A solid plunger double-tube oil pump and method

Abstract

The present invention discloses a solid plunger double-tube oil pump and method, including a pump barrel, a plunger, a liquid inlet valve, and a liquid outlet valve, wherein the plunger is a solid plunger, and the outer wall of the plunger is connected to the inner wall of the pump barrel in a sliding and sealing manner; and further comprising: a tail pipe, wherein the upper port of the tail pipe is connected to the lower port of the pump barrel, the bottom end of the tail pipe is a blind end, and the inside of the tail pipe forms a liquid sinking cavity, the tail pipe is provided with a radial tail pipe inlet and a tail pipe outlet, and the position of the tail pipe outlet is higher than the position of the tail pipe inlet, the liquid inlet valve and the liquid outlet valve are both arranged on the radial outer side of the pump barrel, and the liquid outlet valve is located above the liquid inlet valve, the outlet of the liquid inlet valve is connected to the inlet of the tail pipe, the inlet of the liquid outlet valve is connected to the outlet of the tail pipe, and the outlet of the liquid outlet valve is connected to the inside of the oil pipe above the pump barrel. The present invention forms a separate liquid discharge channel to eliminate the fixed clearance in the pump. The secondary clearance caused by the anti-shock distance is eliminated, and the influence of gas on the oil pump is completely solved.

Description

Technical Field

[0001] The invention relates to the technical field of deep pumping with a small-diameter rod pump in low-permeability and ultra-low-permeability oil reservoirs, in particular to a solid plunger double-tube oil pump and a method. Background Art

[0002] Low-permeability and ultra-low-permeability oil fields generally have low liquid volume and deep liquid surface. If a large pump is used, it will cause supply-production imbalance, or the depth will be limited due to heavy load. Although reducing the pumping parameters can alleviate the imbalance of supply and production in the oil field, it is still necessary to replace the reducer or add a frequency conversion adjustment device to achieve the supply and production standard of oil wells with a daily liquid production of less than 2m3, which will bring additional cost investment and cannot solve the problem of "heavy load and shallow depth" caused by the large pump diameter. Therefore, it is a practical way to use a small-diameter oil pump for deep pumping.

[0003] There are two types of oil well pump plungers: hollow structure and solid structure. The hollow structure is not suitable for small diameter rod pumps, because the diameter of small diameter rod pumps is generally below 32mm. If it is made into a hollow structure, the outer wall of the part will be too thin, and the strength and life will not meet the use requirements. In comparison, the plunger with a solid structure is much more reliable for small diameter pumps. In deep pumping of low permeability and ultra-low permeability reservoirs, the production pressure difference is large, and the crude oil is easy to precipitate dissolved gas, affecting the normal operation of the oil well pump. There are currently two main types of solid plunger oil well pumps. One is that the liquid inlet valve and liquid outlet valve are both at the bottom, and the liquid is discharged through a two-way structure. The liquid inlet valve, liquid outlet valve, and two-way at the bottom are arranged together to produce a large clearance. Repeated pumping of the oil well pump will cause gas to accumulate in the clearance, affecting the operation of the oil well pump, and in severe cases, it will also cause "gas lock". The other is that the inlet valve is at the bottom and the outlet valve is at the side. This structure reduces the fixed clearance to a certain extent, but when the plunger hits the pump upper bevel, there is still a clearance between the bottom dead center of the plunger and the inlet valve, and the gas effect cannot be completely overcome. Therefore, it is very necessary to invent a small-diameter solid oil pump that can overcome the gas effect.

[0004] Publication (announcement) number: CN204941871U, Publication (announcement) date: 2016-01-06 Discloses an anti-gas lock oil pump with an external oil inlet valve on the top of the pump barrel, comprising an upper joint, upper and lower couplings of the pump barrel, an oil pumping rod, a plunger and a pump barrel; the upper coupling of the pump barrel is connected to the external oil inlet valve; the upper end of the external oil inlet valve is connected to the anti-backflow valve; the external oil inlet valve comprises upper and lower circular openings of the valve housing, an offset valve cavity, a valve ball and a reset spring, the axis of the upper and lower circular openings of the valve housing coincides with the axis of the oil pumping rod; the offset valve cavity is located on the outside of the pump barrel; a valve ball is provided in the offset valve cavity, the lower end of the reset spring sits on the bottom wall of the offset valve cavity, and the offset valve cavity is communicated with the cavity between the lower circular opening of the valve housing and the upper circular opening of the valve housing. The anti-gas lock oil pump with an external oil inlet valve on the top of the pump barrel not only eliminates the conditions for gas release during the entire oil inlet and oil discharge process in principle, is not affected by the gas content of the liquid, and avoids the occurrence of the "gas lock" phenomenon. It also has a simple structure and is easy to manufacture.

[0005] Publication (announcement) number: CN2547902Y, Publication (announcement) date: 2003-04-30. It relates to a high-efficiency oil pump that prevents leakage and gas lock. The pump is composed of a reducer, a pressure reducing pipe clamp, an annular valve, a pump barrel, a plunger assembly, an elastic valve pipe clamp, an oil outlet hole, a center cover, an elastic claw, an oil inlet valve ball, a ball seat, an oil inlet valve working barrel, etc. The pump can reduce the influence of gas on the oil pump in oil wells with a high oil-gas ratio and prevent gas lock from occurring; it has a valve ball straightening and strong closing function when used in directional inclined wells and side-drilling horizontal wells; it is not affected by the pressure of the liquid column or the depth of the pump when used in deep wells or ultra-deep wells, and can reduce the leakage between the piston and the pump barrel and the leakage of the pump valve; in addition, since the flow channel area of ​​the pump barrel oil inlet is large, the flow resistance of the incoming oil becomes small, and the pump has a sand prevention function. Since the utility model has the characteristics of reasonable structure, simple construction, high pump efficiency and long service life, it can be widely used in oil production in deep wells, ultra-deep wells, high oil-gas ratio wells and side-drilling horizontal wells.

[0006] Publication (announcement) number: CN110894779A, Publication (announcement) date: 2020-03-20 An anti-stuck and anti-gas oil pump and oil pumping method, a sand scraper ring and an automatic compensation combined sealing ring assembly are placed on the outer wall of a strong opening and closing anti-gas oil outlet valve assembly, tightly fitting with the pump barrel to form an anti-sand jam structure. The tightly fitting anti-sand jam structure prevents sand and gravel from entering the pump cavity when the pump barrel moves up and down, and scrapes off the dirt deposited on the inner wall of the pump barrel to prevent the occurrence of sand jam. The strong opening and closing anti-gas oil outlet valve assembly When the sucker rod drives the pull rod upward, the upper anti-gas lock valve is sealed on the oil outlet valve seat, and the upper anti-gas lock valve opens to inhale liquid. When the upper push block drives the lower valve stem of the upper anti-gas lock valve to move downward, the fixed valve ball is opened, and the fluid in the pump chamber passes through the inner hole of the fixed valve seat to realize the discharge of the pump to the oil pipe. The main structure of the anti-gas card includes the forced opening of the upper anti-gas lock valve to ensure that the gas in the lower part of the pump chamber can be discharged upward smoothly; the strong opening and closing anti-gas oil outlet valve assembly is closely matched with the spherical valve surface to ensure the universal sealing and effective operation.

[0007] The technical solutions, technical problems to be solved and beneficial effects produced by the above-disclosed technologies are different from the present invention, or are in different technical fields or application scenarios. Regarding more technical features, technical problems to be solved and beneficial effects of the present invention, the above-disclosed technical documents do not contain any technical inspiration. Summary of the invention

[0008] The purpose of the present invention is to provide a solid plunger double-tube oil well pump and method to address the above-mentioned defects in the prior art. Through the double-tube design, with the double valves placed on the side, a separate liquid discharge channel is formed to eliminate the fixed clearance in the pump. Through the tail pipe closed liquid sinking design, the secondary clearance caused by the anti-shock distance is eliminated, and the influence of gas on the oil well pump is completely solved.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A solid plunger double-tube oil pump, comprising a pump barrel, a plunger, a liquid inlet valve, and a liquid outlet valve, wherein the plunger is a solid plunger, and the outer wall of the plunger is connected to the inner wall of the pump barrel in a sliding and sealing manner;

[0011] Also includes:

[0012] A tail pipe, wherein the upper port of the tail pipe is connected to the lower port of the pump barrel, the bottom end of the tail pipe is a blind end, a liquid sinking chamber is formed inside the tail pipe, a radial tail pipe inlet and a tail pipe outlet are provided in the tail pipe, the position of the tail pipe outlet is higher than the position of the tail pipe inlet, the inlet valve and the outlet valve are both arranged on the radial outside of the pump barrel, and the outlet valve is located above the inlet valve, the outlet of the inlet valve is communicated with the inlet of the tail pipe, the inlet of the outlet valve is communicated with the outlet of the tail pipe, and the outlet of the outlet valve is communicated with the inside of the oil pipe above the pump barrel.

[0013] Furthermore, the lower end of the plunger extends into the tail pipe, and the outer diameter of the plunger is smaller than the inner diameter of the tail pipe.

[0014] Furthermore, it also includes:

[0015] The drain pipe is arranged on the radial outer side of the pump barrel, the lower end of the drain pipe is connected to the outlet of the liquid outlet valve, and the upper end of the drain pipe is connected to the radial oil inlet hole opened in the oil pipe.

[0016] Furthermore, the upper port of the pump barrel is connected to the oil pipe, the outer diameter of the plunger is smaller than the inner diameter of the oil pipe, and the upper end of the plunger is connected to the sucker rod.

[0017] Furthermore, the liquid inlet valve and the liquid outlet valve are both commonly used one-way floating valves.

[0018] Furthermore, the lower end of the plunger is a conical guide head.

[0019] In order to achieve the above object, the present invention adopts the following technical solutions:

[0020] A solid plunger double-tube oil pumping method comprises the following steps:

[0021] The sucker rod carries the plunger down into the pump barrel until it hits the pump, and then it is lifted up to prevent the impact. After the anti-impact distance is lifted up, the bottom dead point of the plunger is still located in the tail pipe. After that, the sucker rod can drive the plunger to pump up and down normally.

[0022] When the plunger moves upward, the crude oil enters the tail pipe and the pump barrel through the liquid inlet valve. If the crude oil entering at this time is in a gas-liquid two-phase state, then due to the effect of gravity, the gas is on the top and the liquid is on the bottom. Most of the liquid will gather in the liquid sinking cavity of the tail pipe, and most of the gas will gather in the pump barrel. After multiple pumping, the liquid sinking cavity will be filled with liquid.

[0023] After the sinking chamber is filled with liquid, the plunger moves downward, first compressing the space in the pump barrel. When the lower end of the plunger protrudes out of the pump barrel, the space in the pump barrel can be considered to be compressed to zero. The plunger continues to move downward and then compresses the space in the sinking chamber. Since the sinking chamber is filled with liquid and the liquid is incompressible, the liquid and gas will be forced to be discharged into the oil pipe on the pump through the liquid outlet valve and the drain pipe.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The inlet valve and the outlet valve are both on the side, and a separate discharge pipe connects the outlet valve to the oil pipe on the pump. When the plunger moves upward, the crude oil enters the tail pipe and the pump barrel through the inlet valve. When the plunger moves downward, the crude oil is discharged into the oil pipe on the pump through the outlet valve and the discharge pipe. During this period, the tail pipe is always filled with liquid, forming a liquid sinking cavity. Since the bottom dead point of the plunger is still located in the tail pipe after the oil pump has completed the anti-thrust distance, it is always lower than the inlet valve and the outlet valve. Therefore, every time the plunger reaches the bottom dead point, it sinks into the liquid in the tail pipe. Even if there is gas in the pump, it will be forced to be discharged, and there is no clearance space for gas accumulation.

[0026] The double-tube design, combined with the double-valve side placement, forms a separate drainage channel to eliminate the fixed clearance in the pump. The tail pipe closed liquid sinking design eliminates the secondary clearance caused by the anti-shock distance, completely solving the impact of gas on the oil well pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a structural schematic diagram of a solid plunger double-tube oil pump.

[0028] In the figure: 1-discharge pipe; 2-liquid outlet valve; 3-liquid inlet valve; 4-sucker rod; 5-oil pipe; 6-plunger; 7-pump barrel; 8-tail pipe; 9-liquid sinking chamber. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] See also Figure 1 , the present invention provides a technical solution:

[0032] A solid plunger double-tube oil pump, comprising a pump barrel 7, a plunger 6, a liquid inlet valve 3, and a liquid outlet valve 2, wherein the plunger is a solid plunger, and the outer wall of the plunger is connected to the inner wall of the pump barrel in a sliding and sealing manner;

[0033] Also includes:

[0034] Tail pipe 8, the upper port of the tail pipe is connected to the lower port of the pump barrel, the bottom end of the tail pipe is a blind end, the interior of the tail pipe constitutes a liquid sinking chamber 9, the tail pipe is provided with a radial tail pipe inlet and a tail pipe outlet, the position of the tail pipe outlet is higher than the position of the tail pipe inlet, the inlet valve and the outlet valve are both arranged on the radial outside of the pump barrel, and the outlet valve is located above the inlet valve, the outlet of the inlet valve is communicated with the inlet of the tail pipe, the inlet of the outlet valve is communicated with the outlet of the tail pipe, and the outlet of the outlet valve is communicated with the interior of the oil pipe 5 above the pump barrel.

[0035] Furthermore, the lower end of the plunger 6 extends into the tail pipe, and the outer diameter of the plunger is smaller than the inner diameter of the tail pipe.

[0036] Furthermore, it also includes:

[0037] The drain pipe 1 is arranged on the radial outer side of the pump barrel, the lower end of the drain pipe is communicated with the outlet of the liquid outlet valve, and the upper end of the drain pipe is communicated with the radial oil inlet hole opened in the oil pipe.

[0038] Furthermore, the upper port of the pump barrel is connected to the oil pipe, the outer diameter of the plunger is smaller than the inner diameter of the oil pipe, and the upper end of the plunger is connected to the sucker rod 4.

[0039] Furthermore, the liquid inlet valve and the liquid outlet valve are both one-way floating valves commonly used in the art, which are themselves well-known technologies.

[0040] Furthermore, the lower end of the plunger is a conical guide head.

[0041] This oil pump is composed of a plunger 6, a pump barrel 7, a discharge pipe 1, an inlet valve 3, an outlet valve 2, and a tail pipe 8. The inlet valve 3 and the outlet valve 2 are both on the side, and a separate discharge pipe 1 connects the outlet valve 2 with the oil pipe 5 on the pump. When the plunger 6 moves upward, the crude oil enters the tail pipe 8 and the pump barrel 7 through the inlet valve 3. When the plunger 6 moves downward, the crude oil is discharged into the oil pipe 5 on the pump through the outlet valve 2 and the discharge pipe 1. During this period, the tail pipe 8 is always filled with liquid to form a liquid sinking cavity 9. Since the bottom dead point of the plunger 6 is still located in the tail pipe 8 after the oil pump has completed the anti-thrust distance, it is always lower than the inlet valve 3 and the outlet valve 2. Therefore, whenever the plunger 6 reaches the bottom dead point, it sinks into the liquid in the tail pipe 8. Even if there is gas in the pump, it will be forced to be discharged, and there is no clearance space for gas accumulation.

[0042] The so-called bottom dead point or top dead point of the plunger 6 is the prior art in this field, and the technicians in this field are clear about it. Simply put, it is the axial sliding stroke of the plunger, that is, the top dead point ensures that the plunger does not fall out of the upper end of the pump barrel, and the bottom dead point ensures that the plunger does not press against the blind end of the tail pipe.

[0043] During construction, the oil pipe 5 is first lowered into the well with the pump barrel, and the sucker rod 4 is lowered into the pump barrel with the plunger 6 until it hits the pump, and then it is lifted up to prevent the impact. After the anti-impact distance is lifted up, the bottom dead point of the plunger 6 is still located in the tail pipe 8, and then the sucker rod 4 can drive the plunger 6 to pump up and down normally. When the plunger 6 moves upward, the crude oil enters the tail pipe 8 and the pump barrel 7 through the liquid inlet valve 3. If the crude oil entering at this time is in a gas-liquid two-phase state, then due to the effect of gravity, the gas is on the top and the liquid is on the bottom. Most of the liquid will gather in the liquid sinking chamber 9 of the tail pipe 8, and most of the gas will gather in the pump barrel 7. After multiple pumping, the liquid sinking chamber 9 will be full of liquid; when the plunger 6 moves downward, the space in the pump barrel 7 is first compressed. When the lower end of the plunger 6 protrudes out of the pump barrel, the space in the pump barrel can be considered to be compressed to zero. The plunger 6 continues to move downward and then compresses the space in the liquid sinking chamber 9. Since the liquid sinking chamber 9 is full of liquid, and the liquid is incompressible, the liquid and gas will be forced to be discharged into the oil pipe 5 on the pump through the liquid outlet valve 2 and the discharge pipe 1.

[0044] 1. Through the double-tube design and the double-valve side placement, a separate discharge channel is formed to eliminate the fixed clearance in the pump.

[0045] 2. The tail pipe 8 is designed to close the liquid and eliminate the secondary clearance caused by the anti-impact distance, thus completely solving the influence of gas on the oil well pump.

[0046] Embodiment 2:

[0047] See also Figure 1 , the present invention provides a technical solution:

[0048] A solid plunger double-tube oil pump, comprising a pump barrel 7, a plunger 6, a liquid inlet valve 3, and a liquid outlet valve 2, wherein the plunger is a solid plunger, and the outer wall of the plunger is connected to the inner wall of the pump barrel in a sliding and sealing manner;

[0049] Also includes:

[0050] Tail pipe 8, the upper port of the tail pipe is connected to the lower port of the pump barrel, the bottom end of the tail pipe is a blind end, the interior of the tail pipe constitutes a liquid sinking chamber 9, the tail pipe is provided with a radial tail pipe inlet and a tail pipe outlet, the position of the tail pipe outlet is higher than the position of the tail pipe inlet, the inlet valve and the outlet valve are both arranged on the radial outside of the pump barrel, and the outlet valve is located above the inlet valve, the outlet of the inlet valve is communicated with the inlet of the tail pipe, the inlet of the outlet valve is communicated with the outlet of the tail pipe, and the outlet of the outlet valve is communicated with the interior of the oil pipe 5 above the pump barrel.

[0051] Furthermore, the lower end of the plunger 6 extends into the tail pipe, and the outer diameter of the plunger is smaller than the inner diameter of the tail pipe, and the lowermost end of the plunger is lower than the tail pipe inlet.

[0052] Furthermore, it also includes:

[0053] The drain pipe 1 is arranged on the radial outer side of the pump barrel, the lower end of the drain pipe is communicated with the outlet of the liquid outlet valve, and the upper end of the drain pipe is communicated with the radial oil inlet hole opened in the oil pipe.

[0054] Embodiment 3:

[0055] See also Figure 1 , the present invention provides a technical solution:

[0056] A solid plunger double-tube oil pump, comprising a pump barrel 7, a plunger 6, a liquid inlet valve 3, and a liquid outlet valve 2, wherein the plunger is a solid plunger, and the outer wall of the plunger is connected to the inner wall of the pump barrel in a sliding and sealing manner;

[0057] Also includes:

[0058] Tail pipe 8, the upper port of the tail pipe is connected to the lower port of the pump barrel, the bottom end of the tail pipe is a blind end, the interior of the tail pipe constitutes a liquid sinking chamber 9, the tail pipe is provided with a radial tail pipe inlet and a tail pipe outlet, the position of the tail pipe outlet is higher than the position of the tail pipe inlet, the inlet valve and the outlet valve are both arranged on the radial outside of the pump barrel, and the outlet valve is located above the inlet valve, the outlet of the inlet valve is communicated with the inlet of the tail pipe, the inlet of the outlet valve is communicated with the outlet of the tail pipe, and the outlet of the outlet valve is communicated with the interior of the oil pipe 5 above the pump barrel.

[0059] Furthermore, the lower end of the plunger 6 extends into the tail pipe, and the outer diameter of the plunger is smaller than the inner diameter of the tail pipe, and the lowermost end of the plunger is lower than the tail pipe inlet.

[0060] Although all the above embodiments use Figure 1 However, as a person skilled in the art can clearly know, there is no need to provide a separate drawing to represent, as long as the missing parts or structural features in the embodiment are removed from the drawing. This is clear to those skilled in the art. Of course, the embodiment with more parts is only the optimal embodiment, and the embodiment with fewer parts is the basic embodiment, but it can also achieve the basic purpose of the invention, so all of them are within the scope of protection of the present invention.

[0061] All parts and components not discussed in detail in this application and the connection methods of the parts and components in this application belong to the well-known technology in this technical field and will not be described in detail, such as welding, threaded connection, etc.

[0062] In the present invention, the term "plurality" refers to two or more than two, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0063] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0064] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A solid plunger double-tube oil pump, comprising a pump barrel, a plunger, a liquid inlet valve, and a liquid outlet valve, wherein the plunger is a solid plunger, and the outer wall of the plunger is connected to the inner wall of the pump barrel in a sliding and sealing manner; It is characterized in that Also includes: A tail pipe, wherein the upper end of the tail pipe is connected to the lower end of the pump barrel, the bottom end of the tail pipe is a blind end, a liquid sinking chamber is formed inside the tail pipe, a radial tail pipe inlet and a tail pipe outlet are provided in the tail pipe, the tail pipe outlet is provided at a position higher than the tail pipe inlet, the liquid inlet valve and the liquid outlet valve are both provided at the radial outer side of the pump barrel, and the liquid outlet valve is located above the liquid inlet valve, the outlet of the liquid inlet valve is communicated with the tail pipe inlet, the inlet of the liquid outlet valve is communicated with the tail pipe outlet, and the outlet of the liquid outlet valve is communicated with the inside of the oil pipe above the pump barrel; The lower end of the plunger extends into the tail pipe, and the outer diameter of the plunger is smaller than the inner diameter of the tail pipe; Also includes: A liquid discharge pipe, the liquid discharge pipe is arranged on the radial outer side of the pump barrel, the lower end of the liquid discharge pipe is connected to the outlet of the liquid discharge valve, and the upper end of the liquid discharge pipe is connected to the radial oil inlet hole opened in the oil pipe; The lower end of the plunger is a conical guide head.

2. A solid plunger double-tube oil pump according to claim 1, characterized in that: The upper port of the pump barrel is connected to the oil pipe, the outer diameter of the plunger is smaller than the inner diameter of the oil pipe, and the upper end of the plunger is connected to the pumping rod.

3. A solid plunger double-tube oil pump according to claim 2, characterized in that: The liquid inlet valve and the liquid outlet valve are both commonly used one-way floating valves.

4. A method for pumping oil using the solid plunger double-tube oil pump as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: The sucker rod carries the plunger down into the pump barrel until it hits the pump, and then it is lifted up to prevent the impact. After the anti-impact distance is lifted up, the bottom dead point of the plunger is still located in the tail pipe. Then the sucker rod drives the plunger to pump up and down normally. When the plunger moves upward, the crude oil enters the tail pipe and the pump barrel through the liquid inlet valve. If the crude oil entering at this time is in a gas-liquid two-phase state, then due to the effect of gravity, the gas is on the top and the liquid is on the bottom. Most of the liquid will gather in the liquid sinking cavity of the tail pipe, and most of the gas will gather in the pump barrel. After multiple pumping, the liquid sinking cavity will be filled with liquid. After the sinking chamber is filled with liquid, the plunger moves downward, first compressing the space in the pump barrel. When the lower end of the plunger protrudes out of the pump barrel, the space in the pump barrel is compressed to zero. The plunger continues to move downward and then compresses the space in the sinking chamber. Since the sinking chamber is filled with liquid and the liquid is incompressible, the liquid and gas will be forced to be discharged into the oil pipe on the pump through the liquid outlet valve and the drain pipe.

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