Shale gas deep pumping drainage process pipe column

Abstract

The utility model discloses a shale gas deep pumping drainage process pipe column which comprises a casing pipe, an oil pipe, a hydraulic anchor, an anti-gas pump, a tail pipe, an anti-leakage check valve, a screen pipe and a screwed plug, the oil pipe is fixed in the casing pipe through the hydraulic anchor, the oil pipe is connected with the tail pipe through the anti-gas pump, the tail pipe is located below the anti-gas pump, the oil pipe is located above the anti-gas pump, and the anti-leakage check valve is connected with the screen pipe. An anti-leakage check valve, a screen pipe and a screwed plug are sequentially arranged at the front part of the tail pipe; and a through central channel is formed from the screen pipe, the anti-leakage check valve, the tail pipe, the anti-gas pump, the hydraulic anchor and the oil pipe. The shale gas deep-pumping drainage process pipe column has the advantages that the shale gas deep-pumping drainage process pipe column is of the structure of the anti-gas pump, the tail pipe and the anti-leakage check valve, the tail pipe is deepened, the anti-leakage check valve is lowered into the middle of the horizontal section, it is ensured that accumulated liquid of the horizontal section is drained when energy of a drainage well in the later period is insufficient, and therefore continuous drainage of a shale gas well is achieved.

Description

Technical Field

[0001] The utility model relates to a shale gas well drainage and production process pipe string, belonging to the technical field of shale gas drainage and gas production. Background Art

[0002] Shale gas is a recoverable natural gas resource found in shale formations. China boasts significant recoverable reserves. The formation and accumulation of shale gas exhibit unique characteristics, often occurring within thick, widespread shale source rock formations within basins. Compared to conventional natural gas, shale gas development offers advantages such as a longer mining life and production cycle. Most shale gas-producing formations are widely distributed, thick, and generally contain gas, enabling shale gas wells to produce gas at a stable rate over the long term.

[0003] Shale gas refers to unconventional natural gas that is attached to organic-rich mudstone and its interlayers and exists mainly in adsorption and free states. It is mainly composed of methane and is a clean and efficient energy resource and chemical raw material. It is mainly used for residential gas, urban heating, power generation, automobile fuel and chemical production, etc., and has a wide range of uses.

[0004] The drainage and gas production technologies commonly used in domestic shale gas fields mainly include gas lift, foam drainage, electric submersible pump, jet pump, and liquid drive rodless pump drainage and production technology, but each drainage technology has certain application conditions. Gas lift drainage and gas production mainly consists of a gas lift valve to form a drainage and production string. Its main disadvantage is that the gas lift valve cannot be opened. When the formation pressure of foam drainage and gas production is lower than the lifting pressure of the accumulated liquid in the horizontal section, the accumulated liquid in the horizontal section cannot be discharged. The electric submersible pump drainage and gas production technology is not suitable for liquid production below 20m 3 The main reason for the production wells is that the liquid production is less than 20m 3 When the pump is underloaded, the electric submersible pump will experience an underload shutdown. The jet pump's pumping depth for drainage and gas production is less than 2600m. The surface reversing valve of the liquid-driven rodless pump for drainage and gas production is prone to leakage, and the current pumping depth of the liquid-driven rodless pump is less than 1200m, which cannot meet the needs of deep well drainage and gas production.

[0005] According to the production characteristics of shale gas wells at different stages, with the goal of maximizing production, the drainage and production process measures are optimized in stages. The liquid volume, well depth, oil pressure, gas-liquid ratio and other factors are used as the basis for selecting the drainage and production process. The production stages of shale gas are divided, and the dominant shale gas drainage and production processes in different blocks are formed.

[0006] Initial stage: Implement reasonable production adjustment, optimize velocity string, control the decay rate of gas well pressure, and extend the flowing production cycle.

[0007] Medium term: adopt composite drainage and production technology (gas lift + bubble drainage, bubble drainage + pressurization, gas lift + pressurization) to ensure continuous and stable production of gas wells under conditions below the critical liquid carrying capacity.

[0008] Later: Combined with reduced-pressure production, downhole negative-pressure jetting, hydraulic rodless pumping, and mechanical pumping combined with air-proof pumping for lifting are being adopted. However, negative-pressure gas production increases downhole production pressure differentials, boosting production. The downhole tubing design utilizes a pipe-inserted bridge plug / hydraulic anchor combined with a single-tube jet pump. Currently, the pumping depth is limited to 2,600 meters, insufficient for lifting at vertical depths of 4,000-4,600 meters.

[0009] In the later stage of drainage, as the formation pressure decreases, the existing drainage process measures are unable to discharge the accumulated fluid in the horizontal section, resulting in the inability of the drainage well to produce normally.

[0010] Through on-site analysis, it was found that as the formation pressure decreased in the later stage of drainage, the existing drainage process measures were unable to drain the accumulated liquid in the horizontal section, resulting in the inability of the drainage well to produce normally. The main reasons are as follows:

[0011] 1. The burial depth of the stratum is greater than 4000 m;

[0012] 2. The horizontal well is a down-dip horizontal well;

[0013] 3. The height difference between target points A and B is 300 to 700 meters;

[0014] 4. The existing drainage and gas production technologies in domestic shale gas fields, such as gas lift, bubble drainage, electric submersible pumps, and jet pumps, cannot meet the needs of deep drainage and gas production in normal pressure shale gas fields. Summary of the Invention

[0015] Purpose of the invention: The purpose of the present invention is to overcome the above-mentioned technical deficiencies and provide a shale gas deep pumping and production process string with gas-proof function, so as to solve the problem that the accumulated liquid in the horizontal section of the shale gas well cannot be discharged as the formation pressure decreases in the later stage of production, extend the pump inspection cycle of the production well, and realize the continuous production of the shale gas well in the later stage.

[0016] To address the aforementioned technical issues, the present invention provides a deep shale gas extraction and production process string, comprising a sucker rod, tubing, casing, hydraulic anchor, air pump, tail pipe, anti-loss check valve, sand screen, and a plug. The lower portion of the tubing is connected to the hydraulic anchor, which is then connected to the air pump, which is then connected to the tail pipe, which is then connected to the anti-loss check valve, which is then connected to the sand screen, which is then connected to the plug. The tubing is conventionally secured within the casing via the hydraulic anchor. The sand screen serves as the liquid intake for the string, forming a central channel extending from the sand screen, anti-loss check valve, tail pipe, air pump, hydraulic anchor, and tubing. The entire process string employs an "air pump + tail pipe + anti-loss check valve" structure.

[0017] During normal production, gas produced from the formation is extracted through the annulus between the tubing and casing, while liquid is discharged through a sand-control screen, a leak-proof check valve, a tail pipe, an air pump, and the central channel of the hydraulic anchor. The shale gas deep extraction and production process uses a "air pump + tail pipe + leak-proof check valve" structure. By deepening the tail pipe and lowering the leak-proof check valve into the middle of the horizontal section, this ensures that when the well's energy is insufficient in the later stages, the accumulated liquid in the horizontal section can be discharged, thus achieving continuous shale gas production.

[0018] In a preferred embodiment, to address the issue of liquid accumulation in the horizontal section of a shale gas well remaining undischarged as formation pressure decreases in the later stages of production, the liner is lowered into the horizontal section of the shale gas well through the casing, and the anti-loss check valve is lowered into the middle of the horizontal section. The anti-loss check valve ensures that the liner below the gas pump remains filled with liquid during tubing operation.

[0019] Preferably, in order to prevent sand from entering the tail pipe between the anti-air pump and the anti-loss check valve and causing a malfunction of the anti-air pump, a screen pipe connecting the casing and the oil pipe is provided on the tail pipe. The screen pipe is located at the front end of the anti-loss check valve. The screen pipe can prevent sand in the formation from entering the tail pipe.

[0020] Preferably, a wire plug is provided at the front end of the tail pipe to ensure that the accumulated liquid in the horizontal section of the shale gas well can only enter the tail pipe through the screen pipe, which can effectively prevent sand from entering the tail pipe.

[0021] Preferably, the sucker rod is connected to a plunger inside the anti-air pump, and the sucker rod extends from the anti-air pump to the wellhead. The sucker rod drives the plunger inside the anti-air pump to move up and down, thereby draining the liquid in the tail pipe and the oil pipe.

[0022] Preferably, in order to prevent "air lock", the anti-air pump adopts a forced pull rod type deep pumping bridge anti-air pump, which can effectively discharge the gas entering the pump.

[0023] Preferably, in order to achieve the purpose of deep pumping with a small pump, the air-proof pump is lowered to a depth of 100m above target point A.

[0024] Beneficial effect: The utility model adopts the structure of "anti-air pump + tail pipe + anti-leakage check valve". By deepening the tail pipe and lowering the anti-leakage check valve into the middle of the horizontal section, it ensures that when the energy of the drainage well is insufficient in the later stage, the accumulated liquid in the horizontal section is discharged, thereby realizing the continuous drainage of shale gas wells; the anti-air pump and anti-leakage check valve are used as a two-level anti-air process to ensure that the oil pipe below the anti-air pump is always full of liquid, avoiding the "air lock" caused by the oil pipe below the pump being filled with gas; the anti-air pump adopts a forced pull rod type deep pumping bridge anti-air pump, which The pump has high strength and can be lowered to a depth of 100m above target point A, achieving the goal of deep pumping with a small pump. The screen pipe uses a sand-proof screen pipe with a hole diameter of 0.12mm, which effectively prevents sand from entering the pump. The screen pipe is lowered into the middle of the horizontal section, and the suction port of the pipe string is always in the liquid, avoiding the phenomenon of the pump failing to suck out liquid when the liquid level is low. It solves the problem of liquid accumulation in the horizontal section of shale gas wells that cannot be discharged as the formation pressure decreases in the late stage of drainage and production, extends the pump inspection cycle of the drainage and production wells, and realizes continuous drainage and production in the late stage of shale gas wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the downhole tubular structure of the utility model. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, a shale gas deep extraction and production process string includes a casing 1, an oil pipe 2, a hydraulic anchor 3, an air pump 4, a tail pipe 5, an anti-loss check valve 6, a screen pipe 7 and a wire plug 8. The oil pipe 2 is fixed in the casing 1 by the hydraulic anchor 3. The oil pipe 2 and the tail pipe 5 are connected through the air pump 4. The tail pipe 5 is located at the lower part of the air pump 4, and the oil pipe 2 is located at the upper part of the air pump 4. The front part of the tail pipe 5 is sequentially provided with an anti-loss check valve 6, a screen pipe 7 and a wire plug 8. The anti-loss check valve 6 is connected from the tail pipe 5 to the oil pipe 2, and the tail pipe 5 is filled with liquid from the anti-loss check valve 6 to the air pump 4.

[0028] During normal production, gas produced from the formation is produced through the annular space formed by the oil pipe 2 and the casing 1, and liquid is discharged through the screen 7, the anti-leakage check valve 6, the tail pipe 5, the anti-air pump 4, and the central channel of the hydraulic anchor 3. The utility model ensures that the tail pipe 5 below the anti-air pump 4 is always filled with liquid through the anti-leakage check valve 6. This can prevent the anti-air pump 4 from generating "gas lock" due to gas and affect the discharge of bottomhole liquid, thereby affecting the continuous drainage of the shale gas well in the later stage.

[0029] In order to solve the problem that the accumulated liquid in the horizontal section of the shale gas well cannot be discharged as the formation pressure decreases in the later stage of drainage, the tail pipe 5 is lowered into the middle of the horizontal section of the shale gas well along the casing 1, and the anti-leakage check valve 6 is located in the front of the tail pipe 5. The anti-leakage check valve is lowered into the middle of the horizontal section. The anti-leakage check valve 6 ensures that the oil pipe below the air pump 4 is always full of liquid when the pipe string is lowered.

[0030] To prevent sand from entering the tail pipe 5 between the air pump 4 and the anti-loss check valve 6 and causing malfunction of the air pump 4, a screen 7 is installed on the tail pipe 5, connecting the casing 1 and the oil pipe 2. The screen 7 is located in front of the anti-loss check valve 6. The sand-proof screen 7 has a hole diameter of 0.12 mm, which effectively prevents sand from entering the air pump 4 and causing malfunction of the air pump 4.

[0031] In order to further prevent sand from entering the liner 5, a wire plug 8 is provided at the front end of the liner 5. Due to the provision of the wire plug 8, the accumulated liquid in the horizontal section of the shale gas well can only enter the liner 5 through the screen 7, which can effectively prevent sand from entering the liner 5.

[0032] A sucker rod 9 is provided in the oil pipe 2 above the air pump 4 and is connected to a plunger inside the air pump 4. The sucker rod 9 extends from the air pump 4 to the wellhead. The sucker rod 9 drives the plunger inside the air pump 4 up and down, thereby draining the liquid from the tail pipe 5 and the oil pipe 2.

[0033] The utility model adopts the structure of "anti-air pump 4 + tail pipe 5 + anti-leakage check valve 6". By deepening the tail pipe 5 and lowering the anti-leakage check valve 6 into the middle of the horizontal section, it is ensured that when the energy of the drainage well is insufficient in the later stage, the accumulated liquid in the horizontal section is discharged, thereby realizing continuous drainage of shale gas wells; a two-level anti-air process of anti-air pump 4 and anti-leakage check valve 6 is adopted to ensure that the tail pipe 5 below the anti-air pump 4 is always full of liquid, avoiding the tail pipe 5 being filled with gas and causing "air lock"; after the tail pipe 5 below the anti-air pump 4 is lowered, the tail pipe 5 is filled with water, and then the anti-air pump 4 and the oil pipe 2 above the anti-air pump 4 are lowered, so that the gas in the tail pipe 5 below the anti-air pump 4 can be discharged to prevent "air lock".

[0034] The forced pull-rod deep-draw cross-bridge air-proof pump can effectively discharge the gas entering the pump and prevent "gas lock". The function of the anti-leakage check valve 6 is to ensure that the pipe string below the air-proof pump 4 is always filled with liquid to prevent gas from entering the pump; the air-proof pump 4 adopts a forced pull-rod deep-draw cross-bridge air-proof pump, which has high strength and a lowering depth of 100m above target point A, achieving the purpose of deep pumping with a small pump; the sand-proof screen pipe 7 of the liquid suction port of the deep pumping and production process pipe string adopts a sand-proof screen pipe with a hole diameter of 0.12mm, which effectively prevents sand from entering the pump; the sand-proof screen pipe 7 of the liquid suction port of the deep pumping and production process pipe string is lowered into the middle of the horizontal section, and the suction port of the pipe string is always in the liquid, avoiding the phenomenon that the pump cannot suck out liquid when the liquid level is low.

[0035] Here's how it works:

[0036] During normal production, gas produced from the formation is produced through the annulus between tubing 2 and casing 1, while liquid is discharged through the central channel of sand-proof screen 7, anti-loss check valve 6, tail pipe 5, anti-air pump 4, and hydraulic anchor 3. The shale gas deep extraction and production process string adopts the "anti-air pump 4 + tail pipe 5 + anti-loss check valve 6" structure. By deepening the tail pipe 5 and lowering the sand-proof screen 7 into the middle of the horizontal section, the accumulated liquid in the horizontal section can be discharged when the well's energy is insufficient in the later stages, thus achieving continuous production of shale gas wells.

[0037] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A shale gas deep extraction and production process string, comprising a casing (1), an oil pipe (2), a hydraulic anchor (3), an air pump (4), a tail pipe (5), a leakage prevention check valve (6), a screen pipe (7) and a wire plug (8), wherein the oil pipe (2) is fixed in the casing (1) by the hydraulic anchor (3), and is characterized in that: The oil pipe (2) and the tail pipe (5) are connected via an air pump (4). The tail pipe (5) is located below the air pump (4), and the oil pipe (2) is located above the air pump (4). A leakage prevention check valve (6), a screen pipe (7), and a wire plug (8) are sequentially provided at the front of the tail pipe (5). The leakage prevention check valve (6) has a central channel extending from the tail pipe (5) to the oil pipe (2).

2. The shale gas deep extraction and production process string according to claim 1, characterized in that: The tail pipe (5) is lowered into the middle of the horizontal section of the shale gas well along the casing (1); the anti-leakage check valve (6) is located in front of the tail pipe (5); and the anti-leakage check valve (6) is lowered into the middle of the horizontal section of the shale gas well.

3. The shale gas deep extraction and production process string according to claim 1, characterized in that: The tail pipe (5) is connected to a screen pipe (7), which is connected to the tail pipe (5). The screen pipe (7) is located at the front end of the anti-leakage check valve (6).

4. The shale gas deep extraction and production process string according to claim 1 or 2, characterized in that: After the tail pipe (5) at the lower part of the air pump (4) enters the well, the tail pipe (5) with the anti-leakage check valve (6) is filled with water.

5. The shale gas deep extraction and production process string according to claim 1, characterized in that: A threaded plug (8) is provided at the front end of the tail pipe (5).

6. The shale gas deep extraction and production process string according to claim 1, characterized in that: A sucker rod (9) connected to a plunger inside the anti-air pump (4) is provided in the oil pipe (2) above the anti-air pump (4), and the sucker rod (9) extends from the anti-air pump (4) to the wellhead.

7. The shale gas deep extraction and production process string according to claim 1, characterized in that: The anti-air pump (4) adopts a forced pull rod type deep-draw bridge anti-air pump.

8. The shale gas deep extraction and production process string according to claim 1, characterized in that: The anti-air pump (4) is lowered to a depth of 100 m above target point A.

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