An electrically controlled volumetric polymer dispensing device and method of use thereof

Abstract

A downhole electrically controlled volumetric polymer injection device includes a central tube, an upper positioning sleeve, an outer tube, a circuit board, a support frame, a piston, an upper valve seat, a lower valve seat, a lower positioning sleeve, a cable, a motor and reducer, a translation plate, an upper solenoid valve, a check valve, and a lower solenoid valve. The outer tube is fitted onto the central tube and fixed vertically by the upper and lower positioning sleeves. The cable is connected to the upper end face of the outer tube via a pressure cap. The motor and reducer, circuit board, support frame, translation plate, piston, upper solenoid valve, upper valve seat, check valve, lower valve seat, and lower solenoid valve are sequentially placed from top to bottom in the annular space between the central tube and the outer tube. This invention features a simple structure, high safety and reliability, and modular installation and adjustment; it uses a low-shear solenoid valve to control the flow channel and a motor to drive polymer injection, ensuring precision and reliability.

Description

Technical Field

[0001] This invention relates to a low-shear polymer injection device at the wellhead of an oil well, and particularly to a downhole electrically controlled volumetric polymer injection device and its implementation method. Background Technology

[0002] In the process of developing old oilfields, a very important technology is tertiary oil recovery and polymer injection, which can stabilize production, improve the crude oil recovery rate of old oil wells, and achieve the goals of increasing oil production and reducing water content.

[0003] Currently, centralized preparation and decentralized injection are the main methods of tertiary recovery polymer injection technology. Tertiary recovery polymer injection technology can generally be divided into two types: single-pump single-well and single-pump multi-well. During tertiary recovery polymer injection in oil wells, the viscosity loss rate from the start to the end of the polymer injection pipeline should be controlled within 10% to improve oil production. To achieve single-pump multi-well polymer injection, a low-shear-force diversion injection device is needed.

[0004] In the prior art, CN105401928B discloses a multifunctional concentric injection device, which includes an upper connector, a connecting sleeve, a main body, and a lower connector. The connecting sleeve contains an anti-rotation connector and an inner sleeve. Below the anti-rotation connector is a rotating body whose upper end rotatably engages with the anti-rotation connector. The connecting sleeve contains a core sleeve fitted into the inner sleeve and the central hole of the main body. The lower half of the rotating body is fitted into the core sleeve. The inner wall of the core sleeve has an internal thread, and the outer wall of the rotating body has an external thread that mates with the internal thread. It can be used for water injection, polymer injection, and profile adjustment. After water injection, polymer injection can be performed without changing the tubing string, eliminating the need for repeated replacement and retrieval of the polymer injector core, and does not affect the technical parameters of other sections that have already been calibrated, saving significant manpower, resources, and time.

[0005] CN107060710A discloses a bridge-type concentric cohesive device, comprising: a short outer tube and a long outer tube concentrically connected together, with upper and lower connectors respectively provided at the outer ends of the short and long outer tubes; a positioning mechanism disposed inside the short outer tube and cooperating with the support arm of a measuring and adjusting instrument for guidance and positioning, the upper end of the positioning mechanism being provided with at least one positioning post corresponding to the support arm of the measuring and adjusting instrument; an adjusting sleeve disposed inside the short outer tube and whose upper end is threadedly engaged with the threaded structure of the positioning mechanism; a hollow valve core disposed inside the long outer tube and connected to the lower end of the adjusting sleeve, the outer surface of the hollow valve core being provided with a plurality of wavy convex surfaces spaced axially; an upper chuck and a lower chuck disposed at the upper and lower ends of the inner wall of the long outer tube; a valve sleeve connected at both ends to the upper chuck and the lower chuck respectively, the inner wall of the valve sleeve being provided with a plurality of wavy concave surfaces adapted to the wavy convex surfaces along the axial direction, a liquid damping channel being formed between the wavy convex surfaces and the wavy concave surfaces.

[0006] CN207609411U discloses a concentric measurement and adjustment polymer injection system for offshore oilfields. This system, through a ground control mechanism and a testing and adjustment mechanism, can achieve precise downhole positioning and nozzle adjustment via a positioning module. Furthermore, the system is a closed-loop control system, enabling automatic adjustment of stratified injection volumes. This eliminates the need for traditional offshore oilfield operations involving the deployment and retrieval of polymer injector cores. The instrument can automatically adjust the nozzles of all injection layers in a single well run to achieve the target polymer injection volume for each layer, significantly improving work efficiency, reducing labor intensity, and saving operating costs.

[0007] CN212837616U discloses an insertion sealing device for polymer injection and a concentric double-tube layered polymer injection column. The insertion sealing device includes an outer tube and a core tube. The outer tube comprises a female connector, a sealing tube, and a male connector, which are sealed and fixed sequentially from top to bottom. The female connector, sealing tube, and male connector have the same inner diameter. The upper inner wall of the female connector forms a first stepped hole with an enlarged diameter. The core tube can be slidably inserted into the outer tube, and the outer wall of the core tube and the wall of the first stepped hole can form an annular sealing cavity. This invention provides a simple structure and a small outer diameter for the insertion sealing device, making it suitable for concentric double-tube layered polymer injection columns with small inner diameters, and enabling effective vertical separation of the inner and outer annular spaces.

[0008] Existing polymer flooding flow control downhole devices are basically improved from water injection well dispensers. They regulate flow by using valve cores, which can easily cause blockages. Summary of the Invention

[0009] To address the aforementioned issues, this invention proposes a downhole electrically controlled volumetric polymer injection device and its implementation method. A steel-armored cable is run downhole with the process tubing to provide surface power and collect data. Energizing a solenoid valve opens the channel from the central tubing to the annulus. A motor drives a piston to slide upwards, allowing polymer from the surface to enter the annulus through the tubing, opening a ball valve to enter the annulus space. This continues until the piston reaches top dead center. Upon receiving a feedback signal from the contactor, the solenoid valve is de-energized and closed. Simultaneously, another solenoid valve is energized, opening the channel from the annulus to the casing and reservoir. At the same time, the motor drives the piston downwards, closing the ball valve and squeezing the polymer from the annulus into the reservoir. This continues until the piston reaches bottom dead center. Under the action of a contact sensor, the corresponding solenoid valve is de-energized, the motor reverses, and the piston slides upwards to begin the next polymer injection process.

[0010] The specific technical solution is as follows:

[0011] A downhole electrically controlled volumetric polymerizing device includes a central tube, an upper positioning sleeve, an outer tube, a circuit board, a support frame, a piston, an upper valve seat, a lower valve seat, a lower positioning sleeve, a cable, a motor and reducer, a translation plate, an upper solenoid valve, a check valve, and a lower solenoid valve. The outer tube is fitted onto the central tube and is fixed vertically by the upper and lower positioning sleeves. The cable is connected to the upper end face of the outer tube through a pressure cap. In the annular space between the central tube and the outer tube, the motor and reducer, circuit board, support frame, translation plate, piston, upper solenoid valve, upper valve seat, check valve, lower valve seat, and lower solenoid valve are sequentially placed from top to bottom.

[0012] The upper part of the central tube is provided with an external thread for connecting to the upper positioning sleeve. After being threadedly connected to the upper positioning sleeve, it is fixed by a pin.

[0013] The upper outer side of the central tube is provided with a step, and the step abuts against the motor and circuit board placed in the annular space between the central tube and the outer tube.

[0014] The central tube has an injection hole in the middle, and the outer tube has an outlet hole in the lower middle part.

[0015] The support frame is provided with a positioning threaded hole on one side.

[0016] The outer diameter of the large circular web of the support frame is intermittently matched with the inner diameter of the outer tube.

[0017] The support frame's large circular web plate is provided with a screw through hole and an upper contactor mounting hole.

[0018] The support frame has a lower contactor mounting hole and a screw hole for connecting to the upper solenoid valve on its small semi-circular web plate.

[0019] The outer cylindrical surface of the upper valve seat and the inner cylindrical surface of the piston are intermittently fitted and sealed with a rubber ring.

[0020] The upper valve seat is provided with an inlet hole. When the large hole of the upper valve seat is fitted onto the central tube, the inlet hole is concentric with the injection hole of the central tube.

[0021] The upper valve seat is provided with a side hole, which intermittently seals with the outer diameter of the upper solenoid valve body.

[0022] The upper valve seat has four threaded holes on its upper side for mounting and fixing the upper solenoid valve.

[0023] The piston's outer cylindrical surface intermittently engages with the outer tube for sealing, and its lower inner cylindrical surface intermittently engages with the central tube for sealing.

[0024] The inner side of the upper end of the piston is connected to the translation plate by a pin.

[0025] The translation plate and the screw are connected by a kinematic threaded pair.

[0026] The piston has a shaped hole at its lower end and a steel ball type check valve is installed thereon.

[0027] The outer cylindrical surface of the lower valve seat intermittently fits the inner cylindrical surface of the outer tube and is sealed with a rubber ring.

[0028] The lower valve seat is provided with an outlet hole. When the large hole of the lower valve seat is fitted onto the central tube, the outlet hole is concentric with the injection hole of the outer tube.

[0029] The lower valve seat is provided with a positioning hole and is connected to the outer tube for positioning by a pin.

[0030] The lower valve seat is provided with a side hole, which intermittently seals with the outer diameter of the lower solenoid valve body.

[0031] The lower valve seat has four threaded holes on its lower side for mounting and fixing the lower solenoid valve.

[0032] The maximum outer diameter of the upper end of the lower positioning sleeve is consistent with the outer diameter of the outer tube, and the upper stepped surface intermittently seals with the inner cylindrical surface of the outer tube.

[0033] The lower positioning sleeve is fitted onto the central tube and provides intermittent sealing, and is positioned on the central tube by a pin.

[0034] A method of using a downhole electrically controlled volumetric polymerization device includes:

[0035] ① A steel-armored cable is used to connect the surface control box to the circuit board in the device via the process tubing. The wellhead flow path fills the process tubing with polymer.

[0036] ② The surface electrical control box supplies power to the downhole and sends commands to open the channel from the central tube to the annular space. At the same time, the motor drives the piston to slide upwards and move horizontally. The polymer in the tubing flows through the injection hole of the central tube, the inlet hole of the upper valve seat, and the valve body of the upper solenoid valve, pushing open the valve ball and flowing downwards through the check valve into the annular space formed by the piston, central tube, outer tube, and lower valve seat.

[0037] ③ After filling, the solenoid valve on the circuit board is de-energized and closed, cutting off the channel between the central tube and the annular space.

[0038] ④ The circuit board controls the solenoid valve to open the passage from the annular space to the casing and reservoir. At the same time, the motor drives the piston to slide downwards. The valve ball moves upwards under the combined action of hydraulic pressure and spring, causing the check valve to close. During the downward movement of the piston, the polymer in the annular space is squeezed out and enters the reservoir through the lower solenoid valve body, outlet hole, and injection hole until the piston reaches the bottom dead center.

[0039] ⑤ The translation plate triggers the lower contactor, the circuit board controls the lower solenoid valve to de-energize, closing the annular space and reservoir channel. Then the circuit board controls the motor to reverse so that the piston slides upward and translates. The circuit board controls the upper solenoid valve to energize and open the channel from the central tube to the annular space, starting the next polymer injection cycle.

[0040] This invention features a simple structure, high safety and reliability, and modular installation and adjustment; it employs a low-shear solenoid valve to control the flow channel and a motor to drive the polymerization injection, ensuring precision and reliability. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the polymerization apparatus described in this invention;

[0042] Figure 2 This is a partially enlarged schematic diagram of the area around the translation plate of the polymerization device described in this invention.

[0043] Figure 3a and Figure 3b These are, respectively, a bottom view and a front view of the support frame structure of the polymerizing device described in this invention.

[0044] Figure 4a and Figure 4b These are, respectively, a front view and a top view of the upper valve seat structure of the polymerizing device described in this invention.

[0045] Figure 5a and Figure 5b The figures shown are a bottom view and a front view of the lower valve seat structure of the polymerizing device described in this invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0047] See appendix Figure 1 The downhole electrically controlled volumetric polymerizing device includes a central tube 1, an upper positioning sleeve 2, an outer tube 3, a circuit board 4, a support frame 5, a piston 6, an upper valve seat 7, a lower valve seat 8, a lower positioning sleeve 9, a cable 10, a motor 11, a translation plate 12, an upper solenoid valve 13, a check valve 14, and a lower solenoid valve 15. The outer tube 3 is fitted onto the central tube 1 and is fixed vertically by the upper positioning sleeve 2 and the lower positioning sleeve 9. The cable 10 is connected to the upper end face of the outer tube 3 through a pressure cap 1001. The motor 11, the reducer 1101, the circuit board 4, the support frame 5, the translation plate 12, the piston 6, the upper solenoid valve 13, the upper valve seat 7, the check valve 14, the lower valve seat 8, and the lower solenoid valve 15 are placed sequentially from top to bottom in the annular space between the central tube 1 and the outer tube 3.

[0048] The upper part of the central tube 1 is provided with an external thread for connecting to the upper positioning sleeve 2. After being threadedly connected to the upper positioning sleeve 2, it is fixed by a pin 201. The threaded connection and the positioning pin maintain the absolute stability of the central tube 1. A step 101 is provided at the outer third of the upper part of the central tube 1, and the step abuts against the placed motor 11 and circuit board 4. An injection hole 102 is provided in the middle of the central tube 1. An outlet hole 301 is provided in the lower part of the outer tube 3. The two-hole design maintains the flow rate of the mixture.

[0049] See appendix Figure 1 Appendix Figure 2 Appendix Figure 3a and attached Figure 3b The support frame 5 has a positioning threaded hole 502 on one side. The outer diameter of the large circular web 505 of the support frame 5 is clearance-fitted with the inner diameter of the outer tube 3. The large circular web 505 of the support frame 5 has a screw through hole 504 and an upper contactor mounting hole 503. The small semi-circular web 506 of the support frame 5 has a lower contactor mounting hole 507 and a screw hole 508 for connecting to the upper solenoid valve.

[0050] See appendix Figure 1 Appendix Figure 4a and attached Figure 4b The outer cylindrical surface of the upper valve seat 7 is clearance-fitted with the inner cylindrical surface of the piston 6 and sealed with a rubber ring. The upper valve seat 7 has an inlet hole 701. When the large hole 704 of the upper valve seat 7 is fitted onto the central tube 1, the inlet hole 701 is concentric with the injection hole 102 of the central tube 1. The upper valve seat 7 has a side hole 702, which intermittently seals with the outer diameter of the upper solenoid valve 13. The upper valve seat 7 has four threaded holes 703 on its upper side for mounting and fixing the upper solenoid valve 13.

[0051] See appendix Figure 1 The piston 6 has an intermittently fitted cylindrical surface with the inner cylindrical surface of the outer tube 3 for sealing, and a clearance fitted cylindrical surface with the central tube 1 for sealing. The inner side of the upper end of the piston 6 is connected to the translation plate 12 by a pin 1201. The translation plate 12 is connected to the screw 1103 by a moving thread pair. The lower end of the piston 6 has a special-shaped hole and a steel ball type check valve 14 is installed thereon.

[0052] See appendix Figure 1 Appendix Figure 5a and attached Figure 5bThe lower valve seat 8 has an intermittent fit between its outer cylindrical surface and the inner cylindrical surface of the outer tube 3, sealed with a rubber ring. The lower valve seat 8 has a discharge hole 802, which is concentric with the injection hole 301 of the outer tube 3 when the large hole of the lower valve seat 8 is fitted onto the central tube 1. The lower valve seat 8 has a positioning hole 806, which is connected and positioned to the outer tube 3 by a pin 801. The lower valve seat 8 has a side hole 804, which intermittently seals with the outer diameter of the lower solenoid valve 15. The lower valve seat 8 has four threaded holes 803 on its lower side for mounting and fixing the lower solenoid valve 15.

[0053] See appendix Figure 1 The maximum outer diameter of the upper end of the lower positioning sleeve 9 is the same as the outer diameter of the outer tube 3, and the upper stepped surface intermittently seals with the inner cylindrical surface of the outer tube 3. The lower positioning sleeve 9 is fitted onto the central tube 1 and intermittently seals, and is positioned on the central tube 1 by a pin 901.

[0054] In practical use, after the device is lowered into the polymer injection well along with the polymer injection process string, a steel-armored cable 10 is lowered into the well to connect the surface control box and the circuit board 4 in the device. The wellhead flow fills the process string with polymer. The surface control box supplies power to the well and sends commands. The circuit board 4 in this device energizes the upward solenoid valve 13 to open the channel from the central tube 1 to the annular space. At the same time, the motor 11 drives the piston 6 to slide upward (if the piston 6 is already at the top dead center, the sliding plate will not move as it contacts the upper contactor 1102). The polymer in the string flows through the injection hole 102 of the central tube 1, the upper valve seat inlet hole 701, and the valve body of the upper solenoid valve 13, opening the valve ball 1401 and flowing downward through the check valve 14 into the annular space formed by the piston 6, the central tube 1, the outer tube 3, and the lower valve seat 8. After filling, the circuit board 4 controls the power supply. When solenoid valve 13 is de-energized and closed, it cuts off the channel between the central tube 1 and the annular space. Subsequently, circuit board 4 controls the lower solenoid valve 15 to be energized and open the channel from the annular space to the casing and reservoir. At the same time, the motor drives piston 6 to slide downwards. Under the combined action of hydraulic pressure and spring, valve ball 1401 moves upwards, causing check valve 14 to close. During the downward movement of piston 6, the polymer in the annular space is squeezed out and enters the reservoir through the valve body of lower solenoid valve 15, outlet hole 802, and injection hole 301. Until piston 6 reaches the bottom dead center, translation plate 12 touches lower contactor 1104. Circuit board 4 controls the lower solenoid valve 15 to be de-energized and close the channel between the annular space and the reservoir. Subsequently, circuit board 4 controls motor 11 to reverse and make piston 6 slide upwards. Circuit board 4 controls the upper solenoid valve 13 to be energized and open the channel from the central tube 1 to the annular space, starting the next polymer injection cycle.

[0055] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A downhole electrically controlled volumetric polymerization device, characterized in that: The system includes a central tube (1), an upper positioning sleeve (2), an outer tube (3), a circuit board (4), a support frame (5), a piston (6), an upper valve seat (7), a lower valve seat (8), a lower positioning sleeve (9), a cable (10), a motor (11), a translation plate (12), an upper solenoid valve (13), a flow valve (14), and a lower solenoid valve (15). The outer tube (3) is fitted onto the central tube (1), and its vertical movement is limited and fixed by the upper positioning sleeve (2) and the lower positioning sleeve (9). The cable (10) is connected to the upper end face of the outer tube (3) through the pressure cap (1001). The motor (11), reducer (1101), circuit board (4), support frame (5), translation plate (12), screw (1103), piston (6), upper solenoid valve (13), upper valve seat (7), check valve (14), lower valve seat (8), and lower solenoid valve (15) are placed in the annular space between the central tube (1) and the outer tube (3) in sequence from top to bottom. The central tube (1) is provided with an injection hole (102) in the middle, and the outer tube (3) is provided with an outlet hole (301) in the lower middle part. The upper valve seat (7) is provided with an inlet hole (701). When the large hole (704) of the upper valve seat (7) is fitted onto the central tube (1), the inlet hole (701) is concentric with the injection hole (102) of the central tube (1). The upper valve seat (7) is provided with a side hole (702) that intermittently seals with the outer diameter of the upper solenoid valve (13). The upper valve seat (7) is provided with four threaded holes (703) on the upper side for installing and fixing the upper solenoid valve (13). The piston (6) is connected to the translation plate (12) via a pin (1201) on the inner side of the upper end; the translation plate (12) is connected to the screw (1103) via a moving thread pair; the piston (6) has a special-shaped hole at the lower end and a steel ball type check valve (14) is installed thereon. The lower valve seat (8) is provided with an outlet hole (802). When the large hole of the lower valve seat (8) is fitted onto the central tube (1), the outlet hole (802) is concentric with the injection hole (301) of the outer tube (3). The lower valve seat (8) is provided with a side hole (804) which intermittently seals with the outer diameter of the lower solenoid valve (15).

2. The downhole electrically controlled volumetric polymerization device as described in claim 1, characterized in that: The upper part of the central tube (1) is provided with an external thread for connecting the upper positioning sleeve (2). After being threadedly connected to the upper positioning sleeve (2), it is fixed by a pin (201).

3. The downhole electrically controlled volumetric polymerization device as described in claim 1 or 2, characterized in that: The upper outer side of the central tube (1) is provided with a step (101), and the step (101) abuts against the motor (11) and the circuit board (4) placed thereon.

4. The downhole electrically controlled volumetric polymerization device as described in claim 1, characterized in that: The support frame (5) has a positioning threaded hole (502) on one side.

5. A method of using a downhole electrically controlled volumetric polymerization device as described in any one of claims 1-4, characterized in that: ①Use cable (10) to connect the surface electrical control box and the circuit board (4) in the device with the process tubing as it is lowered into the well. The wellhead flow fills the process tubing with polymer. ② The ground control box supplies power to the well and sends commands to open the channel from the central tube (1) to the annular space. At the same time, the motor (11) drives the piston (6) to slide upwards and horizontally. The polymer in the tubing passes through the injection hole (102) of the central tube (1), the inlet hole (701) of the upper valve seat, and the valve body of the upper solenoid valve (13), opening the valve ball (1401). It then flows downwards through the one-way valve (14) and enters the annular space formed by the piston (6), the central tube (1), the outer tube (3), and the lower valve seat (8). ③ After filling, the circuit board (4) controls the solenoid valve (13) to shut off, cutting off the channel between the central tube (1) and the annular space. ④ The circuit board (4) controls the lower solenoid valve (15) to open the passage from the annular space to the casing and reservoir. At the same time, the motor drives the piston (6) to slide downwards. The valve ball (1401) moves upwards under the combined action of hydraulic pressure and spring, causing the check valve (14) to close. During the downward movement of the piston (6), the polymer in the annular space is squeezed out and enters the reservoir through the valve body of the lower solenoid valve (15), the outlet hole (802), and the injection hole (301) until the piston (6) reaches the bottom dead center. ⑤ The translation plate (12) triggers the lower contactor (1104), and the circuit board (4) controls the lower solenoid valve (15) to de-energize, closing the annular space and the reservoir channel. Then, the circuit board (4) controls the motor (11) to reverse so that the piston (6) slides upward and moves horizontally. The circuit board (4) controls the upper solenoid valve (13) to energize and open the channel from the central tube (1) to the annular space, starting the next injection cycle process.

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