Variable-displacement pump with reduced clearance volume

Abstract

A variable displacement oil pump with reduced clearance volume comprises an upper pump barrel, an upper plunger, an upper pump discharge valve, a flow divider joint, a communication pipe, an eccentric valve body, an upper pump intake valve, an eccentric pipe, an isolation pump barrel, an isolation plunger, a communication joint, an inter-pump pipe, an inter-pump connecting rod, a lower pump barrel, a lower plunger, the upper pump and the lower pump simultaneously pumping oil at the initial stage of well opening, the displacement being the total of the upper and lower pumps, the lower pump pumping oil after the dynamic liquid level in the well drops below the upper pump at the later stage of well opening, realizing variable displacement production, the distance between the upper pump and the lower pump being designed according to the well condition, the upper pump and the lower pump being at different depths in the well, the well still being able to produce normally after the dynamic liquid level drops, being able to produce automatically with variable displacement, the isolation pump barrel and the isolation plunger separating the upper pump barrel from the lower pump barrel, the clearance of the upper pump not being the volume of the inter-pump pipe, eliminating the influence of this part of clearance on the pumping of the upper pump, the pump efficiency of the upper pump being high, not being gas locked, the several eccentric structures provided being able to lower the lower pump with a larger diameter into a commonly used casing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil extraction equipment, and is a variable displacement oil pump, in particular a variable displacement oil pump with reduced clearance volume. BACKGROUND

[0002] Some oil extraction wells have low crude oil viscosity at the initial stage of production, strong formation liquid supply capacity, high dynamic liquid level in the casing, and high liquid production. For example, heavy oil wells after steam stimulation require large displacement production. In the later stage of well opening, the formation liquid supply capacity becomes poor, the dynamic liquid level in the casing is low, the liquid production decreases, the crude oil viscosity increases, and the displacement of the oil pump needs to be reduced. In order to ensure a certain production of the oil well, the depth of the pump needs to be deepened. Ordinary oil pumps cannot adapt to such changes and requirements. Only by pulling out the oil extraction string and lowering the oil extraction string with small pump diameter and deep pump hanging depth can the production of the oil well be intermittent, the production of the oil well be affected, the internal migration of the oil layer be disturbed, and the future oil production be affected. On the other hand, the existing string needs to be pulled out by using power equipment, and a new deep pumping string needs to be lowered, which increases the operating cost of the oil well.

[0003] In order to overcome the above problems, technical personnel have developed a variable displacement oil pump, which produces large displacement at the initial stage of well opening, and produces small displacement when the production and liquid supply capacity decrease. Although the existing variable displacement pump does not need to pull out the entire string, it needs to be bumped or lifted or lowered at the wellhead. These operations need to stop pumping for a certain period of time (several hours if successful), and still need to use power equipment. Since the tool needs to be actuated at the wellhead to achieve variable displacement, the existing variable displacement pump still has reliability problems, and the well tool often cannot be actuated reliably, which makes the success rate of variable displacement less than 100%.

[0004] The existing variable displacement pump also has the problem that the pump depth cannot be adjusted. When the displacement is large, the load of the oil extraction system is large. In order to meet the requirements of the oil pumping machine and the oil extraction rod, the depth of the pump cannot be deepened. When the dynamic liquid level of the oil well decreases and the submergence of the pump decreases in the later stage of production, the submergence of the pump cannot meet the pumping condition of the oil pump, resulting in production stoppage due to insufficient liquid supply.

[0005] According to the above problems of the variable displacement oil pump, technical personnel have developed a new variable displacement oil pump, such as Chinese patent application 2021114964360 "Variable displacement oil pump". This variable displacement oil pump can automatically change the displacement for production, and overcomes the shortcomings of the existing variable displacement oil pump. However, the inter-pump tubing is 100m-2000m, and the volume of this part is the clearance of the upper pump. The well fluid contains gas, which can easily cause gas influence under such a large clearance, resulting in low pump efficiency of the upper pump, and even gas locking and inability to pump oil. SUMMARY

[0006] The purpose of the present application is to design a variable displacement oil well pump with reduced clearance volume, overcome the shortcomings of Chinese patent application: 2021114964360 "A variable displacement oil well pump", improve the pump efficiency of the variable displacement pump, avoid gas locking, and improve the oil well production.

[0007] The application is characterized in that the upper pump cylinder, the upper plunger, the upper pump discharge valve, the shunt joint, the connecting pipe, the eccentric valve body, the upper pump inlet valve, the eccentric pipe, the isolation pump cylinder, the isolation plunger, the connecting joint, the inter-pump pipe, the inter-pump connecting rod, the lower pump cylinder, the lower plunger, the upper plunger is sealed with the upper pump cylinder, the lower plunger is provided with a discharge valve, the lower plunger is sealed with the lower pump cylinder, the lower part of the lower pump cylinder is provided with a lower pump inlet valve, the upper pump inlet valve is connected to the eccentric hole thread of the eccentric valve body, the upper part of the eccentric hole thread is provided with a connecting hole, the connecting hole is communicated with the inside of the eccentric valve body, the upper pump cylinder, the upper plunger, the upper pump discharge valve, the eccentric valve body, the upper pump inlet valve and the eccentric pipe form the upper pump, the lower pump cylinder, the lower plunger and the lower pump inlet valve of the lower pump cylinder form the lower pump, the upper part of the inter-pump pipe is connected with the lower part of the eccentric pipe, the upper part of the lower pump cylinder is connected with the lower part of the inter-pump pipe, the upper plunger, the shunt joint, the inter-pump connecting rod and the lower plunger are sequentially connected, the length of the inter-pump pipe is greater than 100 m, the length of the inter-pump connecting rod is matched with the length of the inter-pump pipe, so that the lower plunger is in the lower pump cylinder when the inter-pump connecting rod reciprocates, the pump diameter of the upper pump cylinder is greater than the pump diameter of the lower pump cylinder, the diameter of the upper plunger is greater than the diameter of the lower plunger, the upper thread axis of the upper part of the eccentric valve body is different from the valve body axis, the upper thread axis is located on the right side of the valve body axis, the lower thread axis of the lower part of the eccentric valve body is different from the valve body axis, the lower thread axis is located on the right side of the valve body axis, the upper hole is below the upper thread of the eccentric valve body, the axis of the upper hole is coaxial with the upper thread axis, the diameter of the upper hole is greater than the diameter of the lower plunger, the lower hole is above the lower thread of the eccentric valve body, the axis of the lower hole is coaxial with the axis of the upper hole, the diameter of the lower hole is greater than the diameter of the lower plunger, the upper part of the eccentric pipe is provided with an eccentric thread, the axis of the eccentric thread is the eccentric thread axis, the axis of the eccentric pipe is the pipe axis, the eccentric thread axis is different from the pipe axis, the eccentric thread axis is located on the right side of the pipe axis, the eccentric pipe is provided with an eccentric hole, the axis of the eccentric hole is the eccentric hole axis, the eccentric hole axis is different from the pipe axis, the eccentric hole axis is located on the right side of the pipe axis, the left side wall of the eccentric pipe is provided with a mounting groove, the right side of the upper pump inlet valve is located in the mounting groove, the isolation pump cylinder is mounted between the eccentric pipe and the inter-pump pipe, the connecting pipe, the isolation plunger and the connecting joint are connected between the shunt joint and the inter-pump connecting rod, the connecting joint is provided with a connecting groove, the well fluid in the inter-pump pipe can enter the isolation plunger through the connecting groove, the isolation plunger is sealed with the isolation pump cylinder, the shunt joint is provided with an upper pump discharge passage and a lower pump discharge passage, the lower end of the upper pump discharge passage is communicated with the inside of the upper pump cylinder of the lower part of the upper plunger, the upper end of the upper pump discharge passage is mounted with the upper pump discharge valve, the upper pump discharge valve is located in the upper plunger, the lower end of the lower pump discharge passage is communicated with the connecting pipe, the upper end of the lower pump discharge passage is communicated with the inside of the upper plunger, the upper thread axis, the pipe axis, the axis of the isolation pump cylinder and the axis of the upper pump cylinder are coaxial.

[0008] The transition pipe is installed between the pump cylinder and the eccentric pipe, the inner diameter of the transition pipe is larger than the inner diameter of the eccentric hole and the isolation pump cylinder, the downward projection of the eccentric hole is in the inner hole of the transition pipe, and the length of the transition pipe is larger than the length of the isolation plunger and the lower plunger, so that the isolation plunger and the lower plunger enter the transition pipe and then enter the isolation pump cylinder.

[0009] The beneficial effects of the present application are as follows: the upper pump and the lower pump simultaneously pump oil at the initial stage of well opening, the displacement is the total displacement of the upper pump and the lower pump, after the dynamic liquid level in the well drops below the upper pump at the later stage of well opening, the lower pump is used to pump oil, the displacement becomes the displacement of the lower pump, variable displacement production is realized, the distance between the upper pump and the lower pump can be designed according to the well condition, so that the upper pump and the lower pump are at different depths in the well, the oil well can still produce normally after the dynamic liquid level drops, and can automatically produce with variable displacement, the isolation pump cylinder and the isolation plunger separate the upper pump cylinder and the lower pump cylinder, so that the clearance of the upper pump is not the volume of the inter-pump tubing, the influence of this part of the clearance on the oil pumping of the upper pump is eliminated, the pump efficiency of the upper pump is high, and the upper pump can normally pump oil and produce, the several eccentric structures can realize the lowering of the larger-diameter lower pump in the commonly used casing (inner diameter ¢124), so as to reasonably distribute the displacements of the upper pump and the lower pump according to the well condition, and remarkable economic benefits are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a structural diagram of the present application.

[0011] Figure 2 is Figure 1 a structural diagram of the upper part.

[0012] Figure 3 is Figure 1 a structural diagram of the lower part.

[0013] Figure 4 is Figure 1 a partial enlarged view of the present application.

[0014] Figure 5 is Figure 4 a sectional view of the eccentric valve body 6.

[0015] Figure 6 is Figure 4 a sectional view of the eccentric pipe 9.

[0016] Figure 7 is Figure 6 a sectional view of the present application after being cut along A-A. DETAILED DESCRIPTION

[0017] The embodiments of the present application will be described below with reference to the drawings.

[0018] As shown in the figure, the embodiment of the application comprises an upper pump cylinder 1, an upper plunger 2, an upper pump discharge valve 3, a shunt joint 4, a connecting pipe 5, an eccentric valve body 6, an upper pump inlet valve 8, an eccentric pipe 9, an isolation pump cylinder 11, an isolation plunger 12, a connecting joint 13, an inter-pump oil pipe 14, an inter-pump connecting rod 15, a lower pump cylinder 16, a lower plunger 17, the upper plunger 2 is in sealing cooperation with the upper pump cylinder 1, the lower plunger 17 is provided with a discharge valve, the lower plunger 17 is in sealing cooperation with the lower pump cylinder 16, the lower part of the lower pump cylinder 16 is provided with a lower pump inlet valve, the upper pump inlet valve 8 is connected to the eccentric hole thread 6-2 of the eccentric valve body 6, the upper part of the eccentric hole thread 6-2 is provided with a connecting hole 6-1, the connecting hole 6-1 is communicated with the inside of the eccentric valve body 6, the upper pump cylinder 1, the upper plunger 2, the upper pump discharge valve 3, the shunt joint 4, the eccentric valve body 6, the upper pump inlet valve 8 and the eccentric pipe 9 form an upper pump, the lower pump cylinder 16, the lower plunger 17 and the lower pump inlet valve of the lower part of the lower pump cylinder 16 form a lower pump, the upper part of the inter-pump oil pipe 14 is connected to the lower part of the eccentric pipe 9, the upper part of the lower pump cylinder 16 is connected to the lower part of the inter-pump oil pipe 14, the upper plunger 2, the shunt joint 4, the inter-pump connecting rod 15 and the lower plunger 17 are sequentially connected, the length of the inter-pump oil pipe 14 is greater than 100 m, the length of the inter-pump connecting rod 15 is matched with the length of the inter-pump oil pipe 14, so that the lower plunger 17 is located in the lower pump cylinder 16 when the lower plunger 17 reciprocates along with the inter-pump connecting rod 15, the pump diameter of the upper pump cylinder 1 is greater than the pump diameter of the lower pump cylinder 16, the diameter of the upper plunger 2 is greater than the diameter of the lower plunger 17, the upper thread axis 6-4 of the upper part of the eccentric valve body 6 is different from the valve body axis 6-3, the upper thread axis 6-4 is located at the right side of the valve body axis 6-3, the lower thread axis 6-7 of the lower part of the eccentric valve body 6 is different from the valve body axis 6-3, the lower thread axis 6-7 is located at the right side of the valve body axis 6-3, the upper hole 6-5 is located below the upper thread of the eccentric valve body 6, the axis of the upper hole 6-5 is coaxial with the upper thread axis 6-4, the diameter of the upper hole 6-5 is greater than the diameter of the lower plunger 17 and smaller than the thread diameter of the upper pump cylinder 1, so as to form a shoulder to lock the thread and seal the end face, the lower hole 6-6 is located above the lower thread of the eccentric valve body 6, the axis of the lower hole 6-6 is coaxial with the axis of the upper hole 6-5, the diameter of the lower hole 6-6 is greater than the diameter of the lower plunger 17 and smaller than the outer diameter of the upper thread of the eccentric pipe 9, so as to form a shoulder to lock the thread and seal the end face, the diameter of the upper hole 6-5 is greater than the diameter of the lower hole 6-6, so as to form an annular space to ensure the overflow passage of the upper pump, the upper part of the eccentric pipe 9 is provided with an eccentric thread, the axis of the eccentric thread is the eccentric thread axis 9-2, the axis of the eccentric pipe 9 is the pipe axis 9-3, the eccentric thread axis 9-2 is different from the pipe axis 9-3, the eccentric thread axis 9-2 is located at the right side of the pipe axis 9-3, the eccentric pipe 9 is provided with an eccentric hole 9-5, the axis of the eccentric hole 9-5 is the eccentric hole axis 9-4, the eccentric hole axis 9-4 is different from the pipe axis 9-3,The eccentric bore axis 9-4 is located to the right of the pipe axis 9-3. An installation groove 9-1 is provided on the left side wall of the eccentric pipe 9. The right side of the upper pump inlet valve 8 is located in the installation groove 9-1, ensuring that the overall outer diameter of the invention is less than ¢116, facilitating its insertion into the ¢124 casing (the ¢124 casing is currently a commonly used casing in oil fields). An isolation pump barrel 11 is installed between the eccentric pipe 9 and the pump-interval tubing 14. A connecting pipe 5, an isolation plunger 12, and a connecting joint 13 are connected between the diverter 4 and the pump-interval connecting rod 15. The connecting joint 13 has a connecting groove, allowing the well fluid in the pump-interval tubing 14 to enter the isolation plunger 12 through the connecting groove. The isolation plunger 12 is located within the isolation pump barrel 11. The system features an internal seal. The flow divider 4 has an upper pump discharge channel 4-1 and a lower pump discharge channel 4-2. The lower end of the upper pump discharge channel 4-1 communicates with the interior of the upper pump cylinder 1 below the upper plunger 2. An upper pump discharge valve 3 (in an eccentric position) is installed at the upper end of the upper pump discharge channel 4-1, located inside the upper plunger 2. The lower end of the lower pump discharge channel 4-2 communicates with the connecting pipe 5, and the upper end communicates with the interior of the upper plunger 2. The upper threaded axis 6-4, the pipe axis 9-3, and the axis of the isolation pump cylinder 11 are coaxial with the axis of the upper pump cylinder, ensuring reasonable stress on the tubing and reducing accidents.

[0019] A further provision of the present invention is that a transition pipe 10 is installed between the isolation pump cylinder 11 and the eccentric tube 9. The inner diameter of the transition pipe 10 is larger than the inner diameter of the eccentric hole 9-5 and the isolation pump cylinder 11. The downward projection of the eccentric hole 9-5 is located within the inner hole of the transition pipe 10. The length of the transition pipe 10 is greater than the length of the isolation plunger 12 and the lower plunger 17, so that the isolation plunger 12 and the lower plunger 17 can be lowered into the isolation pump cylinder 11 only after they have fully entered the transition pipe 10. This technical feature is to allow the insertion of isolation plungers 12 and 17 with larger diameters. If the diameters of the isolation plungers 12 and 17 are small, and the downward projection of the eccentric hole 9-5 is located within the inner hole of the isolation pump cylinder 11, then the transition pipe 10 is not required.

[0020] A guide sleeve 7 is installed inside the eccentric valve body 6. The well fluid from the upper pump inlet valve 8 can enter the lower part of the upper pump barrel 1 through the guide sleeve 7. The guide sleeve 7 is used to guide the isolation plunger 12 and the lower plunger 17 into the lower part to prevent them from colliding at this point.

[0021] In the initial stage of well opening, both the upper and lower pumps pump oil simultaneously, with the total displacement being the sum of the upper and lower pumps. In the later stage of well opening, after the dynamic fluid level in the well drops below the upper pump, the upper pump can no longer pump oil, and the lower pump switches to pump oil, with the displacement becoming the lower pump's displacement, thus achieving variable displacement production. The distance between the upper and lower pumps can be designed according to the well conditions, generally ranging from 100m to 2000m. The well can still produce normally after the dynamic fluid level drops.

[0022] During the oil pumping process, the upper plunger 2 reciprocates in the upper pump barrel 1, the lower plunger 17 reciprocates in the lower pump barrel 16, and the isolation plunger 12 reciprocates in the isolation pump barrel 11.

[0023] The inter-pump connecting rod 5 is a common oil pumping rod. The upper pump barrel 1, the upper plunger 2, the isolation pump barrel 11, the isolation plunger 12, the lower pump barrel 16 and the lower plunger 17 are standard components.

[0024] The upper pump barrel 1, the eccentric valve body 6, the upper pump inlet valve 8, the eccentric pipe 9, the isolation pump barrel 11, the inter-pump oil pipe 14 and the lower pump barrel 16 are first lowered into the well (generally more than 1000m), and then the upper plunger 2, the upper pump outlet valve 3, the shunt joint 4, the interconnecting pipe 5, the isolation plunger 12, the interconnecting joint 13, the inter-pump connecting rod 15 and the lower plunger 17 are lowered. The present application is provided with several eccentric mechanisms, which are used to lower the large-diameter lower pump in the casing with a diameter of ¢124. If the upper pump has a diameter of ¢70, the lower pump can be designed to have a diameter of ¢56. The diameter of the isolation pump barrel 11 can be the same as that of the lower pump.

[0025] The eccentric hole 9-5 and the mounting groove 9-1 are processed after the eccentric valve body 6 and the eccentric pipe 9 are connected into one body, so as to ensure the formation of the state in the formula. Figure 1 or Figure 2 or Figure 4 ​

Claims

1. A variable displacement pump with reduced clearance volume, comprising an upper pump barrel (1), an upper plunger (2), an upper pump discharge valve (3), a flow divider (4), a communication pipe (5), an eccentric valve body (6), an upper pump intake valve (8), an eccentric pipe (9), an isolation pump barrel (11), an isolation plunger (12), a communication joint (13), an inter-pump oil pipe (14), an inter-pump connecting rod (15), a lower pump barrel (16), a lower plunger (17), the upper plunger (2) being sealed with the upper pump barrel (1), the lower plunger (17) having a discharge valve, the lower plunger (17) being sealed with the lower pump barrel (16), the lower pump barrel (16) having a lower pump intake valve at its lower part, the upper pump intake valve (8) being connected to an eccentric hole thread (6-2) of the eccentric valve body (6), the eccentric hole thread (6-2) having a communication hole (6-1) above it, the communication hole (6-1) being in communication with the interior of the eccentric valve body (6), the upper pump barrel (1), the upper plunger (2), the upper pump discharge valve (3), the eccentric valve body (6), the upper pump intake valve (8), and the eccentric pipe (9) forming an upper pump, the lower pump barrel (16), the lower plunger (17), and the lower pump intake valve of the lower pump barrel (16) forming a lower pump, the upper part of the inter-pump oil pipe (14) being connected to the lower part of the eccentric pipe (9), the upper part of the lower pump barrel (16) being connected to the lower part of the inter-pump oil pipe (14), the upper plunger (2), the flow divider (4), the inter-pump connecting rod (15), and the lower plunger (17) being connected in sequence, the length of the inter-pump oil pipe (14) being greater than 100 m, the length of the inter-pump connecting rod (15) being matched with the inter-pump oil pipe (14) so that the lower plunger (17) is located in the lower pump barrel (16) when the lower plunger (17) reciprocates with the inter-pump connecting rod (15), the pump diameter of the upper pump barrel (1) being greater than the pump diameter of the lower pump barrel (16), and the diameter of the upper plunger (2) being greater than the diameter of the lower plunger (17), characterized in that the eccentric hole thread (6-2) of the eccentric valve body (6) is provided with a communication hole (6-1) above it. The upper threaded axis (6-4) of the valve body (6) is eccentric to the valve body axis (6-3), the upper threaded axis (6-4) is on the right side of the valve body axis (6-3), the lower threaded axis (6-7) of the eccentric valve body (6) is eccentric to the valve body axis (6-3), the lower threaded axis (6-7) is on the right side of the valve body axis (6-3), the upper hole (6-5) is below the upper thread of the eccentric valve body (6), the axis of the upper hole (6-5) is coaxial with the upper threaded axis (6-4), the diameter of the upper hole (6-5) is larger than the diameter of the lower plunger (17), the lower hole (6-6) is above the lower thread of the eccentric valve body (6), the diameter of the lower hole (6-6) is larger than the diameter of the lower plunger (17), the upper part of the eccentric tube (9) has an eccentric thread, the axis of the eccentric thread is the eccentric thread axis (9-2), the axis of the eccentric tube (9) is the tube axis (9-3), the eccentric thread axis (9-2) is eccentric to the tube axis (9-3), the eccentric thread axis (9-2) is on the right side of the tube axis (9-3), the eccentric hole (9-5) is in the eccentric tube (9), the axis of the eccentric hole (9-5) is the eccentric hole axis (9-4), the eccentric hole axis (9-4) is eccentric to the tube axis (9-3), the eccentric hole axis (9-4) is on the right side of the tube axis (9-3), the mounting groove (9-1) is arranged on the left side wall of the eccentric tube (9), the right side of the upper pump inlet valve (8) is in the mounting groove (9-1), the isolation pump cylinder (11) is installed between the eccentric tube (9) and the inter-pump oil pipe (14), the communication pipe (5), the isolation plunger (12) and the communication joint (13) are connected between the shunt joint (4) and the inter-pump connecting rod (15), the communication joint (13) has a communication groove, the well fluid in the inter-pump oil pipe (14) can enter the isolation plunger (12) through the communication groove, the isolation plunger (12) is matched and sealed in the isolation pump cylinder (11), the shunt joint (4) has an upper pump discharge passage (4-1) and a lower pump discharge passage (4-2), the lower end of the upper pump discharge passage (4-1) is communicated with the inside of the upper pump cylinder (1) at the lower part of the upper plunger (2), the upper end of the upper pump discharge passage (4-1) is provided with the upper pump discharge valve (3), the upper pump discharge valve (3) is in the upper plunger (2), the lower end of the lower pump discharge passage (4-2) is communicated with the communication pipe (5), the upper end of the lower pump discharge passage (4-2) is communicated with the inside of the upper plunger (2), the upper threaded axis (6-4), the tube axis (9-3) and the axis of the isolation pump cylinder (11) are coaxial with the axis of the upper pump cylinder.

2. The variable- displacement progressive- cavity pump of claim 1, wherein: The transition pipe (10) is installed between the isolation pump cylinder (11) and the eccentric pipe (9), the inner diameter of the transition pipe (10) is greater than the inner diameter of the eccentric hole (9-5) and the isolation pump cylinder (11), the downward projection of the eccentric hole (9-5) is in the inner hole of the transition pipe (10), and the length of the transition pipe (10) is greater than the length of the isolation plunger (12) and the lower plunger (17), so that the isolation plunger (12) and the lower plunger (17) enter the transition pipe (10) and then enter the isolation pump cylinder (11).

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