoir; opposite the upper reservoir, the pipe string with a filter with a hydrophilic surface is perforated, moving from the lower reservoir along the borehole, the fluid it is filtered through the capillary openings of the filters, separating into oil, which, getting through the filter with a hydrophobic surface into the pipe string, is pumped to the surface by the pump, and water, which, getting through the filter with the hydrophilic surface into another pipe string, is pumped into the upper layer through perforations holes in the pipe string opposite the formation.