Plunger with self-expansion and self-contraction double-sealing structure

Abstract

The plunger of the self-expansion and self-contraction double-sealing structure comprises a fishing head, an upper sleeve, a middle sleeve and a lower sleeve, and an internal thread at the opening edge of the lower end of the fishing head is connected with an external thread at the outer circumference of the upper end of the upper sleeve in a sleeving mode; a first elastic block group is connected between the lower part of the upper sleeve and the upper part of the middle sleeve, and a first sliding sleeve is encircled in the first elastic block group; a second elastic block group is connected between the lower part of the middle sleeve and the upper part of the lower sleeve; a second sliding sleeve is encircled in the second elastic block group; a center rod is installed in inner cavities of the upper sleeve, the first sliding sleeve, the middle sleeve, the second sliding sleeve and the lower sleeve in a penetrating mode. According to the plunger and the plunger tool, the upper-stage elastic block set, the lower-stage elastic block set and the two-stage turbulent flow pieces are arranged, each stage of elastic block set is provided with 6-8 elastic blocks, the double-sealing effect is achieved, the elastic blocks are opened, the outer diameter of the plunger is increased, accumulated liquid is effectively prevented from leaking when the plunger ascends, and the lifting and liquid discharging effect of the plunger is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field drainage and gas production equipment, and relates to a self-expanding and contracting double-sealing structure plunger. Background Art

[0002] As the gas field is developed over time, the pressure and production of the gas well formation gradually decrease, the liquid carrying capacity gradually deteriorates, and the liquid accumulation in the wellbore continues to increase, which significantly affects the normal production of the gas well. Plunger gas lift technology is a drainage and gas production technology that uses the gas well's own energy to discharge the liquid from the wellbore. This technology makes full use of the gas well's own energy to drive the plunger to reciprocate in the oil pipe, and then periodically lifts the liquid produced by the formation to the ground and produces gas. As the plunger at the gas-liquid interface, it can effectively prevent the gas from rising and the liquid from falling back, reduce the "slippage" effect of the liquid running from the bottom of the well to the wellhead, improve the efficiency of gas lifting liquid, and achieve stable drainage production of liquid-accumulated wells.

[0003] The existing plunger gas lift technology mainly uses columnar plungers, brush plungers and gasket plungers according to the production conditions of gas wells, which improves the applicability of plunger gas lift technology. The structure of the plunger determines the efficiency of plunger gas lift drainage. In order to prevent gas slippage and liquid leakage during plunger lifting, the outer diameter of the conventional plunger is very close to the inner diameter of the tubing. However, since the tubing may have a variable diameter, and the outer diameter of the plunger is constant, the plunger is easy to fall; or for gas wells where the casing is used as the production string, there is no oil casing annulus to accumulate energy. Therefore, in order to minimize the slippage of the liquid column during the operation of the plunger and increase the plunger's falling speed, higher requirements are placed on the plunger body structure. However, the existing structure has problems such as the inability to drain liquid when the plunger is stuck and the plunger's sealing performance does not meet the requirements, resulting in large leakage. It is urgent to develop a new structure that meets the above technical requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a self-expanding and contracting double-sealing structure plunger to solve the problems in the prior art that the plunger cannot discharge liquid when it is stuck while moving upward, and the plunger has poor sealing performance and large leakage when lifting liquid.

[0005] The technical solution adopted by the present invention is a self-expanding and contracting double-sealing structure plunger, including a fishing head, an upper sleeve, a middle sleeve, and a lower sleeve. The internal thread of the lower end edge of the fishing head is sleeved with the external thread of the outer circumference of the upper end of the upper sleeve; a first spring block group is connected between the lower part of the upper sleeve and the upper part of the middle sleeve, and a first sliding sleeve is surrounded in the first spring block group; a second spring block group is connected between the lower part of the middle sleeve and the upper part of the lower sleeve, and a second sliding sleeve is surrounded in the second spring block group; a center rod is installed through the inner cavities of the upper sleeve, the first sliding sleeve, the middle sleeve, the second sliding sleeve, and the lower sleeve.

[0006] The self-expanding and contracting double-sealing structure plunger of the present invention is also characterized by:

[0007] A limiting nut is installed at the lower end of the center rod, a limiting screw is installed along the inner bottom of the lower port of the salvage head, and the top end of the center rod is fixedly connected with the salvage head through the limiting screw.

[0008] The lower ring wall of the upper sleeve, the upper and lower ring walls of the middle sleeve, and the upper ring wall of the lower sleeve are respectively radially provided with 6-8 bullet block holes; and a bullet block is radially movably arranged in each bullet block hole.

[0009] The first spring block group includes 6-8 spring blocks, which are evenly distributed in a circular shape along the circumference; the second spring block group includes 6-8 spring blocks, which are also evenly distributed in a circular shape along the circumference.

[0010] The specific structure of the spring block is: the middle part of the spring block is a convex-shaped main body, and the upper and lower ends of the convex-shaped main body of the spring block are respectively fixed with extension sections outward, each extension section is provided with a mounting edge near the top or bottom end, and grooves and slopes are sequentially arranged inwardly adjacent to the mounting edge, and the grooves, slopes and mounting edges are all arranged on the outer surface of the extension section, the outer surface of the groove is lower than the slope, and the outer surface of the slope is lower than the mounting edge.

[0011] The inner wall surface of the middle part of the bullet block is provided with 2-3 blind holes, and a spring is installed in each blind hole.

[0012] The structure of the sliding sleeve is that a convex ridge is respectively arranged on the outer edges of the upper and lower ends of the sliding sleeve, 2-3 annular grooves are arranged on the central outer circular surface of the sliding sleeve, and two springs arranged in the middle of each spring block are correspondingly clamped in each annular groove.

[0013] The middle outer circle of the middle sleeve is provided with 3-4 turbulent flow sheets; the middle outer circle of the lower sleeve is also provided with 2-3 turbulent flow sheets.

[0014] The beneficial effect of the present invention is that the self-expanding and contracting double-sealing structure plunger of the present invention (hereinafter referred to as the plunger of the present invention) is provided with an upper and lower two-stage spring block group and two-stage turbulence sheets. Each stage of the spring block group is provided with 6-8 spring blocks, which are staggered and annularly connected in sequence from top to bottom, and have a double sealing effect. The spring blocks are expanded and the outer diameter of the plunger is increased, which effectively prevents the leakage of accumulated liquid when the plunger moves upward and improves the lifting and drainage effect of the plunger. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the plunger of the present invention;

[0016] Figure 2 It is a schematic structural diagram of the upper sleeve in the plunger of the present invention;

[0017] Figure 3 It is a schematic structural diagram of a middle sleeve in the plunger of the present invention;

[0018] Figure 4 It is a schematic structural diagram of the lower sleeve in the plunger of the present invention;

[0019] Figure 5 It is a schematic diagram of the structure of the spring block in the plunger of the present invention;

[0020] Figure 6 It is a schematic structural diagram of the sliding sleeve in the plunger of the present invention.

[0021] In the figure, 1. fishing head, 2. limiting screw, 3. upper sleeve, 4. spring block, 5. spring block hole, 41. groove, 42. mounting edge, 43. slope, 6. sliding sleeve, 61. convex ridge, 62. annular groove, 7. middle sleeve, 8. turbulence sheet, 9. lower sleeve, 10. center rod, 11. limiting nut. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Reference Figure 1 , Figure 2 The structure of the plunger of the present invention is that it includes a fishing head 1, an upper sleeve 3, a middle sleeve 7, and a lower sleeve 9. The internal thread of the lower port edge of the fishing head 1 is sleeved with the external thread of the outer circumference of the upper end of the upper sleeve 3; a first spring block group is connected between the lower part of the upper sleeve 3 and the upper part of the middle sleeve 7, and a first sliding sleeve 6 is surrounded in the first spring block group; a second spring block group is connected between the lower part of the middle sleeve 7 and the upper part of the lower sleeve 9, and a second sliding sleeve 6 is surrounded in the second spring block group; a center rod 10 is installed through the inner cavity of the upper sleeve 3, the first sliding sleeve 6, the middle sleeve 7, the second sliding sleeve 6, and the lower sleeve 9; a limiting nut 11 is installed at the lower end of the center rod 10, a limiting screw 2 is installed at the inner bottom of the lower port edge of the fishing head 1, and the top of the center rod 10 is fixedly connected to the fishing head 1 by the limiting screw 2; the first spring block group and the second spring block group respectively include 6-8 spring blocks 4, and are evenly distributed along the circumference.

[0024] Reference Figure 2 , Figure 3 , Figure 4 The lower ring wall of the upper sleeve 3, the upper and lower ring walls of the middle sleeve 7, and the upper ring wall of the lower sleeve 9 are respectively radially opened with 6-8 bullet holes 5; a bullet 4 is radially movably arranged in each bullet hole 5.

[0025] Reference Figure 5All the spring blocks 4 have the same structure. The specific structure of the spring block 4 is as follows: the middle part of the spring block 4 is a convex-shaped main body, and the upper and lower ends of the convex-shaped main body of the spring block 4 are respectively fixedly provided with extension sections outwardly, and each extension section is provided with a mounting edge 42 near the top or bottom end, and a groove 41 and a slope 43 are sequentially provided inwardly adjacent to the mounting edge 42. The groove 41, the slope 43 and the mounting edge 42 are all provided on the outer surface of the extension section, and the outer surface of the groove 41 is lower than the slope 43, and the outer surface of the slope 43 is lower than the mounting edge 42. Each spring block hole 5 serves as a clamping window for the mounting edge 42, the groove 41, and the slope 43 at the upper and lower ends of the spring block 4, respectively, to realize the upper and lower hooking and positioning of the three components of the upper sleeve 3, the middle sleeve 7, and the lower sleeve 9;

[0026] There are 2-3 blind holes on the inner wall of the middle part of the spring block 4, and a spring is installed in each blind hole. When the 6-8 spring blocks 4 of the first spring block group are evenly distributed along the circumference, the convex-shaped main body in the middle part of the spring block 4 is staggered and connected up and down in sequence to achieve the effect of radial expansion and contraction; the installation method of the second spring block group is the same as that of the first spring block group.

[0027] Reference Figure 6 The structure of the sleeve 6 is that a convex ridge 61 is respectively arranged on the outer edges of the upper and lower ports of the sleeve 6, and 2-3 annular grooves 62 are arranged on the outer circular surface of the middle part of the sleeve 6. Two springs arranged in the middle part of each spring block 4 are correspondingly stuck in each annular groove 62 to control the radial outward expansion and inward contraction of each spring block 4. The outer diameter of the spring block 4 is the largest when it is opened outward, and the outer diameter of the spring block 4 is the smallest when it is contracted inward, thereby minimizing the gap between the plunger and the pipe column, improving the sealing performance, and ensuring that the plunger can run smoothly up and down.

[0028] Reference Figure 3 , Figure 4 The middle outer circle of the middle sleeve 7 is provided with 3-4 turbulence sheets 8, and the middle outer circle of the lower sleeve 9 is also provided with 2-3 turbulence sheets 8. Each turbulence sheet 8 is formed by ring cutting. The function of the turbulence sheet 8 is to increase the overall resistance of the plunger in the liquid and improve the liquid lifting efficiency.

[0029] The two groups of spring blocks 4 and the two groups of turbulent sheets 8 together constitute four seals of the plunger of the present invention.

[0030] The above-mentioned fishing head 1, limiting nut 11, upper sleeve 3 and center rod 10 are all fixed parts, and the above-mentioned spring block 4, sliding sleeve 6, middle sleeve 7 and lower sleeve 9 are all movable parts (the middle sleeve 7 and lower sleeve 9 can move up and down in the spring block hole 5 along with the groove 41 and slope 43 of the spring block 4).

[0031] When both ends of the plunger of the present invention are impacted, the upper sleeve 3 moves downward due to inertia, causing the spring block 4 of the first spring block group to move toward the groove 41 or the slope 43 in the respective spring block holes 5 associated with the upper sleeve 3 and the middle sleeve 7, and the spring block 4 of the second spring block group moves toward the groove 41 or the slope 43 in the respective spring block holes 5 associated with the middle sleeve 7 and the lower sleeve 9; due to the inertia effect of the plunger, the spring block 4 cooperates with the sliding sleeve 6 to slide up and down on the center rod 10, so that the groove 41 and the slope 43 of the spring block 4 move up and down in the shrapnel hole 12, thereby achieving the effect of changing the overall outer diameter through the expansion and contraction of the spring block 4.

[0032] Example 1

[0033] The structure of the plunger embodiment 1 of the present invention is that the internal thread on the edge of the lower port of the fishing head 1 is sleeved with the external thread on the outer circumference of the upper end of the upper sleeve 3; a first spring block group is connected between the upper sleeve 3 and the middle sleeve 7, and a first sliding sleeve 6 is surrounded in the first spring block group; a second spring block group is connected between the middle sleeve 7 and the lower sleeve 9, and a second sliding sleeve 6 is surrounded in the second spring block group; a center rod 10 is installed through the inner cavity of the upper sleeve 3, the first sliding sleeve 6, the middle sleeve 7, the second sliding sleeve 6, and the lower sleeve 9; a limiting nut 11 is installed at the lower end of the center rod 10, a limiting screw 2 is installed at the bottom of the lower port of the fishing head 1, and the top of the center rod 10 is fixedly connected to the fishing head 1 by the limiting screw 2; the first spring block group and the second spring block group both have 6 spring blocks 4, and are evenly distributed along the circumference.

[0034] Six block holes 5 are respectively provided on the lower annular wall of the upper sleeve 3, the upper and lower annular walls of the middle sleeve 7, and the upper annular wall of the lower sleeve 9; mounting edges 42 are provided at both upper and lower ends of the block 4, and each mounting edge 42 is radially movable in a block hole 5; two blind holes are provided on the inner wall surface in the middle of the block 4, and a spring is respectively installed in each blind hole; two annular grooves 62 are provided on the outer circular surface in the middle of the sliding sleeve 6, and two springs provided in the middle of each block 4 are correspondingly clamped in an annular groove 62.

[0035] The middle outer circle of the middle sleeve 7 is provided with three turbulent flow sheets 8 , and the middle outer circle of the lower sleeve 9 is provided with two turbulent flow sheets 8 .

[0036] Example 2

[0037] The difference from the structure of the plunger embodiment 1 of the present invention is that three turbulence sheets 8 are arranged on the middle outer circle of the middle sleeve 7, and two turbulence sheets 8 are arranged on the middle outer circle of the lower sleeve 9. The other structures are consistent with the embodiment 1.

[0038] Example 3

[0039] The difference from the structure of the plunger embodiment 1 of the present invention is that the first spring block group and the second spring block group are both 8 spring blocks 4, and are evenly distributed along the circumference. Correspondingly, the lower ring wall of the upper sleeve 3, the upper and lower ring walls of the middle sleeve 7, and the upper ring wall of the lower sleeve 9 are respectively provided with 8 spring block holes 5; the middle outer circle of the middle sleeve 7 is provided with 3 turbulent sheets 8, and the middle outer circle of the lower sleeve 9 is provided with 2 turbulent sheets 8. The other structures are consistent with the embodiment 1.

[0040] Example 4

[0041] The difference from the structure of the plunger embodiment 1 of the present invention is that the first spring block group and the second spring block group are both 8 spring blocks 4, and are evenly distributed along the circumference. Correspondingly, the lower ring wall of the upper sleeve 3, the upper and lower ring walls of the middle sleeve 7, and the upper ring wall of the lower sleeve 9 are respectively provided with 8 spring block holes 5; the middle outer circle of the middle sleeve 7 is provided with 3 turbulent sheets 8, and the middle outer circle of the lower sleeve 9 is provided with 2 turbulent sheets 8. The other structures are consistent with the embodiment 1.

[0042] The working principle of the plunger of the present invention is:

[0043] Before working, the plunger catcher on the blowout preventer hooks the fishing head 1 at the upper end of the plunger, and the spring set on the inner wall of the bullet block 4 is compressed, so that the overall outer diameter of the plunger is at the minimum and remains in a contracted state. During working, the plunger catcher releases the plunger, and the plunger shrinks and maintains the minimum outer diameter. As a result, the plunger of the present invention falls rapidly, and under the action of its own gravity, it falls on the bottom-hole buffer locator. The upper sleeve 3 mounted on the center rod 10 moves downward by inertia. The bullet blocks 4 of the first bullet group move in the direction of the slope 43 in the respective bullet holes 5 associated with the upper sleeve 3 and the middle sleeve 7, and the bullet blocks 4 of the second bullet group move in the direction of the slope 43 in the respective bullet holes 5 associated with the middle sleeve 7 and the lower sleeve 9. Due to the inertia and the spring force, the outer diameter of the plunger expands to the maximum according to the inner diameter of the oil pipe to meet the bottom-hole sealing requirements. When drilling a well, the plunger of the present invention is lifted upward, and the outer diameter of the plunger is kept at a maximum value that is basically close to the inner diameter of the oil pipe, which effectively prevents the loss of accumulated liquid when the plunger moves upward. When the upper end of the fishing head 1 hits the wellhead blowout preventer and reaches the catcher for fixing, the upper sleeve 3, the middle sleeve 7, and the lower sleeve 9 sleeved on the center rod 10 simultaneously squeeze each bullet block 4 to move toward the groove 41, the bullet block 4 shrinks, all the bullet blocks 4 and the three sleeves return to their initial positions, and the outer diameter of the plunger shrinks and decreases.

[0044] When the plunger of the present invention is working, it can be divided into two states: upward and downward, which are described as follows:

[0045] 1) Downward state: first, the bottom hole buffer locator is placed at a determined position in the well by means of the logging vehicle, and then the plunger catcher on the wellhead blowout preventer is hung on the fishing head 1 of the plunger of the present invention. During the downward process, the springs of all the bullet blocks 4 are contracted, and the outer diameter of the plunger is at the minimum; when the well is shut in, the catcher releases the plunger of the present invention, and the plunger contracts to keep the outer diameter at the minimum and falls rapidly, and falls to the bottom hole buffer locator under its own gravity, and the bullet blocks 4 of the upper sleeve 3, the middle sleeve 7, and the lower sleeve 9 on the center rod 10 move to both sides, and the spring installed between the bullet block 4 and the sliding sleeve 6 is expanded, and the outer diameter of the plunger is increased by self-expansion to meet the bottom hole sealing requirements.

[0046] 2) Upward state: when the well is opened, the gas at the bottom of the well pushes the plunger of the present invention and the liquid above the plunger to move upward to the wellhead, the outer diameter of the plunger is kept at the maximum, the sealing effect is good, and the leakage and discharge of the accumulated liquid when the plunger moves upward are effectively prevented; when the plunger of the present invention reaches the inside of the blowout preventer and is captured by the catcher, the plunger is rebounded downward, the block 4 and the upper sleeve 3, the middle sleeve 7, and the lower sleeve 9 are all restored to the initial position, the spring in the block 4 contracts, and the outer diameter of the plunger is in the minimum state.

Claims

1. A self-expanding and shrinking double-sealing structure plunger, characterized in that: The invention comprises a fishing head (1), an upper sleeve (3), a middle sleeve (7) and a lower sleeve (9); the lower end edge of the fishing head (1) is sleeved with an external thread on the outer circumference of the upper end of the upper sleeve (3); a first spring block group is connected between the lower part of the upper sleeve (3) and the upper part of the middle sleeve (7), and a first sliding sleeve (6) is surrounded in the first spring block group; a second spring block group is connected between the lower part of the middle sleeve (7) and the upper part of the lower sleeve (9), and a second sliding sleeve (6) is surrounded in the second spring block group; and a center rod (10) is installed through the inner cavities of the upper sleeve (3), the first sliding sleeve (6), the middle sleeve (7), the second sliding sleeve (6) and the lower sleeve (9).

2. The self-expanding and contracting double-sealing structure plunger according to claim 1, characterized in that: A limiting nut (11) is installed at the lower end of the center rod (10), a limiting screw (2) is installed along the inner bottom of the lower port of the fishing head (1), and the top end of the center rod (10) is fixedly connected to the fishing head (1) via the limiting screw (2).

3. The self-expanding and contracting double-sealing structure plunger according to claim 1, characterized in that: The lower ring wall of the upper sleeve (3), the upper and lower ring walls of the middle sleeve (7), and the upper ring wall of the lower sleeve (9) are respectively radially provided with 6 to 8 bullet holes (5); and a bullet (4) is radially movably arranged in each bullet hole (5).

4. The self-expanding and contracting double-sealing structure plunger according to claim 1, characterized in that: The first spring block group comprises 6-8 spring blocks (4) which are evenly distributed in a circular shape along the circumference; the second spring block group comprises 6-8 spring blocks (4) which are also evenly distributed in a circular shape along the circumference.

5. The self-expanding and contracting double-sealing structure plunger according to claim 4 is characterized in that: The specific structure of the spring block (4) is as follows: the middle part of the spring block (4) is a convex-shaped main body, and the upper and lower ends of the convex-shaped main body of the spring block (4) are respectively fixedly provided with extension sections outwardly, and each extension section is provided with a mounting edge (42) near the top or bottom end, and a groove (41) and a slope (43) are sequentially provided inwardly adjacent to the mounting edge (42), and the groove (41), the slope (43) and the mounting edge (42) are all provided on the outer surface of the extension section, the outer surface of the groove (41) is lower than the slope (43), and the outer surface of the slope (43) is lower than the mounting edge (42).

6. The self-expanding and contracting double-sealing structure plunger according to claim 4, characterized in that: The inner wall surface of the middle part of the spring block (4) is provided with 2-3 blind holes, and a spring is installed in each blind hole.

7. The self-expanding and contracting double-sealing structure plunger according to claim 1, characterized in that: The structure of the sliding sleeve (6) is that a convex ridge (61) is respectively arranged on the outer edges of the upper and lower ends of the sliding sleeve (6), 2-3 annular grooves (62) are arranged on the outer circular surface of the middle part of the sliding sleeve (6), and two springs arranged in the middle part of each spring block (4) are correspondingly clamped in each annular groove (62).

8. The self-expanding and contracting double-sealing structure plunger according to claim 1, characterized in that: The middle outer circle of the middle sleeve (7) is provided with 3-4 turbulent flow sheets (8); the middle outer circle of the lower sleeve (9) is also provided with 2-3 turbulent flow sheets (8).

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