RU2770015C1 - Device for bypass of annular gas - Google Patents

Abstract

FIELD: oil industry.SUBSTANCE: invention relates to the oil industry and is intended for the bypass of annular gas into the flow string, with the maintenance of excess gas pressure in the annular space of the well, when using rod pumps. The device for bypass of annular gas as part of the flow string contains an annular chamber with a check valve, inlet and outlet openings of the hydraulic channel. The device is made in the form of a housing connected through a coupling with the flow string. A shank is installed in the axial channel of the housing to form an annular chamber, blocked in the middle part by a seat rigidly connected to the housing and forming an annular gap with the shank. A spring-loaded annular piston with a pusher equipped with grooves at the end and passed through the annular gap between the seat and the shank is installed on the seat, with the possibility of end contact with the body of a check valve made in the form of a sleeve with an end protrusion. The inlet openings in the body of the housing and the outlet openings in the body of the shank are blocked by the body of the check valve in the initial position, the annular chamber above the check valve is connected by a hydraulic channel in the shank with its axial channel. The annular chamber under the annular piston is connected by holes to the annular space of the well.EFFECT: ensuring the possibility of regulating the supply of annular gas to the flow string while maintaining the design gas pressure in the annular space and replacing the plug-in rod pump without lifting the flow string.1 cl, 3 dwg

Description

The invention relates to the oil industry and is intended for bypassing the annular gas into the axial channel of the tubing tubing during rod production.

An automatic valve device is known (AS USSR No. 625021, IPC E21V 33/03, publ. 09/25/1978), consisting of a check valve with a device for its control in the form of a piston and a housing. The piston is connected to the flow line by means of corrugated tubes and a pusher concentrically installed under it. Spring-loaded wedge-shaped pushers are installed in the walls of the housing. The check valve is connected by a hydraulic channel to the flow line.

The bypass of gas by this device does not depend on the magnitude of the gas pressure in the annulus, and it is used in wells during oil rod production.

At low temperatures, when bypassing the annular gas, the check valve on the flow line and in the corrugated pipes may freeze. This leads to a rupture of the corrugated tubes, with the loss of tightness of the device and the cessation of operation.

The design of the device as a whole is quite complex.

An automatic valve device for bypassing annular gas is known (see Pat. RF No. 2305171, IPC E21B 34/06, publ. 27.08.2007, Bull. No. 24).

The automatic valve device contains a check valve and a L-shaped hydraulic channel, which is made in the coupling of the tubing string (tubing). The coupling is part of the tubing string and is placed in the well at the level of the well fluid. The inner surface of the coupling is made convex relative to the outer surface. At the placement level, there is a cylinder of a larger diameter than the diameter of the pump rods. The length of the cylinder is assumed to be greater than the stroke length of the rod pump plunger. At the ends of the coupling there are centralizers covering the cylinder.

The hydraulic channel in the coupling enters the center of the segment part where the cylinder is located. A rod pump is installed in the productive formation zone, the plunger of which is connected by rods to the cylinder.

Bypass of annular gas occurs as follows.

During the operation of the sucker rod pump and the passage of the well fluid through the annular space formed by the cylinder and the segmental part of the coupling, the pressure in the fluid flow decreases. This leads to the opening of the check valve and the bypass of gas through the hydraulic channel from the annulus to the axial channel of the tubing string, above the cylinder, with a decrease in pressure in the annulus.

The disadvantages of the design include:

- The rod pump can be replaced only when the entire assembly is lifted, including the coupling;

- The technological clearance between the coupling segment and the cylinder is a hydraulic resistance. However, it is difficult enough to obtain a pressure drop across it to open the check valve to allow gas to pass from the annulus. This is due to the fact that the delivery volume of the rod pump is several liters and a limited number of strokes per cylinder.

A simple calculation can determine the flow rate of formation fluid in the annular gap between the sleeve and the cylinder. Readings are calculated at several centimeters per second, which is not enough for the device to work;

- the design of the device does not allow to regulate the pressure drop between the annulus and the axial channel of the tubing string.

An automatic device for bypassing annular gas is known (see Pat. RF No. 2318983, class IPC E21B 34/06, publ. 10.03.2008), taken as a prototype.

The device consists of a special coupling, as part of a tubing string, in which a ring-type check valve is located, in which a hydraulic channel is placed to connect the annular space formed by the inner wall of the production string and the outer wall of the tubing string, with its axial channel. The check valve is made in the form of a sleeve and is installed in such a way that in the upper position it opens a hole in the valve for bypassing the annular gas in the lower position.

This prevents the outflow of the gas-liquid mixture from the tubing cavity into the annulus, when the gas pressure in the annulus is lower than in the axial channel of the tubing string. The seal in the special coupling does not prevent the movement of the pump rod string and facilitates the supply of gas-liquid mixture from the axial channel of the tubing string to the branched hydraulic channel.

The length of the seal is chosen so as not to block the inlet and outlet of the hydraulic channel, which has a narrowing in the middle part.

Device operation.

The seal placed in the mouth channel of the special coupling covers the rod of the sucker-rod pump and blocks the direct flow of the gas-liquid mixture, with its supply through the inlet opening into the branched hydraulic channel, with a central constriction.

At the constriction point, when the gas-liquid mixture moves, the pressure decreases, the check valve sleeve is under excess pressure of the annular gas, which leads to the displacement of the sleeve to the upper position, with the bypass of the annular gas from the annulus and its mixing with the gas-liquid mixture. The mixture is fed through the outlet into the axial channel of the tubing string under the seal located in the axial channel of the special coupling.

When the gas pressure in the annulus decreases compared to the pressure of the gas-liquid mixture at the narrowing of the branched hydraulic channel, under the action of excess pressure, the check valve bushing moves down, with the overlap of the gas-liquid mixture outflow from the axial channel of the tubing string back into the annulus.

The disadvantages of the design include:

- the complexity of the design and installation of the device, namely a special coupling in the well, with a seal in the central channel;

- the presence of a seal in the central channel does not make it possible to replace the rod pump without lifting the entire assembly;

- the operation of the rod pump is periodic, which predetermines the periodic supply of a gas-liquid mixture through a narrowing channel, with a corresponding cessation of supply during the suction period. This means uncertainty in the operation of the device;

- the device is not designed to maintain the calculated pressure drop between the annulus and the axial channel of the tubing string.

The technical result that can be obtained by implementing the proposed invention:

- the ability to control the supply of annular gas to the axial channel of the tubing string while maintaining the calculated gas pressure in the annulus;

- the possibility of replacing the plug-in rod pump in the well without lifting the tubing string;

- optimization of the sucker-rod pump operation by maintaining the required pressure at the pump intake, in the presence of a high GOR; that is, the pressure is maintained above the saturation pressure.

The technical result is achieved by the fact that the annular gas bypass device, which is part of the tubing string, has an annular chamber with a check valve, a hydraulic channel with inlet and outlet openings, the annular chamber is made between the body connected through the coupling with the tubing string and the liner. In the annular chamber, in the middle part, there is a seat rigidly connected to the body and forming an annular gap; end and passed through the annular gap between the seat and the shank, with the possibility of end contact with the body of the check valve inside the end ledge. The inlet holes in the housing body and the outlet holes in the liner body, in the initial position, are blocked by the check valve body, and the annular chamber above it is connected by a hydraulic channel to the axial channel of the liner, the annular chamber under the annular piston is connected by holes to the annulus of the well.

The design of the annular gas bypass device is illustrated by drawings, where:

- in Fig. 1 general layout of equipment inside the well;

- in Fig. 2 general view of the device in section, in the initial position of the parts;

- Fig.3 General view of the device in section, in the position of the supply of annular gas.

The device 1 assembly is installed as part of the tubing string 2 with the location above the formation fluid level. In the axial channel of the string, the tubing is introduced into the rod pump 3 on the rod string 4, freely passing through the axial channel of the device 1.

The device 1 (special coupling) consists of a housing 5 connected by its upper end to the coupling 6 of the tubing string 2, with which the liner 7 is connected, equipped with a coupling 8, for communication with the underlying tubing string 2. Between the inner surface of the housing 5 and the outer liner 7 is formed an annular chamber 9 closed from below by a nut 10. A seat 11 is installed in the annular chamber 9, on which a spring-loaded check valve 12 rests in the form of a sleeve with an end ledge 13.

An annular gap is formed between the seat 11 and the body of the shank 7, into which the upper end of the pusher 14 is passed, connected by the lower end to the annular piston 15. A compression spring 16 is installed between the seat 11 and the annular piston 15.

The upper end of the pusher 14 is provided with a number of grooves 17, and it is installed freely relative to the seat 11, with the possibility of end contact with the check valve 12. Inlet holes 18 are made in the body of the body 5, blocked in the initial position by the body of the check valve 12.

In the body of the liner 7, outlet holes 19 and a hydraulic channel 20 are made to connect the annular chamber 9 above the seat 11 with the axial channel of the liner 7. The annular chamber 9 under the annular piston 15 is constantly hydraulically connected by holes 21 in the body of the housing 5 with the annulus of the well. The check valve 12 is equipped with sealing rings 22 and 23. The annular piston 15 with the pusher 14 is equipped with sealing rings 24 and 25.

Operation of the annular gas bypass device.

The device 1 on the tubing string is introduced into the well, with placement above the formation fluid level in the annulus. The well is equipped with a plug-in rod pump 3, which is lowered on a string of rods 4, which are freely placed in the axial channel of the tubing 2 and the axial channel of the liner 7 of the device (see Fig. 2, 3).

The development of wells is possible by supplying, for example, gas into the annulus with an exit through the device into the axial channel of the tubing. When the sucker rod pump 3 is operating, the formation fluid contains a sufficiently large amount of dissolved gas, which must be separated at the pump intake, with supply to the annulus of the well, from where it must be discharged, for example, into the axial channel of the tubing string.

At the same time, it is necessary to maintain a certain excess gas pressure in the annular space, which exceeds the total pressure in the field reservoir and the hydrostatic pressure of the formation fluid column at the depth of the annular gas bypass device.

After the development of the well and the descent of the rod pump, gas enters the annulus, with an increase in pressure.

At the estimated pressure of the gas that enters the annular chamber 9 through the holes 21 under the annular piston 15, which, together with the pusher 14, moves upward.

The end surface of the pusher 14 comes into contact with the surface of the check valve 12, which overcomes the resistance of the spring 16 and moves upward, with the separation of the end ledge 13 from the seat 11, with the opening of the gas supply through the inlet holes 18 into the annular chamber 9 and further through the outlet holes 19 in axial channel of the shank 7. When the end protrusion 13 is separated from the seat 11, an additional area appears on the check valve 12 inside from the end protrusion 13, which is affected by excess gas pressure. This leads to a sharp rise upwards of the check valve 12.

Under the action of gas pressure passing into the axial channel of the shank 7, the pusher 14, together with the annular piston 15, returns to its original position by the force of the compressed spring 16.

The spring-loaded check valve 12 remains in the "open" position until the pressure in the annulus decreases and the force from the compressed spring 16 returns the check valve 12 to its original position, with the end protrusion 13 landing on the seat 11.

This completes the cycle of gas discharge from the annulus into the axial channel of the liner 7 and further into the axial channel of the string tubing.

Claims (1)

Annular gas bypass device as part of the tubing string, containing an annular chamber with a check valve, inlet and outlet openings of the hydraulic channel, characterized in that it is made in the form of a housing connected through a coupling with the tubing string, a liner is installed in the axial channel of the housing to form an annular chamber, blocked in the middle part by a seat rigidly connected to the body and forming an annular gap with the shank, a spring-loaded annular piston with a pusher is installed on the seat, provided with grooves at the end and passed through the annular gap between the seat and the shank, with the possibility of end contact with the body of the check valve , made in the form of a sleeve with an end ledge, wherein the inlets in the body of the body and the outlets in the body of the shank are blocked by the body of the check valve in the initial position, the annular chamber above the check valve is connected by a hydraulic channel in the shank with its axial channel, and the annular chamber under the annular piston St. is associated with holes with the annulus of the well.

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