RU2382181C1 - Well operation method - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: during well operation execute separate oil pumping from a top oil reservoir to daylight surface with a top pump, installed on the operation regime maximum working height, and water into reservoir's water saturated bottom area, or underlying water absorbing layer with a bottom centrifugal pump, directed downwards, which has a tail with parker from the bottom, installed over the water absorbing layer roof or in the reservoir bottom area. Select top and bottom pumps production rates ratio dependant on amount of supplied into the well oil and water ratio. Select pumps total capacity according to formation fluid oil/water separation condition and pumping with the bottom pump of water, without oil content. Between top and bottom pumps, on the depression regime operation depth locate a medium centrifugal pump with a capacity, greater the top pump's one. Change well production regime to well depression regime periodically, for that disconnect the top pump and turn on medium and bottom pumps. Preliminary perforate the water saturated bottom area or the water absorbing layer lower than water-oil contact, at distance not less 5 m. Create 2 groups of holes, in the tubing string, between pumps. Locate the bottom group of holes over the reservoir perforation area, at distance in a range from 50 up to 100 m. Locate the top group of holes on a distance from the bottom group of holes in a range from 50 up to 300 m.

EFFECT: minimises oil reservoir product watering and content of oil pumped into the water saturated bottom area or accompanying water to the bottom lifts, depression in the production reservoir.

1 ex, 1 dwg

Description

The invention relates to the oil industry and may find application at the same time separately producing oil and produced water in the well.

A known method of developing an oil reservoir, including the selection of fluid through production wells, pumping a working agent through injection wells, periodic depression in production wells without stopping submersible downhole pumping equipment, and periodic restoration of the equilibrium filtration mode. Production wells are equipped with two deep pumps of different capacities. A pump of lower capacity is placed on top of the working depth of the equilibrium filtration mode. A pump with a higher capacity is placed at the bottom at the working depth of the depression mode. The equilibrium filtration mode provides a pump with a lower capacity when the pump is turned off with a higher capacity. The depression mode provides the pump with higher performance when the pump is turned off with lower productivity and with a decrease in the liquid level in the well below the working depth of the equilibrium filtration mode. In this case, when switching from the depression mode to the equilibrium filtration mode, the upper pump is put into operation immediately after reaching the liquid level in the well, the pump depth of the lower productivity, while maintaining the liquid flow in the well (RF patent No. 2320860, published. 2008.03.27).

The method does not allow to separate the produced products in the well into oil and water and to direct water to the water-saturated plantar region of the formation or the underlying aquifer. A well only works as a producing well.

Closest to the proposed invention in technical essence is a method of oil production, comprising separate pumping from a reservoir through a well of oil to the surface and water to the underlying horizon with two pumps installed at different depths. As the lower pump, an electric centrifugal pump is used, facing down and having a shank from below with a packer installed above the roof of the formation into which water is pumped, or lower. The upper pump is installed at maximum height. The ratio of the productivity of the lower and upper pumps is selected depending on the ratio of the amount of water and oil entering the well, and the total productivity of the pumps is selected from the conditions of gravity separation of the formation fluid in the well into oil and water and pumping of oil-free water with the lower pump (RF patent No. 2290497 , published. 2006.12.27 - prototype).

The known method provides combining in one well the functions of the producing and injection wells and returning part of the produced water back to the reservoir to maintain reservoir pressure without raising it to the surface. However, the method does not allow minimizing the water cut of the produced oil and the oil content of the produced water injected into the lower horizons, as well as causing periodic depression in the reservoir.

The proposed invention solves the problem of minimizing the water cut of produced products from an oil-saturated well formation and the oil content in the water injected into the water-saturated plantar area of the formation or lower horizons of incidentally produced water, as well as conducting depression in the producing formation.

The problem is solved in that in the method of operating the well, comprising separately pumping oil from the upper productive formation to the day surface with an upper pump installed at the maximum operating height of the operating mode, and water into the water-saturated plantar region or the underlying water-absorbing formation with the lower electric centrifugal pump facing down and having a bottom shank with a packer installed above the roof of the water-absorbing layer or in the plantar region of the formation, with a lower productivity ratio the first and the upper pumps, selected depending on the ratio of the amount of water and oil entering the well, and the total pump capacity, selected from the condition of gravitational separation of the formation fluid in the well into oil and water and pumping oil-free water according to the invention between the lower pump between the upper and lower pumps at the working depth of the depression mode place an average electric centrifugal pump with a capacity greater than that of the upper pump, periodically change the operating mode wells for the depression mode, for which the upper pump is turned off and the middle and lower pumps are turned on, while the water-saturated bottom area of the formation or the water-absorbing formation is pre-punched below the oil-water contact at a distance of at least 5 m, two groups of holes are made in the tubing string between the pumps : the lower group of holes is placed above the perforation of the reservoir at a distance in the range from 50 to 100 m, the upper group of holes is placed at a distance from the lower group of holes in the range from 50 to 300 m.

The features of the invention are:

1) separate pumping from the upper reservoir of oil to the day surface by the upper pump installed at the maximum working height of the operating mode;

2) separate pumping of water into the water-saturated bottom area of the formation or the underlying water-absorbing layer by the lower electric centrifugal pump, facing down and having a shank from below with a packer installed above the roof of the water-absorbing layer or in the bottom of the formation;

3) the ratio of the productivity of the lower and upper pumps, selected depending on the ratio of the amount of water and oil entering the well;

4) the total performance of the pumps, selected from the conditions of gravity separation of the formation fluid in the well into oil and water and pumping water containing no oil with the lower pump;

5) placement between the upper and lower pumps at the working depth of the depression mode of the middle electric centrifugal pump with a capacity greater than that of the upper pump;

6) a periodic change in the mode of operation of the well to a mode of depression;

7) turning off the upper pump and turning on the middle and lower pumps;

8) preliminary perforation of the water-saturated bottom area of the formation or water-absorbing layer below the oil-water contact at a distance of not less than 5 m;

9) the implementation in the string of tubing between the pumps of two groups of holes;

10) the placement of the lower group of holes above the perforation of the reservoir at a distance ranging from 50 to 100 m;

11) the placement of the upper group of holes at a distance from the lower group of holes in the range from 50 to 300 m

Signs 1-4 are common with the prototype, signs 5-11 are the essential distinguishing features of the invention.

SUMMARY OF THE INVENTION

The combination of the functions of the producing and injection wells and the return of the main part of the produced water back to the formation without raising it to the surface leads to water injection with part of the oil and oil production with a large amount of water. In addition, such operation of the well leads to an increase in water cut in the produced products. The proposed method solves the problem of minimizing the water cut of the produced oil and the oil content of the produced water injected into the lower horizons. The problem is solved as follows.

The drawing shows the applicable layout. When separately pumping oil from the perforated reservoir 1 through the well 2 to the surface and water into the water-saturated plantar region 3 using two pumps installed at different depths, an electric centrifugal pump 4 is used as the lower pump, facing downward and having a shank 5 with packer 6 installed above the perforation holes 7 of the reservoir 3 into which water is injected. Packer 6 is placed at the lowest possible mark above or in the interval of the water-saturated plantar region 3, into which the associated water is injected, which helps to create the largest volume in the well 2 in which the formation fluid is separated into oil and water. Perforation 7 of the well 2 is carried out in the interval of the water-absorbing formation 3 at a distance “a” from the oil-water contact 8. The distance “a” is at least 5 m. This distance allows the packer to be placed and ensures that water is not pumped into the upper oil-saturated part of the formation. The upper pump 9 is installed at maximum height. The tubing string connecting the pumps 4 and 9 is perforated with two groups of holes. The lower group of holes 10 is placed above the perforation 11 of the reservoir 1 at a distance of "b". The distance "b" is carried out in the range from 50 to 100 m. This distance guarantees from direct oil flow into the water-saturated part of the reservoir. The upper group of holes 12 is placed at a distance "in" from the lower group of holes 10 in the range from 50 to 300 m. This placement creates the conditions for the separation of liquid into oil and water.

Between the upper 9 and lower 4 pumps at the working depth of the depression mode, an average 13 electric centrifugal pump is installed with a capacity greater than that of the upper pump 9. The upper pump is selected so that it allows fluid to flow through the pump when it is turned off. As a rule, sucker rod pumps correspond to this condition.

When operating wells in oil production mode, the upper 9 and lower 4 pumps are included in the operation. Periodically change the operating mode of the well to the depression mode, for which the upper 9 pump is turned off and the middle 13 and lower 4 pumps are turned on. Due to the greater productivity of the pump 13 create a depression on the oil-saturated formation 1.

As a result of depression, the bottom-hole zone is cleared and the overall well production increases, productive tongues of formation fluids are pulled to the well and the water cut of the produced products is reduced.

Formations 1 and 3 can be isolated from each other or combined into one formation.

As the upper pump 9, sucker-rod pumps of the type 25-175-RHAM-12-4-2-2 can be used, as the middle pump 13, higher-performance pumps of the ETsN5A-400-1050 type can be used, as the lower pump 4, facing down - pumps type ЭЦНМ5-80-1300.

Concrete example

A well 2 is operated at a depth of 1300 m, which uncovered the productive formation 1 at a depth of 800 m and the aquifer 3 at a depth of 830 m. From the productive formation 1, formation fluid with a water cut of 70% is extracted. In well 2, at the maximum possible height at a depth of 450 m, an upper sucker-rod pump 9 of type 25-175-RHAM-12-4-2-2 is placed, capable of supplying fluid from the well with a flow rate of 8 -15 m ³ / day. As the average pump 13, use the pump type ETsN5A-250-1050 with a productivity of 250-300 m ³ / day and place it at a depth of 630 m.

As the lower electric centrifugal pump 4, a pump of the UETSNM5-30-1300 brand is used, capable of supplying fluid from the well with a flow rate of 30-35 m ³ / day. The pump is installed at a depth of 805 m, it is facing down and has a shank 5 with a packer 6 installed below the perforations 7 of the formation 3 into which water is pumped. Packer 6 is positioned at 815 meters, i.e. the lowest possible mark in the interval of the water-absorbing formation 3. Perforation 7 of the well 2 is carried out in the interval of the water-saturated plantar region of the formation 3 at a distance “a” equal to 10 m from the oil-water contact 8. The tubing string connecting the pumps 4, 9 and 13, perforated with two groups of holes. The lower group of holes 10 is placed above the perforation 11 of the reservoir 1 at a distance of "b" equal to 50 m. The upper group of holes 12 is placed at a distance of "c" from the bottom group of holes 10, equal to 100 m.

During the operation of the wells, separate oil is pumped from the upper producing formation 1 to the day surface with an upper pump of type 25-175-RHAM-12-4-2-2 and water into the underlying water-absorbing formation with a lower electric centrifugal pump of type UETsNM5-30-1300. The total performance of the pumps is selected from the conditions of gravitational separation of the formation fluid in the well into oil and water and pumping of oil-free water with the lower pump. With a decrease in the current flow rate of the well and an increase in the water content of the produced products, the well is transferred from the operating mode to the depression mode, for which the upper pump 9 is turned off and the middle 13 pump of the ЭЦН5А-250-1050 type is turned on with the lower pump working 4. When the bottomhole pressure decreases from 8 MPa to 4 MPa are returned to the well operation mode, for which all pumps are turned off, technological shutter speed is held to restore the liquid level in the well, and the upper 9 and lower pump 4 are turned on.

Compared with the prototype, oil production increases, ceteris paribus, by 15%, water cut of extracted products is reduced by 8%.

The application of the proposed method will allow to solve the problem of minimizing the water cut of the produced oil and the oil content in the produced water injected into the lower horizons, as well as conducting depression in the reservoir.

Claims (1)

A method of operating a well, including separately pumping oil from the upper productive formation to the surface by an upper pump installed at the maximum working height of the operating mode, and water into the water-saturated plantar area or the underlying water-absorbing formation by the lower electric centrifugal pump, facing down and having a shank with a packer below, installed above the roof of the water-absorbing layer or in the plantar area of the formation, with a ratio of the productivity of the lower and upper pumps, under wound depending on the ratio of the amount of water and oil entering the well, and the total productivity of the pumps, selected from the condition of gravitational separation of the formation fluid in the well into oil and water and pumping water containing no oil with the lower pump, characterized in that between the upper and lower pumps at the working depth of the depression mode, an average electric centrifugal pump is placed with a productivity higher than that of the upper pump, the well operation mode is periodically changed to the depression mode why turn off the upper pump and turn on the middle and lower pumps, while pre-perforating the water-saturated sole area of the formation or the water-absorbing layer below the oil-water contact at a distance of at least 5 m, two groups of holes are made in the string of tubing between the pumps: the lower group of holes is placed above the perforation of the reservoir at a distance ranging from 50 to 100 m, the upper group of holes is placed at a distance from the lower group of holes in the range from 50 to 300 m

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