RU2290497C1 - Oil extraction method - Google Patents

Abstract

FIELD: oil industry, possible use during simultaneously separate extraction of oil and bed water in the well.

SUBSTANCE: method includes separate draining from productive bed through well of oil onto day surface and of water into lower level by two pumps, mounted at various depths. In accordance to method, as lower pump, electric centrifugal pump is used, directed downwardly and having tail with packer on lower part, packer being mounted above ceiling of formation into which water is forced, or lower. Upper pump is mounted at maximal height. Ratio of productiveness for lower and upper pumps is selected depending on ratio of amount of water and oil coming into well. Total productiveness of pumps is selected from condition of gravitational division of bed liquid in well onto oil and water and draining water without any oil by lower pump. Emulsion breaker is dosed into space between lower and upper pumps.

EFFECT: minimization of water presence in extracted oil and oil presence in water extracted collaterally and fed into lower levels.

2 cl, 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 of the reservoir type, according to which they carry out the drilling of vertical wells and horizontal lateral shafts from them. First, a vertical well is drilled. Open the perforated reservoir. Oil from the reservoir is recovered until the reservoir is depleted. Then they drill a lateral horizontal trunk. The horizontal well exit point is located below the dynamic fluid level in the well. The same reservoir is perforated in the sidetrack. Then, a double-acting pump is installed in the vertical shaft. The oil pump intake is positioned above the sidetrack exit point. A water pump intake is positioned below the sidetrack exit point. The pump is equipped with a shank with a packer. It is installed in the interval from the point of departure to the roof of the reservoir in a vertical trunk. The well is operated in such a way that the water that came with the oil from the lateral horizontal well is pumped into the same formation through a vertical well without lifting it to the surface (RF Patent No. 2179234, publ. 02/10/2002).

The method provides combining the functions of 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 requires for its application special drilling of a horizontal shaft, which increases the cost and complicates the method.

Closest to the proposed invention in technical essence is a method of raising well products and injecting a working agent into the formation, which consists in pumping oil and water separately or in a predetermined combination of them from two wells with deep pumps installed at different depths in the upper and lower chambers -accumulators, in which oil and water respectively enter, in which oil enters from the upper side of the chamber and flows downward to the pumping pump, and water flows from the lower side of the chamber, along the “shank”, from which it enters through a tube ending in the upper part of the storage chamber, which is connected by an annular space formed between the hollow rod connecting the lower pump pump to the motor pump, and a part of the lifting pipe string located concentrically to the hollow rod connected to the upper chamber - a reservoir through which oil can float, which can then be pumped out through separate channels on the surface of the earth, or oil - to the surface of the earth, and water along the annular channel down, below the oil-water contact and into the reservoir or in a horizontal borehole in its remote area, towards the bottom portion of the oil bearing reservoir (Application for RF invention №98106980 / 03, class. E 21 B 43/00, publ. 02/10/2000 - 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 to minimize the water cut of the produced oil and the oil content of the produced water injected into the lower horizons.

The proposed invention 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 in that in a method of oil production, including separate pumping from a reservoir through a well of oil to the surface and water to the underlying horizon by two pumps installed at different depths, according to the invention, an electric centrifugal pump facing down and having a bottom is used as the lower pump a shank with a packer installed above the roof of the formation into which water is injected or lower, the upper pump is installed at the maximum height, the ratio of productivity is lower th and the upper pump is adjusted depending on the ratio of incoming water into the well and oil, and the overall performance of the pumps are chosen from the condition of gravitational separation of produced fluid in oil wells, and water and a lower pump pumping water containing no oil.

In the space between the lower and upper pumps, dosing of the demulsifier is possible.

The features of the invention are:

1. separate pumping from the reservoir through the oil well to the surface and water to the underlying horizon by two pumps installed at different depths;

2. use as the bottom pump of an electric centrifugal pump;

3. the location of the electric centrifugal pump as facing down;

4. the presence of a shank under the electric centrifugal pump;

5. the same with the packer;

6. the same installed above the roof of the reservoir into which water is injected, or lower;

7. installation of the upper pump at maximum height;

8. the ratio of the productivity of the lower and upper pumps, depending on the ratio of the amount of water and oil entering the well;

9. selection of the total performance of the pumps 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.

10. dosing of the demulsifier into the space between the lower and upper pumps.

Sign 1 is common with the prototype, signs 2-9 are significant distinguishing features, sign 10 is a private feature of the invention.

SUMMARY OF THE INVENTION

Combining the functions of the producing and injection wells and returning part of the produced water back to the reservoir without raising it to the surface leads to water injection with part of the oil and oil production with a large amount of water. 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 underlying reservoir 3 by two pumps installed at different depths, an electric centrifugal pump 4 is used as the lower pump, facing down and having a shank 5 with packer 6 installed below above the roof 7 of the formation 3, into which water is injected, or lower. The location of the packer 6 at the lowest possible mark (in particular, below the roof 7 of the formation 3 into which water is injected) helps to create the largest volume in the well 2 in which the formation fluid is separated into oil and water. The packer 6 can be installed at the bottom 8 of the formation 3. Perforation 9 of the casing 10 of the well 2 is carried out under the packer 6 in the formation 3. The upper pump 11 is installed at the maximum height. The input 12 to the upper pump 11 and the input 13 to the lower pump 4, i.e. the holes in the pipe string 14 connecting the pumps 4 and 11 are placed near the pumps 4 and 11. The separation of the pumps 4 and 11 to the maximum height helps to create the maximum space for the separation of the formation fluid into oil and water. The ratio of the productivity of the lower 4 and upper 11 pumps is selected depending on the ratio of the amount of water and oil entering the well. This prevents the involvement of one fluid in the production of another. The total performance of pumps 4 and 11 is selected from the conditions of gravity separation of the formation fluid in the well into oil and water and pumping lower oil 4 of oil-free water. With this overall performance, conditions are created for the most complete separation of oil and water. In addition, based on the condition that some part of the oil emulsion inevitably remains in the well 2, this emulsion is directed by the upper pump 11 to the day surface. Due to this, it is possible to avoid oil losses and pump mainly water without oil into the lower pump 4. To ensure better separation of the borehole fluid into the space between the lower 4 and upper 11 pumps, it is possible to dose a demulsifier, for example, delivered from the wellhead through a thin sleeveless tube of a coiled tubing installation (not shown in the drawing) or from a container located in this space (not shown in the drawing )

As the upper pump 11, it is possible to use a sucker rod, electric centrifugal pump, etc. Layers 1 and 3 can be isolated from each other, as shown in the drawing, or combined into one layer.

Concrete example

A well 2 is operated at a depth of 1,500 m, which uncovered the productive formation 1 at a depth of 800 m and the aquifer 3 at a depth of 815 m. From the productive formation 1, formation fluid with a water cut of 50% is extracted. In the well 2, at the maximum possible height at a depth of 450 m, the upper sucker-rod pump 11 of the NN2B-44 brand is placed. The lower electric centrifugal pump 4 of the UECNM5-30-1300 brand, facing downward and having a shank 5 with a packer 6 below, is installed above the roof 7 of the aquifer 3 at a depth of 1450 m. The inlet 12 to the upper pump 11 and the inlet 13 to the lower pump 4 are placed near the pumps 11 and 4. The ratio of the productivity of the lower 4 and upper 11 pumps is selected depending on the ratio of the amount of water and oil entering the well, i.e. set equal. The total productivity of pumps 4 and 11 is selected from the conditions of gravitational separation of the formation fluid in the well 2 into oil and water and pumping the bottom pump 4 of water containing no oil. In this case, the total capacity of pumps 4 and 11 is 40 m ³ / day. With this overall performance, the formation fluid manages to separate in the space of the well 2 between the pumps 4 and 11 into oil and water. Based on the condition that some part of the oil emulsion inevitably remains in well 2, in order to avoid oil losses, the produced oil is analyzed and the residual water is determined. The decrease in the amount of water in oil indicates incomplete selection of the oil emulsion by the upper pump 11. In this case, the productivity of the upper pump 11 is increased or a demulsifier is delivered into the well 2 in the space between the pumps 44 and 11. Due to this, it is possible to avoid oil losses and pump mainly water without oil into the lower pump 4. As a result, it is possible to minimize the water cut of the produced oil and the oil content in the produced water injected into the lower horizons.

Compared with the prototype, oil production increases ceteris paribus by 15-20%.

Claims (2)

1. A method of oil production, including separate pumping from a reservoir through a well of oil to the surface and water to the underlying horizon by two pumps installed at different depths, characterized in that the lower pump uses an electric centrifugal pump, facing down and having a liner with a bottom a packer installed above the roof of the formation into which water is injected or lower, the upper pump is installed at the maximum height, the ratio of the productivity of the lower and upper pumps under they are 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 condition of gravitational separation of the formation fluid in the well into oil and water and pumping of oil-free water with the lower pump. 2. The method according to claim 1, characterized in that a demulsifier is dosed into the space between the lower and upper pumps.