Fixed-liquid-volume lifting device and fixed-liquid-volume lifting method

Abstract

The application provides a fixed-liquid-volume lifting device and a fixed-liquid-volume lifting method. The fixed-liquid-volume lifting device comprises a main body, a first piston and a second piston. The main body has a hollow structure, and a first through hole and a second through hole are arranged on the side surface of the main body and penetrate the main body from the inside to the outside. The first through hole is located above the second through hole. The first piston is axially movably arranged in the main body and has a first closed position and a first open position. When the wellbore liquid column height reaches a preset height, the wellhead pressure drives the first piston to move to the first closed position. The second piston has a hollow flow channel and is axially movably arranged in the main body below the first piston. The second piston has a second closed position and a second open position. When the well bottom pressure reaches a preset well bottom pressure, the well bottom pressure drives the second piston to move to the second open position. The application solves the problem of poor drainage gas recovery in the plunger gas lifting process in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas exploitation, in particular to a fixed-liquid-volume lifting device and a fixed-liquid-volume lifting method. BACKGROUND

[0002] With the production of gas wells entering the middle and late stages, the pressure and productivity gradually decrease, the gas well cannot meet the requirement of continuous liquid carrying, and the formation water cannot be discharged from the wellbore in time, resulting in liquid loading in the wellbore and affecting the play of the gas well productivity. The plunger gas lifting process is an important means for drainage and gas production at this stage of gas well production. The technology uses a plunger as a mechanical interface between gas and liquid, and uses the energy of the gas well to push the plunger to lift the water out of the wellbore.

[0003] The conventional plunger generally controls the up-and-down operation of the plunger by opening and closing the wellhead device at regular time intervals. However, this method has many problems. First, the well is opened for production, and there is a lot of liquid in the gas well stage. A large amount of liquid enters the wellbore at one time. When a large amount of liquid loading in the horizontal section of the horizontal well enters the wellbore, a high liquid column will be generated in the wellbore at this time. At this time, the well is closed, the plunger reaches the bottom of the well, and the well is opened again. Because the position of the upper liquid column is high, it is easy to cause the plunger to fail to rise or the plunger to fail to reach the wellhead, and the plunger cannot efficiently drain and produce gas. Second, when the well is opened at regular time intervals, the amount of liquid loading in the wellbore is small, which causes the plunger to run empty and affects the implementation effect of the plunger gas well process.

[0004] As known from the above, the current plunger gas lifting process has the problems of poor drainage and gas production effect, i.e., inefficient drainage and gas production, empty running of the plunger, etc. SUMMARY

[0005] The main purpose of the present application is to provide a fixed-liquid-volume lifting device and a fixed-liquid-volume lifting method to solve the problem of poor drainage and gas production effect in the plunger gas lifting process in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a fixed-liquid-volume lifting device is provided, which comprises: a main body part, a first piston and a second piston. The main body part has a hollow structure, and the side surface of the main body part is provided with a first through hole and a second through hole which penetrate in and out. The first through hole is located above the second through hole. The first piston is axially movably arranged in the main body part and has a first closed position and a first open position. When the liquid column height of the wellbore reaches a preset height, the wellhead pressure drives the first piston to move to the first closed position. The second piston has a hollow flow channel and is axially movably arranged in the main body part below the first piston. The second piston has a second closed position and a second open position. When the bottom-hole pressure reaches a preset bottom-hole pressure, the bottom-hole pressure drives the second piston to move to the second open position.

[0007] Further, the side surface of the second piston is provided with a communication hole, when the second piston is located at the second open position, the communication hole is aligned with the second through hole, and the hollow flow channel is communicated with the gap between the constant liquid volume lifting device and the wellbore through the communication hole and the second through hole.

[0008] Further, the constant liquid volume lifting device further comprises a first reset member, the first reset member abuts against the first piston and drives the first piston to move towards the first open position.

[0009] Further, the constant liquid volume lifting device further comprises a second reset member, the second reset member abuts against the second piston and drives the second piston to move towards the second closed position.

[0010] Further, the first piston is located above the second piston, and the first piston and the second piston are spaced apart in an up-down direction.

[0011] Further, the first through hole and / or the second through hole are a plurality of and are spaced apart in a circumferential direction of the constant liquid volume lifting device.

[0012] Further, the main body part comprises an axially arranged upper segment and a lower segment, the first through hole and the second through hole are located in the upper segment, and the constant liquid volume lifting device further comprises a sealing assembly, the sealing assembly comprises a radially expandable expansion member, the expansion member is arranged between the upper segment and the lower segment, and the lower segment is pressed to expand the expansion member radially when moving relative to the upper segment to block the gap between the constant liquid volume lifting device and the wellbore.

[0013] Further, the sealing assembly further comprises a connecting segment and a first shear pin, the connecting segment is located in the main body part and passes through between the upper segment and the lower segment, the top end of the connecting segment abuts against the upper segment, the bottom end of the connecting segment has an expansion space relative to the lower segment, the first shear pin passes through between the connecting segment and the lower segment, and the first shear pin is broken when sealing, and the lower segment moves upward under the action of the bottom hole pressure and presses the expansion member to expand radially.

[0014] Further, the constant liquid volume lifting device further comprises an anchoring assembly, the anchoring assembly comprises a cone part, a retaining ring, a launching head, a fishing neck, and a plurality of slips, the cone part is connected with the top end of the main body part; the retaining ring is arranged on the top side surface of the cone part; the launching head is located at the top end of the cone part and is connected with the retaining ring through a second shear pin; the fishing neck is sleeved on the outer ear of the cone part and is located below the retaining ring; the slips are located at the tapered surface of the cone part and are connected with the bottom end of the fishing neck, and when the slips move axially relative to the cone part, the tapered surface of the cone part presses the slips and drives the slips to expand radially to abut against the inner wall of the wellbore.

[0015] According to another aspect of the present application, there is provided a constant liquid level lifting method using the constant liquid level lifting device described above, the constant liquid level lifting method comprising: the wellbore liquid column height reaching a preset height, the first piston moving to the first closed position under the action of the wellhead pressure, the first through hole being closed, the gas well being opened when the wellhead pressure reaches a preset wellhead pressure, at this time, the bottom hole pressure reaches a preset bottom hole pressure, the second piston moving to the second open position under the action of the bottom hole pressure, the second through hole being opened, the gas and liquid at the bottom hole being transported to the upper side of the constant liquid level lifting device through the hollow flow channel of the second piston, the gap between the second through hole, the wellbore and the constant liquid level lifting device, and the liquid in the wellbore being lifted and discharged, the wellbore liquid column height being lowered, and the wellhead pressure and the bottom hole pressure both being lowered; with the decrease of the wellhead pressure, the first piston moves to the first open position, the first through hole is opened, and at the same time, with the decrease of the bottom hole pressure, the second piston moves to the second closed position, the second through hole is closed, the gas and liquid at the bottom hole are transported to the upper side of the constant liquid level lifting device through the hollow flow channel of the second piston, the gap between the first through hole, the wellbore and the constant liquid level lifting device, the wellbore liquid column height gradually increases, and the wellhead pressure gradually increases; when the wellbore liquid column height reaches the preset height, the first piston moves to the first closed position under the action of the wellhead pressure, the first through hole is closed, the bottom hole is disconnected from the wellhead, the wellhead flow rate is 0, and the gas well is closed; after the well is closed, the bottom hole pressure rises, and when the bottom hole pressure reaches the preset bottom hole pressure, the second piston moves to the second open position, the second through hole is opened, the gas and liquid at the bottom hole are transported to the upper side of the constant liquid level lifting device through the hollow flow channel, the gap between the second through hole, the wellbore and the constant liquid level lifting device, and the wellhead pressure gradually increases, the first through hole remains closed, and when the wellhead pressure reaches the preset wellhead pressure, the gas well is opened, and the above process is repeated.

[0016] Further, the constant liquid level lifting method further comprises: when the wellbore liquid column height does not reach the preset height, the first piston remains in the first open position under the action of the first restoring member; and when the bottom hole pressure does not reach the preset bottom hole pressure, the second piston remains in the second closed position under the action of the second restoring member.

[0017] Further, the constant liquid level lifting method further comprises a sealing process, the sealing process comprising: after the constant liquid level lifting method is placed at a predetermined position in the wellbore, the first shear pin is sheared, the lower segment of the main body part moves upward relative to the upper segment and the connecting segment under the action of the bottom hole pressure, and in the process of upward movement of the lower segment, the lower segment extrudes the expansion member, the expansion member expands radially and contacts and seals with the inner wall of the wellbore.

[0018] Further, the constant-liquid-volume lifting method also comprises an anchoring process, the anchoring process comprising: during launching, the constant-liquid-volume lifting device is lowered into the wellbore through the launching head by connecting the external tool with the launching head, at this time, the diameter of the slip is smaller than the diameter of the wellbore; when reaching the predetermined position, the launching head is lifted, so that the slip moves downward relative to the conical part, the slip is radially expanded under the action of the conical surface of the conical part and is in contact with the inner wall of the wellbore to anchor; the second shear pin is sheared, the launching head is recovered, and the launching and anchoring of the constant-liquid-volume lifting device are completed.

[0019] By adopting the technical scheme of the present application, the movement relationship between the first piston and the second piston under different pressure conditions is adopted to realize the constant-liquid-volume lifting and discharge of the bottom hole accumulated liquid, specifically, when the liquid column height is higher than the preset height, the wellhead pressure exceeds the preset wellhead pressure, the first piston moves downward to the first closed position, the first through hole is shielded to be closed, and the gas well is opened; at this time, the bottom hole pressure also reaches the preset bottom hole pressure, the second piston moves upward to the second open position, the second through hole is in communication with the communication hole, the gas and liquid at the bottom hole are upwardly conveyed through the second through hole, the liquid column in the wellbore is lifted and discharged, the liquid column height in the wellbore is lowered, and the wellhead pressure is lowered; after the wellhead pressure is lowered, the first piston moves to the first open position, the first through hole is avoided to be opened, and at the same time, the bottom hole pressure is lowered, the second piston moves to the second closed position, the second through hole is shielded to be closed, the gas and liquid at the bottom hole are upwardly conveyed through the first through hole, the liquid column height in the wellbore is gradually increased, and the wellhead pressure is gradually increased; when the liquid column height in the wellbore reaches the preset height, the wellhead pressure reaches the corresponding preset wellhead pressure, the first piston moves to the first closed position under the action of the wellhead pressure, the first through hole is shielded to be closed, the wellhead is no longer in communication with the bottom hole, the wellhead flow rate is 0, and the gas well is closed; after the well is closed, the bottom hole pressure is increased, when the bottom hole pressure reaches the preset bottom hole pressure, the second piston moves to the second open position, the second through hole is in communication with the communication hole to be opened, the gas and liquid at the bottom hole are upwardly conveyed through the second through hole, the first through hole remains closed, the gas well is opened, and the above process is repeated. Such a setting makes the liquid lifted by the plunger controlled by the constant-liquid-volume lifting device be a fixed amount, avoids the plunger from running empty or failing to reach the wellhead, and improves the efficiency of the plunger operation. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their descriptions are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0021] Figure 1 A structural schematic diagram of the constant-liquid-volume lifting device of the present application is shown;

[0022] Figure 2 A structural schematic diagram of the constant-liquid-volume lifting device in the present application is shown Figure 1 when anchoring;

[0023] Figure 3 a schematic view of the structure of the fixed-liquid-volume lifting device in the well in the sealing state is shown in FIG. 2; Figure 1

[0024] Figure 4 a schematic view of the structure of the fixed-liquid-volume lifting device in the well in the opening state is shown in FIG. 3; Figure 1

[0025] Figure 5 a schematic view of the structure of the fixed-liquid-volume lifting device in the well in the liquid discharge completion state is shown in FIG. 4; Figure 1

[0026] Figure 6 a schematic view of the structure of the fixed-liquid-volume lifting device in the well in the gas well continuous flow production state is shown in FIG. 5; Figure 1

[0027] Figure 7 a schematic view of the structure of the fixed-liquid-volume lifting device in the well in the closing state is shown in FIG. 6. Figure 1

[0028] wherein the above drawings include the following reference signs:

[0029] 11, first through hole; 12, second through hole; 13, upper section; 14, lower section; 141, outer cylinder; 142, outer sleeve; 20, first piston; 30, second piston; 31, communication hole; 40, first reset member; 50, second reset member; 60, sealing assembly; 61, expansion member; 62, connecting section; 63, first shear pin; 64, expansion space; 70, anchoring assembly; 71, cone portion; 72, blocking ring; 73, launching head; 74, fishing neck; 75, slip; 76, second shear pin; 80, plug. DETAILED DESCRIPTION

[0030] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0031] It should be noted that, unless otherwise specified, all the technical and scientific terms used in the present application have the same meaning as that generally understood by the ordinary skilled in the art to which the present application belongs.

[0032] In the present application, unless otherwise specified, the orientation words such as "upper", "lower", "top", "bottom" are generally directed to the directions shown in the drawings, or are directed to the vertical, perpendicular or gravity directions of the components themselves; similarly, for the convenience of understanding and description, "inner" and "outer" refer to the inner and outer relative to the contour of the components themselves, but the above orientation words are not used to limit the present application.

[0033] ​​​​​To address the problem of poor drainage and gas extraction efficiency in existing plunger gas lift processes, this invention provides a constant liquid volume lift device and a constant liquid volume lift method.

[0034] like Figures 1 to 7 A constant volume lifting device is shown, comprising: a main body, a first piston 20, and a second piston 30. The main body has a hollow structure, and a first through hole 11 and a second through hole 12 are provided on the side of the main body, with the first through hole 11 located above the second through hole 12. The first piston 20 is axially movable and is inserted into the main body, having a first closed position that blocks the first through hole 11 and a first open position that avoids the first through hole 11. When the wellbore liquid column height reaches a preset height, the wellhead pressure drives the first piston 20 to move to the first closed position. The second piston 30 has a hollow flow channel and is axially movable and is inserted into the main body, located below the first piston 20. The second piston 30 has a second closed position that blocks the second through hole 12 and a second open position that avoids the second through hole 12. When the bottom hole pressure reaches a preset bottom hole pressure, the bottom hole pressure drives the second piston 30 to move to the second open position.

[0035] In the embodiment, the quantitative lifting and discharging of the well bottom accumulated liquid is realized by adopting the movement relationship of the first piston 20 and the second piston 30 under different pressure conditions. Specifically, when the wellhead pressure exceeds the wellhead preset pressure, the first piston 20 moves downward to the first closed position, blocks the first through hole 11 to make it closed, and the gas well is opened; when the well bottom pressure reaches the well bottom preset pressure, the second piston 30 moves upward to the second open position, the second through hole 12 is opened, the gas and liquid at the well bottom are upwardly transported through the second through hole 12, the liquid column in the wellbore is lifted and discharged, the wellbore liquid column height is lowered, and the wellhead pressure is lowered; after the wellhead pressure is lowered, the first piston 20 moves to the first open position to avoid the first through hole 11 to make it open, at the same time, the well bottom pressure is lowered, the second piston 30 moves to the second closed position, the second through hole 12 is blocked and closed, at this time, it is in the continuous flow section, the gas and liquid at the well bottom are upwardly transported through the first through hole 11, the wellbore liquid column height is gradually increased, and the wellhead pressure is gradually increased; when the wellbore liquid column height reaches the preset height, the wellhead pressure reaches the corresponding wellhead preset pressure, the first piston 20 moves to the first closed position under the action of the wellhead pressure, the first through hole 11 is blocked and closed, the wellhead flow is 0, and the gas well is shut down; after the well is shut down, the well bottom pressure rises, when the well bottom pressure reaches the well bottom preset pressure, the second piston 30 moves to the second open position, the second through hole 12 is opened, the gas and liquid at the well bottom are upwardly transported through the second through hole 12, the first through hole 11 remains closed, the gas well is opened, and the above process is repeated. Such a setting makes the liquid lifted by the plunger controlled by the liquid-quantity-lifting device a fixed amount, which not only avoids the situation that the plunger cannot rise or cannot reach the wellhead due to the high position of the upper liquid column, thereby affecting the efficient drainage and gas production, but also avoids the situation that the plunger runs empty due to the small amount of accumulated liquid in the wellbore, thereby affecting the implementation effect of the plunger gas well technology, and improves the efficiency of the plunger operation.

[0036] In the embodiment, the main body part is a cylinder with a hollow structure inside, and the central axis of the main body part is consistent with the central axis direction of the wellbore during the liquid-quantity-lifting process using the liquid-quantity-lifting device. Since the wellbore referred to here is a vertically arranged section, the main body part is used in a vertical manner, that is, the liquid-quantity-lifting device is vertically downwardly hung into the wellbore for use. The first piston 20 and the second piston 30 are arranged in the cavity of the main body part and can move upwardly and downwardly in the longitudinal direction parallel to the central axis of the main body part. And since the first through hole 11 is located above the second through hole 12, the first piston 20 is arranged above the second piston 30 in the embodiment, which makes the cooperation more convenient.

[0037] The first piston 20 and the second piston 30 of the embodiment have one end bearing the gas-liquid pressure and the other end shielding and avoiding the through hole. The top end of the first piston 20 is the one bearing the gas-liquid pressure, which is affected by the pressure of the wellbore liquid column to realize the up and down movement of the first piston 20, and the bottom end of the first piston 20 is the one shielding and avoiding the first through hole 11. In contrast to the first piston 20, the bottom end of the second piston 30 is the one bearing the gas-liquid pressure, which is affected by the bottom hole pressure to realize the up and down movement of the second piston 30, and the top end of the second piston 30 is the one shielding and avoiding the second through hole 12. In this way, when the first piston 20 moves upward as a whole, the first through hole 11 is avoided, i.e. the first piston 20 is in the first open position, and when the first piston 20 moves downward as a whole, the first through hole 11 is shielded, i.e. the first piston 20 is in the first closed position. Similarly, when the second piston 30 moves downward as a whole, the second through hole 12 is avoided, i.e. the second piston 30 is in the second open position, and when the second piston 30 moves upward as a whole, the second through hole 12 is shielded, i.e. the second piston 30 is in the second closed position. Of course, the specific movement mode and the positional relationship between the corresponding through hole of the first piston 20 and the second piston 30 may also change accordingly based on the different specific arrangement modes of the first piston 20 and the second piston 30.

[0038] Considering that the up and down movements of the first piston 20 and the second piston 30 are relatively independent, the first piston 20 and the second piston 30 are arranged in an up and down spaced manner in the embodiment, and the spacing between the two can ensure that one of them will not abut against the other when moving, and ensure that the movement of one will not affect the other.

[0039] Since the first piston 20 moves downward to shield the first through hole 11, the side surface of the bottom end of the first piston 20 can directly cooperate with the first through hole 11 to achieve the shielding and avoiding effect of the through hole. However, the second piston 30 cooperates with the second through hole 12 at the top end, and avoids the second through hole 12 when the second piston 30 moves upward. Therefore, the embodiment is provided with a communication hole 31 on the side surface of the second piston 30. When the second piston 30 moves upward to the second open position, the communication hole 31 is radially aligned with the second through hole 12, and at this time the hollow flow channel is communicated with the gap between the constant liquid volume lifting device and the wellbore through the communication hole 31 and the second through hole 12. When the second piston 30 moves downward to the second closed position, the communication hole 31 moves downward and is staggered with the second through hole 12, and the second through hole 12 is shielded by the side surface of the top end of the second piston 30 to be closed.

[0040] The O-shaped sealing ring is used to seal between the first piston 20 and the main body part in the embodiment, and the O-shaped sealing ring can also be used between the second piston 30 and the main body part, and multiple O-shaped sealing rings can be provided to ensure the sealing effect and prevent the gas pressure from flowing up from the gap between the piston and the main body part.

[0041] In the embodiment, the constant-liquid-volume lifting device further comprises a first reset member 40, which can be a spring or the like. The first reset member 40 abuts against the first piston 20 and always provides a force for the first piston 20 to move to the first open position. When the end surface of the first piston 20 that bears the gas-liquid pressure is not subjected to sufficient pressure, i.e., the wellbore liquid column does not reach the preset height, the first piston 20 is driven to move to the first open position, and the first piston 20 is kept in the first open position under the action of the first reset member 40. The first through hole 11 is not blocked by the first piston 20 and remains open. Only when the wellbore liquid column reaches the preset height, the first piston 20 is closed under the pressure of the wellbore liquid column. In this way, the first reset member 40 and the wellbore liquid column pressure jointly act to realize the up-and-down movement of the first piston 20 according to the wellbore liquid column.

[0042] In the embodiment, the constant-liquid-volume lifting device further comprises a second reset member 50, which can be a spring or the like. The second reset member 50 abuts against the second piston 30 and always provides a force for the second piston 30 to move to the second closed position. When the end surface of the second piston 30 that bears the gas-liquid pressure is not subjected to sufficient pressure, i.e., the bottom-hole pressure does not reach the bottom-hole preset pressure, the second piston 30 is driven to move to the second closed position, and the second piston 30 is kept in the second closed position under the action of the second reset member 50. The second through hole 12 is blocked by the second piston 30, and the hollow flow passage of the second piston 30 is in a disconnected state with the second through hole 12. In this way, the second reset member 50 and the bottom-hole pressure jointly act to realize the up-and-down movement of the second piston 30 according to the wellbore liquid column. Of course, the second reset member 50 can not be provided, and in this case, the automatic downward movement of the second piston 30 can be realized by using the gravity of the second piston 30 itself.

[0043] In actual use, the spring force of the first reset member 40 and the second reset member 50 can be adjusted according to the required wellbore liquid column preset height, wellhead preset pressure, bottom-hole preset pressure and other parameters, so that the spring force matches the parameters, thereby achieving the required parameter effect.

[0044] In the embodiment, the first through hole 11 and / or the second through hole 12 are multiple. In the embodiment, the first through hole 11 and the second through hole 12 are both extended along the radial direction of the constant-liquid-volume lifting device and both provided with multiple, so as to meet the gas production demand. The first through hole 11 and the second through hole 12 are spaced apart along the circumferential direction of the constant-liquid-volume lifting device to ensure the uniformity of the gas and avoid the accumulation of the gas at some place outside the wellbore.

[0045] As Figure 1 and Figure 3As shown, in the present embodiment, the main body part comprises an upper section 13 and a lower section 14 arranged axially in sequence from top to bottom, and both the upper section 13 and the lower section 14 of the main body part have hollow cavities in which other fittings can be arranged, wherein the first through hole 11 and the second through hole 12 are both located on the side of the upper section 13, the first piston 20 and the first return member 40 are located in the upper section 13, the second piston 30 and the second return member 50 are located in the lower section 14, and the top end of the second piston 30 extends upward into the upper section 13 so as to cooperate with the second through hole 12. The upper section 13 and the lower section 14 of the present embodiment are not fixedly arranged, but can be arranged to move up and down relative to each other, more specifically, the lower section 14 can move upward so as to approach the upper section 13. Meanwhile, the constant fluid volume lifting device further comprises a sealing assembly 60, which comprises a radially expandable expansion member 61, which can be formed by a rubber member such as a rubber sleeve, and has a circular ring shape with a middle part through which the second piston 30 and other components pass, and the expansion member 61 is arranged between the upper section 13 and the lower section 14. In this way, when sealing is required, the lower section 14 moves upward under the action of the bottom hole pressure, and since the upper section 13 is anchored and does not move, the lower section 14 will squeeze the expansion member 61 to cause the expansion member 61 to deform, and the expansion member 61 will expand radially to contact the inner wall of the wellbore, thereby achieving the effect of sealing the gap between the constant fluid volume lifting device and the wellbore.

[0046] In the embodiment, the sealing assembly 60 further comprises a connecting segment 62 and a first shear pin 63, the connecting segment 62 is located in the main body and is arranged between the upper segment 13 and the lower segment 14, the connecting segment 62 and the first shear pin 63 serve to control the movement of the lower segment 14. Specifically, the top end of the connecting segment 62 abuts against the upper segment 13, and the bottom end of the connecting segment 62 has an expandable and compressible expansion space 64 with the lower segment 14, and the first shear pin 63 is arranged radially between the connecting segment 62 and the lower segment 14 and fixes the two, so that when the constant-liquid-level lifting device is lowered, the relative position between the connecting segment 62 and the upper segment 13 and the lower segment 14 is fixed, and thus the upper segment 13 and the lower segment 14 cannot move relative to each other, so that the expansion member 61 remains contracted and does not contact the inner wall of the wellbore, thereby ensuring smooth lowering. When the sealing assembly 60 needs to seal the space between the wellbore and the constant-liquid-level lifting device, the first shear pin 63 breaks, and at this time, the fixed relationship between the lower segment 14 and the connecting segment 62 is released, and the lower segment 14 can move upward under the action of the bottom hole pressure. Due to the existence of the expansion space 64 between the connecting segment 62 and the lower segment 14, the lower segment 14 has space to rise, and the gas in the expansion space 64 can be transmitted to the inside of the expansion member 61, so that the lower segment 14 presses the expansion member 61 to expand radially, and the expansion member 61 further contacts the inner wall of the wellbore to achieve sealing. In the embodiment, the first shear pin 63 is a dissolvable pin, which dissolves after the constant-liquid-level lifting device is placed in the wellbore, the fixed relationship between the connecting segment 62 and the lower segment 14 is released, and the lower segment 14 can rise and the expansion member 61 can expand, thereby completing the corresponding sealing process.

[0047] The lower segment 14 of the embodiment comprises an outer cylinder 141 and an outer sleeve 142, wherein the outer cylinder 141 is located directly below the expansion member 61 and is flush with the outer surface of the upper segment 13, the top end of the outer sleeve 142 is located inside the outer cylinder 141 and forms a space with the inner wall of the outer cylinder 141, the bottom end of the connecting segment 62 is located in the space, and the expansion space 64 is also located in the space, the bottom end of the outer sleeve 142 is located directly below the outer cylinder 141 and is flush with the outer surface of the outer cylinder 141, the top end and the bottom end of the outer sleeve 142 form a stepped structure, the bottom end of the outer cylinder 141 abuts against the stepped structure, and sealing members such as sealing rings are arranged between the connecting segment 62 and the outer cylinder 141 and between the outer cylinder 141 and the outer sleeve 142 to seal the gaps. Meanwhile, there is a space between the bottom end of the outer sleeve 142 and the second piston 30 arranged therein, and the second return member 50 is located in the space, thereby applying a downward return force to the second piston 30.

[0048] In the embodiment, the constant-liquid-volume lifting device further comprises a plug 80 located at the bottom end of the lower section 14 and connected to the lower section 14 by threads or other structures. The plug 80 is annular and has an inner diameter smaller than the outer diameter of the second piston 30, so as to block the second piston 30 in the lower section 14 and prevent the second piston 30 from being pulled out of the lower section 14.

[0049] As shown in Figure 1 and Figure 2 In the embodiment, the constant-liquid-volume lifting device further comprises an anchoring assembly 70, which comprises a cone part 71, a retaining ring 72, a delivery head 73, a fishing neck 74, and a plurality of slips 75. The cone part 71 is connected to the top end of the main body part by threads or other connection methods. The cone part 71 is divided into two parts and has a shape of a combination of a circular truncated cone and a circular cylinder. The circular cylinder is located at the top surface of the circular truncated cone with a smaller area, and the bottom surface of the circular truncated cone with a larger area is connected to the top end of the upper section 13 of the main body part. In other words, the circular truncated cone has a structure of being smaller at the top and larger at the bottom. The retaining ring 72 is arranged at the top side of the cone part 71 and connected to the cone part 71 by threads or other connection methods. The retaining ring 72 protrudes from the outer side of the circular cylinder of the cone part 71, so as to limit the movement of the cone part 71. The delivery head 73 is located at the top end of the cone part 71 and connected to the retaining ring 72 and the cone part 71 by a second shear pin 76. The delivery head 73 is mainly used for cooperating with external equipment connected to the constant-liquid-volume lifting device, so as to facilitate the lifting of the constant-liquid-volume lifting device by the external equipment. When the constant-liquid-volume lifting device is lowered to a predetermined position, the second shear pin 76 is separated from the retaining ring 72 and the cone part 71, and the delivery head 73 is removed, while the other parts of the constant-liquid-volume lifting device are left in the wellbore. The fishing neck 74 is sleeved on the outer ear of the cone part 71 and located below the retaining ring 72. The fishing neck 74 is mainly used for fishing the constant-liquid-volume lifting device and taking the constant-liquid-volume lifting device out of the wellbore. Since the retaining ring 72 is located above the fishing neck 74, the fishing neck 74 is stopped by the retaining ring 72 when moving upward, so as to prevent the fishing neck 74 and the slips 75 from moving upward and separating from the cone part 71. The slips 75 are located at the tapered surface of the cone part 71 and connected to the bottom end of the fishing neck 74. The slips 75 are movably arranged axially opposite to the cone part 71. When the slips 75 are located at the outer side of the circular cylinder, the slips 75 are not in a squeezing relationship with the tapered surface of the cone part 71, and the slips 75 are radially contracted, so as to reduce the diameter to be smaller than the inner diameter of the wellbore, thereby facilitating the lowering of the constant-liquid-volume lifting device. When the constant-liquid-volume lifting device is lowered to the predetermined position and needs to be anchored, the slips 75 move from the circular cylinder to the circular truncated cone. At this time, the slips 75 are squeezed by the tapered surface, and the slips 75 are radially expanded under the squeezing of the tapered surface, so as to abut against the inner wall of the wellbore. The slips 75 are engaged with the inner wall of the wellbore through the tooth-shaped structure on the outer side, so as to realize the anchoring of the constant-liquid-volume lifting device.

[0050] In the present embodiment, when producing and fixed-liquid-lifting, the fixed-liquid-lifting device needs to be anchored and sealed first. The specific process is as follows: first, the device is lowered into the wellbore by connecting the launching head 73 with the wireline tool. During the launching process, under the action of gravity, the slips 75 are in a radially contracted state. When the device reaches the designed setting position, the wireline tool is slowly lifted, the launching head 73 and the cone part 71 go up compared with the slips 75, the slips 75 are extruded by the taper surface of the cone part 71 and driven to expand radially to be clamped with the inner wall of the wellbore, then the second shear pin 76 is cut off, the launching head 73 is retrieved to the wellhead under the action of the wireline tool, and the anchoring of the fixed-liquid-lifting device is completed. After the anchoring of the fixed-liquid-lifting device is completed, the first shear pin 63 in the present embodiment, i.e. the soluble pin, is cut off, and the fixed state of the connecting section 62 and the lower section 14 is released. Under the action of the bottom hole pressure, the lower section 14 moves upward, the closed expansion space 64 formed by the connecting section 62 and the lower section 14 expands under the action of the high pressure in the well, the expansion space 64 transmits gas to the inside of the expansion member 61, the expansion member 61 expands radially under the action of the force, and the wellbore is sealed, as shown in the state of FIG. 8. Figures 1 to 3

[0051] In the present embodiment, sealing rings or other sealing members can be arranged at the positions where sealing is needed between the components to seal the gap between the components. The specific sealing positions can be arranged as needed, and the present embodiment will not be described in detail.

[0052] ​In the embodiment, a fixed-liquid-volume lifting method is provided, which uses the fixed-liquid-volume lifting device. The fixed-liquid-volume lifting method comprises the following steps: the wellbore liquid column height reaches a preset height, the first piston 20 moves to the first closed position under the action of the wellhead pressure, and the first through hole 11 is closed; when the wellhead pressure reaches a preset wellhead pressure, the gas well is opened, at this time, the bottom hole pressure reaches a preset bottom hole pressure, the second piston 30 moves to the second open position under the action of the bottom hole pressure, and the second through hole 12 is opened; the gas and liquid at the bottom hole are transported to the upper side of the fixed-liquid-volume lifting device through the hollow flow channel of the second piston 30, the second through hole 12, and the gap between the wellbore and the fixed-liquid-volume lifting device, and the liquid in the wellbore is lifted and discharged at the same time, so that the wellbore liquid column height and the wellhead pressure and the bottom hole pressure are all decreased; with the decrease of the wellhead pressure, the first piston 20 moves to the first open position, the first through hole 11 is opened, and at the same time, with the decrease of the bottom hole pressure, the second piston 30 moves to the second closed position, the second through hole 12 is closed, the gas and liquid at the bottom hole are transported to the upper side of the fixed-liquid-volume lifting device through the hollow flow channel of the second piston 30, the first through hole 11, and the gap between the wellbore and the fixed-liquid-volume lifting device, the wellbore liquid column height gradually increases, and the wellhead pressure gradually increases; when the wellbore liquid column height reaches the preset height, the first piston 20 moves to the first closed position under the action of the wellhead pressure, the first through hole 11 is closed, the bottom hole is disconnected from the wellhead, the wellhead flow rate is 0, and the gas well is closed; after the well is closed, the bottom hole pressure increases, when the bottom hole pressure reaches the preset bottom hole pressure, the second piston 30 moves to the second open position, the second through hole 12 is opened, the gas and liquid at the bottom hole are transported to the upper side of the fixed-liquid-volume lifting device through the hollow flow channel, the second through hole 12, and the gap between the wellbore and the fixed-liquid-volume lifting device, so that the wellhead pressure gradually increases, and the first through hole 11 remains closed; when the wellhead pressure reaches the preset wellhead pressure, the gas well is opened, and the above process is repeated.

[0053] In the embodiment, the fixed-liquid-volume lifting device and the fixed-liquid-volume lifting method are matched with each other, so that the liquid lifted by the plunger controlled by the fixed-liquid-volume lifting device is a fixed amount, the situations that the plunger runs empty or cannot reach the wellhead are avoided, and the efficiency of the plunger operation is improved.

[0054] In the embodiment, the preset wellbore liquid column height is 300 m, the preset wellhead pressure is 5 MPa, and the preset bottom hole pressure is 5 MPa. When the fixed-liquid-volume lifting device in the embodiment is used for fixed-liquid-volume lifting, the fixed-liquid-volume lifting device is also matched with a wellhead remote controller to sense parameters such as the wellhead pressure and the wellhead flow rate and to control the related operations of opening and closing the gas well.

[0055] In combination with the specific parameters, the fixed-liquid-volume lifting method in the embodiment is specifically as follows:

[0056] When the wellbore fluid column height reaches 300m, the wellhead pressure reaches 5MPa. At this time, the first piston 20 in the downhole constant fluid volume lift device moves downward against the force provided by the first reset member 40 under the action of the wellhead pressure. The first piston 20 switches from the first open position to the first closed position, and the first through hole 11 is blocked and closed by the first piston 20. The wellhead remote controller senses that the wellhead oil pressure is 5MPa, and the bottom hole pressure is 8MPa. The gas well initiates a well opening operation, such as... Figure 4 As shown. At this time, since the bottom hole pressure has also reached the preset bottom hole pressure, under the action of the bottom hole pressure, the second piston 30 moves upward against the opposite force provided by the second reset member 50. The second piston 30 is in the second open position, the connecting hole 31 is connected to the second through hole 12, the second through hole 12 is opened, and the bottom hole gas and liquid are transported upward through the hollow flow channel of the second piston 30 and the second through hole 12, while the liquid in the wellbore is lifted and discharged by the plunger.

[0057] As the 300m liquid column is completely discharged, the wellhead pressure drops to 2MPa. At this point, the wellhead and bottom hole are connected. Neglecting the pressure gradient, the bottom hole pressure is also 2MPa. Under the reset force of the first reset member 40, the first piston 20 moves upward, switching from the first closed position to the first open position. The first through hole 11 is opened by the first piston 20. Due to the decrease in bottom hole pressure, the second piston 30 moves downward under the action of the second reset member 50, blocking the second through hole 12 and closing it. The gas and liquid at the bottom hole are transported upward through the first through hole 11, as... Figure 5 As shown.

[0058] Gas wells enter the follow-through phase, such as Figure 6 As shown, as the liquid column in the wellbore gradually rises, the pressure at the wellhead and bottom gradually increases, and the first piston 20 gradually moves downward. During the process of switching from the first open position to the first closed position, the first through-hole 11 gradually closes. When the liquid column reaches 300m, the wellhead pressure reaches 5MPa, the first piston 20 completes the switching process and is in the first closed position, and the first through-hole 11 is completely closed. At this time, the wellhead flow rate is 0. When the wellhead remote controller detects that the gas well flow rate is 0, it shuts off the well. Figure 7 As shown.

[0059] During the process of gradually increasing the bottom hole pressure, the second piston 30 overcomes the second reset member 50 and moves upward, the second piston 30 is in the process of switching from the second closed position to the second open position, but the second through hole 12 and the communication hole 31 are still not communicated; due to the shut-in, the bottom hole pressure continues to rise, the second piston 30 continues to move upward, when the bottom hole pressure is once greater than 5 MPa, the second through hole 12 and the communication hole 31 are communicated, the second through hole 12 is opened, and the gas and liquid at the bottom of the well are transported upward through the hollow flow channel of the second piston 30 and the second through hole 12, with the increase of the liquid column height, the wellhead oil pressure starts to rise from 2 MPa, the pressure of the first piston 20 rises, the first through hole 11 is always in a closed state, when the wellbore liquid column height reaches 300 m, the wellhead oil pressure reaches 5 MPa, and the wellhead remote controller carries out the opening of the gas well, such as Figure 4

[0060] In the embodiment, the fixed-liquid-lifting method further comprises: when the wellhead pressure does not exceed the wellhead preset pressure, the first piston 20 is kept in the first open position under the action of the first reset member 40; and when the bottom hole pressure does not exceed the bottom hole preset pressure, the second piston 30 is kept in the second closed position under the action of the second reset member 50.

[0061] In the embodiment, the fixed-liquid-lifting method further comprises a sealing process and an anchoring process before normal use, that is, when the fixed-liquid-lifting device is lowered. The sealing process comprises: after the fixed-liquid-lifting device is lowered to a predetermined position in the wellbore, the first shear pin 63 is sheared, and the lower segment 14 of the main body part moves upward relative to the upper segment 13 and the connecting segment 62 under the action of the bottom hole pressure, in the process of upward movement of the lower segment 14, the lower segment 14 extrudes the expansion member 61, and the expansion member 61 expands radially and is in contact with the inner wall of the wellbore to seal. The anchoring process comprises: when being lowered, the fixed-liquid-lifting device is lowered into the wellbore through the lowering head 73 by connecting the external tool with the lowering head 73, at this time, the diameter of the slip 75 is smaller than the diameter of the wellbore; when reaching the predetermined position, the lowering head 73 is lifted to make the slip 75 move downward relative to the conical part 71, the slip 75 expands radially under the action of the conical surface of the conical part 71 and is in contact with the inner wall of the wellbore to anchor; the second shear pin 76 is sheared, and the lowering head 73 is recovered, and the anchoring of the fixed-liquid-lifting device is completed. The specific process of sealing and anchoring and the matching mode between components have been described in the foregoing fixed-liquid-lifting device, and will not be described here.

[0062] It should be noted that the plurality in the above embodiment means at least two.

[0063] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0064] ​1. The problem that the plunger cannot reach the wellhead or the plunger runs empty when the plunger gas lift drains water due to excessive and insufficient wellbore fluid accumulation is solved.

[0065] 2. The problem that the plunger cannot go up or reach the wellhead, resulting in inefficient drainage and gas recovery, is avoided.

[0066] 3. The problem that the plunger runs empty due to insufficient wellbore fluid accumulation, affecting the implementation effect of the plunger gas well technology, is avoided, and the efficiency of the plunger operation is improved.

[0067] Obviously, the above-described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0068] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, work, device, component and / or combination thereof.

[0069] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0070] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A fixed volume lifting device, characterized in that, The device comprises: a main body having a hollow structure, the side of the main body being provided with a first through hole (11) and a second through hole (12) penetrating in and out, the first through hole (11) being located above the second through hole (12); a first piston (20) axially movably arranged in the main body and having a first closed position shielding the first through hole (11) and a first open position avoiding the first through hole (11), when the wellbore fluid column height reaches a preset height, the wellhead pressure drives the first piston (20) to move to the first closed position; a second piston (30) having a hollow flow passage, the second piston (30) being axially movably arranged in the main body and located below the first piston (20), the second piston (30) having a second closed position shielding the second through hole (12) and a second open position avoiding the second through hole (12), when the bottom hole pressure reaches a preset bottom hole pressure, the bottom hole pressure drives the second piston (30) to move to the second open position; the main body comprises an upper segment (13) and a lower segment (14) arranged axially, the first through hole (11) and the second through hole (12) are both located in the upper segment (13), the constant fluid volume lifting device further comprises a sealing assembly (60), the sealing assembly (60) comprises a radially expandable expansion member (61), the expansion member (61) is arranged between the upper segment (13) and the lower segment (14), and the lower segment (14) is pressed to expand radially when moving relative to the upper segment (13) to block the gap between the constant fluid volume lifting device and the wellbore; the sealing assembly (60) further comprises a connecting segment (62) and a first shear pin (63), the connecting segment (62) is located in the main body and arranged between the upper segment (13) and the lower segment (14), the top end of the connecting segment (62) abuts against the upper segment (13), the bottom end of the connecting segment (62) has an expansion space (64) with the lower segment (14), the first shear pin (63) is arranged between the connecting segment (62) and the lower segment (14), and when sealed, the first shear pin (63) is broken, the lower segment (14) moves upward under the action of the bottom hole pressure and presses the expansion member (61) to expand radially; the constant fluid volume lifting device further comprises an anchoring assembly (70), the anchoring assembly (70) comprises: a cone body (71) connected with the top end of the main body; a stop ring (72) arranged on the top side of the cone body (71); a launching head (73) located at the top end of the cone body (71) and connected with the stop ring (72) through a second shear pin (76); A fishing neck (74) is sleeved outside the conical part (71) and is located below the blocking ring (72); A plurality of slips (75) are located at the conical surface of the conical part (71) and are connected with the bottom end of the fishing neck (74), when the conical part (71) and the slip (75) move axially opposite, the conical surface of the conical part (71) extrudes the slip (75) and drives the slip (75) to expand radially to abut against the inner wall of the wellbore.

2. The liquid metering lifting device of claim 1, wherein, The side surface of the second piston (30) is provided with a communication hole (31), when the second piston (30) is located at the second opening position, the communication hole (31) is aligned with the second through hole (12), the hollow flow channel is communicated with the gap between the constant liquid volume lifting device and the wellbore through the communication hole (31) and the second through hole (12).

3. The liquid metering lifting device of claim 1, wherein, The constant liquid volume lifting device further comprises a first reset member (40), the first reset member (40) abuts against the first piston (20) and drives the first piston (20) to move to the first opening position.

4. The liquid metering lifting device of claim 1, wherein, The constant liquid volume lifting device further comprises a second reset member (50), the second reset member (50) abuts against the second piston (30) and drives the second piston (30) to move to the second closing position.

5. The liquid metering lifting device of claim 1, wherein, The first piston (20) is located above the second piston (30), and the first piston (20) and the second piston (30) are spaced apart in an up-down direction.

6. The liquid metering lifting device of claim 1, wherein, The first through hole (11) and / or the second through hole (12) are a plurality of and are spaced apart in a circumferential direction of the constant liquid volume lifting device.

7. A fixed volume lifting method, characterized by, The constant liquid volume lifting method comprises: When the wellbore liquid column height reaches a preset height, the first piston (20) moves to the first closing position under the action of the wellhead pressure, the first through hole (11) is closed, when the wellhead pressure reaches a preset wellhead pressure, the gas well is opened, at this time, the bottom hole pressure reaches a preset bottom hole pressure, the second piston (30) moves to the second opening position under the action of the bottom hole pressure, the second through hole (12) is opened, the gas and liquid at the bottom hole are transported to the upper side of the constant liquid volume lifting device through the hollow flow channel of the second piston (30), the second through hole (12) and the gap between the wellbore and the constant liquid volume lifting device, while the liquid in the wellbore is lifted and discharged, the wellbore liquid column height decreases, and the wellhead pressure and the bottom hole pressure decrease. With the decrease of wellhead pressure, the first piston (20) moves to the first open position, the first through hole (11) is opened, at the same time, with the decrease of bottom hole pressure, the second piston (30) moves to the second closed position, the second through hole (12) is closed, the gas and liquid at the bottom hole are transported to the top of the constant liquid volume lifting device through the hollow flow passage of the second piston (30), the first through hole (11), the gap between the wellbore and the constant liquid volume lifting device, the height of the wellbore liquid column gradually increases, and the wellhead pressure gradually increases; When the height of the wellbore liquid column reaches the preset height, the first piston (20) moves to the first closed position under the action of the wellhead pressure, the first through hole (11) is closed, the bottom hole is disconnected from the wellhead, the wellhead flow is 0, and the gas well is shut in; After the well is shut in, the bottom hole pressure rises, and when the bottom hole pressure reaches the bottom hole preset pressure, the second piston (30) moves to the second open position, the second through hole (12) is opened, the gas and liquid at the bottom hole are transported to the top of the constant liquid volume lifting device through the hollow flow passage, the second through hole (12), the gap between the wellbore and the constant liquid volume lifting device, so that the wellhead pressure gradually increases, and the first through hole (11) remains closed, when the wellhead pressure reaches the wellhead preset pressure, the gas well is opened, and the above process is repeated.

8. The fixed fluid volume lifting method of claim 7, wherein, The constant liquid volume lifting method further comprises: When the height of the wellbore liquid column does not reach the preset height, the first piston (20) remains in the first open position under the action of the first reset member (40); When the bottom hole pressure does not reach the bottom hole preset pressure, the second piston (30) remains in the second closed position under the action of the second reset member (50).

9. The fixed fluid volume lifting method of claim 7, wherein, The constant liquid volume lifting method further comprises a sealing process, and the sealing process comprises: After the constant liquid volume lifting method is put into the predetermined position in the wellbore, the first shear pin (63) is sheared, the lower segment (14) of the main body part moves upward relative to the upper segment (13) and the connecting segment (62) under the action of the bottom hole pressure, and in the process that the lower segment (14) moves upward, the lower segment (14) extrudes the expansion member (61), and the expansion member (61) expands radially and is in contact sealing with the inner wall of the wellbore.

10. The fixed fluid volume lifting method of claim 7, wherein, The constant liquid volume lifting method further comprises an anchoring process, and the anchoring process comprises: When being put in, the constant liquid volume lifting device is lowered into the wellbore through the launching head (73) by connecting an external tool with the launching head (73), at this time, the diameter of the slip (75) is smaller than the diameter of the wellbore; When reaching the predetermined position, the launching head (73) is lifted upward, so that the slip (75) moves downward relative to the conical part (71), the slip (75) expands radially under the action of the conical surface of the conical part (71) and is in contact anchoring with the inner wall of the wellbore; The second shear pin (76) is sheared, the launching head (73) is recovered, and the constant liquid volume lifting device is put in and anchored.

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