Downhole hydraulic double acting pump

Abstract

The application discloses a downhole hydraulic double-acting pump, which comprises a pump barrel assembly and a piston assembly. The pump barrel assembly comprises an upper joint, a power pump barrel, an upper outer tube, a short pump barrel, a middle joint, a lower outer tube and a drainage pump barrel. The upper joint is internally formed with a channel A and channels B1, B2 and B3. The piston assembly comprises a power plunger, a long plunger rod, an inner tube, a double-channel joint and a drainage plunger. An upstream drainage valve is arranged at the power plunger. A downstream drainage valve is arranged at the drainage plunger. The power pump barrel is formed with a pump cavity C. The lower part of the power pump barrel is provided with a drainage hole b. The channel B2 is communicated with the pump cavity C through the drainage hole b. The upper part of the long plunger rod is provided with a drainage hole a. The pump cavity C is communicated with a channel D through the drainage hole a. The drainage pump barrel is formed with a pump cavity E. The upper part of the drainage pump barrel is provided with a drainage hole d. The channel B3 is communicated with the pump cavity E through the drainage hole d. The double-channel joint is provided with a drainage hole e at the side. The lower end of the inner tube is connected with the drainage hole e. The pump type has the advantages of small size, large displacement and well washing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of downhole pump group, in particular to a downhole hydraulic double-acting pump. BACKGROUND

[0002] The hydraulic piston device and method for concentric pipe in coalbed methane well is an invention patent applied by the applicant on July 12, 2012, with the publication number CN102758602B. The technical solution is limited in actual use: in the development process of unconventional gas well and oil well, due to the limitation of well trajectory, well size, and more impurities (wax, sand, and coal powder) in the produced liquid, normal production cannot be carried out, and thus the requirement of large displacement well conditions cannot be met.

[0003] In view of this situation, the applicant has researched and improved and designed a downhole hydraulic double-acting pump to meet the requirement of large displacement well conditions. SUMMARY

[0004] The present application provides a downhole hydraulic double-acting pump to solve the problems in the prior art.

[0005] To solve the above technical problems, the present application adopts the following technical solution:

[0006] A downhole hydraulic double-acting pump comprises a pump cylinder assembly and a piston assembly, wherein:

[0007] The pump cylinder assembly comprises an upper joint, a power pump cylinder, an upper outer pipe, a short pump cylinder, a middle joint, a lower outer pipe, and a production pump cylinder, and the pump cylinder assembly is fixedly arranged in the wellbore with the oil pipe.

[0008] The upper end of the upper joint is sealingly connected and fixed with the central pipe, and the lower end of the upper joint is sealingly connected and fixed with the upper end of the power pump cylinder; the power pump cylinder is installed and fixed in the upper outer pipe, and the power pump cylinder and the upper outer pipe are fixedly connected and sealed with the middle joint; the short pump cylinder is installed and fixed in the middle joint; the production pump cylinder is installed and fixed in the lower outer pipe, and the production pump cylinder and the lower outer pipe are fixedly connected and sealed with the middle joint.

[0009] A passage A is formed in the upper joint, an annular passage B1 is formed between the oil pipe and the central pipe, an annular passage B2 is formed between the upper outer pipe and the power pump cylinder, and an annular passage B3 is formed between the lower outer pipe and the production pump cylinder; the passage B1 and the passage B2 are communicated, and the passage B2 and the passage B3 are separated by the middle joint.

[0010] The piston assembly comprises a power plunger, a long plunger rod, an inner pipe, a double-channel joint, and a production plunger, and the piston assembly is reciprocally movable in the pump cylinder assembly.

[0011] The power plunger is mounted in the power pump cylinder and is in sliding sealing connection with the power pump cylinder, the drainage plunger is mounted in the drainage pump cylinder and is in sliding sealing connection with the drainage pump cylinder, the upper end of the long plunger rod is fixedly connected with the power plunger, the lower end of the long plunger rod is fixedly connected with the double-channel joint, the double-channel joint is fixedly connected with the drainage plunger, and meanwhile, the long plunger rod is located in the short pump cylinder and is in sliding sealing connection with the short pump cylinder;

[0012] The power plunger is provided with an axially penetrating first flow channel, the long plunger rod is provided with an axially penetrating second flow channel, the double-channel joint is provided with an axially penetrating third flow channel, the drainage plunger is provided with an axially penetrating fourth flow channel, and the second flow channel, the third flow channel and the fourth flow channel are communicated;

[0013] The inner tube is sleeved on the second flow channel of the long plunger rod, the inner tube is provided with an axially penetrating fifth flow channel, the upper end of the fifth flow channel is communicated with the first flow channel, and the inner tube and the long plunger rod form a channel D;

[0014] The power pump cylinder forms a pump cavity G above the power plunger, the pump cavity G is communicated with the channel A, and the power plunger is provided with an upstream dynamic drainage valve at the first flow channel, and the upstream dynamic drainage valve is one-way conducted from the first flow channel to the pump cavity G;

[0015] The power pump cylinder forms a pump cavity C below the power plunger and above the short pump cylinder, the lower part of the power pump cylinder is provided with a drainage hole b, the channel B2 is communicated with the pump cavity C through the drainage hole b, the upper part of the long plunger rod is provided with a drainage hole a, and the pump cavity C is communicated with the channel D through the drainage hole a;

[0016] The drainage pump cylinder forms a pump cavity E above the drainage plunger and below the short pump cylinder, the upper part of the drainage pump cylinder is provided with a drainage hole d, the channel B3 is communicated with the pump cavity E through the drainage hole d, the side part of the double-channel joint is provided with a drainage hole e, the lower end of the inner tube is connected with the drainage hole e, so that the lower end of the fifth flow channel is communicated with the pump cavity E through the drainage hole e;

[0017] The drainage pump cylinder forms a pump cavity F below the drainage plunger, the drainage plunger is provided with a downstream dynamic drainage valve at the fourth flow channel, and the downstream dynamic drainage valve is one-way conducted from the pump cavity F to the fourth flow channel;

[0018] The drainage pump cylinder is respectively provided with a lower fixed valve and an upper fixed valve, the lower fixed valve is communicated with the pump cavity F and a wellbore, and the lower fixed valve is one-way conducted from the wellbore to the pump cavity F; the upper fixed valve is communicated with the wellbore and the channel B3, and the upper fixed valve is one-way conducted from the wellbore to the channel B3.

[0019] Further, the lower part of the long plunger rod is provided with an axially penetrating pressure relief groove, the length of the pressure relief groove is greater than the length of the short pump cylinder, when the plunger assembly is raised to the upper dead point, the pressure relief groove on the long plunger rod communicates the pump cavities C and E above and below the short pump cylinder to form pressure relief.

[0020] Further, the power plunger is installed in the power pump cylinder with a certain gap to form a gap seal and slides in the stroke of the pump.

[0021] Further, the production plunger is installed in the production pump cylinder with a certain gap to form a gap seal and slides in the stroke of the pump.

[0022] Further, the upper joint is threadedly connected with the upper end of the power pump cylinder and is sealed; the lower end of the power pump cylinder is threadedly connected with the middle joint, the lower end of the upper outer tube is threadedly connected with the middle joint and is sealed, and the short pump cylinder is threadedly connected with the middle joint and is sealed.

[0023] The upper end of the production pump cylinder is threadedly connected with the middle joint, and the upper end of the upper outer tube is threadedly connected with the middle joint and is sealed.

[0024] Further, the power plunger is threadedly connected with the upper end of the long plunger rod, the lower end of the long plunger rod is threadedly connected with the double-channel joint and is sealed, the double-channel joint is threadedly connected with the production plunger and is sealed.

[0025] Further, the upper joint is connected with the central tube in an inner insertion or outer insertion manner.

[0026] The pump of the present application has the advantages of small size, large displacement, and well washing.

[0027] 1. The pump of the present application has the advantages of small size, large displacement, and well washing.

[0028] 2. The present application has an axial pressure relief groove in the lower part of the long plunger rod, and the length of the pressure relief groove is greater than the length of the short pump cylinder. When the plunger assembly rises to the top dead center, the pressure relief groove on the long plunger rod communicates the upper and lower pump cavities C and E of the short pump cylinder to form pressure relief and complete the well washing function. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a structural schematic diagram of the present application.

[0030] The drawings are only used for illustrative description and cannot be understood as a limitation of the present patent; in order to better illustrate the present embodiment, some components in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application.

[0032] As shown in Figure 1 , the present embodiment discloses a downhole hydraulic double-acting pump, which comprises a pump cylinder assembly and a plunger assembly. Specifically:

[0033] The pump barrel assembly comprises an upper joint 1, a power pump barrel 2, an upper outer tube 5, a short pump barrel 7, a middle joint 8, a lower outer tube 11 and a drainage pump barrel 14, and the pump barrel assembly is fixed in the wellbore with the oil tube.

[0034] The upper joint 1 has a hole into which a central tube plug is inserted and sealed, and the lower end of the upper joint 1 is threadedly connected to the upper end of the power pump barrel 2 and sealed. The power pump barrel 2 is fixedly installed in the upper outer tube 5, and the power pump barrel 2 and the upper outer tube 5 are threadedly connected to the middle joint 8 and sealed. The short pump barrel 7 is installed in the middle joint 8, and the short pump barrel 7 is threadedly connected to the middle joint 8 and sealed. The drainage pump barrel 14 is fixedly installed in the lower outer tube 11, and the drainage pump barrel 14 and the lower outer tube 11 are threadedly connected to the middle joint 8 and sealed.

[0035] A passage A is formed in the upper joint 1, an annular passage B1 is formed between the oil tube and the central tube, an annular passage B2 is formed between the upper outer tube 5 and the power pump barrel, and an annular passage B3 is formed between the lower outer tube 11 and the drainage pump barrel 14, the passage B1 and the passage B2 are communicated, and the passage B2 and the passage B3 are separated by the middle joint 8.

[0036] The piston assembly comprises a power plunger 3, a long plunger rod 6, an inner tube 9, a double-channel joint 10 and a drainage plunger 13, and the piston assembly is reciprocable in the pump barrel assembly.

[0037] The power plunger 3 is slidably and sealingly connected in the power pump barrel 2, the drainage plunger 13 is slidably and sealingly connected in the drainage pump barrel 14, the upper end of the long plunger rod 6 is threadedly connected to the power plunger 3 and sealed, the lower end of the long plunger rod 6 is threadedly connected to the double-channel joint 10 and sealed, the double-channel joint 10 is threadedly connected to the drainage plunger 13 and sealed, and the long plunger rod 6 is slidably and sealingly connected in the short pump barrel 7.

[0038] The power plunger 3 is provided with an axially penetrating first flow channel, the long plunger rod 6 is provided with an axially penetrating second flow channel, the double-channel joint 10 is provided with an axially penetrating third flow channel, and the drainage plunger 13 is provided with an axially penetrating fourth flow channel, and the second flow channel, the third flow channel and the fourth flow channel are communicated.

[0039] The inner tube 9 is sleeved on the second flow channel of the long plunger rod 6, and the inner tube 9 is provided with an axially penetrating fifth flow channel, and the upper end of the fifth flow channel is communicated with the first flow channel; and the inner tube 9 and the long plunger rod 6 form a passage D.

[0040] The power pump barrel 2 forms a pump cavity G above the power plunger 3, and the pump cavity G is communicated with the passage A; and the power plunger 3 is provided with an upstream dynamic drainage valve 4 at the first flow channel, and the upstream dynamic drainage valve 4 is unidirectionally communicated from the first flow channel to the pump cavity G.

[0041] The power pump cylinder 2 forms a pump cavity C below the power plunger 3 and above the short pump cylinder 7, the power pump cylinder 2 has a liquid discharge hole b in the lower part, and the passage B2 is communicated with the pump cavity C through the liquid discharge hole b; the long plunger rod 6 has a liquid discharge hole a in the upper part, and the pump cavity C is communicated with the passage D through the liquid discharge hole a.

[0042] The drainage pump cylinder 14 forms a pump cavity E above the drainage plunger 13 and below the short pump cylinder 7, the drainage pump cylinder 14 has a liquid discharge hole d in the upper part, and the passage B3 is communicated with the pump cavity E through the liquid discharge hole d; the double-channel joint 10 is provided with a liquid discharge hole e in the side part, and the lower end of the inner tube 9 is connected with the liquid discharge hole e, so that the fifth flow channel is communicated with the pump cavity E through the liquid discharge hole e.

[0043] The drainage pump cylinder 14 forms a pump cavity F below the drainage plunger 13, and the drainage plunger 13 is provided with a downstream dynamic liquid discharge valve 12 at the fourth flow channel, and the downstream dynamic liquid discharge valve 12 is from the pump cavity F to the fourth flow channel to the one-way conduction.

[0044] The drainage pump cylinder 14 is respectively provided with a lower fixed valve 16 and an upper fixed valve 15 in the lower part, the lower fixed valve 16 is communicated with the pump cavity F and the wellbore, and the lower fixed valve 16 is from the wellbore to the pump cavity F one-way conduction; the upper fixed valve 15 is communicated with the wellbore and the passage B3, and the upper fixed valve 15 is from the wellbore to the passage B3 one-way conduction.

[0045] In the embodiment, the power plunger 3 is installed in the power pump cylinder 2, and a certain gap forms a gap seal and slides within a certain stroke (pump stroke).

[0046] In the embodiment, the long plunger rod 6 is installed in the short pump cylinder 7, and a certain gap forms a gap seal and slides within a certain stroke (pump stroke). The long plunger rod 6 has an axial pressure relief groove h in the lower part, the length of the pressure relief groove h is greater than the length of the short pump cylinder 7, when the plunger assembly is raised to the top dead center, the pressure relief groove h on the long plunger rod 6 communicates the pump cavities C and E above and below the short pump cylinder 7 to form pressure relief, and the well flushing function is completed.

[0047] In the embodiment, the drainage plunger 13 is installed in the drainage pump cylinder 14, and a certain gap forms a gap seal and slides within a certain stroke (pump stroke).

[0048] The working principle of the present application is as follows:

[0049] Downlink: high pressure power liquid is injected by the inner hole of the central tube (from A channel into pump cavity G), channel B1 is vented at the ground equipment, and there is a pressure difference between the two parts of channels A and B, the high pressure water pressure acts on the upper surface of the power plunger 3, generating a downward thrust, at this time the upstream dynamic liquid discharge valve 4 is closed, the thrust acts on the displacement plunger 13 through the long plunger rod 6 and the double-channel joint 10, pushing the displacement plunger 13 to go down, at this time the volume of pump cavity E increases, the pressure decreases, the upper fixed valve 15 opens, and the liquid absorption of pump cavity E is completed; at the same time, the volume of pump cavity F decreases, the pressure increases, the lower fixed valve 16 closes, the downstream dynamic liquid discharge valve 12 opens, and the liquid in pump cavity F is discharged through channel D, liquid discharge hole a, into pump cavity C, and then into channel B2 through liquid discharge hole b, and then transmitted to the water tank of the ground equipment through channel B1.

[0050] Upward: high pressure power liquid enters pump cavity C through channel B1, channel A is vented at the ground equipment, and there is a pressure difference between the two parts of channels B and A, the high pressure water enters pump cavity C, the downstream dynamic liquid discharge valve 12 is closed, the pressure acts on the annular area of the power plunger 3 and the long plunger rod 6, generating an upward thrust, the thrust pulls the displacement plunger 13 to go up, at this time the volume of E cavity decreases, the pressure increases, the upper fixed valve 15 closes, the upstream dynamic liquid discharge valve 4 opens, the liquid in pump cavity E enters channel A through liquid discharge hole e, the fifth flow channel of inner tube 9, the first flow channel of power plunger 3, upstream dynamic liquid discharge valve 4 and pump cavity G, and is transmitted to the water tank of the ground equipment through channel A. At the same time, the volume of pump cavity F increases, the pressure decreases, the lower fixed valve 16 opens, the downstream dynamic liquid discharge valve 12 closes, and the liquid absorption of pump cavity F is completed.

[0051] Washing well: when the plunger assembly goes up to the upper dead center, the pressure relief groove h on the long plunger rod 6 communicates the pump cavities C and E above and below the short pump cylinder 7, the high pressure water injected through channel B enters pump cavity E through the pressure relief groove h, enters channel A through liquid discharge hole e, the fifth flow channel of inner tube 9, the first flow channel of power plunger 3, upstream dynamic liquid discharge valve 4 and pump cavity G, and is transmitted to the water tank of the ground equipment through channel A. Washing well can carry a large amount of impurities in the well fluid to the ground water tank.

[0052] The present application is designed for the condition that the well trajectory and the size of the wellbore, and the large amount of impurities (wax, sand, coal powder) in the produced liquid are limited in the development process of unconventional gas wells and oil wells. The pump has the advantages of small size, large displacement, and washable well.

[0053] The above examples are only used to illustrate but not to limit the technical solutions of the present application. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the present application can still be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or partial replacement should be covered in the scope of the claims of the present application.

[0054] If the terms "first", "second" or the like are used in the description herein to describe various components, it should be understood that these components should not be limited by these terms. These terms are only used to distinguish one component from another. Terms such as "first", "second", and the like can be interchanged with respect to the description of the present application.

[0055] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0056] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

Claims

1. A downhole hydraulic double-acting pump, characterized in that: It includes a pump barrel assembly and a piston assembly, wherein: The pump barrel assembly includes an upper joint, a power pump barrel, an upper outer tube, a short pump barrel, a middle joint, a lower outer tube and a drainage pump barrel. The pump barrel assembly is lowered into the wellbore along with the oil pipe and is fixed in place. The upper end of the upper joint is sealed and fixed with the central tube, and the lower end of the upper joint is sealed and fixed with the upper end of the power pump barrel; the power pump barrel is installed and fixed in the upper outer tube, and the power pump barrel and the upper outer tube are both fixedly connected and sealed with the middle joint, and the short pump barrel is installed and fixed in the middle joint; the drainage pump barrel is installed and fixed in the lower outer tube, and the drainage pump barrel and the lower outer tube are both fixedly connected and sealed with the middle joint; A channel A is formed in the upper joint, an annular channel B1 is formed between the oil pipe and the center pipe, an annular channel B2 is formed between the upper outer pipe and the power pump barrel, and an annular channel B3 is formed between the lower outer pipe and the drainage pump barrel. Channels B1 and B2 are connected, and channels B2 and B3 are separated by the middle joint; The piston assembly includes a power plunger, a long plunger rod, an inner tube, a dual-channel joint and a drainage plunger. The piston assembly can reciprocate in the pump barrel assembly; The power plunger is installed in the power pump barrel and is connected to it in a sliding and sealing manner. The drainage piston is installed in the drainage pump barrel and is connected to it in a sliding and sealing manner. The upper end of the long plunger rod is fixedly connected to the power plunger, and the lower end of the long plunger rod is fixedly connected to the dual-channel joint. The dual-channel joint is fixedly connected to the drainage plunger. At the same time, the long plunger rod is located in the short pump barrel and is connected to it in a sliding and sealing manner. The power plunger is provided with a first flow channel extending axially therethrough, the long plunger rod is provided with a second flow channel extending axially therethrough, the dual-channel joint is provided with a third flow channel extending axially therethrough, and the drainage piston is provided with a fourth flow channel extending axially therethrough, and the second flow channel, the third flow channel and the fourth flow channel are connected; The inner tube is sleeved in the second flow channel of the long plunger rod. An axial fifth flow channel is provided in the inner tube. The upper end of the fifth flow channel is connected to the first flow channel. A channel D is formed between the inner tube and the long plunger rod. The power pump barrel forms a pump chamber G above the power plunger, and the pump chamber G is connected to the channel A. The power plunger is provided with an upstream movable discharge valve at the first flow channel, and the upstream movable discharge valve is a one-way conduction valve from the first flow channel to the pump chamber G. The power pump barrel forms a pump chamber C below the power plunger and above the short pump barrel. A drainage hole b is provided at the lower portion of the power pump barrel, and channel B2 is connected to the pump chamber C through the drainage hole b. A drainage hole a is provided at the upper portion of the long plunger rod, and pump chamber C is connected to channel D through the drainage hole a. The drainage pump barrel forms a pump chamber E above the drainage piston and below the short pump barrel. A drainage hole d is provided on the upper portion of the drainage pump barrel, and channel B3 communicates with the pump chamber E through the drainage hole d. A drainage hole e is provided on the side of the dual-channel joint, and the lower end of the inner tube is connected to the drainage hole e, so that the lower end of the fifth flow channel communicates with the pump chamber E through the drainage hole e. The drainage pump barrel forms a pump chamber F below the drainage piston. The drainage plunger is provided with a downstream movable discharge valve at the fourth flow channel. The downstream movable discharge valve is unidirectional from the pump chamber F to the fourth flow channel. A lower fixed valve and an upper fixed valve are provided at the lower part of the drainage pump barrel. The lower fixed valve connects the pump chamber F and the wellbore, and the lower fixed valve is a one-way conduction from the wellbore to the pump chamber F; the upper fixed valve connects the wellbore and the channel B3, and the upper fixed valve is a one-way conduction from the wellbore to the channel B3. There is an axial pressure relief groove at the lower part of the long plunger rod, and the length of the pressure relief groove is greater than the length of the short pump barrel. When the plunger assembly moves up to the top dead center, the pressure relief groove on the long plunger rod communicates with the upper and lower pump chambers C and E of the short pump barrel to form pressure relief.

2. A downhole hydraulic double-acting pump according to claim 1, characterized in that: The power plunger is installed in the power pump barrel with a certain gap to form a gap seal and slides within the stroke of the pump.

3. A downhole hydraulic double-acting pump according to claim 1, characterized in that: The drainage plunger is installed in the drainage pump barrel, with a certain gap forming a gap seal, and slides within the stroke of the pump.

4. A downhole hydraulic double-acting pump according to claim 1, characterized in that: The upper joint is threadedly connected to the upper end of the power pump barrel and sealed; the lower end of the power pump barrel is threadedly connected to the middle joint, the lower end of the upper outer tube is threadedly connected to the middle joint and sealed, and the short pump barrel is threadedly connected to the middle joint and sealed; The upper end of the drainage pump barrel is threadedly connected to the middle joint, and the upper end of the upper outer pipe is threadedly connected to the middle joint and sealed.

5. A downhole hydraulic double-acting pump according to claim 1, characterized in that: The power plunger is threadedly connected to the upper end of the long plunger rod, the lower end of the long plunger rod is threadedly connected to the double-channel joint and sealed, and the double-channel joint is threadedly connected to the drainage plunger and sealed.

6. A downhole hydraulic double-acting pump according to claim 1, characterized in that: The upper joint is connected to the central pipe by internal insertion or external insertion.

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