Batch polymer injection well positive displacement low shear polymer injection device and method of use

Abstract

The present application provides a kind of injection well volume low shear polymer injection device and its use method, the device includes first electric valve, buffer device, second electric valve, energy accumulator and third electric valve, pipeline A is the input main line of polymer solution, the inlet and outlet of the first electric valve are connected with pipeline A and the buffer device respectively, the inlet and outlet of the second electric valve are connected with the buffer device and the energy accumulator respectively, the inlet of the third electric valve is connected with the buffer device, and the outlet is connected with pipeline B leading to wellhead device, the buffer device and the energy accumulator indirectly regulate the speed of polymer liquid by regulating the flow of buffer liquid.The injection well volume low shear polymer injection device and its use method can be used in oilfield injection well ground flow, realize low shear injection of polymer solution from main line to wellhead, and has important significance for improving polymer solution viscosity retention rate and improving oil displacement effect.

Description

Technical Field

[0001] This invention relates to the field of surface distribution devices for polymer injection wells in oilfields, and in particular to a volumetric low-shear polymer injection device for polymer injection wells and its usage method. Background Technology

[0002] Polymer flooding is an effective method for enhancing oil recovery and is widely used in the field. Its main principle is to increase the viscosity of the injected fluid, improve the mobility ratio, and increase the swept area of ​​the displaced phase, thereby improving oil recovery. Therefore, the viscosity of the injected fluid significantly affects the oil displacement effect. Currently, low-shear surface flow control devices for polymer flooding mainly reduce the kinetic energy of the fluid through energy loss, thereby mitigating the damage to polymer molecular chains caused by turbulence and mechanical shearing, achieving low-shear flow control. The main problem is that under high pressure differentials, excessively high fluid velocity can tear polymer molecular chains, resulting in low solution viscosity retention and affecting the oil displacement effect.

[0003] Chinese patent application CN98214357.5 discloses a cone valve-type low-shear flow controller, comprising a valve body and a valve core. The inner cavity wall of the valve body is shaped like a Venturi tube. The valve body has an inlet pipe, and a gland flange is located at the upper end of the valve body. A valve stem is connected in series within the gland flange, which is statically sealed to the valve body. The upper end of the valve stem is connected to an actuator, and the lower end is connected to the valve core, which is cone-shaped. This design utilizes a double-long cone valve structure to achieve polymer flow regulation. It combines the principle and method of Venturi tube flow regulation with the structure of a needle valve to form a cone-shaped flow controller. The main structure includes the valve body and the valve core.

[0004] Chinese patent application CN201020579853.2 discloses a low-shear flow control valve, comprising a valve body, an outlet cap, an adjusting ring, a right cap, an adjusting rod, a pressure cap, a first valve core, a second valve core, a third valve core, a fourth valve core, and a fifth valve core. It utilizes the conical fit between valve cores and the adjusting rod to change the distance of the adjusting ring and the conical fit between valve cores to alter the structure of the polymer inlet and outlet pressure difference. This achieves a polymer viscosity retention rate >90% under a 3 MPa pressure difference.

[0005] Chinese patent application CN201520023319.6 discloses a novel low-shear mother liquor flow controller for oilfields. The static mixer comprises a housing (1) and a low-shear spindle-shaped cone valve (2). The housing (1) contains multiple sealing components, and the low-shear spindle-shaped cone valve (2) is inserted within the housing (1), with its centerline coinciding with the centerline of the housing (1). The polymer mother liquor flows smoothly from the outlet by relying on the radial rotation and diffusion principle of the spindle-shaped cone valve, avoiding the mechanical shear force of conventional cone valves and reducing polymer viscosity loss caused by the mother liquor flow controller.

[0006] Chinese patent application CN201520897670.8 discloses a low-shear polymer flow controller, specifically a valve controller comprising a valve body, a valve core, and an electric valve. The valve body has a venturi-shaped internal cavity, housing the valve core. A valve core rod is fixedly connected to the top of the valve core, passing through a sealing cap connected to a screw at the top of the valve body. The top of the valve core rod is connected to the output rod of the electric valve via a connector. The valve core body has a cylindrical body in the middle, with its top fixedly connected to the bottom surface of cone I; the bottom of the cylinder is fixedly connected to the bottom surface of cone II. The valve body has an outlet at the bottom and an inlet at the top. Connecting the top of the valve core to a cone increases the flow area, reduces the flow velocity, and simultaneously forms a pressure-reducing chamber, significantly reducing viscosity loss.

[0007] The above-mentioned existing technologies are all quite different from the present invention and have failed to solve the technical problem we want to solve. Therefore, we have invented a new volumetric low-shear polymer injection device for polymer injection wells and its usage method. Summary of the Invention

[0008] The purpose of this invention is to provide a volumetric low-shear polymer injection device for polymer injection wells, which is of great significance for improving the viscosity retention rate of polymer solutions and enhancing oil displacement effect, and its usage method.

[0009] The objective of this invention can be achieved through the following technical measures: a volumetric low-shear polymer injection device for polymer injection wells, comprising a first electric valve, a buffer device, a second electric valve, an accumulator, and a third electric valve. Pipeline A is the main input line for the polymer solution. The inlet and outlet of the first electric valve are connected to pipeline A and the buffer device, respectively. The inlet and outlet of the second electric valve are connected to the buffer device and the accumulator, respectively. The inlet of the third electric valve is connected to the buffer device, and the outlet is connected to pipeline B leading to the wellhead device. The buffer device and the accumulator indirectly regulate the velocity of the polymer liquid by adjusting the flow rate of the buffer solution.

[0010] The objective of this invention can also be achieved through the following technical measures:

[0011] The volumetric low-shear polymer injection device for polymer injection wells also includes a timing module connected to the first electric valve, the second electric valve, and the third electric valve, which controls the opening and closing sequence and degree of the first electric valve, the second electric valve, and the third electric valve.

[0012] The buffer device includes a piston and a cylinder. The piston is installed inside the cylinder and can reciprocate within the cylinder. The piston is initially located at the leftmost position of the cylinder, and the cavity to the right of the piston is pre-filled with hydraulic oil.

[0013] The accumulator includes an air bladder and a housing, with the air bladder located within the housing. The pressure within the air bladder can be adjusted via a top valve.

[0014] When the polymer solution enters the volumetric low-shear polymer injection device of the injection well from the main line A, the timing module controls the opening of the first electric valve and keeps the third electric valve closed. At this time, the piston is located at the leftmost end, and the timing module controls the opening of the second electric valve so that the polymer solution can slowly enter the buffer device.

[0015] As the liquid enters the buffer device, it pushes the piston to the right. The hydraulic oil on the right side of the piston enters the accumulator and compresses the air bladder. When the piston reaches the far right, the timing module closes the first electric valve and opens the third electric valve.

[0016] Since the wellhead pressure is lower than the main line pressure, the airbag inflates, pressurizing the hydraulic oil back into the buffer device and pushing the piston to the left. The timing module controls the opening of the second electric valve to control the piston's movement speed, so that the piston slowly pushes the polymer solution out of the buffer device and into the polymer injection well via pipeline B.

[0017] After the piston returns to the leftmost end, the timing module closes the third electric valve and opens the first electric valve, allowing the polymer solution to flow back into the device from the mains.

[0018] The objective of this invention can also be achieved through the following technical measures: a volumetric low-shear polymer injection method for polymer injection wells, characterized in that the method employs a volumetric low-shear polymer injection device for polymer injection wells, comprising:

[0019] Step 1: The polymer solution enters the volumetric low-shear polymer injection device of the injection well through the main line A. The timing module controls the first electric valve to open and keeps the third electric valve closed. At this time, the piston of the buffer device is located at the leftmost end. The timing module controls the opening of the second electric valve so that the polymer solution can slowly enter the buffer device.

[0020] Step 2: As the liquid enters the buffer device, it pushes the piston to the right. The hydraulic oil on the right side of the piston enters the accumulator and compresses the air bladder of the accumulator. When the piston reaches the far right, the timing module closes the first electric valve and opens the third electric valve.

[0021] Step 3: Since the wellhead pressure is lower than the main line pressure, the airbag inflates, pressurizing the hydraulic oil back into the buffer device and pushing the piston to the left; the timing module controls the opening of the second electric valve to control the piston movement speed, so that the piston slowly pushes the polymer solution out of the buffer device and into the polymer injection well through pipeline B.

[0022] Step 4: After the piston returns to the leftmost end, the timing module closes the third electric valve and opens the first electric valve, allowing the polymer solution to flow back into the device from the main line.

[0023] This invention relates to a volumetric low-shear polymer injection device for polymer injection wells and its application method. For the first time, a volumetric device is applied to a polymer surface flow control system, achieving low-shear polymer injection through energy conversion. A buffer device and accumulator are incorporated, and the flow rate of the polymer liquid is indirectly regulated by adjusting the flow rate of the buffer solution. This invention is primarily applicable to surface processes in oilfield polymer injection wells, enabling low-shear injection of the polymer solution from the mains line to the wellhead. This is of significant importance for improving the viscosity retention rate of the polymer solution and enhancing oil displacement efficiency. Attached Figure Description

[0024] Figure 1 This is a structural diagram of a specific embodiment of the volumetric low-shear polymer injection device for polymer injection wells according to the present invention. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0027] This invention addresses the problem of low viscosity retention in polymer surface flow control devices under high pressure differentials by designing a volumetric low-shear polymer injection device. It mainly comprises three electric valves, a buffer device, and an accumulator. The electric valves are electrically controlled for switching and opening, with the switching sequence and timing controlled by a timing module. The buffer device consists of a cylinder and a piston, with the piston reciprocating inside the cylinder. A position sensor inside the cylinder measures the flow rate of the polymer solution. The accumulator mainly comprises a shell and an air bladder. The three electric valves are respectively located between the main pipeline and the buffer device inlet, between the buffer device and the accumulator, and between the buffer device outlet and the wellhead.

[0028] The timing module controls the opening and closing sequence and degree of the electric valves, allowing the polymer solution to enter the buffer device at a shear-free rate and charge the accumulator. The timing module then again controls the opening and closing sequence and degree of the electric valves, allowing the polymer solution to flow out of the buffer device and into the injection well at a shear-free rate, thus achieving low-shear injection of the polymer solution. Simultaneously, by controlling the volume of solution entering the buffer device, the flow rate of the polymer solution can be controlled.

[0029] A buffer device and an accumulator are installed to achieve low-shear injection through energy conversion. By controlling the opening sequence and degree of the electric valves, the polymer solution can enter the buffer device at a shear-free rate and charge the accumulator. By controlling the opening sequence and degree of the electric valves again, the polymer solution can flow out of the buffer device at a shear-free rate and into the well, thus achieving low-shear injection of the polymer solution. At the same time, the flow rate of the polymer solution can be controlled by controlling the volume of solution entering the buffer device.

[0030] The following are several specific embodiments of the application of the present invention.

[0031] Example 1

[0032] The device described in this invention comprises a first electric valve 1, a buffer device 2, a second electric valve 3, an accumulator 4, a third electric valve 5, and a timing module 6. Pipeline A is the main input line for the polymer solution. The inlet and outlet of electric valve 1 are connected to pipeline A and buffer device 2, respectively, and its on / off state is controlled by electricity. It is connected to the timing module 6 via electrical wires. Buffer device 2 comprises a piston 21 and a cylinder 22. Piston 21 is installed inside cylinder 22 and can reciprocate within cylinder 22. The initial position of piston 21 is located at the leftmost side of cylinder 22, and the cavity on the right side of piston is pre-filled with hydraulic oil. The inlet and outlet of the second electric valve 3 are connected to buffer device 2 and accumulator 4, respectively, and its on / off state and opening degree are controlled by electricity. It is connected to the timing module 6 via electrical wires. Accumulator 4 comprises an air bladder 41 and a housing 42. The pressure in air bladder 41 can be adjusted by a top valve. The inlet of the third electric valve 5 is connected to the buffer device 2, and the outlet is connected to the pipe B leading to the wellhead device. Its on / off state is controlled by electricity and connected to the timing device 6 via an electric wire.

[0033] Example 2

[0034] The method of using the device described in this invention is as follows: The polymer solution enters the device through main line A. The timing module controls the opening of electric valve 1 while keeping the third electric valve 5 closed. At this time, piston 21 is at the leftmost end. The opening of the second electric valve 3 is controlled to allow the polymer solution to slowly enter the buffer device 2. As the liquid enters the buffer device, it pushes the piston to the right. The hydraulic oil on the right side of the piston enters the accumulator 4 and compresses the air bladder 41. When piston 21 reaches the rightmost position, the timing module 6 closes the first electric valve 1 and opens the third electric valve 5. Because the wellhead pressure is lower than the main line pressure, the air bladder 41 in the accumulator 4 expands, pushing the hydraulic oil back into the buffer device 2 and pushing piston 21 to the left. The opening of electric valve 2 is controlled by the timing module 6 to control the movement speed of piston 21, allowing piston 21 to slowly push the polymer solution out of the buffer device 2 and into the injection well via pipeline B. After the piston returns to the leftmost end, the third electric valve is closed and the first electric valve is opened, allowing the polymer solution to flow back into the device from the main line.

[0035] During device operation, the first electric valve 1 and the third electric valve 5 remain fully open or fully closed, effectively preventing mechanical shearing caused by sudden changes in the inner diameter of the polymer solution as it flows through the valves, thus improving viscosity retention. By controlling the opening of the second electric valve 3, the movement speed of the piston 21 can be controlled, ensuring the polymer solution flows into or out of the device at a low speed to prevent excessive flow rate from tearing the polymer molecular chains and causing a decrease in viscosity. These two design features significantly improve the viscosity retention of the polymer solution, achieving low-shear polymer injection.

[0036] Example 3:

[0037] In the specific embodiment 3 of the present invention, valves 1 and 5 can also be pneumatic ball valves, which have a relatively fast execution speed, can reduce the opening and closing time of the ball valve, further reduce the shearing effect on the polymer during the opening and closing process, and improve the viscosity retention rate.

[0038] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0039] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. A volumetric low-shear polymer injection device for polymer wells, characterized in that, The volumetric low-shear polymer injection device for polymer wells includes a first electric valve, a buffer device, a second electric valve, an accumulator, and a third electric valve. Pipeline A is the main input line for the polymer solution. The inlet and outlet of the first electric valve are connected to pipeline A and the buffer device, respectively. The inlet and outlet of the second electric valve are connected to the buffer device and the accumulator, respectively. The inlet of the third electric valve is connected to the buffer device, and the outlet is connected to pipeline B leading to the wellhead device. The buffer device and the accumulator indirectly regulate the velocity of the polymer liquid by adjusting the flow rate of the buffer solution. The volumetric low-shear polymer injection device for polymer injection wells also includes a timing module, which is connected to the first electric valve, the second electric valve and the third electric valve, and controls the opening and closing sequence and opening degree of the first electric valve, the second electric valve and the third electric valve. The buffer device includes a piston and a cylinder. The piston is installed inside the cylinder and can reciprocate within the cylinder. The initial position of the piston is located at the far left of the cylinder, and the cavity on the right side of the piston is pre-filled with hydraulic oil. The accumulator includes an air bladder and a housing, with the air bladder located inside the housing. The pressure inside the air bladder can be adjusted by a valve at the top. When the polymer solution enters the volumetric low-shear polymer injection device of the injection well from the main line A, the timing module controls the first electric valve to open and keeps the third electric valve closed. At this time, the piston is located at the leftmost end, and the timing module controls the opening of the second electric valve so that the polymer solution can slowly enter the buffer device. As the liquid enters the buffer device, it pushes the piston to the right. The hydraulic oil on the right side of the piston enters the accumulator and compresses the air bladder. When the piston reaches the far right, the timing module closes the first electric valve and opens the third electric valve. Because the wellhead pressure is lower than the main line pressure, the airbag inflates, pressurizing the hydraulic oil back into the buffer device and pushing the piston to the left; the timing module controls the opening of the second electric valve to control the piston movement speed, so that the piston slowly pushes the polymer solution out of the buffer device and into the polymer injection well via pipeline B; After the piston returns to the leftmost end, the timing module closes the third electric valve and opens the first electric valve, allowing the polymer solution to flow back into the device from the mains.

2. A volumetric low-shear polymer injection method for polymer injection wells, characterized in that, The volumetric low-shear polymer injection method for polymer injection wells employs the volumetric low-shear polymer injection device described in claim 1, comprising: Step 1: The polymer solution enters the volumetric low-shear polymer injection device of the injection well through the main line A. The timing module controls the first electric valve to open and keeps the third electric valve closed. At this time, the piston of the buffer device is located at the leftmost end. The timing module controls the opening of the second electric valve so that the polymer solution can slowly enter the buffer device. Step 2: As the liquid enters the buffer device, it pushes the piston to the right. The hydraulic oil on the right side of the piston enters the accumulator and compresses the air bladder of the accumulator. When the piston reaches the far right, the timing module closes the first electric valve and opens the third electric valve. Step 3: Since the wellhead pressure is lower than the main line pressure, the airbag inflates, pressurizing the hydraulic oil back into the buffer device and pushing the piston to the left; the timing module controls the opening of the second electric valve to control the piston movement speed, so that the piston slowly pushes the polymer solution out of the buffer device and into the polymer injection well through pipeline B. Step 4: After the piston returns to the leftmost end, the timing module closes the third electric valve and opens the first electric valve, allowing the polymer solution to flow back into the device from the main line.

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