Full-bore eccentricity-free gas lift valve drainage device and drainage method

Abstract

This invention discloses a full-bore, non-eccentric gas lift valve drainage device, comprising an oil pipe, an outer sleeve of which forms an annulus between the oil pipe and the sleeve, a throttle nozzle connected to the bottom of the oil pipe, a packer positioned above the throttle nozzle to separate the vertical and horizontal sections of the annulus, and a gas lift valve device positioned above the packer. A bottom liquid pipe is connected to the top of the oil pipe, and a high-pressure gas injection pipe is connected to the upper part of the annulus. This invention solves the problem of limited fracturing capacity in unconventional reservoirs caused by the existing non-full-bore, eccentric gas lift valve structure. The drainage method of this invention's full-bore, non-eccentric gas lift valve drainage device reduces production steps, improves operational efficiency, and lowers costs.

Description

Technical Field

[0001] This invention belongs to the field of petroleum fracturing technology, and relates to a full-bore, non-eccentric gas lift valve drainage device, as well as a drainage method for the aforementioned full-bore, non-eccentric gas lift valve drainage device. Background Technology

[0002] In recent years, my country's natural gas resources have entered the mid-to-late stage of development and exploitation. The continuous decline in gas field pressure has brought numerous difficulties to natural gas extraction. After a significant drop in gas field pressure, the wellbore's ability to lift fluids has noticeably decreased. Low pressure and fluid carrying capacity have become important issues restricting the development of gas production companies. For water-bearing reservoirs, after hydraulic fracturing, some wells produce large amounts of water, exceeding the critical fluid carrying capacity of gas wells, resulting in a large amount of fluid remaining in the wellbore and a decrease in natural gas production. Currently available gas lift valves are non-full-bore and eccentric in structure. However, unconventional ultra-low permeability reservoirs often require high-flow-rate fracturing technology to increase the fracturing and production enhancement reach. Existing gas lift valves limit the fracturing flow rate in unconventional reservoirs, leading to insufficient reservoir stimulation volume and affecting production enhancement effects. Summary of the Invention

[0003] The purpose of this invention is to provide a full-bore, non-eccentric gas lift valve discharge device, which solves the problem that the existing non-full-bore, eccentric gas lift valve structure leads to limited discharge capacity in unconventional reservoir fracturing.

[0004] One technical solution adopted in this invention is a full-bore, non-eccentric air lift valve drainage device, including an oil pipe, a sleeve connected to the outside of the oil pipe, forming an annulus between the oil pipe and the sleeve, a throttle nozzle connected to the bottom of the oil pipe, a packer installed above the throttle nozzle, the packer separating the vertical and horizontal sections of the annulus; an air lift valve device installed above the packer, a bottom liquid pipe connected to the top of the oil pipe, and a high-pressure air injection pipe connected to the upper part of the annulus.

[0005] The invention is further characterized in that,

[0006] The air lift valve device includes, from bottom to top, a four-stage air lift valve, a three-stage air lift valve, a two-stage air lift valve, and a one-stage air lift valve. The four-stage air lift valve, the three-stage air lift valve, the two-stage air lift valve, and the one-stage air lift valve are all arranged around the oil pipe axis.

[0007] The bottom of the four-stage, three-stage, two-stage, and one-stage air lift valves all have liquid inlets, and a flow switch is installed above the liquid inlets. The four-stage, three-stage, two-stage, and one-stage air lift valves all have liquid outlets radially around the oil pipe.

[0008] The four-stage, three-stage, two-stage, and one-stage air lift valves installed on the oil pipe are all check valves. These four-stage, three-stage, two-stage, and one-stage air lift valves are equidistant from each other on the oil pipe.

[0009] Another technical solution adopted in this invention is,

[0010] The drainage method of the full-bore, non-eccentric air lift valve drainage device is implemented according to the following steps:

[0011] In the initial stage of fracturing, during the fluid discharge phase, the fluid is discharged from the tubing. In the later stage, when the rate of water discharge is lower than the rate of water production, fluid begins to accumulate in the tubing and casing annulus. The gas lift valve below the fluid accumulation level opens, and gas is injected from the annulus to lift the fluid. Under the injection pressure, the accumulated fluid in the annulus continuously enters the tubing through the opened gas lift valve and is discharged from the wellhead through the tubing.

[0012] The invention is further characterized in that,

[0013] The specific process of the gas lift valve device discharging the fluid from the wellhead through the tubing is as follows: when the fluid level in the annulus is lower than the position of the first-stage gas lift valve, the flow switch of the first-stage gas lift valve automatically closes; the annulus fluid continues to enter the tubing through the flow switch of the second-stage gas lift valve under the gas injection pressure, and this process is repeated until the flow switch of the fourth-stage gas lift valve at the bottom closes, and the fluid discharge process is completed.

[0014] The beneficial effects of this invention are as follows: In the later drainage stage, when the rate of produced water discharge is lower than the production rate, liquid begins to accumulate in the tubing and annulus. The gas lift valve below the liquid accumulation level opens its flow switch step-by-step under the gas lift injection pressure, allowing the accumulated liquid to be discharged from the tubing through the gas lift valve, ultimately draining all the liquid from the wellbore. This achieves high-volume fracturing while ensuring rapid drainage and recovery of production after fracturing. This invention solves the problem of limited drainage capacity in unconventional reservoir fracturing caused by existing non-full-bore, eccentric gas lift valve structures. It has the advantages of convenient operation and management, and large fracturing drainage capacity. In field applications at oil (gas) wells, gas lift quickly and thoroughly drains accumulated liquid from the wellbore and fluids from the formation near the bottom of the well. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the full-bore, non-eccentric air lift valve liquid discharge device of the present invention;

[0016] Figure 2 This is a schematic diagram of the connection structure between the air lift valve device and the oil pipe of the present invention.

[0017] In the diagram, 1. Throttling nozzle, 2. Packer, 3. Four-stage air lift valve, 4. Three-stage air lift valve, 5. Two-stage air lift valve, 6. One-stage air lift valve, 7. Liquid inlet, 8. Liquid outlet, 9. Flow switch. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0019] This invention relates to a full-bore, non-eccentric air lift valve drainage device, such as... Figure 1 As shown, the system includes an oil pipe, an outer sleeve of which forms an annulus between the oil pipe and the sleeve. A throttle nozzle 1 is connected to the bottom of the oil pipe, and a packer 2 is installed above the throttle nozzle 1. The packer 2 separates the vertical and horizontal sections of the annulus. A gas lift valve is installed above the packer 2. The top of the oil pipe is connected to a bottom liquid pipe, and a high-pressure gas injection pipe is connected to the upper part of the annulus. The high-pressure gas injection pipe provides a gas extraction channel.

[0020] The air lift valve assembly includes, from bottom to top, a four-stage air lift valve 3, a three-stage air lift valve 4, a two-stage air lift valve 5, and a one-stage air lift valve 6. These four stages are arranged axially around the oil pipe. Figure 2 As shown, the bottom of the four-stage air lift valve 3, the three-stage air lift valve 4, the two-stage air lift valve 5, and the one-stage air lift valve 6 all have liquid inlets 7. A flow switch 9 is installed above the liquid inlets 7. The four-stage air lift valve 3, the three-stage air lift valve 4, the two-stage air lift valve 5, and the one-stage air lift valve 6 all have liquid outlets 8 radially surrounding the oil pipe. The flow switch 9 controls the opening and closing of the liquid inlets 7, thereby allowing the backflow liquid to flow from the annulus into the oil pipe. The four-stage air lift valve 3, the three-stage air lift valve 4, the two-stage air lift valve 5, and the one-stage air lift valve 6 installed on the oil pipe are all check valves, providing a one-way channel for the flow of accumulated liquid from the annulus to the oil pipe.

[0021] The liquid discharge method of the full-bore, non-eccentric air lift valve discharge device of the present invention is implemented according to the following steps:

[0022] In the initial stage of fracturing, during the fluid discharge phase, the fluid is discharged from the tubing. In the later stage, when the rate of water discharge is lower than the rate of water production, fluid begins to accumulate in the tubing and casing annulus. The gas lift valve below the fluid accumulation level opens, and gas is injected from the annulus to lift the fluid. Under the injection pressure, the accumulated fluid in the annulus continuously enters the tubing through the opened gas lift valve and is discharged from the wellhead through the tubing.

[0023] The specific process of the gas lift valve device discharging the fluid from the wellhead through the tubing is as follows: When the fluid level in the annulus is lower than the position of the first-stage gas lift valve 6, the flow switch 9 of the first-stage gas lift valve 6 is automatically closed; the annulus fluid continuously enters the tubing through the flow switch 9 of the second-stage gas lift valve 5 under the gas injection pressure, and this process is repeated until the flow switch 9 of the fourth-stage gas lift valve 3 at the bottom is closed, and the fluid discharge process is completed.

[0024] Example 1

[0025] The full-bore, non-eccentric gas lift valve drainage device in this embodiment includes an oil pipe, an outer sleeve of which forms an annulus between the oil pipe and the sleeve, a throttle nozzle 1 connected to the bottom of the oil pipe, a packer 2 installed above the throttle nozzle 1, which separates the vertical and horizontal annulus sections of the annulus; a gas lift valve device is installed above the packer 2, a bottom liquid pipe is connected to the top of the oil pipe, and a high-pressure gas injection pipe is connected to the upper part of the annulus, which provides a gas extraction channel.

[0026] Example 2

[0027] The full-bore, non-eccentric gas lift valve drainage device in this embodiment includes an oil pipe with a sleeve connected to the outside, forming an annulus between the oil pipe and the sleeve. A throttle nozzle 1 is connected to the bottom of the oil pipe, and a packer 2 is installed above the throttle nozzle 1, separating the vertical and horizontal sections of the annulus. A gas lift valve device is installed above the packer 2. The top of the oil pipe is connected to a bottom liquid pipe, and a high-pressure gas injection pipe is connected to the upper part of the annulus, providing a gas extraction channel. The gas lift valve device includes, from bottom to top, a four-stage gas lift valve 3, a three-stage gas lift valve 4, a two-stage gas lift valve 5, and a one-stage gas lift valve 6. These four-stage gas lift valves are equidistant from each other and are arranged around the oil pipe along its axial direction.

[0028] Example 3

[0029] The full-bore, non-eccentric gas lift valve drainage device in this embodiment includes an oil pipe, an outer sleeve of which forms an annulus between the oil pipe and the sleeve, a throttle nozzle 1 connected to the bottom of the oil pipe, a packer 2 installed above the throttle nozzle 1, which separates the vertical and horizontal annulus sections of the annulus; a gas lift valve device is installed above the packer 2, a bottom liquid pipe is connected to the top of the oil pipe, and a high-pressure gas injection pipe is connected to the upper part of the annulus, which provides a gas extraction channel. The air lift valve device includes, from bottom to top, a four-stage air lift valve 3, a three-stage air lift valve 4, a two-stage air lift valve 5, and a one-stage air lift valve 6. The four-stage air lift valve 3, the three-stage air lift valve 4, the two-stage air lift valve 5, and the one-stage air lift valve 6 are all arranged around the oil pipe axially. The bottom of the four-stage air lift valve 3, the three-stage air lift valve 4, the two-stage air lift valve 5, and the one-stage air lift valve 6 are all provided with a liquid inlet 7. A flow switch 9 is provided above the liquid inlet 7. The four-stage air lift valve 3, the three-stage air lift valve 4, the two-stage air lift valve 5, and the one-stage air lift valve 6 are all provided with a liquid outlet 8 around the oil pipe radially.

[0030] Example 4

[0031] The full-bore, non-eccentric gas lift valve drainage device in this embodiment includes an oil pipe, an outer sleeve of which forms an annulus between the oil pipe and the sleeve, a throttle nozzle 1 connected to the bottom of the oil pipe, a packer 2 installed above the throttle nozzle 1, which separates the vertical and horizontal annulus sections of the annulus; a gas lift valve device is installed above the packer 2, a bottom liquid pipe is connected to the top of the oil pipe, and a high-pressure gas injection pipe is connected to the upper part of the annulus, which provides a gas extraction channel.

[0032] The air lift valve device includes, from bottom to top, a four-stage air lift valve 3, a three-stage air lift valve 4, a two-stage air lift valve 5, and a one-stage air lift valve 6. All four stages are arranged axially around the oil pipe, and the valves are equidistantly spaced on the oil pipe. Each of the four stages is equipped with a liquid inlet 7 at its bottom, and a flow switch 9 (pressure-sensitive) is installed above the inlet 7. Each of the four stages is equipped with a liquid outlet 8 radially around the oil pipe, and all four stages are single-flow valves.

[0033] The full-bore, non-eccentric gas lift valve drainage device described in the above embodiments is applied to various operating conditions for drainage. The specific process is as follows: In the initial stage of fracturing fluid drainage, the fluid is discharged from the tubing; in the later drainage stage, when the rate of discharged produced water is lower than the rate of produced water, fluid begins to accumulate in the tubing and casing annulus. The gas lift valve device located below the fluid accumulation level opens, and gas lift begins from the annulus; the main steam pressure is 20-30 MPa, and the accumulated fluid in the annulus continuously enters the tubing through the opened gas lift valve device under the gas injection pressure, and is discharged from the wellhead through the tubing; when the fluid level in the casing annulus is lower than the position of the first-stage gas lift valve 6, the flow switch 9 of the first-stage gas lift valve 6 automatically closes; the accumulated fluid in the annulus continues to enter the tubing through the opened flow switch 9 of the second-stage gas lift valve 5 under the gas injection pressure, and this process is repeated until the flow switch 9 of the lowest-level fourth-stage gas lift valve 3 closes, and the drainage process is completed.

[0034] The present invention relates to a drainage method for a full-bore, non-eccentric gas lift valve drainage device, which forms a complete set of rapid return drainage technology and achieves good results. It can keep the bottom of the well in a non-liquid state. The device of the present invention has the advantages of strong adaptability, fast drainage speed and safe construction. It not only realizes energy saving and consumption reduction, but also ensures the full production of formation gas and improves production efficiency.

Claims

1. A method for draining liquid from a full-bore, non-eccentric air lift valve draining device, comprising an oil pipe, an outer sleeve of the oil pipe, an oil-sleeve annulus between the oil pipe and the sleeve, a throttle nozzle (1) connected to the bottom of the oil pipe, a packer (2) set above the throttle nozzle (1), the packer (2) separating the oil-sleeve annulus between the vertical and horizontal sections; an air lift valve device set above the packer (2), a bottom liquid pipe connected to the top of the oil pipe, and a high-pressure air injection pipe connected to the upper part of the oil-sleeve annulus; The air lift valve device includes a four-stage air lift valve (3), a three-stage air lift valve (4), a two-stage air lift valve (5), and a one-stage air lift valve (6) arranged sequentially from bottom to top. The four-stage air lift valve (3), the three-stage air lift valve (4), the two-stage air lift valve (5), and the one-stage air lift valve (6) are all arranged around the oil pipe axis. The bottom of the four-stage air lift valve (3), the three-stage air lift valve (4), the two-stage air lift valve (5), and the first-stage air lift valve (6) are all provided with liquid inlets (7), and a flow switch (9) is provided above the liquid inlets (7). The four-stage air lift valve (3), the three-stage air lift valve (4), the two-stage air lift valve (5), and the first-stage air lift valve (6) are all provided with liquid outlets (8) in the radial direction around the oil pipe. The four-stage air lift valve (3), the three-stage air lift valve (4), the two-stage air lift valve (5), and the one-stage air lift valve (6) are all single-flow valves; The four-stage air lift valve (3), the three-stage air lift valve (4), the two-stage air lift valve (5), and the one-stage air lift valve (6) are equidistant from each other; characterized in that The specific steps are as follows: In the initial stage of fracturing, during the fluid drainage phase, the fluid is discharged from the tubing. In the later stage, when the rate of water discharge is lower than the rate of water production, fluid begins to accumulate in the tubing and annulus. The gas lift valve below the fluid accumulation level opens, and gas is injected from the annulus to lift the fluid. Under the injection pressure, the accumulated fluid in the annulus continuously enters the tubing through the opened gas lift valve and is discharged from the wellhead through the tubing.

2. The method of unloading the full-gauge, unbiased gas-lift valve unloading device according to claim 1, characterized in that, The specific process of the gas lift valve device discharging the wellhead through the tubing is as follows: when the liquid level in the annulus is lower than the position of the first-stage gas lift valve (6), the flow switch (9) of the first-stage gas lift valve (6) is automatically closed; the annulus liquid continuously enters the tubing under the gas injection pressure by opening the flow switch (9) of the second-stage gas lift valve (5), and this process is repeated until the flow switch (9) of the fourth-stage gas lift valve (3) located at the bottom is closed, and the liquid discharge process is completed.

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