Forward drainage gas recovery gas lift valve, gas lift pipe column and drainage gas recovery method

Abstract

The invention provides a forward drainage gas recovery gas lift valve, a gas lift pipe column and a drainage gas recovery method. The gas lift valve comprises a coupling and a working barrel, a groove cavity is formed in the working barrel, an oil pressure control valve is arranged in the groove cavity, a communicating hole is formed in the working barrel, and the oil pressure control valve is communicated with the liquid channel of the working barrel through the communicating hole. The oil pressure control valve is arranged in a groove cavity of the working barrel, and effective mechanical protection is achieved; the diameter of the channel in the gas lift valve is equal to that of the tripping-in oil pipe, so that other operations caused by tripping-in of the gas lift valve are not affected. The oil pressure control valve is an adjustable valve, the opening pressure is changed through an adjusting nut, and different well depth requirements are met. The forward drainage gas recovery gas lift valve and an oil pipe are connected and enter a well together, one or more forward drainage gas recovery gas lift valves are connected in a straddle mode from top to bottom according to well conditions, and working pressure is gradually reduced from top to bottom. When working is needed, high-pressure nitrogen is injected into the oil pipe to improve the two-phase flow state of a production layer, pressure loss of vertical pipe flow is reduced, and enough production pressure difference is established to discharge accumulated liquid at the bottom of a well.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas exploration and development, and in particular relates to a forward water-discharge gas-production gas lift valve, a gas-lift pipe column and a water-discharge gas-production method. Background Art

[0002] Most of my country's gas reservoirs are closed elastic water-driven gas reservoirs, and they all produce formation water to varying degrees during development. Due to the interference of formation water, the gas field enters the decline stage early when the recovery rate is not high, and even causes gas wells to be flooded and shut down, affecting the final recovery rate of the gas field. Therefore, how to effectively drain water and produce gas to improve the recovery rate of water-containing gas reservoirs has long been one of the important topics that both domestic and foreign countries have devoted themselves to studying and solving.

[0003] At present, the more commonly used drainage gas production technologies at home and abroad include optimized tubing drainage gas production, foam drainage gas production, plunger gas lift drainage gas production, gas lift drainage gas production, mechanical pumping drainage gas production, electric submersible pump drainage gas production and jet pump drainage gas production. The selection of these technologies mainly depends on the geological characteristics of the gas reservoir, the production status of water-producing gas wells and economic investment considerations.

[0004] At present, due to the high water production rate of production wells, the deadweight of the liquid column and the bottom hole flow pressure are balanced during gas production, causing the gas wells to stop blowing and production. Small oil pipes are connected to gas lift valves at different depths and gas lift drainage is carried out using on-site nitrogen generation vehicles or leading high-pressure wells.

[0005] CN202121396192.4 A bridge-type eccentric built-in forward gas lift valve is composed of an upper joint, a working cylinder, a lower joint and a gas lift valve. A crescent-shaped main fluid channel and a bridge-type eccentric counterbore are made in the working cylinder. The upper part of the bridge-type eccentric counterbore is installed with a gas lift valve through a threaded connection, and the bottom is made with an outlet hole connected to the outside of the working cylinder. Since the forward gas lift valve adopts a bridge-type eccentric structure inside the working cylinder and the main fluid channel is made into a crescent shape, the outer diameter of the working cylinder is minimized and the flow area of ​​the main fluid channel is maximized, avoiding the phenomenon of a large throttling pressure difference caused by reducing the flow area of ​​the main fluid channel while reducing the outer diameter of the working cylinder; and making full use of the existing processing and debugging technology of the gas lift valve, the structure is simple, and the difficulty of processing and debugging is greatly reduced. It can be combined with a continuous oil pipe or a small oil pipe to form a speed string and lowered into the original completion string of an ultra-deep high-yield gas well for gas lift drainage. However, the built-in eccentric installation of the forward reverse lift valve causes the channel in the working cylinder to be too small, and it cannot pass the test instrument in the subsequent measures. Summary of the invention

[0006] The object of the present invention is to provide a positive drainage gas production gas lift valve to overcome the above-mentioned technical problems existing in the prior art.

[0007] Another object of the present invention is to provide a gas lift string, in which a plurality of positive drainage gas production gas lift valves are connected to the tubing and gradually decrease from top to bottom, reducing the pressure loss of the vertical tubing flow, thereby establishing a sufficient production pressure difference to discharge the liquid accumulation at the bottom of the well.

[0008] Another object of the present invention is to provide a method for draining gas and producing gas, which solves the problem that when using tubing gas lift alone, the construction pressure is high, the back pressure on the gas reservoir is too large, and the gas reservoir is pressed to death, thereby ensuring the smooth and continuous production of the gas well.

[0009] To this end, the technical solution provided by the present invention is as follows:

[0010] A positive drainage gas production gas lift valve includes a coupling and a working barrel. A groove chamber is provided on the working barrel, an oil pressure control valve is provided in the groove chamber, a communication hole is provided on the working barrel, and the oil pressure control valve is communicated with the liquid passage of the working barrel through the communication hole.

[0011] The oil pressure control valve includes an end cap, an outer cylinder and a joint connected in sequence from top to bottom. A plurality of exhaust holes are circumferentially provided on the outer cylinder. A valve seat is provided in the joint. A valve stem is provided on the valve seat. The spherical surface of the valve seat is sealingly connected to the ball head of the valve stem. An adjusting nut is provided on the valve stem, and a spring is provided between the adjusting nut and the end cap.

[0012] Both ends of the working barrel are provided with external threads and are respectively connected to the coupling and the tubing. The outer diameters of both ends of the working barrel are smaller than the middle outer diameter.

[0013] A tapered sealing internal thread is provided at the lower end of the groove chamber, and the oil pressure control valve is connected to the tapered sealing internal thread.

[0014] The lower part of the end cap is a cylindrical barrel. The valve stem can be inserted into the cylindrical barrel. The spring is provided between the adjusting nut and the bottom end of the cylinder. A retaining ring is provided at the upper end of the valve seat.

[0015] A gas lift string includes a tubing and also includes a positive drainage gas production gas lift valve. The positive drainage gas production gas lift valve is connected to the tubing. The positive drainage gas production gas lift valve is one or more. A plurality of positive drainage gas production gas lift valves are arranged step by step from top to bottom, and the working pressure decreases step by step.

[0016] The working pressures of a plurality of positive drainage gas production gas lift valves are gradually decreased according to a pressure of 2 MPa.

[0017] A method for draining gas and producing gas uses a gas lift string. High-pressure nitrogen is injected into the tubing. The high-pressure nitrogen sequentially passes through each stage of positive drainage gas production gas lift valve from top to bottom and enters the casing to mix with the liquid, making the liquid weight in the casing lighter, thereby reducing the wellbore pressure and enabling the well fluid to rise rapidly, realizing the smooth and continuous production of the gas well.

[0018] The process of high-pressure nitrogen passing through the positive drainage gas-lift valve for gas production is as follows: High-pressure nitrogen enters the fluid passage of the oil pressure control valve through the communication hole, and the air pressure pushes the valve stem to move, thus separating the valve stem from the valve seat, connecting the oil casing, and enabling the high-pressure nitrogen to enter the outer cylinder and then enter the casing through the exhaust hole.

[0019] Positive drainage gas-lift valves of different levels can adjust the working pressure by adjusting the position of the adjusting nut on the valve stem.

[0020] The beneficial effects of the present invention are as follows:

[0021] For the positive drainage gas-lift valve provided by the present invention, the oil pressure control valve is in the groove chamber of the working cylinder, providing effective mechanical protection; the inner channel of the gas-lift valve is equal in diameter to the inner diameter of the tubing run in, without affecting other operations due to the installation of the gas-lift valve. The oil pressure control valve is an adjustable valve, and its opening pressure can be changed by adjusting the nut to adapt to the requirements of different well depths.

[0022] The positive drainage gas-lift valve of the present invention is connected to the tubing and runs into the well together. When the gas-lift string runs into the well, all gas-lift valves are in the closed state, and the opening and closing pressures of the gas-lift valves decrease step by step from top to bottom. One or more gas-lift valves will be connected across intervals from top to bottom according to the well conditions; when work is required, high-pressure nitrogen is injected into the tubing to improve the two-phase flow state of the pay zone, reduce the pressure loss of the vertical tubing flow, and establish sufficient production pressure difference to discharge the liquid accumulation at the bottom of the well.

[0023] The injection gas of the method of the present invention can successively pass through each stage of the gas-lift valve from top to bottom and enter the casing to mix with the liquid, making the liquid weight in the casing lighter, thereby reducing the wellbore pressure and enabling the well fluid to rise rapidly; and it solves the problem that the construction pressure is high and the backpressure on the gas reservoir is too large when using tubing gas-lift alone, resulting in the situation of gas reservoir being choked off, thus ensuring the smooth and continuous production of the gas well. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a cross-sectional view of an embodiment of the positive drainage gas-lift valve of the present invention;

[0025] Figure 2 is an overall schematic diagram of the positive drainage gas-lift valve of the present invention;

[0026] Figure 3 is a cross-sectional view of an embodiment of the oil pressure control valve.

[0027] In the figure: 1, coupling; 2, oil pressure control valve; 3, working cylinder; 4, groove chamber; 5, communication hole; 6, end cap; 7, outer cylinder; 8, spring; 9, adjusting nut; 10, valve stem; 11, retaining ring; 12, exhaust hole; 13, sealing ring; 14, valve seat; 15, fluid passage; 16, joint. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0029] Now, exemplary implementation manners of the present invention will be introduced with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely, and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary implementation manners shown in the accompanying drawings are not limitations on the present invention. In the drawings, the same unit / element is denoted by the same reference numeral.

[0030] Unless otherwise specified, the terms (including scientific and technical terms) used herein have the ordinary meaning understood by those skilled in the art. In addition, it can be understood that the terms defined in the commonly used dictionary should be understood to have a meaning consistent with the context of their related fields, and should not be understood as idealized or overly formal meanings.

[0031] Embodiment 1

[0032] This embodiment provides a positive drainage gas-lift valve for gas production, as Figure 1 , Figure 2 shown, which includes a coupling 1 and a working barrel 3. A groove chamber 4 is formed on the working barrel 3. An oil pressure control valve 2 is arranged in the groove chamber 4. A communication hole 5 is provided on the working barrel 3. The oil pressure control valve 2 is communicated with the liquid channel of the working barrel 3 through the communication hole 5.

[0033] For the positive drainage gas-lift valve for gas production provided by the present invention, the oil pressure control valve 2 is externally installed outside the groove of the working barrel 3, providing effective mechanical protection; the inner channel of the gas-lift valve has the same diameter as the tubing string to be lowered, without affecting other operations due to the lowering of the gas-lift valve.

[0034] Embodiment 2

[0035] Based on Embodiment 1, this embodiment provides a positive drainage gas-lift valve for gas production, as Figure 3 shown. The oil pressure control valve 2 includes an end cap 6, an outer cylinder 7 and a joint 16 connected in sequence from top to bottom. A plurality of exhaust holes 12 are circumferentially arranged on the outer cylinder 7. A valve seat 14 is arranged in the joint 16. A valve rod 10 is arranged on the valve seat 14. The spherical surface of the valve seat 14 and the ball head of the valve rod 10 are hermetically connected. An adjusting nut 9 is arranged on the valve rod 10. A spring 8 is arranged between the adjusting nut 9 and the end cap 6.

[0036] An outer ring of the valve seat 14 is equipped with a sealing ring 13. The sealing ring 13 is inserted from the end of the joint 16, and a retaining ring 11 is inserted into a groove of the joint 16 to limit the valve seat 14. The valve stem 10 is screwed into the adjusting nut 9 from the end of the end cover 6, and then the spring 8 is sleeved. The spherical head of the valve stem 10 is sealed with the spherical surface of the valve seat 14. The lower end of the outer cylinder 7 is threadedly connected to the joint 16, and the upper end of the outer cylinder 7 is threadedly connected to the end cover 6 to form an oil pressure control valve 2.

[0037] During operation, the oil pressure (positive oil pipe pressure) is guided by the communication hole 5 inside the working cylinder 3, and the sleeve pressure (reverse casing pressure) is guided by the outer cylinder 7 of the oil pressure control valve 2. When the oil pressure acts on the right end spherical surface of the valve stem 10 through the joint 16 and the valve seat 14 of the oil pressure control valve 2 and overcomes the compression force of the spring 8, the oil sleeve is connected, and forward gas lift can be carried out.

[0038] Embodiment 3

[0039] Based on Embodiment 1, this embodiment provides a forward drainage gas production gas lift valve. Both ends of the working cylinder 3 are provided with external threads and are respectively connected to the coupling 1 and the oil pipe. The outer diameters of both ends of the working cylinder 3 are smaller than the middle outer diameter.

[0040] The coupling 1 has tubing threads at both ends, one end is connected to the working cylinder 3, and the other end is connected to the oil pipe. Both ends of the working cylinder 3 are smaller, so as to be connected to the coupling 1 and the oil pipe. A groove chamber 4 with a thick wall in the middle is processed to place the oil pressure control valve 2.

[0041] Embodiment 4

[0042] Based on Embodiment 1, this embodiment provides a forward drainage gas production gas lift valve. A tapered sealing internal thread is provided at the lower end of the groove chamber 4, and the oil pressure control valve 2 is connected to the tapered sealing internal thread.

[0043] The oil pressure control valve 2 is installed in the groove chamber 4 of the working cylinder 3 and is connected to the tapered sealing internal thread to prevent the oil pressure control valve 2 from bumping against the inner wall of the small-diameter casing, causing mechanical damage to the gas lift valve.

[0044] Embodiment 5

[0045] Based on Embodiment 1, this embodiment provides a forward drainage gas production gas lift valve. The lower part of the end cover 6 is a cylindrical barrel. The valve stem 10 can be inserted into the cylindrical barrel. The spring 8 is arranged between the adjusting nut 9 and the bottom end of the barrel. A retaining ring 11 is provided at the upper end of the valve seat 14.

[0046] As Figure 3 shown, the spring 8 can be limited around the cylindrical barrel to achieve compression, and a moving space can be provided inside the cylindrical barrel. The position of the adjusting nut 9 on the valve stem 10 can be adjusted left and right to change the compression force of the spring 8, so as to set different working pressures.

[0047] Embodiment 6

[0048] This embodiment provides a gas lift string, which includes a tubing string and also includes a positive drainage gas production gas lift valve. The positive drainage gas production gas lift valve is connected to the tubing string. There is one or more positive drainage gas production gas lift valves, and multiple positive drainage gas production gas lift valves are arranged step by step from top to bottom, and the working pressures decrease step by step.

[0049] The positive drainage gas production gas lift valve and the tubing string are connected and lowered into the well together. One or more positive drainage gas production gas lift valves will be connected across intervals from top to bottom according to the well conditions. When the gas lift string is lowered into the well, all gas lift valves are in the closed state, and the opening and closing pressures of the gas lift valves decrease step by step from top to bottom.

[0050] When work is required, high-pressure nitrogen is injected into the tubing string to improve the two-phase flow state of the pay zone, reduce the pressure loss of the vertical pipe flow, and establish a sufficient production pressure difference to discharge the liquid accumulation at the bottom of the well. The injected gas can successively pass through each stage of the gas lift valve from top to bottom and enter the casing to mix with the liquid, making the liquid weight in the casing lighter, thereby reducing the wellbore pressure and enabling the well fluid to rise rapidly; and it solves the problem of excessive backpressure on the gas reservoir due to high construction pressure when using tubing gas lift alone, resulting in the situation of gas reservoir being pressed to death, thus ensuring the smooth and continuous production of the gas well.

[0051] The working pressures of multiple positive drainage gas production gas lift valves decrease step by step according to a pressure of 2 MPa.

[0052] Embodiment 7

[0053] This embodiment provides a drainage gas production method. A gas lift string is adopted, and high-pressure nitrogen is injected into the tubing string. The high-pressure nitrogen successively passes through each stage of the positive drainage gas production gas lift valve from top to bottom and enters the casing to mix with the liquid, making the liquid weight in the casing lighter, thereby reducing the wellbore pressure and enabling the well fluid to rise rapidly, realizing the smooth and continuous production of the gas well.

[0054] In the natural gas exploration and development of the present invention, the positive drainage gas production gas lift valve is connected to the well by the tubing string, and positive drainage gas production gas lift is carried out by controlling the opening through the tubing pressure, so as to solve the problems of fast annular liquid accumulation, great difficulty in later plunger lift, and pressure measurement obstruction caused by reverse lifting of the production string through the casing pressure in the prior art.

[0055] Embodiment 8

[0056] On the basis of Embodiment 7, this embodiment provides a drainage gas production method. The process of high-pressure nitrogen passing through the positive drainage gas production gas lift valve is as follows: The high-pressure nitrogen enters the fluid passage 15 of the oil pressure control valve 2 through the communication hole 5, and the air pressure pushes the valve stem 10 to move, so that the valve stem 10 is separated from the valve seat 14, and the oil-casing is communicated, enabling the high-pressure nitrogen to enter the outer cylinder 7 and then enter the casing through the exhaust hole 12.

[0057] Positive drainage gas lift valves of different levels can adjust the working pressure by adjusting the position of the adjusting nut 9 on the valve stem 10.

[0058] The oil pressure control valve 2 is an adjustable valve. By adjusting the nut 9, the pressure of the spring 8 is changed, and the opening pressure is changed to meet the requirements of different well depths.

[0059] The above examples are only illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. Any design identical or similar to the present invention falls within the scope of protection of the present invention.

Claims

1. A positive drainage gas-lift valve, characterized in that: It includes a coupling and a working barrel. A groove chamber is formed on the working barrel, and an oil pressure control valve is arranged in the groove chamber. A communication hole is provided on the working barrel, and the oil pressure control valve is communicated with the liquid channel of the working barrel through the communication hole.

2. The positive drainage gas lift valve according to claim 1, characterized in that: The oil pressure control valve includes an end cap, an outer cylinder and a connector which are connected in sequence from top to bottom. A plurality of exhaust holes are circumferentially arranged on the outer cylinder. A valve seat is arranged in the connector. A valve rod is arranged on the valve seat. The spherical surface of the valve seat is sealingly connected with the spherical head of the valve rod. An adjusting nut is arranged on the valve rod. A spring is arranged between the adjusting nut and the end cap.

3. The positive drainage gas lift valve according to claim 1, characterized in that: External threads are provided at both ends of the working barrel and are respectively connected to the coupling and the tubing. The outer diameters at both ends of the working barrel are smaller than the outer diameter in the middle.

4. A positive drainage gas-lift valve according to claim 1, characterized in that: A tapered sealing internal thread is provided at the lower end of the groove chamber, and the oil pressure control valve is connected to the tapered sealing internal thread.

5. The positive drainage gas lift valve according to claim 2, wherein: The lower part of the end cap is a cylindrical barrel. The valve rod can be inserted into the cylindrical barrel. The spring is arranged between the adjusting nut and the bottom end of the barrel. A retaining ring is arranged at the upper end of the valve seat.

6. A gas lift string, comprising a tubing string, characterized in that: It further includes the positive drainage gas lift valve according to any one of claims 1-5. The positive drainage gas lift valve is connected to the tubing. The positive drainage gas lift valve is one or more. A plurality of positive drainage gas lift valves are arranged step by step from top to bottom, and the working pressure decreases step by step.

7. The gas lift string according to claim 6, characterized in that: The working pressures of a plurality of positive drainage gas lift valves decrease step by step according to a pressure of 2 MPa.

8. A gas drainage and production method, using the gas lift string described in claim 6, characterized in that: High-pressure nitrogen is injected into the tubing. The high-pressure nitrogen sequentially passes through each level of the positive drainage gas lift valve from top to bottom and enters the casing to be mixed with the liquid, making the liquid weight in the casing lighter, thereby reducing the wellbore pressure and enabling the well fluid to rise rapidly, realizing the smooth and continuous production of the gas well.

9. A gas drainage and production method according to claim 8, characterized in that: The process of the high-pressure nitrogen passing through the positive drainage gas lift valve is as follows: The high-pressure nitrogen enters the fluid channel of the oil pressure control valve through the communication hole. The air pressure pushes the valve rod to move, so that the valve rod is separated from the valve seat, and the oil casing is communicated, enabling the high-pressure nitrogen to enter the outer cylinder and then enter the casing through the exhaust hole.

10. A gas drainage and production method according to claim 8, characterized in that: The working pressures of different levels of the positive drainage gas lift valve can be adjusted by adjusting the position of the adjusting nut on the valve rod.

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