A gas well reinjection water system

Abstract

The utility model relates to a kind of gas well reinjection water system, belong to oil production equipment technical field.The technical scheme is: the wellhead (1) of gas well is connected with reinjection tank (3) by drain pipe manifold (2), and reinjection tank is connected with control box (4) by reinjection effluent pipe (5), and control box is connected with reinjection aluminium plastic pipe by reinjection high-pressure hose (6), and reinjection aluminium plastic pipe is set in oil jacket annulus;Reinjection tank includes reinjection tank box (3.2), water inlet bin (3.12), closed bulkhead (3.13) and water outlet bin (3.14), and reinjection tank box is divided into water inlet bin and water outlet bin by closed bulkhead, and the upper portion of closed bulkhead is provided with filter port;Piston pump (12) and flowmeter (13) are provided in control box, and flowmeter is connected with piston pump, and piston pump is connected with reinjection aluminium plastic pipe by reinjection high-pressure hose.The utility model lifts water through the filtration of reinjection water system again and then reinjects into the well, avoids producing hydrops, maintains downhole pressure stable, and further guarantees production stability.

Description

Technical Field

[0001] This utility model relates to a gas well water reinjection system, belonging to the technical field of oil production equipment. Background Technology

[0002] Most gas reservoirs in gas wells contain formation water. During gas well production, both gas and water are lifted to the surface. As production progresses, formation pressure decreases, and edge water or bottom water may intrude into the producing layer, or condensate may precipitate. When the gas flow rate is insufficient to carry these liquids to the surface, they accumulate at the bottom of the wellbore, forming "cumulonimbus."

[0003] Fluid accumulation can cause the following problems: 1. Back pressure of the liquid column: The liquid column at the bottom of the well will generate an additional hydrostatic pressure, which is equivalent to "carrying a heavy burden" on the gas layer, severely hindering the flow of gas from the formation to the wellbore; 2. Decreased production: The gas needs to consume more energy to "push" the liquid column, resulting in a sharp decrease in production; 3. Unstable production: The airflow may become erratic, sometimes even exhibiting a "gasping" phenomenon; 4. Final flooding: If the accumulated liquid becomes severe enough, it will completely crush the gas layer, causing the gas well to stop production and become unusable.

[0004] The above-mentioned problems are prone to occur during the gas well extraction process, which affects the production output. Therefore, it is urgent to study a gas well water reinjection system to solve these problems. Utility Model Content

[0005] The purpose of this invention is to provide a gas well reinjection water system that filters the lifted water through the reinjection water system before reinjecting it into the well, thereby maintaining stable downhole pressure and ensuring stable production, and solving the problems existing in the background technology.

[0006] The technical solution of this utility model is: A gas well reinjection water system includes a reinjection tank and a control box. The wellhead of the gas well is connected to the reinjection tank via a drainage manifold. The reinjection tank is connected to the control box via a reinjection outlet pipe. The control box is connected to a reinjection aluminum-plastic pipe via a high-pressure reinjection hose. The reinjection aluminum-plastic pipe is installed within the annulus of the oil casing. The reinjection tank includes a tank body, an inlet chamber, a sealed partition, and an outlet chamber. The tank body is divided into an inlet chamber and an outlet chamber by the sealed partition. A filter is installed on the upper part of the sealed partition. The water inlet chamber is equipped with a water inlet for the reinjection tank at its upper part, which is connected to the drain manifold. The water outlet chamber is equipped with an overflow port at its upper part, which is connected to an overflow pipe, which is connected to a water storage tank. The control box is equipped with a plunger pump and a flow meter. The water outlet chamber is equipped with a water outlet for the reinjection tank, which is connected to the flow meter via a reinjection outlet pipe. The flow meter is connected to the plunger pump, which is connected to the reinjection aluminum-plastic pipe via a high-pressure reinjection hose.

[0007] The inlet and outlet water chambers are each equipped with a sedimentation tank at their bottom. The two sedimentation tanks are connected to the sewage pipe via connecting pipes, each equipped with a ball valve. Gravel and other debris will continuously accumulate in the sedimentation tanks, requiring regular cleaning. During cleaning, the ball valves at the bottom of both sedimentation tanks are opened, and the gravel will flow along the connecting pipes to the sewage discharge port, which is connected to the sewage pipe.

[0008] One end of the sewage pipe is equipped with a water storage tank connection port and a second ball valve. An overflow pipe is connected to the sewage pipe and positioned between the water storage tank connection port and the second ball valve. The other end of the sewage pipe is equipped with a drain connection port and is connected to a drain pipe. The second ball valve is always closed to prevent impurities in the sewage pipe from entering the water storage tank. When the sewage pipe is blocked, the second ball valve can be opened to flush away the blockage through the water in the overflow pipe.

[0009] The power and control lines of the flow meter and plunger pump are connected to the frequency converter control cabinet and participate in the control. The downhole unit is equipped with a downhole sensor that can detect the downhole fluid level. When the fluid level is low, the frequency converter control cabinet can control the plunger pump to increase its speed and increase the reinjection flow rate via the PLC. When the fluid level is high, the PLC can control the plunger pump to decrease its speed and reduce the reinjection flow rate to maintain the pressure balance in the well.

[0010] The frequency converter control cabinet is connected to the junction box, and the junction box is connected to the downhole unit via a power cable.

[0011] The top of the reinjection tank is equipped with a reinjection tank cover, and the bottom is equipped with a reinjection tank support.

[0012] The filter inlet is equipped with a filter screen and filter cotton. The filter cotton is long and needs to be replaced regularly.

[0013] The annulus is the space formed between the casing and the tubing, with the tubing located inside the casing. The annulus is connected to the gas storage tank, through which the gas lifted by the downhole unit enters the gas storage tank.

[0014] The drainage manifold is designed according to the gas well's discharge capacity to ensure that all the water lifted from the wellhead enters the drainage manifold and does not fall into the well casing.

[0015] The gas storage tank, water storage tank, filter screen, filter cotton, casing, oil pipe, drainage manifold, connecting pipe, sedimentation tank, ball valve one, sewage pipe, ball valve two, overflow pipe, control box, reinjection water outlet pipe, reinjection high-pressure hose, reinjection aluminum-plastic pipe, downhole unit, power cable, junction box, frequency converter control cabinet, plunger pump and flow meter, etc., are all equipment known and commonly used in this field.

[0016] The downhole unit simultaneously lifts water and gas from the wellhead. After gas-liquid separation, the gas enters the gas storage tank through the annulus, while the water flows from the oil pipe along the drain pipe into the water inlet of the reinjection tank. The water inlet and outlet are completely separated by a sealed partition. A filter screen and filter cotton are installed at the filter port above the sealed partition. Water in the water inlet enters the water outlet through the filter port, preventing sand and coal dust from entering the water outlet. Due to gravity, sand and coal dust in the water in the water inlet and outlet will settle in the sedimentation tank at the bottom of the reinjection tank and be discharged through the drain pipe. Water in the water outlet enters the flow meter through the reinjection outlet pipe. The flow meter can display the instantaneous flow rate and total flow rate of the injected water. After passing through the flow meter, it enters the plunger pump. After continuous pressurization by the plunger pump, it flows back into the well through the reinjection high-pressure hose and reinjection aluminum-plastic pipe to ensure downhole pressure balance. Water overflowing from the water outlet enters the water storage tank through the overflow pipe for storage.

[0017] The beneficial effects of this invention are: the water lifted up is filtered through the reinjection water system before being reinjected into the well, thus avoiding the accumulation of liquid, maintaining stable downhole pressure, and thereby ensuring stable production. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a perspective view of the present utility model; Figure 3 This is a schematic diagram of the internal structure of the reinjection tank of this utility model; In the diagram: 1. Wellhead; 2. Drainage manifold; 3. Reinjection tank; 3.1. Reinjection tank cover; 3.2. Reinjection tank body; 3.3. Reinjection tank support; 3.4. Reinjection tank outlet; 3.5. Overflow port; 3.6. Connecting pipe; 3.7. Reinjection tank inlet; 3.8. Sedimentation chamber; 3.9. Ball valve one; 3.10. Sewage pipe; 3.11. Inlet chamber; 3.12. Enclosed partition; 3.13. Outlet chamber; 3.14. Water storage tank connection port; 3.15. Sewage discharge connection port; 3.16. Ball valve two; 3.17. Overflow pipe; 3.18. Control box; 4. Reinjection outlet pipe; 5. Reinjection high-pressure hose; 6. Reinjection aluminum-plastic pipe; 7. Downhole unit; 8. Power cable; 9. Junction box; 10. Variable frequency control cabinet; 11. Plunger pump; 12. Flow meter; 13. Surface; 14. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and examples.

[0020] A gas well reinjection water system includes a reinjection tank 3 and a control box 4. The wellhead 1 of the gas well is connected to the reinjection tank 3 via a drainage manifold 2. The reinjection tank 3 is connected to the control box 4 via a reinjection outlet pipe 5. The control box 4 is connected to a reinjection aluminum-plastic pipe 7 via a reinjection high-pressure hose 6. The reinjection aluminum-plastic pipe 7 is installed within the annulus of the oil casing. The reinjection tank 3 includes a reinjection tank body 3.2, an inlet chamber 3.12, a sealing partition 3.13, and an outlet chamber 3.14. The reinjection tank body 3.2 is divided into the inlet chamber 3.12 and the outlet chamber 3.14 by the sealing partition 3.13. A filter port 3.11 is provided at the upper part of the sealing partition 3.13. The upper part of the water inlet 3.12 is provided with a water inlet 3.7 for the reinjection tank, which is connected to the drain manifold 2; the upper part of the water outlet 3.14 is provided with an overflow port 3.5, which is connected to an overflow pipe 3.18 through the overflow port 3.5, and the overflow pipe 3.18 is connected to the water storage tank; the control box 4 is provided with a plunger pump 12 and a flow meter 13, the water outlet 3.14 is provided with a water outlet 3.4 for the reinjection tank, which is connected to the flow meter 13 through a reinjection outlet pipe 5, the flow meter 13 is connected to the plunger pump 12, and the plunger pump 12 is connected to the reinjection aluminum-plastic pipe 7 through a reinjection high-pressure hose 6.

[0021] The bottom of the inlet chamber 3.12 and the outlet chamber 3.14 are respectively equipped with sedimentation chambers 3.8. The two sedimentation chambers 3.8 are connected to the sewage pipe 3.10 through connecting pipes 3.6. Ball valves 3.9 are installed on the connecting pipes 3.6. Gravel and other debris will continuously accumulate in the sedimentation chambers 3.8 and need to be cleaned regularly. When cleaning, the ball valves 3.9 at the lower end of the two sedimentation chambers 3.8 are opened, and the gravel will flow along the connecting pipes 3.6 to the sewage discharge port 3.16 of the sewage pipe 3.10. The sewage discharge port is connected to the sewage pipe.

[0022] One end of the sewage pipe 3.10 is equipped with a water storage tank connection port 3.15 and a ball valve 3.17. An overflow pipe 3.18 is connected to the sewage pipe 3.10 and is positioned between the water storage tank connection port 3.15 and the ball valve 3.17. The other end of the sewage pipe 3.10 is equipped with a sewage discharge connection port 3.16, which is connected to a sewage discharge pipe. The ball valve 3.17 is always closed to prevent impurities in the sewage pipe 3.10 from entering the water storage tank. When the sewage pipe 3.10 is blocked, the ball valve 3.17 can be opened, and the water in the overflow pipe 3.18 can be used to flush away the blockage in the sewage pipe 3.10.

[0023] The power and control lines of the flow meter 13 and the plunger pump 12 are connected to the frequency converter control cabinet 11 and participate in the control. The downhole unit 8 is equipped with a downhole sensor that can detect the downhole fluid level. When the fluid level is low, the PLC can control the plunger pump to increase its speed and increase the reinjection flow. When the fluid level is high, the PLC can control the plunger pump to decrease its speed and reduce the reinjection flow to maintain the pressure balance in the well.

[0024] The frequency converter control cabinet 11 is connected to the junction box 10, and the junction box 10 is connected to the downhole unit 8 via the power cable 9.

[0025] The reinjection tank body 3.2 has a reinjection tank cover 3.1 on the top and a reinjection tank support 3.3 on the bottom.

[0026] The filter port 3.11 is equipped with a filter screen and filter cotton. The filter cotton is long and needs to be replaced regularly.

[0027] The annulus is the space formed between the casing and the tubing, with the tubing located inside the casing. The annulus is connected to the gas storage tank, through which the gas lifted by the downhole unit enters the gas storage tank.

[0028] The drainage manifold 2 is designed according to the gas well's discharge capacity to ensure that all the water lifted from the wellhead enters the drainage manifold 2 and does not fall into the well casing.

[0029] Downhole unit 8 simultaneously lifts water and gas from the well to wellhead 1. After gas-liquid separation, the gas enters the gas storage tank through the annulus, while the water flows from the oil pipe along the drain manifold 2 into the water inlet 3.12 of the reinjection tank 3. The water inlet 3.12 and the water outlet 3.14 are completely separated by a sealing partition 3.13. A filter screen and filter cotton are installed at the filter port 3.11 above the sealing partition 3.13. Water in the water inlet enters the water outlet 3.14 through the filter port 3.11, preventing sand and coal dust from entering the water outlet 3.14. Gravel and coal dust in the water in the reservoir and outlet reservoir will be deposited into the sedimentation tank 3.8 at the bottom of the reinjection tank due to gravity, and discharged through the drain pipe; the water in the outlet reservoir enters the flow meter 13 through the reinjection outlet pipe 5. The flow meter 13 can display the instantaneous flow rate and total flow rate of the injected water. After passing through the flow meter 13, it enters the plunger pump 12. After being continuously pressurized by the plunger pump, it flows back into the well through the reinjection high-pressure hose 6 and the reinjection aluminum-plastic pipe 7 to ensure the pressure balance downhole; the water overflowing from the outlet reservoir enters the water storage tank through the overflow pipe 3.18 for storage.

[0030] In practical applications, the downhole unit 8 simultaneously lifts water and gas from the well to the wellhead 1 on the surface 14. After gas-liquid separation, the gas enters the gas storage tank through the annulus, while the water flows from the oil pipe along the drain manifold 2 into the water inlet 3.12 of the reinjection tank. The drain manifold 2 connects the wellhead 1 and the water inlet 3.7 of the reinjection tank. The water contains impurities and foreign objects such as sand, gravel, and coal dust. Due to gravity, these impurities and foreign objects will settle in the sedimentation tank 3.8 at the bottom of the reinjection tank. A closed baffle 3.13 completely separates the water inlet and outlet. A filter port 3.11 is provided above the closed baffle 3.13, and a filter screen and filter cotton are installed at the filter port 3.11. The purpose of the closed baffle 3.13 and the filter port 3.11 (with long strips of filter cotton at the filter port, which need to be replaced regularly) is to prevent impurities such as sand and coal dust from entering the water outlet 3.14, which could easily clog the subsequent plunger pump and pipelines, resulting in insufficient reinjection pressure and flow. After the inlet chamber 3.12 is full, the water flows through the filter port to the outlet chamber 3.14. Below the outlet chamber 3.14 is a sedimentation chamber 3.8. A reinjection tank outlet 3.4 is located at a low position within the outlet chamber, connected to the inlet of the flow meter 13 via a reinjection outlet pipe 5. This location ensures that sediment at the bottom does not enter the outlet pipe while maintaining sufficient pressure in the outlet. Above the outlet chamber 3.14 is an overflow port 3.5, connected to the sewage pipe 3.10 via an overflow pipe 3.18. Overflow water flows through the overflow pipe 3.18 to the storage tank connection port 3.15, which connects to the storage tank, storing the overflowed water. Ball valve 2 3.17 is closed to prevent impurities from the sewage pipe from entering the storage tank. The sedimentation chamber 3.8 will continuously accumulate sediment and requires regular cleaning. During cleaning, open the two ball valves 3.9 at the lower end of the sedimentation tank 3.8. The gravel will travel along the sewage pipe to the drain connection 3.16, which connects to the drain pipe. Regular cleaning reduces the accumulation of gravel in the sedimentation tank, reduces the entry of foreign objects into the pump, and ensures stable reinjection operation.

[0031] Water exits from the reinjection tank outlet 3.4 of the water outlet chamber 3.14 and flows along the reinjection outlet pipe 5 to the flow meter 13, which displays the instantaneous and total flow rates of the injected water. After passing through the flow meter 13, the water enters the plunger pump 12, which operates at a pressure of 5 MPa. After continuous pressurization by the plunger pump, the water flows back into the well via the high-pressure reinjection hose 6 and the reinjection aluminum-plastic pipe 7, ensuring downhole pressure balance. The high-pressure reinjection hose 6 and the reinjection aluminum-plastic pipe 7 are connected by threads at the wellhead 1. The reinjection aluminum-plastic pipe 7, with an outer diameter of 16 mm, is fixed to the tubing using a cable protector to prevent it from falling off. The purpose of the plunger pump 12 is to smoothly reinject water into the well, increasing pressure and reducing resistance.

[0032] The power and control lines of the flow meter 13 and the plunger pump 12 are both connected to the frequency converter control cabinet 11 and participate in the control. The downhole unit 8 is equipped with a downhole sensor that can detect the downhole fluid level. When the fluid level is low, the frequency converter control cabinet 11 can control the plunger pump to increase its speed and increase the reinjection flow rate through the PLC. When the fluid level is high, the PLC can control the plunger pump to decrease its speed and reduce the reinjection flow rate to maintain the pressure balance in the well.

[0033] Controlled by a PLC, the reinjection volume can be adjusted based on the actual submersion depth in the well. A downhole sensor at the bottom of the downhole unit 8 monitors the downhole fluid level in real time. When the sensor detects a high level, the PLC sends a command to the plunger pump's frequency converter control cabinet to reduce the pump speed, thus slowing the reinjection. Conversely, when the sensor detects a low level, the PLC sends a command to the pump's frequency converter control cabinet to increase the pump speed, accelerating the reinjection and maintaining a constant downhole fluid level to prevent depletion or excessive pressure.

[0034] The reinjection system of this invention is used in Xinjiang, where temperatures can reach -30 to -40°C in winter and there is a huge temperature difference between day and night. To prevent the reinjection system from freezing and becoming unusable, we designed insulation measures for the reinjection system.

[0035] (1) The reinjection tank and the outer wall of the reinjection tank are evenly wrapped with heat tracing tape, and a temperature sensor is placed inside the cabinet. When the temperature drops below 0℃, the heat tracing tape will automatically heat up to ensure that the tank does not freeze. (2) Wrap a layer of insulation cotton around the outside of the heat tracing cable. This will not only keep the reinjection tank and pipeline warm, but also reduce the heat loss of the heat tracing cable.

[0036] Wrap a layer of fiberglass tape around the outer layer of the insulation cotton. This will not only help to shape the insulation layer but also prevent rainwater from getting the insulation cotton wet.

Claims

1. A gas well water reinjection system, characterized in that: The system includes a reinjection tank (3) and a control box (4). The wellhead (1) of the gas well is connected to the reinjection tank (3) via a drainage manifold (2). The reinjection tank (3) is connected to the control box (4) via a reinjection outlet pipe (5). The control box (4) is connected to the reinjection aluminum-plastic pipe (7) via a reinjection high-pressure hose (6). The reinjection aluminum-plastic pipe (7) is installed in the annulus of the oil casing. The reinjection tank (3) includes a reinjection tank body (3.2), an inlet chamber (3.12), a closed partition (3.13), and an outlet chamber (3.14). The reinjection tank body (3.2) is divided into an inlet chamber (3.12) and an outlet chamber (3.14) by the closed partition (3.13). The upper part of the closed partition (3.13) is provided with a filter port (3.11). The inlet chamber (3.12) is divided into an inlet chamber (3.12) and an outlet chamber (3.14). .12) The upper part is provided with a water inlet (3.7) of the reinjection tank, which is connected to the drain pipe manifold (2); the upper part of the water outlet (3.14) is provided with an overflow port (3.5), which is connected to the overflow pipe (3.18) through the overflow port (3.5), and the overflow pipe (3.18) is connected to the water storage tank; the control box (4) is provided with a plunger pump (12) and a flow meter (13), the water outlet (3.14) is provided with a water outlet (3.4) of the reinjection tank, which is connected to the flow meter (13) through the reinjection water outlet pipe (5), the flow meter (13) is connected to the plunger pump (12), and the plunger pump (12) is connected to the reinjection aluminum-plastic pipe (7) through the reinjection high-pressure hose (6).

2. A gas well reinjection water system according to claim 1, characterized in that: The bottom of the inlet chamber (3.12) and the outlet chamber (3.14) are respectively equipped with sedimentation chambers (3.8). The two sedimentation chambers (3.8) are respectively connected to the sewage pipe (3.10) through connecting pipes (3.6). A ball valve (3.9) is provided on the connecting pipe (3.6).

3. A gas well reinjection water system according to claim 2, characterized in that: One end of the sewage pipe (3.10) is provided with a water storage tank connection port (3.15) and a ball valve (3.17). An overflow pipe (3.18) is connected to the sewage pipe (3.10) and is located between the water storage tank connection port (3.15) and the ball valve (3.17). The other end of the sewage pipe (3.10) is provided with a sewage discharge connection port (3.16) and is connected to the sewage discharge pipe through the sewage discharge connection port (3.16).

4. A gas well reinjection water system according to claim 1 or 2, characterized in that: The power and control lines of the flow meter (13) and the plunger pump (12) are connected to the frequency converter control cabinet (11).

5. A gas well reinjection water system according to claim 4, characterized in that: The frequency converter control cabinet (11) is connected to the junction box (10), and the junction box (10) is connected to the downhole unit (8) through the power cable (9).

6. A gas well reinjection water system according to claim 1 or 2, characterized in that: The top of the reinjection tank body (3.2) is provided with a reinjection tank cover (3.1), and the bottom is provided with a reinjection tank support (3.3).

7. A gas well reinjection water system according to claim 1 or 2, characterized in that: The filter port (3.11) is provided with a filter screen and filter cotton, and the filter cotton is long and narrow.

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