RU2844102C1 - Well separator and method of operation of well separator - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: group of inventions relates to the oil industry, in particular to the well separator and its operation method. Well separator consists of a separation chamber installed in a well, of a tubing string for water drainage and of a wellhead equipment. Wellhead equipment includes vertical housing, supply and discharge branch pipes with unions. Upper part of the tubing string for water drainage is located inside coaxially to the housing, the housing is made of a hollow cylindrical shape tapering to the bottom, lower part of the housing is rigidly connected to the lower flange pipe, providing connection with the column pipe of the well, upper part of the housing is rigidly connected to the upper flange branch pipe, which provides connection to the upper part of the tubing string for water drainage and cable entry of the electric centrifugal pump. On upper flange pipe internal thread is made for suspension of tubing string with downhole pumping equipment, oil-bearing fluid feed branch pipe with union is rigidly jointed with housing side surface and composed of L-like branch pipe jointed with perforated tube arranged inside said housing. Demulsifier feed assembly is arranged on feed branch pipe with union while discharge branch pipe with union for oil is rigidly jointed by branch pipe on opposite side of the housing relative to feed branch pipe with union and arranged above the level of feed branch pipe with union. Housing is connected to retractable supports made with grounding devices and rigidly installed on foundation plates. Separation chamber for supply of oil-containing liquid in well is made in form of annular space between inner cavity of production string in well and outer surface of tubing string for water removal and is connected with annular space between inner surface of housing of wellhead equipment and outer surface of tubing string for water removal.

EFFECT: increased efficiency of operation with the gravitational method of separating the oil-containing liquid due to the expansion of the field of application by enabling the mixing of oil-containing products with chemicals (demulsifiers) at the wellhead, simplified design of separation chamber, providing operation at variable parameters of flow rate, viscosity of highly watered liquid, reduction of power consumption for pumping of highly water-flooded liquid and treatment of waste water by providing cluster discharge of associated water.

2 cl, 2 dwg

Description

The invention relates to the oil industry, in particular to methods for preparing highly watered liquid during well operation and in-field transportation of well products to an oil treatment unit (OPU) and can find application in the creation and use of wellhead equipment for mixing highly watered oil-containing liquid with chemical reagents (demulsifiers) during well separation, by ensuring the separation of produced associated water with subsequent injection of the separated water directly into an injection well.

A system for collecting and preparing oil field products is known, which includes wells, group metering units connected by pipelines to a booster pumping station (BPS) equipped with separators, settling tanks, reservoirs, pressure pipelines for pumping pre-dehydrated oil from the BPS to a central collection point and supplying waste water separated from the oil using pumps of a cluster pumping station (CPS) to a reservoir pressure maintenance system (RPMS) (RD 39-01-0148311-605-86, p. 13).

The disadvantages are low efficiency due to high energy consumption for pumping and preparing highly watered well products from the production well to the pumping station, amounting to 6.65 kW*h/ ^m3 , with subsequent pumping of water to the pumping station and injection wells, the complexity of the system, including settling tanks in the pumping station/gas well: vertical steel tanks, bullets, the pumping station system, and overstocking of storage areas with excess wastewater.

A method of operating a well separator is known, including feeding a gas-water-oil mixture through a well product supply line into an ejector and through a pipeline into a pipe separator, from where the circulating water-oil mixture with gas residues, partially separated from the gas and water, is sent through a pipeline to a pit, the gas and water-oil-containing portion of the well product is diverted into a pressure pipeline into the transport system to an oil pretreatment unit (OPTU), the circulating water-oil mixture with gas residues is sent to the pit annulus through a through hole located in the lower part of the column head, in the annulus, part of the gas of the circulating water-oil mixture is bled through holes in the wall of the coupling centralizer, after which it passes through an annular through channel between the outer side surface of the coupling and the inner side surface of the through central channel of the column head, rising further along the through annular gap between the outer surface of the tubing and the inner surface of the through the channel of the column head, some of the gas is directed through a through horizontal hole in the upper part of the column head with a gas discharge tube installed in it into a pipeline connected to the well production supply line, the circulating water-oil mixture, having freed itself from some of the gas at the inlet, is directed into the pit through the annular space, changes direction by 180 at the inlet of the submersible motor, and having lost some more gas when the flow changes, enters the intake of the ESP, is fed under pressure into the inner channel of the tubing, some of the gas released when the direction of the circulating water-oil mixture flow changes at the inlet of the submersible motor rises along the annular space, the internal channels of the coupling centralizer and coupling, the through annular channel between the outer surface of the tubing and the inner channel of the column head, and also exits through the gas discharge tube installed in the horizontal through hole in the upper part of the column head into a pipeline connected to the well production supply line, cleaned of gas component, the water-oil circulating mixture, without the formation of gas locks, under the required pressure developed by the ESP, enters the well product supply line through a pipeline, enters the ejector nozzle, and mixing with the flow, ensures the suction of well product, and compression of the mixture to the separation pressure and transportation of product to the UPPN (patent RU No. 95787, published 10.07.2010).

A known installation for transporting multiphase well production comprises a flow inlet into a pit for supplying a circulating water-oil mixture, made in the form of a through horizontal opening in the lower part of the column head, hydraulically connected to a through horizontal opening for gas removal in the upper part of the column head through through longitudinal openings of a coupling centralizer, and a through annular gap formed by the lateral surface of the internal central channel of the column head and the external lateral surfaces of the coupling for fastening the production column and gas tubing in the circulating water-oil mixture, which is the working fluid. (RU patent No. 95787, published 10.07.2010). The installation ensures stable operation due to a decrease in the gas content in the circulating water-oil mixture, which is the working fluid.

The disadvantage of the method and device is the small internal volume of the wellhead fittings/lack of capacity for more efficient separation of gas and mixing of oil-containing liquid with chemical reagents (demulsifiers).

A method for operating a well separator is known, including

the flow of a water-oil emulsion through a supply pipeline into the upper part of a column located in a well, the swirling of the emulsion due to a tangential entry into an annular cavity formed by the inner surface of the column and the outer surface of the oil discharge pipeline, the separation of the emulsion into oil and water under the action of centrifugal forces, wherein the oil moves along the outer surface of the oil discharge pipeline, after the liquid separated into oil and water passes through the oil discharge pipeline, a cavern filled with oil is formed at the entry to it, which enters the inlet opening of the oil discharge pipeline, the heavier water moves down the annular cavity formed by the inner surface of the well and the outer surface of the column (RU patent No. 2252312, published 20.05.2005).

A separation unit is known that contains a column with pipelines for supplying a water-oil emulsion and removing oil and water. According to the invention, the device is provided with a packer in the well in which the column is located. The pipeline for supplying a water-oil emulsion is connected tangentially in the upper part of the column with the possibility of twisting the water-oil emulsion and separating it under the action of centrifugal forces into oil and water. The lower part of the column is open. The oil removal pipeline is located inside the column. The water removal pipeline is formed by the inner surface of the well and the outer surface of the column and is connected to the wellhead (patent RU No. 2252312, published 20.05.2005). The invention relates to the field of oil producing industry, namely to methods and installations for separating oil well products into oil and water. Provides reduced operation of the device and the ability to operate in winter conditions without artificial heating.

The disadvantage of the method and device is that effective separation of water-oil emulsion is not ensured, in particular, sufficiently effective water purification is not ensured - some oil droplets are carried away with water. Separation occurs in a limited annular space, as a result of which there are no conditions for water purification. And also a decrease in the efficiency of operation when changing the parameters of water-oil emulsion, such as viscosity or flow rate of the supplied liquid.

A method for operating a well separator is known, including

direction of gas flow along the main wellhead equipment shaft through the root and above-root valves, pulling the bottom water cone toward the perforation holes due to the rise of the gas-water contact, when water and sand appear in the well production, the above-root valve is closed and the gas-liquid flow is directed through the lower branch into the gas separator, the root valve is closed only in an emergency, therefore the root valve remains constantly open, the separation of the gas-liquid flow into components in the gas separator occurs under the action of centrifugal forces directed radially with respect to the vertical axis of the separator, the separated liquid with mechanical impurities flows down the walls of the gas separator body under the action of gravity and is removed together with sand through the drain pipe, the gas purified from liquid and sand is returned through the upper branch into the main wellhead equipment shaft (RU patent No. 129551, published on 27.06.2013).

The disadvantage of the method is that the device is intended exclusively for filtering gas condensate liquid and acts as a filter, in the lower part of which solid particles are deposited. When used as a separator of oil-containing liquid, effective separation of water-oil emulsion is not ensured, in particular, sufficiently effective water purification is not ensured - some of the oil droplets are carried away with the water.

The closest in essence is a separation unit containing a separation chamber installed in a well with a branch pipe for supplying oil-containing liquid, a column of tubing for water drainage and a branch pipe for oil drainage, and wellhead equipment (RU patent No. 2291292, published 10.01.2007).

A separation chamber, open at the bottom, is installed in the well. A water-oil emulsion supply pipeline, connected to the upper part of the chamber, and water and oil discharge pipelines are located at the wellhead. According to the invention, a row of swirlers made in the form of blades is located along the height of the chamber, equal to 8-10 chamber diameters. The blades of the subsequent row of the swirler are located with an offset relative to the blades of the swirler of the previous row. The water discharge pipeline is installed inside the chamber coaxially with it along a length corresponding to the length of the well. The lower end of the water discharge pipeline is made as a cone, on the surface of which slotted cuts are made.

The closest method is the operation of a well separator, which includes the placement of a well separator assembly, including a column of tubing pipes - tubing and a column of pipes for supplying oil-containing liquid and wellhead equipment, supplying oil-containing liquid, and removing water and oil (patent RU No. 2291292, published 10.01.2007). The water-oil emulsion enters the upper part of the separation chamber through the supply pipeline, where the emulsion is swirled around the annular cavity formed by the inner surface of the chamber and the outer surface of the water discharge pipeline by means of swirlers made in the form of blades placed along the height of the chamber; under the action of centrifugal forces, the emulsion is separated into oil and water, the water is directed down the chamber, mechanical impurities settle to the bottom of the well, and purified water passes through slotted cuts and is removed from the well for further injection into the formation.

The invention relates to the field of gas and oil production, in particular to the separation of an emulsion of two immiscible liquids with different densities, and can be used to separate water and oil in a separation chamber installed in a well that is not currently in operation, and to purify water for pumping it into a formation. It provides an increase in the degree of purification of water discharged from a well, preparation of water in a separation chamber for pumping into a formation, and a reduction in the costs of pumping ballast water produced with oil.

The disadvantage of this method and device is low efficiency due to the narrow scope of application due to the lack of possibility of mixing oil-containing products with chemical reagents (demulsifiers) at the wellhead, the complexity of the design of the separation chamber, including swirlers in the form of blades along the entire length of the chamber with variable flow rate parameters, viscosity of highly watered liquid.

The technical result of the well separator and the method of operating the well separator is an increase in the efficiency of operation with the gravity method of separating oil-containing liquids due to the expansion of the area of application by providing the possibility of mixing oil-containing products with chemical reagents (demulsifiers) at the wellhead, simplifying the design of the separation chamber, ensuring operation with variable flow rate parameters, viscosity of highly watered liquid, reducing energy costs for pumping highly watered liquid and preparing waste water by providing cluster discharge of produced water.

The technical result is achieved by a well separator containing a separation chamber installed in the well with pipes for supplying oil-containing liquid and removing oil, a column of pump and compressor pipes - tubing for removing water, and wellhead equipment.

What is new is that the wellhead equipment contains a vertical casing, inlet and outlet pipes with fittings, the upper part of the water discharge tubing string is located inside coaxially with the casing, the casing is made of a hollow cylindrical shape, tapering towards the bottom, the lower part of the casing is rigidly connected to the lower flanged pipe, providing a connection with the well column pipe, the upper part of the casing is rigidly connected to the upper flanged pipe, providing a connection with the upper part of the water discharge tubing string and the cable entry of the electric centrifugal pump, an internal thread is made on the upper flanged pipe for hanging the tubing string with the downhole pumping equipment, the inlet pipe with a fitting is rigidly connected to the side surface of the casing and is made of an L-shaped pipe connected to a perforated pipe located inside the casing, a feed unit is installed on the inlet pipe with a fitting demulsifier, the outlet branch pipe with the oil nozzle is rigidly connected by a branch pipe on the opposite side of the housing relative to the inlet branch pipe and is located above the level of the inlet branch pipe with the nozzle, the housing is connected to retractable supports made with grounding devices and rigidly installed on the foundation slabs, the separation chamber for supplying oil-containing liquid in the well is made in the form of an annular space between the internal cavity of the production string of pipes in the well and the external surface of the water discharge tubing string and is connected to the annular space between the internal surface of the wellhead equipment housing and the external surface of the water discharge tubing string.

The technical result is achieved by a method of operating a well separator, including the placement of a well separator assembly, including a separation chamber, a column of tubing - tubing for water drainage, wellhead equipment, supply of oil-containing liquid, drainage of water and oil.

What is new is that the electric centrifugal pump is placed in the well and the wellhead equipment is placed on retractable supports made with grounding devices and rigidly installed on foundation slabs, the lower flanged branch pipe of the wellhead equipment body is connected to the column branch pipe of the well, the column of water discharge tubing is placed coaxially with the body, the upper end of the column of water discharge tubing is connected by a threaded connection to the upper flanged branch pipe of the wellhead equipment body, the electric centrifugal pump cable is led out through a cable entry on the upper flanged branch pipe, the supply of oil-containing liquid is carried out through a supply pipe with a nozzle, rigidly connected to the side surface of the wellhead equipment body, made of an L-shaped branch pipe connected to a perforated pipe, placed inside the body, at the same time, a demulsifier is supplied through a demulsifier supply unit installed on the upper generatrix of the supply pipe with a nozzle on the outside housings, the oil is discharged through a discharge pipe with a nozzle, rigidly connected to the housing on the opposite side of the housing relative to the supply pipe with a nozzle, and located above the level of the supply pipe with a nozzle.

Fig. 1 shows a well separator with wellhead equipment.

Fig. 2 shows a diagram of the placement of a well separator.

Fig. 1 and 2 are explained by the following positions: 1 - wellhead equipment body, 2 - oil-containing liquid supply pipe, 3 - oil discharge pipe, 4 - lower flanged pipe, 5 - upper flanged pipe, 6 - production pipe string, 7 - retractable supports, 8 - foundation slabs, 9 - perforated pipe, 10 - well column pipe, 11 - water discharge tubing string, 12 - cable entry, 13 - threaded connection for suspension of tubing string, 14 - demulsifier feed unit, 15 - separation chamber, 16 - electric centrifugal pump.

The essence of the invention.

The well separator contains a separation chamber 15 installed in the well with pipes for supplying oil-containing liquid 2 and removing oil 3, a column of pump and compressor pipes - tubing for removing water 11, and wellhead equipment.

The wellhead equipment of the well contains a vertical steel casing 1, supply 2 and discharge 3 pipes with fittings providing connection with pipelines for supplying oil-containing liquid to the well separator, by deploying a check valve on the GZU (and further movement of liquid through the bypass), or by constructing a separate branch of the oil pipeline, and oil discharge to the BPS, with the upper part of the column of pump-compressor pipes of water discharge 11 located inside coaxially with the casing 1, providing connection with the pressure water pipeline to the injection well. The casing 1 is made of a hollow cylindrical shape, tapering towards the bottom. The lower part of the casing 1 is rigidly connected to the lower 4 flanged pipe, providing connection with the column pipe 10 of the well. The upper part of the body 1 is rigidly connected to the upper 5 flanged branch pipe, which ensures connection with the column of pump-compressor pipes for water drainage 11 and the cable entry 12 of the electric centrifugal pump 16. On the upper flanged branch pipe, an internal thread 13 is made for hanging the column of tubing 11 with the pumping downhole equipment.

The inlet pipe 2 with a nozzle is rigidly connected to the side surface of the housing 1 and is made of an L-shaped pipe connected to a perforated pipe 9, located inside the housing 1 above the beginning of the narrowing of the housing 1. On the upper generatrix of the inlet pipe 2 with a nozzle, a demulsifier supply unit 14 is installed. The outlet pipe 3 with a nozzle for oil is rigidly connected by a pipe on the opposite side of the housing 1 relative to the inlet pipe 2 with a nozzle and is located above the level of the inlet pipe 2 with a nozzle. The housing 1 is connected to retractable supports 7, made with grounding devices and rigidly installed on foundation slabs 8. The separation chamber 15 of the oil-containing liquid in the well is made in the form of an annular space between the internal cavity of the production string of pipes 6 in the well and the external surface of the column of water drainage tubing 11 and is connected to the annular space between the internal surface of the housing 1 of the wellhead equipment and the external surface of the column of water drainage tubing 11.

The well separator works as follows.

The method of operating a well separator includes placing a well separator assembly that includes a separation chamber 15, a column of tubing - tubing for water drainage 11, wellhead equipment, supply of oil-containing liquid, drainage of water and oil.

The electric centrifugal pump 16 is placed in the well, and the wellhead equipment is placed on retractable supports 7, made with grounding devices and rigidly installed on foundation slabs 8.

The lower flange branch pipe 4, rigidly connected to the body 1 of the wellhead equipment, is connected to the column branch pipe of the well 10. The column of water discharge tubing pipes 11 is placed coaxially to the body 1. The upper end of the water discharge tubing column 11 is connected by a threaded connection 13 to the upper flange branch pipe 5 of the wellhead equipment body. The cable of the electric centrifugal pump 16 is led out through the cable entry 12 on the upper flange branch pipe 5.

The oil-containing liquid is supplied through the supply pipe 2 with a nozzle, rigidly connected to the side surface of the body 1 of the wellhead equipment. The supply pipe 2 with a nozzle is made of an L-shaped pipe connected to a perforated pipe 9, located inside the body 1.

At the same time, the demulsifier is fed through the demulsifier feed unit 14, installed on the upper generatrix of the supply pipe 2 with a fitting outside the housing 1.

The oil is discharged through the discharge pipe 3 with a nozzle, rigidly connected to the body 1 on the opposite side of the body relative to the supply pipe 2 with a nozzle, and located above the level of the supply pipe 2 with a nozzle.

Thus, the proposed design of a well separator and the method of its operation provide an increase in the efficiency of operation with the gravity method of separating oil-containing liquids by expanding the scope of application by providing the possibility of mixing oil-containing products with chemical reagents (demulsifiers) at the wellhead, simplifying the design of the separation chamber, ensuring operation with variable flow rate parameters, viscosity of highly watered liquid, reducing energy costs for pumping highly watered liquid and preparing waste water by providing cluster discharge of produced water.

An example of a specific implementation.

The well in which the production column 6, water drainage tubing 11, and column head 10 are located is checked for leaks.

An electric centrifugal pump 16 is placed in the well and the well is connected to a special wellhead element - wellhead equipment containing a steel body 1 made of a hollow cylindrical shape, tapering towards the bottom, with a diameter of, for example, 670 mm, a height of 2330 mm, supply 2 and outlet 3 pipes with fittings with a diameter of, for example, 89 mm, an upper part of the water drainage tubing column 11 with a diameter of 60 mm, located inside coaxially with the body 1, with a lower 4 flanged pipe, with an upper 5 flanged pipe.

Fasten the water drainage tubing 11 to the upper flange branch 5 with a threaded connection 13 for hanging the tubing column 11 with the downhole pumping equipment.

Connect the oil-containing liquid supply pipe 2 to the supply oil pipeline, the oil discharge pipe 3 to the discharge oil pipeline, and the water discharge tubing to the water conduit connecting to the injection well.

The oil-containing liquid with a water content of 93% is fed into the well separator with the simultaneous feeding of a demulsifier, for example, the demulsifier "TN-DE 11A" at a dosage of 100 grams per 1 ton of oil, for example, 2.9 kg/day. The feed is carried out and adjusted using a regulator of the dosing unit (for example, UDE) and control of the level of the demulsifier residue along the UDE flow line.

The oil-containing liquid entering the wellhead equipment through the inlet nozzle 2 is pre-saturated with a demulsifier through the chemical reagent insertion unit 14, passes through the perforated branch pipe 9 into the internal cavity of the housing 1, where mixing and primary separation of the phases (gas) occurs. The water portion enters the well, acting as a tank, where secondary separation of the phases occurs due to gravitational settling of the water and the floating of oil globules. The water formed in the lower part of the well is pumped out using the pumping method for further transportation to the PPM system (an injection well, preferably located in the area of the well separator) through the upper flanged connection nozzle 5. The residual oil with a water content of 88%, formed in the upper internal part of the housing 1, is directed through the outlet pipe with the nozzle 3 into the oil gathering system to the BPS (discharge or gathering oil pipeline).

The proposed design of a well separator and the method of its operation make it possible to increase the efficiency of the well separator in the gravity method of separating oil-containing liquids due to:

- expansion of the scope of application by providing the possibility of effective mixing of oil-containing liquid with chemical reagents (demulsifiers) at the wellhead, preliminary saturation of the liquid with a demulsifier, for further separation and discharge of produced water in the conditions of a settling well;

- reduction of energy costs from 6.65 to 5.45 kW*h/ ^m3 due to a reduction in the volume of pumping highly watered oil-containing liquid in the amount of 75-80 ^m3 /day over long distances to the oil treatment plant;

- reducing the corrosive impact of formation water on in-field equipment;

- reducing the costs of preparing wastewater for injection into an injection well and preparing wastewater by ensuring cluster discharge of produced water;

- reducing the time required to prepare wastewater for injection into an injection well;

- simplification of the design of the separation chamber, ensuring operation with variable flow rate parameters and viscosity of highly watered liquid.

Claims (2)

1. A downhole separator comprising a separation chamber installed in a well, a water drainage tubing string and wellhead equipment, characterized in that the wellhead equipment of the well comprises a vertical housing, inlet and outlet pipes with nozzles, the upper part of the water drainage tubing string is located inside coaxially with the housing, the housing is made of a hollow cylindrical shape, tapering towards the bottom, the lower part of the housing is rigidly connected to the lower flanged pipe providing a connection with the well column nozzle, the upper part of the housing is rigidly connected to the upper flanged pipe providing a connection with the upper part of the water drainage tubing string and the cable entry of an electric centrifugal pump, an internal thread is made on the upper flanged pipe for hanging the tubing string with the downhole pumping equipment, the inlet pipe with a nozzle for the oil-containing liquid is rigidly connected to the side surface of the housing and is made of an L-shaped branch pipe connected to a perforated pipe located inside the housing, a demulsifier feed unit is installed on the inlet branch pipe with a nozzle, the outlet branch pipe with a nozzle for oil is rigidly connected by a branch pipe on the opposite side of the housing relative to the inlet branch pipe with a nozzle and is located above the level of the inlet branch pipe with a nozzle, the housing is connected to retractable supports made with grounding devices and rigidly installed on foundation slabs, the separation chamber for supplying oil-containing liquid in the well is made in the form of an annular space between the internal cavity of the production string of pipes in the well and the external surface of the tubing string of water drainage and is connected to the annular space between the internal surface of the wellhead equipment housing and the external surface of the tubing string of water drainage. 2. A method for operating a well separator, including placing a well separator assembly including a separation chamber, a water drainage tubing string, wellhead equipment, supply of oil-containing liquid, water and oil drainage, characterized in that an electric centrifugal pump is placed in the well and the wellhead equipment is placed on retractable supports made with grounding devices and rigidly installed on foundation slabs, the lower flanged branch pipe of the wellhead equipment body is connected to the wellhead tubing string, the water drainage tubing string is placed coaxially with the body, the upper end of the water drainage tubing string is connected by a threaded connection to the upper flanged branch pipe of the wellhead equipment body, the electric centrifugal pump cable is led out through a cable entry on the upper flanged branch pipe, the oil-containing liquid is supplied through a supply branch pipe with a nozzle rigidly connected to the side surface of the wellhead equipment body, made of an L-shaped branch pipe connected to a perforated pipe located inside the housing, simultaneously supplying a demulsifier through a demulsifier supply unit installed on the upper generatrix of the supply pipe with a nozzle outside the housing, oil is discharged through a discharge pipe with a nozzle, rigidly connected to the housing on the opposite side of the housing relative to the supply pipe with a nozzle, and located above the level of the supply pipe with a nozzle.