Built-in cable-conveying coiled tubing electric plunger pump drainage system and construction process thereof

Abstract

The application provides a built-in cable coiled tubing electric plunger pump liquid discharge system and a construction process thereof. The electric plunger pump is lowered into a wellbore through the coiled tubing, and the plunger pump is operated through power supply of the built-in cable to realize lifting of accumulated liquid in the wellbore to the ground. A cable sealing nipple and an electric plunger pump are specially designed and manufactured for the process. The cable sealing nipple is installed on a coiled tubing drum, and the power cable is led out of the coiled tubing under the premise of ensuring sealing and preventing liquid in the coiled tubing from flowing out. The electric plunger pump comprises a connector, a motor protector, a linear plunger motor and a sand prevention screen pipe. The linear plunger motor is designed with an upper electromagnet, a plunger-shaped core, a lower one-way valve and a lower electromagnet. Different from the conventional process of binding the cable outside the oil pipe to deliver the electric submersible pump, the power cable is built in the coiled tubing, and the special electric plunger pump is used for liquid discharge, which has lower requirements for sand content and gas-liquid ratio of the liquid, can directly lift and lower the coiled tubing to adjust the position of the electric plunger pump, does not need to interrupt the liquid discharge by power interruption, has more advantages such as stronger process operability, wider application range, safer operation, lower construction cost and longer equipment life.

Description

Technical Field

[0001] This invention relates to the field of drainage and gas production technology in oil and gas exploration and development, and more specifically, to a drainage system with an electric plunger pump and a built-in cable coiled tubing and its construction process. Background Technology

[0002] Normal and low-pressure shale gas wells have low formation pressure coefficients. During production, the formation energy continuously decreases, and the gas production gradually falls below the critical fluid-carrying velocity, causing fluid to accumulate at the bottom of the well and resulting in adverse consequences such as production stoppage. Therefore, it is necessary to adopt fluid drainage and gas production technology to improve production conditions and increase the recovery efficiency of single wells.

[0003] Currently implemented forced fluid displacement processes mainly include air lift, jet pump, and electric submersible pump, which have the following shortcomings:

[0004] ① Gas lift requires sufficient formation energy to discharge the fluid accumulated in the wellbore;

[0005] ② Jet pump downhole units are complex, have high maintenance costs, and are difficult to operate;

[0006] ③ Conventional electric submersible pump equipment is inconvenient to install, and the cable is placed outside the pipe, making it extremely easy to be damaged during the lowering process. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a fluid discharge system for an electric plunger pump with an internal cable and a construction process thereof. By embedding the power cable inside the continuous tubing, the pump lowering cycle can be shortened, cable damage from impacts can be avoided, construction costs can be reduced, and operational safety can be improved.

[0008] The technical solution adopted by the present invention to solve its technical problem is: to construct a fluid discharge system with an electric plunger pump and a built-in cable coiled tubing, including a blowout tank, an electrical control cabinet, a power cable, a cable sealing short section, a coiled tubing drum, a built-in cable coiled tubing, an injection head, a blowout preventer, a blowout preventer, a wellhead gate assembly, and an electric plunger pump.

[0009] The blowout pool is connected to the ground outlet of the built-in cable coiled tubing via a manifold. The electrical control cabinet is connected to the ground end of the power cable. The cable sealing short section is installed on the coiled tubing drum and located at the ground outlet of the built-in cable coiled tubing. The coiled tubing drum is placed on the ground, and the built-in cable coiled tubing is wound around the coiled tubing drum. The injection head, blowout preventer, blowout preventer and wellhead gate assembly are installed from top to bottom in the wellbore. The electric plunger pump is installed at the downhole outlet of the built-in cable coiled tubing.

[0010] The cable sealing section includes a union joint, a fixed anchor claw, a locking sleeve, a multi-stage sealing outer cylinder, a multi-stage sealing end cap, and a lower joint;

[0011] The union joint is connected to the joint on the continuous tubing drum. The union joint has a conical space inside, and the fixed anchor claw is installed in the conical space. The fixed anchor claw has a cutting slit and an anchoring tooth. The cutting slit allows the fixed anchor claw to retract inward, and the anchoring tooth allows the fixed anchor claw to bite the steel wire armor on the outside of the power cable.

[0012] The locking sleeve is connected to the union joint by a thread. When the locking sleeve is tightened, the fixing anchor claws retract along the conical space to hug the power cable, so that the power cable cannot move.

[0013] The multi-stage sealing outer cylinder is connected to the union joint via threads. The multi-stage sealing end cap is installed at the through hole of the multi-stage sealing outer cylinder. The power cable, after removing the steel wire armor, passes through the inner hole of the multi-stage sealing end cap. The union joint, the multi-stage sealing outer cylinder, and the multi-stage sealing end cap form a sealed inner cavity. The lower connector is connected to the multi-stage sealing outer cylinder via threads. The power cable, after removing the steel wire armor, passes through the inner hole of the lower connector.

[0014] In the above scheme, the power cable is a steel wire armored power cable, which includes two or three independent cable cores.

[0015] In the above scheme, the sealed inner cavity is filled with insulating silicone grease.

[0016] In the above scheme, the connection between the lower connector and the multi-stage sealing outer cylinder is sealed by an O-ring, and the connection between the multi-stage sealing outer cylinder and the union connector is sealed by an O-ring.

[0017] In the above scheme, the multi-stage sealing end cap, the multi-stage sealing outer cylinder, and the power cable are sealed by O-rings.

[0018] In the above scheme, the electric plunger pump includes a connector, a motor protector, a linear plunger motor, and a sand screen. The connector is installed at the downhole outlet end of the built-in cable coiled tubing by rivets. The connector is designed with an upper one-way valve, which allows liquid to flow from bottom to top but does not allow liquid to flow from top to bottom. The connector is designed with a power cable fixing device, which leads the power cable core into the eccentric channel to achieve separation of the hydraulic and electrical channels.

[0019] The motor protector is threadedly connected to the lower end of the connector, and the linear piston motor is threadedly connected to the lower end of the motor protector. The linear piston motor contains an upper electromagnet, a piston-shaped iron core, a lower one-way valve, and a lower electromagnet. When the upper electromagnet is energized, the piston-shaped iron core is attracted downwards by magnetic force and moves axially upwards. When the lower electromagnet is energized, the piston-shaped iron core is attracted upwards by magnetic force and moves axially downwards. The upper and lower electromagnets are switched on / off via a limit switch. The lower one-way valve is installed in the inner hole of the piston-shaped iron core, allowing liquid to flow upwards but not downwards. The sand-proof screen is threadedly connected to the lower end of the linear piston motor.

[0020] The present invention also provides a construction process for the fluid discharge system using the built-in cable coiled tubing electric plunger pump, comprising the following steps:

[0021] S1. Place the coiled tubing drum with the built-in cable coiled tubing on a level surface at the well site.

[0022] S2. Connect the ground outlet of the built-in cable continuous oil pipe to the venting pool through a manifold;

[0023] S3. Insert the built-in cable continuous tubing into the injection head, and connect the blowout preventer and the blowout preventer to the lower end of the injection head;

[0024] S4. Connect the electric plunger pump to the bottom end of the built-in cable continuous tubing, lead the power cable out from the cable sealing section and connect it to the electrical control cabinet, perform a power-on test run on the electric plunger pump, check the display of various parameters of the electric plunger pump through the electrical control cabinet, and disconnect the power after the display is normal.

[0025] S5. Connect the blowout preventer to the wellhead gate assembly, and connect the wellhead gate assembly to the wellbore;

[0026] S6. After filling the blowout preventer with balanced pressure, open the gate valve of the wellhead gate valve group and begin lowering the built-in cable coiled tubing and the electric plunger pump.

[0027] S7. After the electric plunger pump is delivered to the designated position inside the wellbore through the built-in cable continuous tubing, the lowering is stopped.

[0028] S8. Reconnect the power cable to the electrical control cabinet and power on the electric plunger pump to start discharging liquid.

[0029] S9. Monitor the operating status of the electric plunger pump through the electrical control cabinet, and adjust the operating frequency and voltage parameters of the electric plunger pump to achieve the best liquid discharge state;

[0030] S10. When using long-term drainage, the built-in cable continuous tubing can be suspended at the wellhead, leaving the electrical control cabinet to monitor the operation of the electric plunger pump, and other surface equipment except for the wellhead gate assembly can be removed.

[0031] The built-in cable continuous tubing electric plunger pump drainage system and its construction process of the present invention have the following beneficial effects:

[0032] 1. Unlike conventional processes that bundle the cable outside the tubing, this invention embeds the power cable inside the continuous tubing, which can shorten the pumping cycle, avoid cable damage from impacts, reduce construction costs, and improve operational safety.

[0033] 2. This invention differs from conventional electric submersible pump drainage processes by employing a specially designed electric plunger pump for drainage. This results in lower requirements for liquid sand content and gas-liquid ratio, wider application range, durability, and longer service life.

[0034] 3. This invention differs from conventional methods of adjusting the position of the electric submersible pump in the wellbore. It does not require power outage to interrupt fluid discharge and connect the oil-throwing pipe. It can simply be used to raise and lower the continuous tubing, making the process more operable, safer, and more flexible. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0036] Figure 1 This is a schematic diagram of the built-in cable continuous tubing electric plunger pump drainage system of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of a cable sealing sub-section;

[0038] Figure 3 This is a schematic diagram of the structure of an electric plunger pump;

[0039] In the diagram: 1-Blowout pool, 2-Electrical control cabinet, 3-Power cable, 4-Cable sealing section, 5-Continuous tubing roller, 6-Bulking tubing with built-in cable, 7-Injection head, 8-Blowout preventer, 9-Blowout preventer, 10-Wellhead gate valve assembly, 11-Wellbore, 12-Accumulated fluid level, 13-Electric plunger pump, 301-Power cable with removed wire mesh armor, 401-Union connector, 402-Fixing anchor claw, 403-Locking sleeve, 404- Multi-stage sealed outer cylinder, 405-sealed inner cavity, 406-multi-stage sealed end cap, 407-lower connector, 1301-connector, 1302-motor protector, 1303-linear plunger motor, 1304-sand screen pipe, 130101-rivet, 130102-upper check valve, 130301-upper electromagnet, 130302-plunger-shaped iron core, 130303-lower check valve, 130304-lower electromagnet. Detailed Implementation

[0040] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] like Figure 1 As shown, this invention provides a fluid discharge process using an electric plunger pump with a built-in cable and coiled tubing. The electric plunger pump is lowered into the wellbore through coiled tubing, and the plunger pump is powered by the built-in cable to lift the accumulated fluid in the wellbore to the surface. Specifically, it includes a blowout tank 1, an electrical control cabinet 2, a power cable 3, a cable sealing section 4, a coiled tubing drum 5, a coiled tubing with a built-in cable 6, an injection head 7, a blowout preventer 8, a blowout preventer 9, a wellhead gate valve assembly 10, and an electric plunger pump 13.

[0042] The blowout pool 1 is connected to the surface outlet of the built-in cable coiled tubing 6 via a manifold. The wellbore fluid flowing out through the built-in cable coiled tubing 6 will be discharged into the blowout pool 1 for storage.

[0043] The electrical control cabinet 2 is connected to the ground end of the power cable 3. The electrical control cabinet 2 has the functions of supplying power to the electric plunger pump 13 and monitoring downhole pressure, temperature, power supply parameters, etc.

[0044] Power cable 3 is a steel wire armored power cable, containing two or three independent cores, capable of providing three-phase high-voltage power supply. Power cable 3 is inserted into the coiled tubing either pre-installed during manufacturing or pumped in after manufacturing.

[0045] The cable sealing section 4 is specially designed and manufactured for the drainage process of the electric plunger pump with built-in cable coiled tubing. It is installed on the coiled tubing drum 5 and located at the ground outlet of the built-in cable coiled tubing 6. Its function is to lead the power cable 3 out of the coiled tubing and ensure a seal to prevent the liquid inside the coiled tubing from flowing out.

[0046] like Figure 2 As shown, the cable sealing section 4 includes a union joint 401, a fixing anchor claw 402, a locking sleeve 403, a multi-stage sealing outer cylinder 404, a multi-stage sealing end cap 406, and a lower joint 407.

[0047] Union joint 401 can be connected to the joint on the continuous tubing drum 5. Union joint 401 has a conical space inside, and fixed anchor claw 402 is installed in the conical space.

[0048] The fixed anchor claw 402 is designed with a cutting slit and anchoring teeth. The cutting slit allows the fixed anchor claw 402 to retract inward, and the anchoring teeth allow the fixed anchor claw 402 to bite the steel wire armor on the outside of the power cable 3.

[0049] The locking sleeve 403 is connected to the union joint 401 by threads. When the locking sleeve 403 is tightened, the fixed anchor claw 402 retracts along the conical space to hug the power cable 3, so that the power cable 3 cannot move.

[0050] The multi-stage sealing outer cylinder 404 is connected to the union joint 401 via threads, and the connection is sealed with an O-ring. The multi-stage sealing end cap 406 is installed at the through-hole of the multi-stage sealing outer cylinder 404. The power cable 3, after its steel wire armor is removed, passes through the inner hole of the multi-stage sealing end cap 406. The multi-stage sealing end cap 406, the multi-stage sealing outer cylinder 404, and the power cable 3 are sealed with O-rings. The union joint 401, the multi-stage sealing outer cylinder 404, and the multi-stage sealing end cap 406 form a sealed inner cavity 405, which is filled with insulating silicone grease, which provides auxiliary sealing. The number of sets of multi-stage sealing outer cylinders 404 and multi-stage sealing end caps 406 installed is determined based on the sealing pressure and sealing effect.

[0051] The lower connector 407 is connected to the multi-stage sealing outer cylinder 404 by threads, and the connection is sealed by an O-ring. The power cable 301 with the steel wire armor removed passes through the inner hole of the lower connector 407.

[0052] The coiled tubing drum 5 is placed on the ground, and the coiled tubing 6 with built-in cable is wound around the coiled tubing drum 5.

[0053] The wellbore 11 is equipped with an injection head 7, a blowout preventer 8, a blowout preventer 9, and a wellhead gate assembly 10 from top to bottom. The injection head 7 allows the internal cable coiled tubing 6 to be pulled out or lowered into the wellbore 11. The injection head 7, blowout preventer 8, blowout preventer 9, and wellhead gate assembly 10 can form a sealed space, enabling the pulling out and lowering of coiled tubing under pressure without pressurizing the well.

[0054] The electric plunger pump 13 is specially designed and manufactured for the fluid discharge process of the electric plunger pump with built-in cable coiled tubing. It is installed at the downhole outlet of the built-in cable coiled tubing 6 and its function is to lift the fluid accumulated in the wellbore through the built-in cable coiled tubing 6 to the surface.

[0055] like Figure 3 As shown, the electric plunger pump 13 includes a connector 1301, a motor protector 1302, a linear plunger motor 1303, and a sand screen 1304.

[0056] Connector 1301 is installed at the downhole outlet end of the built-in cable coiled tubing 6 via rivet 130101. Connector 1301 is designed with an upper one-way valve 130102, which allows fluid to flow from bottom to top but not from top to bottom. Connector 1301 is also designed with a power cable fixing device, which guides the core of power cable 3 into the eccentric channel, achieving separation of the hydraulic and electrical channels.

[0057] The motor protector 1302 is connected to the lower end of the connector 1301 by a thread. The motor protector 1302 has motor operation protection functions such as overpressure and overload, and also has monitoring probes for downhole pressure, temperature, power supply parameters, etc.

[0058] A linear piston motor 1303 is threadedly connected to the lower end of a motor protector 1302. The linear piston motor 1303 contains an upper electromagnet 130301, a piston-shaped iron core 130302, a lower one-way valve 130303, and a lower electromagnet 130304. When the upper electromagnet 130301 is energized, the piston-shaped iron core 130302 is attracted downwards by magnetic force and moves axially upwards. When the lower electromagnet 130304 is energized, the piston-shaped iron core 130302 is attracted upwards by magnetic force and moves axially downwards. The upper electromagnet 130301 and the lower electromagnet 130304 are switched on and off via a limit switch. The lower one-way valve 130303 is installed in the inner hole of the piston-shaped iron core 130302. The lower one-way valve 130303 allows liquid to flow upwards but does not allow liquid to flow downwards. Specifically, when the upper electromagnet 130301 is energized, the lower electromagnet 130304 is de-energized, and the plunger-shaped iron core 130302 moves from bottom to top. The lower one-way valve 130303 closes due to gravity, and the liquid in the linear plunger pump 13 is pushed upwards by the plunger-shaped iron core 130302 through the upper one-way valve 130102 into the built-in cable continuous oil pipe 6. When the plunger-shaped iron core 130302 reaches its highest point, the upper electromagnet 130301 is de-energized, and the lower electromagnet... When 130304 is energized, the plunger-shaped iron core 130302 moves from top to bottom. The upper check valve 130102 is closed due to gravity, and the accumulated liquid in the wellbore flows into the inner diameter of the linear plunger pump 13 through the lower check valve 130303. When the plunger-shaped iron core 130302 moves to the bottom, the upper electromagnet 130301 is energized again, and the lower electromagnet 130304 is de-energized again. This reciprocating cycle causes the accumulated liquid in the wellbore to be lifted to the ground along the built-in cable continuous tubing 6 and flow into the blowout pool 1.

[0059] The sand screen 1304 is threadedly connected to the lower end of the linear piston motor 1303. The sand screen 1304 has the function of preventing formation gravel or dirt in the wellbore from entering the linear piston motor 1303. The sand screen 1304 can have the function of gas-liquid separation by adjusting its length or by having a built-in hydrocyclone, which can prevent gas in the wellbore from entering the linear piston motor 1303.

[0060] The present invention discloses a construction process for a built-in cable-driven continuous tubing electric plunger pump drainage system, the specific construction steps of which are as follows:

[0061] S1. Place the coiled tubing roller 5, which has the built-in cable coiled tubing 6 wound around it, on the flat ground of the well site.

[0062] S2. Connect the ground outlet of the built-in cable continuous oil pipe 6 to the blowout pool 1 through a manifold.

[0063] S3. Insert the built-in cable continuous oil pipe 6 into the injection head 7, and connect the blowout preventer 8 and the blowout preventer 9 to the lower end of the injection head 7.

[0064] S4. Connect the electric plunger pump 13 to the bottom end of the built-in cable continuous tubing 6. Lead the power cable 3 out from the cable sealing section 4 and connect it to the electrical control cabinet 2. Perform a power-on test run on the electric plunger pump 13. Check the display of various parameters of the electric plunger pump 13 through the electrical control cabinet 2. After the display is normal, disconnect the power.

[0065] S5. Connect the blowout preventer 9 to the wellhead gate assembly 10, and connect the wellhead gate assembly 10 to the wellbore 11.

[0066] S6. After filling the blowout preventer 8 with balanced pressure, open the gate valve group 10 at the wellhead and begin lowering the built-in cable coiled tubing 6 and the electric plunger pump 13.

[0067] S7. After the electric plunger pump 13 is delivered to the designated position inside the wellbore 11 through the built-in cable continuous tubing 13, the lowering is stopped.

[0068] S8. Connect the power cable 3 to the electrical control cabinet 2 again, and turn on the power to start the electric plunger pump 13 to start discharging liquid.

[0069] S9. Monitor the operating status of the electric plunger pump 13 through the electrical control cabinet 2, and adjust the operating frequency, voltage and other parameters of the electric plunger pump 13 to achieve the best liquid discharge state.

[0070] S10. When using long-term drainage, the built-in cable continuous tubing 6 can be suspended to the wellhead, leaving the electrical control cabinet 2 to monitor the operation of the electric plunger pump 13, and removing other surface equipment except for the wellhead gate assembly 10.

[0071] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A fluid discharge system for an electric plunger pump with a built-in cable and continuous tubing, characterized in that, The invention includes a cable sealing sub and an electric plunger pump. The cable sealing sub includes a union joint, a fixed anchor claw, a locking sleeve, a multi-stage sealing outer cylinder, a multi-stage sealing end cap, a continuous tubing roller, and a lower joint. The electric plunger pump includes a connector, a motor protector, a linear plunger motor, and a sand screen. The connector is installed at the downhole outlet end of the built-in cable coiled tubing by rivets. The connector is designed with an upper check valve, which allows liquid to flow from bottom to top but does not allow liquid to flow from top to bottom. The connector is designed with a power cable fixing device, which leads the core of the power cable into the eccentric channel to achieve separation of the hydraulic and electrical channels. The motor protector is threadedly connected to the lower end of the connector, and the linear piston motor is threadedly connected to the lower end of the motor protector. The linear piston motor contains an upper electromagnet, a piston-shaped iron core, a lower one-way valve, and a lower electromagnet. When the upper electromagnet is energized, the piston-shaped iron core is attracted downwards by magnetic force and moves axially upwards. When the lower electromagnet is energized, the piston-shaped iron core is attracted upwards by magnetic force and moves axially downwards. The upper and lower electromagnets are switched on / off via a limit switch. The lower one-way valve is installed in the inner hole of the piston-shaped iron core, allowing liquid to flow upwards but not downwards. The sand-proof screen is threadedly connected to the lower end of the linear piston motor. The union joint is connected to the joint on the continuous tubing drum. The union joint has a conical space inside, and the fixed anchor claw is installed in the conical space. The fixed anchor claw has a cutting slit and an anchoring tooth. The cutting slit allows the fixed anchor claw to retract inward, and the anchoring tooth allows the fixed anchor claw to bite the steel wire armor on the outside of the power cable. The locking sleeve is connected to the union joint by a thread. When the locking sleeve is tightened, the fixing anchor claws retract along the conical space to hug the power cable, so that the power cable cannot move. The multi-stage sealing outer cylinder is connected to the union joint via threads. The multi-stage sealing end cap is installed at the through hole of the multi-stage sealing outer cylinder. The power cable, after removing its steel wire armor, passes through the inner hole of the multi-stage sealing end cap. The union joint, the multi-stage sealing outer cylinder, and the multi-stage sealing end cap form a sealed inner cavity. The lower connector is connected to the multi-stage sealing outer cylinder via threads. The power cable, after removing its steel wire armor, passes through the inner hole of the lower connector. The connection between the lower connector and the multi-stage sealing outer cylinder is sealed with an O-ring, and the connection between the multi-stage sealing outer cylinder and the union connector is sealed with an O-ring; the multi-stage sealing end cap is sealed with an O-ring between itself and the multi-stage sealing outer cylinder and the power cable.

2. A construction process utilizing the electric plunger pump drainage system with built-in cable continuous tubing as described in claim 1, characterized in that, Includes the following steps: S1. Place the coiled tubing drum with the built-in cable coiled tubing on a level surface at the well site. S2. Connect the ground outlet of the built-in cable continuous tubing to the blowout pool via a manifold. S3. Insert the built-in cable continuous tubing into the injection head, and connect the blowout preventer and blowout preventer to the lower end of the injection head; S4. Connect the electric plunger pump to the bottom end of the coiled tubing with built-in cable. Lead the power cable out from the cable sealing section and connect it to the electrical control cabinet. Perform a power-on test run on the electric plunger pump. Check the display of various parameters of the electric plunger pump through the electrical control cabinet. After the display is normal, disconnect the power. S5. Connect the blowout preventer to the wellhead gate assembly, and connect the wellhead gate assembly to the wellbore; S6. After filling the blowout preventer with balanced pressure, open the gate valve group at the wellhead and begin lowering the built-in cable coiled tubing and electric plunger pump. S7. Stop lowering the electric plunger pump to the designated position inside the wellbore via the built-in cable coiled tubing. S8. Reconnect the power cable to the electrical control cabinet and power on the electric plunger pump to start discharging liquid. S9. Monitor the operating status of the electric plunger pump through the electrical control cabinet, and adjust the operating frequency and voltage parameters of the electric plunger pump to achieve the best liquid discharge state. S10. When using long-term drainage, the built-in cable continuous tubing can be suspended to the wellhead, leaving the electrical control cabinet to monitor the operation of the electric plunger pump, and removing other surface equipment except for the wellhead gate assembly.

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