RU2761792C1 - Device and method for separating produced water purified from impurities on oil well clusters - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry, namely to technologies for field preparation of oil well products, and can be used on the pads of oil wells of an oil field. The device contains a sealed cavity with at least five pipelines. The first pipeline is configured to supply an oil and gas-liquid mixture, the second pipeline is configured to take oil and gas-liquid mixture, the third pipeline is configured to take associated water and the fourth pipeline is configured to collect settled impurities from the sealed cavity, the fifth pipeline is equipped with a gas pressure regulator and is configured to gas sampling. The outlet into the sealed cavity from the first pipeline is located above the outlet from the third pipeline and below the outlet from the second pipeline. The outlet into the sealed cavity from the fourth pipeline is located below the outlet from the third pipeline. The outlet into the sealed cavity from the fifth pipeline is located below the outlet from the second pipeline.

EFFECT: increasing the efficiency of separating the produced water, ensuring the possibility of eliminating settled impurities by creating a pressure difference between the inlet and outlet of the pipe string in the upper part of the device, the continuity of the device.

15 cl, 1 dwg, 2 tbl

Description

The invention relates to the oil and gas industry, namely to technologies for field preparation of oil well products, and can be used on the pads of oil wells of an oil field.

Known technical solution "Separation plant" according to the patent of the Russian Federation No. 2296609 (IPC B01D 19/00, publication date 10.04.2007). Common features with the proposed invention are pipelines for supplying a gas-liquid mixture, removing separated water and gas.

The disadvantages are that a constant round-the-clock presence of personnel at the installation is required; high metal consumption; the installation takes up a large area, it is necessary to expand the area of the well cluster; difficult to regulate the process; the installation does not work with a high gas factor; significant decrease in the temperature of the oil-gas-liquid mixture when passing through the unit.

Known technical solution "Method of cluster discharge and disposal of produced water" according to RF patent No. 2548459 (IPC E21B 43/20, publication date 04/20/2015). Common features are the supply of products to a borehole installation for preliminary water discharge through the pipeline for supplying an oil and gas-liquid mixture for preliminary water discharge, dividing products into partially dehydrated oil, gas and water.

The disadvantages are the impossibility of placing more than one pipeline in the well with a diameter of sufficient capacity in each direction of fluid movement, insufficient productivity of the installation, the complexity of regulation, the installation is not designed to discharge free associated gas.

The closest in terms of the totality of essential features to the proposed invention is the technical solution "Method for dumping the produced water and gas separately on the well pads of an oil field" according to RF patent No. 2713544 (IPC E21B 43/34, publication date 02/05/2020), in which also a device for implementing the method is implemented.

The general features of the facility are a hermetically sealed cavity in the form of a vertical pipe, pipelines for supplying and withdrawing oil-and-gas mixtures, produced water and free gas hermetically installed in the upper part of the device.

The general features for the object of the method are the top-down feed of the oil-and-gas mixture to the device, the selection of produced water and free gas through separate pipelines with separation from the oil and gas-liquid mixture.

The disadvantages are that the oil and gas-liquid mixture is delivered only to the middle part of the installation, which reduces the distance from the outlet of the oil and gas-liquid mixture into the cavity of the installation to the water inlet into the water conduit, which entails a decrease in the quality of water for oil products; there is no way to clean the bottom of the installation from the settled impurities during its operation.

The objective of the present invention is to effectively separate the produced water from the oil and gas-liquid mixture, as well as to improve the quality of the separated water due to its effective purification from settled impurities without stopping the operation of the device.

The technical result is an increase in the efficiency of separation of the produced water, ensuring the possibility of eliminating settled impurities by creating a pressure difference between the inlet and outlet of the pipe string in the upper part of the device, the continuity of the device operation, the simplicity of the cleaning process, the simplicity of manufacturing the device, the simplicity of the assembly process, and disassembly of the device, the ability to operate the installation with a high gas factor, low metal consumption of the device, no energy costs for the process of separating water and gas in the device, no need for constant monitoring of the operating personnel, ease of maintenance due to the elimination of the need for personnel to clean from settled impurities in a closed space, long period and safety of operation.

The specified technical result is achieved by a device for separating the produced water purified from impurities, including an airtight cavity with at least five pipelines, of which the first pipeline is configured to supply an oil and gas-liquid mixture, the second pipeline is configured to take oil and gas-liquid mixture, the third pipeline is configured to take of produced water, the fourth pipeline is configured to collect settled impurities from the sealed cavity, the fifth pipeline is equipped with a gas pressure regulator and is configured to take gas, the outlet into the sealed cavity from the first pipeline is located above the outlet from the third pipeline and below the outlet from the second pipeline, the outlet into the sealed cavity from the fourth pipeline is located below the outlet from the third pipeline, and the outlet into the sealed cavity from the fifth pipeline is located above the outlet from the second pipeline.

The claimed layout of the pipeline outlets allows to improve the quality of the produced water taken from the device.

Cleaning of the device from settled impurities is carried out during operation without stopping the operation of the device.

The sealed cavity can be made in the form of a pipe with a bottom and a cover.

A casing installed in a well can be used as a pipe.

Due to the immersion of the device in the ground, additional heating of the sealed cavity (device body) of the device is not required, since the heat of the earth is used for heating, which allows the device to be used at low temperatures.

The device may additionally comprise a sixth pipeline hermetically entering the installation, configured to supply an oil and gas-liquid mixture, the outlet into the sealed cavity from which is located above the outlet from the third pipeline and below the outlet from the second pipeline.

The device can be equipped with shut-off valves.

The distance between the outlet from the first pipeline configured to supply the oil and gas-liquid mixture and the outlet from the third pipeline configured to take the produced water can be at least one third of the height of the sealed cavity.

The device can be additionally equipped with a level gauge connected to a sealed cavity.

The device can be made with the possibility of being used on clusters of oil wells.

Possible features of the device can be combined with each other.

The technical result is achieved by a method of separating the produced water purified from settled impurities, in which the oil and gas-liquid mixture is fed into the sealed cavity through the outlet of the first pipeline, the remainder of the oil and gas-liquid mixture is taken from the sealed cavity through the outlet of the second pipeline located above the outlet from the first pipeline, and the incidentally produced water is separated in the sealed cavity. water from the oil and gas-liquid mixture through the outlet of the third pipeline located below the outlet from the first pipeline, the settled impurities are taken from the sealed cavity through the fourth pipeline located below the outlet from the third pipeline, gas is taken from the upper third part of the sealed cavity through the outlet of the fifth pipeline located above the outlet from second pipeline.

The oil-gas-liquid mixture can be fed into the upper third part of the sealed cavity.

The produced water can be separated from the lower third part of the sealed cavity.

The change in the liquid level in the sealed cavity can be carried out by a gas pressure regulator.

Possible features of the method can be combined with each other.

Liquid level control in a sealed cavity can be carried out with a level gauge.

FIG. 1 shows a longitudinal section of the device A-A, where:

1 - sealed cavity,

2 - the first pipeline,

3 - the second pipeline,

4 - the third pipeline,

5 - fourth pipeline,

6 - the fifth pipeline,

7 - gas pressure regulator,

8 - sixth pipeline,

9 - shut-off valves,

10 - level gauge,

11 - wellhead equipment,

12 - settled impurities,

13 - technological point 1,

14 - technological point 2,

15 - technological point 3,

16 - technological point 4,

17 - technological point 5,

18 - technological point 6.

Technological points correspond to the calculated pressure values (table 2).

The separation of the produced water purified from the settled impurities on the clusters of oil wells is carried out as follows.

The device for separating the produced water purified from impurities includes a sealed cavity 1 with at least five pipelines, of which the first pipeline 2 is made with the possibility of supplying an oil and gas-liquid mixture (OGZHS), the second pipeline 3 is made with the possibility of taking OGZHS, the third pipeline 4 is made with the possibility of taking the produced water, the fourth pipeline 5 is made with the possibility of collecting settled impurities from the sealed cavity 1, the fifth pipeline 6 is equipped with a gas pressure regulator 7 and is made with the possibility of gas sampling. The outlet to the sealed cavity 1 from the first pipeline 2 is located above the outlet from the third pipeline 4 and below the outlet from the second pipeline 3, the outlet to the sealed cavity from the fourth pipeline 5 is located below the outlet from the third pipeline 4, and the outlet to the sealed cavity from the fifth pipeline 6 is located above the exit from the second pipeline. In this case, the outlet from the pipeline is understood as any of its open parts communicating with the sealed cavity (perforation zone, window), through which both inlet and outlet can be carried out under various technological modes. The number of pipelines for each purpose can be more than one. The sealed cavity 1 may additionally contain a sixth pipeline 8, made with the possibility of supplying oil-and-gas mixtures. The first pipeline 2 is the main working pipeline, i.e. works at maximum working performance. Switching to the sixth pipeline 8 is performed during emergency or planned shutdowns of oil wells. The outlet from the sixth pipeline 8 into the sealed cavity 1 is located above the outlet from the third pipeline 4 and below the outlet from the second pipeline 3. The sealed cavity 1 can be made in the form of a pipe with a bottom and a cover, and, for example, a casing pipe can be used as a pipe, installed in the well. All pipelines are equipped with shut-off valves 9. The distance between the outlet from the first pipeline 2 and the outlet from the third pipeline 4 is at least one third of the height of the sealed cavity 1. The device is additionally equipped with a level gauge 10 connected to the inner space of the sealed cavity 1. Wellhead valves 11 serves to seal the device from above and to provide a sealed entry of various pipelines.

The proposed device can be used on clusters of oil wells.

The unit was used at the Yuzhno-Kinyaminskoye field, well cluster No. 6. For this, the following initial data were used: physical and chemical properties of oil, gas and water; technical and technological characteristics of the well cluster - productivity for oil, gas and water, pressure on the cluster, the volume of injected water produced along the way. The choice of the object was determined in accordance with the need to separate the produced water.

OGZhS is fed from top to bottom into the sealed cavity 1 through the first pipeline 2, made with the possibility of supplying OGZhS, to the upper third part of the sealed cavity 1. The free gas, having a lower density, rises up inside the sealed cavity 1 and forms a gas-liquid level, while oil accumulates under the gas-liquid level, and the produced water fills the lower part of the sealed cavity 1. Free gas is removed through the gas pressure regulator 7 through the fifth pipeline 6, made with the possibility of gas sampling, outside the device. The change in the gas-liquid level is carried out by regulating the free gas pressure using the gas pressure regulator 7, which removes the free gas when the predetermined gas pressure in the device is reached. The gas-liquid level is measured by means of a level gauge 10, which is connected to the inner space of the sealed cavity 1 and is sealed to the wellhead 11 from the lower third part of the sealed cavity 1 through the third pipeline 4, the associated water is supplied upward outside the device, for example, to the reservoir maintenance system. pressure. The distance between the outlets from the first pipeline 2 and the outlet from the third pipeline 4 is at least one third of the height of the sealed cavity 1. The separation of the produced water is performed due to its gravitational sediment (dynamic sediment) due to the difference in the density of water and oil. Further, from the upper third part of the sealed cavity 1 through the second pipeline 3, installed in the upper part of the installation above the outlet from the first pipeline 2, the remainder of the oil-and-gas mixture rises up and is directed from the sealed cavity 1 outside the device, for example, to the collection system. The rise of the oil and gas wells and associated water through the corresponding pipelines is carried out both due to the energy, which consists of the pressure energy of the oil wells at the entrance to the sealed cavity 1, the energy of the weight of the oil and gas in the first pipeline 2, the energy of the weight of the liquid in the inner cavity of the body 1 above the points of taking the produced water and NGZhS, and by changing the amount of taken free gas from the sealed cavity 1 by means of the gas pressure regulator 7 due to the energy of the free gas pressure in the upper part of the sealed cavity 1.

The sealed cavity of the device can be located vertically, and the length of the sealed cavity of the device may exceed its diameter, while separating the free gas from the liquid in the upper part of the sealed cavity 1, followed by its controlled removal, taking the produced water from the lower third part of the sealed cavity 1 and selection of the remaining OGZhS from the upper third part of the sealed cavity 1. To control the device, as well as to turn it off, for example, from the collection system, the device was equipped with shut-off valves 9. Wellhead fittings 11 serve to seal the device from above and provide a hermetic entry of various pipelines.

The proper quality of the produced water in terms of the specific content of the permissible amount of oil products and mechanical impurities during its withdrawal from the installation for further use was achieved by ensuring a significant distance between the inlet of the oil and gas condensate mixture into the internal sealed cavity 1 of the installation and the entrance of the produced water into the third pipeline 4, because ... OGZhS is injected into the upper third part of the sealed cavity 1, and the associated water is withdrawn from the lower third part of the sealed cavity.

In the lower part of the sealed cavity 1 below the outlet from the third pipeline 4, a fourth pipeline 5 was installed, which has an open outlet from the bottom, and from above it is equipped with shut-off valves 9, after which the pipeline is connected to cavities (spaces) where atmospheric pressure tends to zero, and where it occurs selection of liquid with settled impurities, for example, a drainage tank (not shown in the figure). The bottom of the installation was cleaned from settled impurities through the fourth pipeline 5. Since excessive pressure arises inside the device during its operation, if the shut-off valve 9 is opened in the direction of movement of the liquid with settled impurities when cleaning the bottom of the device, the liquid from the bottom of the device rose through the fourth pipeline 5 from bottom to top, while carrying with it the settled impurities 12, which accumulated at the bottom of the device during operation. At a distance of 3-4 meters from the bottom of the installation, a signaling device for the presence of mechanical impurities was installed (not shown in the figure). The receipt of a signal from it means that precipitation (settled mechanical impurities) has accumulated at the bottom during operation to the level of the signaling device. The need to clean the bottom of the device from settled mechanical impurities was also determined by their excess in samples from the sampler installed on the line of discharge of produced water from the installation. The cleaning process of the device was carried out periodically as the accumulation of settled impurities at the bottom of the device.

The water and oil produced along the way were taken as one homogeneous liquid - the speed of their flow in the installation was equal, while the density of water did not change with a change in pressure. As the initial data on the properties of the oil-and-gas mixture under the thermobaric conditions of the installation, we used the data of differential degassing, reduced to the thermobaric conditions of the process, while it was assumed that the true gas content of the mixture - the fraction of free gas in the pipe section during the process dynamics, is the same as in statics. When sampling the oil-and-gas-liquid mixture from the installation, the volume of free gas in the liquid was taken to be negligible and was not taken into account in the calculation, the same was taken for the rise of water and residual oil-gas mixture, i.e., at the outlet of water and oil-gas mixture from the installation, in any case, there is no gas in a free state. ... The gas was taken from the installation from the upper third part of the sealed cavity 1 and was discharged through the fifth pipeline 6. The temperature in all parts of the installation was taken equal to 20 ° С - the calculation of the effect of the temperature gradient in dynamics was not performed, since it is negligible - 1 ° С per 100 meters of depth. The pressure at the outlet from the installation, both in terms of the oil-and-gas mixture and the water, was determined by calculation.

Table 1 shows the characteristics of the installation, calculated in accordance with the initial data of the field (about the area of future operation), the initial data on loads and effects, as well as in accordance with the requirements for the design of structures.

Table 1. Characteristics and parameters of the installation

No. Parameter name Unit rev. Meaning one Liquid performance m ³ / day 2626.0 2 Oil productivity t / day 285.3 3 Volumetric water cut % 87.3 4 Minimum water cut % 50 5 Water discharge capacity in% of the inlet liquid to the unit, no more % 90 6 Max. gas performance thousand nm ³ / day 110 7 Lifetime years 12 eight Maximum operating level in the installation m twenty 9 Installation volume without infrastructure cub. m 119.7 10 Liquid volume taking into account the level cub. m 89.8 eleven Volume in the installation for gas, taking into account the level cub. m 29.9 12 Minimum dynamic standing time min 25 thirteen Actual time dyn. sediment liquid min 49.2 14 Unit housing 14.1. - diameter mm 1420 14.2. - depth m 80 15 - Third pipeline 15.1 - diameter mm 114.3 15.2 - depth m 76.0 15.2.1 - On the surface 15.2.2 - diameter mm 114 15.2.3 - length m 5.0 sixteen Second pipeline 16.1. - diameter mm 114.3 16.2 - depth m 25.0 16.2.1 - On the surface 16.2.2 - Diameter mm 114 16.2.3 - Length m 5.0 17 First pipeline 17.1.1 - Diameter mm 114.3 17.1.2 - Depth m 30.0 17.2. - On the surface 17.2.1 - Diameter mm 114 17.2.2 - Length m 5.0 eighteen Sixth pipeline 18.1.1 - Diameter mm 89 18.1.2 - Depth m 30.0 18.2. - On the surface 18.2.1 - diameter mm 89 18.2.2 - length m 5.0 nineteen Fifth pipeline 19.1 - diameter mm 89 19.2 - length m one hundred twenty Fourth pipeline 20.1 -diameter mm 73 20.2 - distance from the bottom of the unit m 3

The calculations of the parameters and characteristics of the oil-gas-liquid mixture in the unit were carried out in the following sequence:

- analysis and preliminary preparation of initial data related to the technology and parameters of oil production facilities - the amount of gas in the well production;

- reduction of differential degassing data to thermobaric conditions of installation;

- calculations of oil and gas-liquid mixture at minimum and maximum operating modes of installations with the determination of the mode (structure) of the flow in the inlet pipelines in installations and hydraulic losses according to the method of J.P. Brill, H. Mukherjee;

- hydraulic calculations to determine hydraulic losses in the pipelines for the outlet of water and oil and gas-liquid mixture from the installation;

- calculation of the throughput of the gas pipeline to remove gas from the installation.

Hydraulic pressure losses at the technological points of the installation show that it is possible to safely and technologically operate the proposed installation at the specified modes.

The steady-state mode of operation was characterized by process points 13-18 indicated in FIG. 1, and the pressure at these points is given in table 2.

Table 2. Results of calculating pressures at technological points of the Yuzhno-Kinyaminskoye field

Production data on the parameters of the oil and gas field Yuzhno-Kinyaminskoye field Liquid performance Q w m3 / day 1000.0 Oil productivity Q n t / day 285.3 Debit PDV Q in m3 / day 666.1 Resetting PDV Q ppd m3 / day 599.5 Water cut V % 66.61 Unit inlet pressure R MPa 1,2 1.8 2.5 Pressure at point # 1 P1 MPa 1.18 1.78 2.49 Pressure at point # 2 P2 MPa 1.22 1.82 2.53 Pressure at point No. 3 P3 MPa 1.17 1.77 2.48 Pressure at point No. 4 P4 MPa 0.93 1.54 2.24 Pressure at point No. 5 P5 MPa 1.68 2.29 2.99 Pressure at point No. 6 P6 MPa 0.93 1.53 2.24

The proposed invention makes it possible to use it with a high gas factor, significantly improve the quality of water taken from the device by increasing the distance between the inlet of the oil and gas-liquid mixture and the point of water withdrawal from the device through the pipeline for withdrawing the produced water. Cleaning of the device from settled impurities is carried out during operation without stopping the operation of the device. If the device is immersed in the ground, additional heating of the device body is not required, since the heat of the ground is used for heating. To carry out repair work, it is enough to disassemble the wellhead fittings and remove the pipelines from the device. To implement the process of separating water and gas, the device does not consume electricity.

Claims (15)

1. A device for separating the produced water purified from impurities, including a sealed cavity with at least five pipelines, of which the first pipeline is made with the possibility of supplying an oil and gas-liquid mixture, the second pipeline is made with the possibility of withdrawing the oil-gas-liquid mixture, the third pipeline is made with the possibility of withdrawing the produced water, the fourth pipeline is configured to collect settled impurities from the sealed cavity, the fifth pipeline is equipped with a gas pressure regulator and is configured to take gas, the outlet to the sealed cavity from the first pipeline is located above the outlet from the third pipeline and below the outlet from the second pipeline, the outlet to the sealed the cavity from the fourth pipeline is located below the outlet from the third pipeline, and the outlet to the sealed cavity from the fifth pipeline is located above the outlet from the second pipeline. 2. The device according to claim. 1, in which the sealed cavity is made in the form of a pipe with a bottom and a cover. 3. The device according to claim 2, in which the casing pipe installed in the well is used as the pipe. 4. The device according to claim. 2, in which the outlet into the sealed cavity from the fifth pipeline is located in the cover of the sealed cavity. 5. The device according to claim 1, further comprising a sixth pipeline configured to supply an oil and gas-liquid mixture, the outlet into the sealed cavity from which is located above the outlet from the third pipeline and below the outlet from the second pipeline. 6. The device according to claim 1, equipped with wellhead equipment. 7. The device according to claim 1 or 5, in which the pipelines are equipped with shut-off valves. 8. The device of claim ... 9. The device according to claim 1, additionally equipped with a level gauge connected to the sealed cavity. 10. The device according to claim 1, made with the possibility of using on pads of oil wells. 11. A method of separating the produced water purified from settled impurities, characterized by the fact that the oil and gas-liquid mixture is supplied into the sealed cavity through the outlet of the first pipeline, the remainder of the oil and gas-liquid mixture is taken from the sealed cavity through the outlet of the second pipeline located above the outlet from the first pipeline, and the sealed cavity is separated incidentally produced water from the oil and gas-liquid mixture through the outlet of the third pipeline located below the outlet of the first pipeline, the settled impurities are taken from the sealed cavity through the outlet of the fourth pipeline located below the outlet from the third pipeline, gas is taken from the upper third part of the sealed cavity through the outlet of the fifth pipeline located above the exit from the second pipeline. 12. The method according to claim 11, wherein the oil-gas-liquid mixture is fed into the upper third part of the sealed cavity. 13. The method according to claim 11, in which the produced water is separated from the lower third part of the sealed cavity. 14. The method of claim 11, wherein the liquid level in the sealed cavity is changed by a gas pressure regulator. 15. The method according to claim 11, wherein the liquid level in the sealed cavity is monitored with a level gauge.

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