Self-balancing differential pressure sand pumping tool and sand pumping method

Abstract

The invention discloses a self-balancing differential pressure sand pumping tool and a sand pumping method. The self-balancing differential pressure sand pumping tool comprises a piston sand pump and a sand setting pipe, and the bottom of a pump cylinder of the piston sand pump extends into the bottom of a shaft and is communicated with the shaft; a piston pull rod of the piston sand pump is of a hollow pipeline structure, one end of the piston pull rod is arranged in a pump cylinder and communicated with an inner cavity of the pump cylinder, and the other end of the piston pull rod is communicated with the sand setting pipe. And a constant pressure valve is arranged below the pump cylinder and is used for balancing the pressure in the pump cylinder and the shaft. A large pressure difference is formed at the bottom of the tool through the constant pressure valve, when the constant pressure valve is opened, sand-carrying fluid rapidly enters the pump cylinder, and therefore balance of pressure inside and outside the pump cylinder is completed, and meanwhile the sand-carrying fluid in a shaft is pumped into the sand setting pipe through reciprocating motion of a piston in the piston sand pump. And after sand-liquid separation is completed, liquid is discharged, and sand is reserved in the sand setting pipe, so that the problem that a standing valve cannot be normally opened is effectively solved, and setting sand in a reservoir can be effectively discharged.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas wellbore cleaning, and particularly relates to a self-balancing differential pressure sand pumping tool and a sand pumping method. Background Art

[0002] During the long-term exploitation of oil and gas wells, formation voidage occurs, formation pressure decreases, and formation sand inevitably enters the wellbore along with the oil and gas flow. A part of the fine silt is carried out of the ground with the oil and gas flow, while most of the sand grains are deposited in the wellbore, burying the producing layer and blocking the oil and gas flow channels, resulting in no channels for the oil and gas produced by the formation to migrate to the surface and reducing the oil and gas recovery rate. The sand grains in the wellbore mainly include cement cuttings from well cementing, cement cuttings from plug drilling, proppant sand, formation sand, etc. At this time, wellbore sand cleaning operations need to be carried out to re-establish the oil and gas migration channels. For wellbore sand cleaning operations of oil and gas wells, methods such as lowering a pipe string to circulate liquid flushing and installing a sand pump on the pipe string are mainly used. For low-pressure oil and gas wells (formation pressure coefficient less than 0.8), since the injected liquid cannot establish a full wellbore circulation, the sand at the bottom of the well cannot be carried out of the wellhead, and even stuck pipe accidents may occur during severe circulating flushing operations; while traditional sand pumps rely on the stroke of the pump to suck liquid, with a small suction differential pressure, difficult suction, and low sand pumping efficiency. For example, in "A Sand Pump" (Patent No. 201520494534.4), the inlet hole of the traveling valve assembly of an ordinary sand pump has a large resistance to liquid inflow, which is not conducive to sand removal and liquid drainage. The piston and pump barrel of the sucker rod pump are used in cooperation, which is extremely prone to sand jamming. At the same time, the inlet resistance of the inlet valve is very large. The sand settling tail pipe and the sand inlet channel are integrated, and the deposited sand grains bury the fixed valve. When the suction differential pressure is equal to the sand column pressure, the fixed valve cannot be opened. Summary of the Invention

[0003] The purpose of the present invention is to provide a self-balancing differential pressure sand pumping tool and a sand pumping method, which can achieve self-balancing of the differential pressure by using a constant pressure valve, and at the same time can effectively pump the sand-carrying liquid into the sand settling pipe by using a piston sand pump, effectively solve the problem that the fixed valve cannot be opened normally, and thus effectively discharge the deposited sand in the reservoir.

[0004] The present invention is achieved by the following technical solutions:

[0005] A self-balancing differential pressure sand pumping tool, comprising a piston sand pump and a sand settling pipe. The bottom of the pump barrel of the piston sand pump extends into the bottom of the wellbore and communicates with the wellbore. The piston rod of the piston sand pump is a hollow pipe structure. One end of the piston rod is arranged inside the pump barrel and communicates with the inner cavity of the pump barrel. The other end of the piston rod communicates with the sand settling pipe. A constant pressure valve is arranged below the pump barrel, and the constant pressure valve is used to balance the pressure between the pump barrel and the wellbore. To solve the above technical problems and achieve the corresponding technical effects, in the present invention, a large pressure difference is formed at the bottom of the tool through the constant pressure valve. When the constant pressure valve is opened, the sand-carrying liquid quickly enters the pump barrel, thereby completing the pressure balance inside and outside the pump barrel. At the same time, the reciprocating movement of the piston inside the piston sand pump is used to pump the sand-carrying liquid in the wellbore into the sand settling pipe. After the sand-liquid separation is completed, the liquid is discharged, and the sand remains in the sand settling pipe, thereby effectively solving the problem that the fixed valve cannot be opened normally and being able to effectively discharge the sand deposited in the reservoir.

[0006] Further technical solution:

[0007] A lower fixed valve is arranged inside the pump barrel of the piston sand pump, and an upper floating valve is arranged inside the piston rod of the piston sand pump;

[0008] When the piston rod is pulled up, the lower fixed valve opens, the upper floating valve closes, and the inner cavity of the pump barrel communicates with the wellbore;

[0009] When the piston rod is pressed down, the lower fixed valve closes, the upper floating valve opens, and the inner cavity of the pump barrel communicates with the sand settling pipe.

[0010] Further: The rated pressure of the constant pressure valve is 30 - 50 KN. When the pressure on the wellbore side of the constant pressure valve reaches the rated pressure, the constant pressure valve opens, and the inner cavity of the pump barrel communicates with the wellbore.

[0011] Further: A sand drill is arranged below the constant pressure valve, and the sand drill is used to loosen the sand surface in the wellbore.

[0012] Further: A connection joint is arranged at the top of the piston rod. The sand settling pipe is inserted into the connection joint, and the connection joint is provided with through holes. The hollow cavity of the piston rod communicates with the sand settling pipe.

[0013] Further: Liquid outlet holes are formed on the pipe wall of the sand settling pipe, and a filtering device is arranged at the liquid outlet holes;

[0014] Further: The setting position of the liquid outlet holes is above the liquid level in the wellbore.

[0015] A sand pumping method using the above sand pumping tool, and the specific sand pumping steps are as follows:

[0016] Step S1: Configuration of the tool;

[0017] Step S2: Hoist the first section of the tool into the well and balance the pressure.

[0018] Step S3: Hoist the second section of the tool into the well and loosen the sand surface.

[0019] Step S4: The piston sand pump starts to pump sand.

[0020] Step S5: Separate the sand from the liquid.

[0021] Furthermore, when configuring the tool in step S1, first fully open the lower fixed valve, the upper floating valve, and the constant pressure valve, and check the connection of the inner cavity of the piston sand pump, the sand settling pipe, and the wellbore. If the connection is not normal, maintenance is required. If the connection is normal, close the lower fixed valve, the upper floating valve, and the constant pressure valve, configure the rated pressure value of the constant pressure valve, and set this state as the initial state.

[0022] Furthermore, in step S2, after the configuration of the tool is completed, use the hoisting equipment to hoist the tool into the well. When the side pressure of the constant pressure valve in the wellbore reaches the rated pressure value as the sand pumping tool descends, the constant pressure valve opens, and the sand-carrying liquid in the wellbore enters the pump barrel under the action of the pressure difference until the pressure difference inside and outside the pump barrel is balanced, and then step S3 is executed. In step S3, hoist the liquid inlet at the bottom of the tool to the bottom of the wellbore, and loosen the sand surface with a sand drill before starting to pump sand.

[0023] Furthermore, in step S4, first, when the piston rod is pulled up, the lower fixed valve opens, the upper floating valve closes, the inner cavity of the pump barrel communicates with the wellbore, and the sand-carrying liquid in the wellbore enters the inner cavity of the pump barrel; then, when the piston rod is pressed down, the lower fixed valve closes, the upper floating valve opens, the inner cavity of the pump barrel communicates with the sand settling pipe, and the sand-carrying liquid in the pump barrel enters the sand settling pipe.

[0024] In step S5, after the sand-carrying liquid enters the sand settling pipe, a filtering device is used at the liquid outlet to separate the sand from the liquid. The sand accumulates in the sand settling pipe, and the liquid flows back into the wellbore from the liquid outlet.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] 1. The self-balancing differential pressure sand pumping tool and sand pumping method of the present invention form a large pressure difference at the bottom of the tool through the constant pressure valve. When the constant pressure valve opens, the sand-carrying liquid quickly enters the pump barrel, thereby completing the pressure balance inside and outside the pump barrel. At the same time, the reciprocating movement of the piston in the piston sand pump is used to pump the sand-carrying liquid in the wellbore into the sand settling pipe. After the sand and liquid are separated, the liquid is discharged, and the sand remains in the sand settling pipe, thereby effectively solving the problem that the fixed valve cannot be opened normally and effectively discharging the sand deposited in the reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings. In the drawings:

[0028] Figure 1 is a schematic structural diagram of the present invention;

[0029] Figure 2 is a schematic structural diagram when configured in a wellbore;

[0030] Figure 3 is a schematic structural diagram of a sand settling pipe;

[0031] Figure 4 is a flow chart of the method in Embodiment 2.

[0032] Reference numerals in the drawings and corresponding component names:

[0033] 1 - piston sand pump, 2 - sand settling pipe, 3 - wellbore, 4 - lower fixed valve, 5 - upper floating valve, 6 - constant pressure valve, 7 - sand drill, 8 - connecting joint, 9 - filtering device, 11 - pump barrel, 12 - piston pull rod, 21 - liquid outlet hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and do not limit the present invention.

[0035] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that: these specific details do not have to be employed to practice the present invention. In other embodiments, well-known structures, circuits, materials or methods are not specifically described in order to avoid obscuring the present invention.

[0036] Throughout the specification, references to "an embodiment", "embodiments", "an example", or "examples" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the phrases "an embodiment", "embodiments", "an example", or "examples" that appear throughout the specification do not necessarily all refer to the same embodiment or example. Additionally, the particular features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art should understand that the diagrams provided herein are for illustrative purposes only and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] In the description of the present invention, the orientation or positional relationship indicated by terms such as "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention.

[0038] Embodiment

[0039] As Figures 1 to 3 shown, a self-balancing differential pressure sand pumping tool of the present invention includes a piston sand pump 1 and a sand settling pipe 2. The bottom of the pump barrel 11 of the piston sand pump 1 extends into the bottom of the wellbore 3 and communicates with the wellbore 3. The piston pull rod 12 of the piston sand pump 1 is a hollow pipe structure. One end of the piston pull rod 12 is arranged in the pump barrel 11 and communicates with the inner cavity of the pump barrel 11, and the other end of the piston pull rod 12 communicates with the sand settling pipe 2. A constant pressure valve 6 is arranged below the pump barrel 11, and the constant pressure valve 6 is used to balance the pressure in the pump barrel 11 and the wellbore 3. In this embodiment, the setting of the constant pressure valve 6 causes a large pressure difference to be formed inside and outside the pump barrel 11 when the tool is lowered. When the pressure value on the wellbore 3 side of the constant pressure valve 6 reaches the preset pressure value, the constant pressure valve 6 opens, and the sand-carrying liquid in the wellbore 3 quickly enters the pump barrel 11, thereby realizing the automatic balance of the pressure difference. At the same time, by using the reciprocating motion of the piston in the piston sand pump 1, the pressure value in the pump barrel 11 is continuously changed, so as to continuously realize the working effect that the sand-carrying liquid enters the pump barrel 11 from the wellbore 3 and then enters the sand settling pipe 2 from the pump barrel, so that the sand can be gathered in the sand settling pipe 2, and the effect of discharging the settled sand from the reservoir can be achieved.

[0040] A lower fixed valve 4 is arranged inside the pump barrel 11 of the piston sand pump 1, and an upper floating valve 5 is arranged inside the piston pull rod 12 of the piston sand pump 1; when the piston pull rod 12 is pulled upward, the lower fixed valve 4 opens, the upper floating valve 5 closes, and the inner cavity of the pump barrel 11 communicates with the wellbore 3; when the piston pull rod 12 is pressed downward, the lower fixed valve 4 closes, the upper floating valve 5 opens, and the inner cavity of the pump barrel 11 communicates with the sand settling pipe 2. In this embodiment, the pressure value inside the pump barrel 11 is changed by the piston sand pump 1, so as to change the opening and closing states of the lower fixed valve 4 and the upper floating valve 5, and further change the connection condition of the tool, so as to realize the working effect that the sand-carrying liquid flows from the wellbore 3 to the pump barrel 11 and then from the pump barrel 11 to the sand settling pipe 2.

[0041] Specifically, a constant pressure valve 6 is arranged below the pump barrel 11, the rated pressure of the constant pressure valve 6 is 30 - 50 KN, when the pressure on the wellbore 3 side of the constant pressure valve 6 reaches the rated pressure, the constant pressure valve 6 opens, and the inner cavity of the pump barrel 11 communicates with the wellbore 3.

[0042] A sand drill 7 is arranged below the constant pressure valve 6, and the sand drill 7 is used to loosen the sand surface in the wellbore 3. During the specific construction process, if the sand surface is too hard to carry the sand normally through the liquid, it is necessary to use the sand drill 7 to loosen the sand surface to ensure that the sand can be effectively mixed into the liquid to form a sand-carrying liquid, so as to effectively use the tool to discharge the sand in the reservoir.

[0043] A connection joint 8 is arranged at the top end of the piston pull rod 12, the sand settling pipe 2 is inserted into the connection joint 8, and the connection joint 8 is provided with a through hole, and the hollow cavity of the piston pull rod 12 communicates with the sand settling pipe 2.

[0044] Liquid outlet holes 21 are formed in the pipe wall of the sand settling pipe 2, and a filtering device 9 is arranged at the liquid outlet holes 21; the setting position of the liquid outlet holes 21 is above the liquid level in the wellbore 3. In this embodiment, when the sand-carrying liquid flows to the liquid outlet holes 21, the filtering device 9 can effectively separate the sand and the liquid, and the liquid can enter the wellbore 3 again through the liquid outlet holes 21, while the filtered sand will accumulate in the sand settling pipe 2, and when the construction is completed, the sand settling pipe 2 can be removed and the sand inside can be cleaned to be reused.

[0045] Embodiment 2

[0046] As Figure 4 shown, on the basis of Embodiment 1, this embodiment provides a sand pumping method using the sand pumping tool described in Embodiment 1, and the specific sand pumping steps are as follows:

[0047] Step S1: Configuration of the tool;

[0048] Step S2: Hoist the first section of the tool into the well and balance the pressure;

[0049] Step S3: Hoist the second section of the tool into the well and loosen the sand surface;

[0050] Step S4: The piston sand pump 1 starts to pump sand;

[0051] Step S5: Separate the sand from the liquid.

[0052] Specifically: When configuring the tool in step S1, first fully open the lower fixed valve 4, the upper floating valve, and the constant pressure valve 6, and check the connectivity of the inner cavity of the piston sand pump 1, the sand settling pipe 2, and the wellbore 3. If they cannot be normally connected, repairs are required. If they can be normally connected, then fully close the lower fixed valve 4, the upper floating valve, and the constant pressure valve 6, and configure the rated pressure value of the constant pressure valve 6, and set this state as the initial state.

[0053] In step S2, after the tool configuration is completed, use the hoisting equipment to hoist the tool into the well. When the side pressure of the constant pressure valve 6 in the wellbore reaches the rated pressure value as the sand pumping tool descends, the constant pressure valve 6 opens, and the sand-carrying liquid in the wellbore 3 enters the pump barrel 11 under the action of the pressure difference until the pressure difference inside and outside the pump barrel 11 is balanced, and then step S3 is executed. In step S3, hoist the liquid inlet at the bottom of the tool to the bottom of the wellbore 3, and use the sand drill 7 to loosen the sand surface before starting to pump sand.

[0054] In step S4, first, when the piston rod 12 is pulled up, the lower fixed valve 4 opens, the upper floating valve 5 closes, and the inner cavity of the pump barrel 11 communicates with the wellbore 3, and the sand-carrying liquid in the wellbore 3 enters the inner cavity of the pump barrel 11; then, when the piston rod 12 is pressed down, the lower fixed valve 4 closes, the upper floating valve 5 opens, and the inner cavity of the pump barrel 11 communicates with the sand settling pipe 2, and the sand-carrying liquid in the pump barrel 11 enters the sand settling pipe 2;

[0055] In step S5, after the sand-carrying liquid enters the sand settling pipe 2, use the filtering device 9 to separate the sand from the liquid at the liquid outlet hole 21. The sand accumulates in the sand settling pipe 2, and the liquid flows back into the wellbore 3 from the liquid outlet hole 21.

[0056] The above specific embodiments have further elaborated on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, 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 self-balancing pressure differential sand pumping tool, characterized in that: It comprises a piston sand pump (1) and a sand settling pipe (2), wherein the bottom of the pump barrel (11) of the piston sand pump (1) extends into the bottom of the wellbore (3) and is connected with the wellbore (3); The piston pull rod (12) of the piston sand pump (1) is a hollow pipe structure, one end of the piston pull rod (12) is arranged in the pump barrel (11) and communicates with the inner cavity of the pump barrel (11), and the other end of the piston pull rod (12) is communicated with the sand settling tube (2); A constant pressure valve (6) is provided below the pump barrel (11), and the constant pressure valve (6) is used to balance the pressure in the pump barrel (11) and the wellbore (3).

2. A self-balancing pressure difference sand pumping tool according to claim 1, characterized in that: A lower fixed valve (4) is arranged in the pump barrel (11) of the piston sand pump (1), and an upper floating valve (5) is arranged in the piston pull rod (12) of the piston sand pump (1); When the piston pull rod (12) is pulled upward, the lower fixed valve (4) is opened, the upper floating valve (5) is closed, and the inner cavity of the pump barrel (11) is connected to the wellbore (3); When the piston pull rod (12) is pressed downward, the lower fixed valve (4) is closed, the upper floating valve (5) is opened, and the inner cavity of the pump barrel (11) is connected to the sand settling tube (2).

3. A self-balancing pressure difference sand pumping tool according to claim 1, characterized in that: The rated pressure of the constant pressure valve (6) is 30-50 kN. When the pressure on one side of the wellbore (3) of the constant pressure valve (6) reaches the rated pressure, the constant pressure valve (6) opens, and the inner cavity of the pump barrel (11) is connected to the wellbore (3).

4. A self-balancing pressure difference sand pumping tool according to claim 3, characterized in that: A sand drill (7) is arranged below the constant pressure valve (6), and the sand drill (7) is used to loosen the sand surface in the wellbore (3).

5. The self-balancing pressure difference sand pumping tool according to claim 1, characterized in that: A connecting joint (8) is provided at the top end of the piston rod (12), the sand settling tube (2) is inserted into the connecting joint (8), and the connecting joint (8) is provided with a through hole, and the hollow cavity of the piston rod (12) is connected to the sand settling tube (2).

6. The self-balancing pressure difference sand pumping tool according to claim 1, characterized in that: A liquid outlet hole (21) is provided on the wall of the sand settling tube (2), and a filtering device (9) is provided at the liquid outlet hole (21); The liquid outlet hole (21) is disposed above the liquid level in the wellbore (3).

7. A sand extraction method using the sand extraction tool according to any one of claims 1 to 5, characterized in that: The specific steps of sand extraction are as follows: Step S1: configuration of tools; Step S2: The first section of the tool is hoisted into the well and the pressure is balanced; Step S3: The second section of the tool is hoisted into the well and the sand surface is loosened; Step S4: the piston sand pump (1) starts pumping sand; Step S5: sand-liquid separation.

8. A sand pumping method according to claim 7, characterized in that: When configuring the tool in step S1, firstly, the lower fixed valve (4), the upper floating valve and the constant pressure valve (6) are all opened, and the connection between the inner cavity of the piston sand pump (1), the sand settling pipe (2) and the wellbore (3) is checked. If the connection is not normal, maintenance is required. If the connection is normal, the lower fixed valve (4), the upper floating valve and the constant pressure valve (6) are all closed, and the rated pressure value of the constant pressure valve (6) is configured, and this state is set as the initial state.

9. A sand pumping method according to claim 7, characterized in that: In step S2, after the configuration of the tool is completed, the tool is hoisted into the well using a hoisting device, and when the sand pumping tool descends to the wellbore side pressure of the constant pressure valve (6) reaches the rated pressure value, the constant pressure valve (6) opens, and the sand-carrying liquid in the wellbore (3) enters the pump barrel (11) under the action of the pressure difference, until the pressure difference between the inside and outside of the pump barrel (11) is balanced, and then step S3 is executed. In step S3, the liquid inlet at the bottom of the tool is hoisted to the bottom of the wellbore (3), and the sand surface is loosened using a sand drill (7) before starting to pump sand.

10. A sand pumping method according to claim 7, characterized in that: In the step S4, first, when the piston pull rod (12) is pulled upward, the lower fixed valve (4) is opened, the upper floating valve (5) is closed, the inner cavity of the pump barrel (11) is communicated with the wellbore (3), and the sand-carrying liquid in the wellbore (3) enters the inner cavity of the pump barrel (11); then, when the piston pull rod (12) is pressed downward, the lower fixed valve (4) is closed, the upper floating valve (5) is opened, the inner cavity of the pump barrel (11) is communicated with the sand settling tube (2), and the sand-carrying liquid in the pump barrel (11) enters the sand settling tube (2); In step S5, after the sand-carrying liquid enters the sand settling pipe (2), the sand and liquid are separated by a filtering device (9) at the liquid outlet (21), the sand is gathered in the sand settling pipe (2), and the liquid flows back into the wellbore (3) from the liquid outlet (21).

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