Returnable leakage detection device for underground oil pipe

Abstract

The utility model relates to the technical field of oil well repair, in particular to a recoverable leakage detection device for an underground oil pipe. The downhole oil pipe recoverable leakage detection device comprises a leakage detection seat and a middle connecting rod inserted in the leakage detection seat, an abutting ball is fixedly embedded in the bottom of the middle connecting rod, an elastic air bag wraps the abutting ball, an air storage cavity is formed in the abutting ball, and a plurality of air guide holes which are annularly distributed and communicated with the elastic air bag are formed in the side wall, close to the bottom, of the air storage cavity. According to the recoverable leakage detection device for the underground oil pipe, the elastic air bag is flexibly inflated or deflated, so that the connection strength between the elastic air bag and the leakage detection seat can be changed, the leakage detection rod structure is easy to be fixedly clamped with and separated from the leakage detection seat, the recovery of the leakage detection rod structure is facilitated, and the recovery efficiency of the leakage detection rod structure is improved. Meanwhile, the construction pipe column does not need to be replaced after the leakage detection rod structure is recycled, and construction is convenient.

Description

Technical Field

[0001] The utility model relates to the technical field of petroleum well repair, in particular to a returnable leakage detection device for downhole oil pipes. Background Art

[0002] Oil wells and water wells in oil fields need to be unblocked due to formation blockage, and cement needs to be squeezed to seal the oil layers that produce water or abandoned oil layers. These are underground high-pressure constructions with huge risks. During construction, the phenomenon of poor construction results or overhaul due to oil pipe leakage often occurs, resulting in ineffective construction and waste of manpower and material resources. The main reasons are as follows: 1. The oil pipe pressure test is not synchronized with the construction. At present, the on-site construction is to first lower the pressure test string to check whether the oil pipe is sealed and intact. After taking out the pressure test string, the construction string is lowered, resulting in the inability to verify the sealing of the construction string; 2. The pulled out string cannot leak, which increases the workload and the difficulty of environmental protection management.

[0003] In response to the above problem, a Chinese patent with announcement number CN201013360Y uses a leak detection rod that is dropped into the oil pipe and falls onto the leak detection seat at the bottom of the pipe string. The sealing body cooperates with the sealing section of the leak detection seat to seal the upper pipe string. Then, a cement truck is used to pump liquid into the oil pipe string to check whether the upper oil pipe is leaking. If the pressure test is normal, it means that the oil pipe seal is intact. Then, a catcher is installed on the upper part of the pipe string, and a large-displacement reverse circulation pump truck is used to wash the well. At this time, the leather cup of the leak detection rod is expanded by the hydraulic pressure from below and sealed with the inner wall of the oil pipe. When the hydraulic pressure is large enough, the leather cup drives the leak detection rod to slide toward the wellhead. After reaching the wellhead, the salvage head knocks open the locking claw of the catcher, and the leak detection rod is fished out and taken out. The inspection work is completed, and the next step of construction can be carried out;

[0004] Since this patent adopts the method of matching the sealing body with the sealing section of the leak detection seat, the sealing body and the sealing section of the leak detection seat are separated by using the leather cup to be driven by the hydraulic pressure expansion from below. The separation is difficult and there is a hidden danger that the sealing body and the leak detection seat cannot be separated because they are too tightly connected.

[0005] Therefore, it is necessary to provide a new downhole oil pipe returnable leak detection device to solve the above technical problems. Utility Model Content

[0006] In order to solve the above technical problems, the utility model provides a returnable leak detection device for downhole oil pipes.

[0007] The utility model provides a downhole oil pipe returnable leak detection device, which comprises a leak detection seat and a middle link rod inserted in the leak detection seat, wherein a contact ball is fixedly embedded at the bottom of the middle link rod, and an elastic air bag is covered on the contact ball, an air storage cavity is provided in the contact ball, and a plurality of annularly distributed air guide holes connected to the elastic air bag are provided on the side wall of the air storage cavity near the bottom;

[0008] A micro cylinder is fixedly embedded in the middle link rod, and the output end of the micro cylinder extends into the air storage cavity and is fixedly installed with a piston, and the piston is slidably connected to the air storage cavity;

[0009] A threaded mounting rod is mounted on the middle link rod, a fishing head is fixedly mounted on the top of the mounting rod, and a plurality of leather cups equidistantly distributed up and down are fixedly sleeved on the mounting rod.

[0010] Preferably, a cone head is fixedly embedded in the bottom of the abutment ball.

[0011] Preferably, the upper bag body of the elastic airbag is provided with a through cavity for sleeve-connecting the middle link rod, and the lower bag body of the elastic airbag is provided with a through cavity for sleeve-connecting the root of the cone head, and a sealing ring is installed on the through cavity provided by the elastic airbag.

[0012] Preferably, the upper rod section of the middle link rod is provided with an external threaded section, and the bottom of the mounting rod is provided with an internal threaded hole, and the external threaded section is adapted to the internal threaded hole.

[0013] Preferably, a flaring cavity with a decreasing inner diameter from top to bottom is provided at the top tube opening of the leak detection seat, and an arc-shaped protrusion for connecting with an abutting ball is provided in the leak detection seat below the flaring cavity.

[0014] Preferably, the elastic airbag is attached to the abutment ball when not expanded.

[0015] Compared with the related art, the downhole oil pipe returnable leak detection device provided by the utility model has the following beneficial effects:

[0016] The utility model utilizes the flexible inflation or exhaust of the elastic airbag to change the connection strength between the airbag and the leak detection seat, so that the leak detection rod structure is easy to be fixedly connected with the leak detection seat and separated, and the leak detection rod structure is convenient for recovery. At the same time, there is no need to replace the construction pipe column after the leak detection rod structure is recovered, and the construction is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of a preferred embodiment of a returnable leak detection device for downhole oil pipes provided by the utility model;

[0018] Figure 2 A schematic cross-sectional view of the returnable leak detection device for downhole oil pipes provided by the utility model;

[0019] Figure 3 for Figure 2 The cross-sectional structural diagram of the leak detection seat shown;

[0020] Figure 4 for Figure 2 A schematic cross-sectional structure diagram of the abutting ball shown;

[0021] Figure 5 for Figure 2 A schematic cross-sectional view of the mounting rod is shown.

[0022] Numbers in the figure: 1, leak detection seat; 1a, expansion cavity; 11, arc-shaped protrusion; 2, middle connecting rod; 21, external thread section; 3, abutment ball; 3a, air storage cavity; 3b, air guide hole; 31, cone head; 4, elastic air bag; 5, micro cylinder; 6, piston; 7, mounting rod; 7a, internal thread hole; 71, salvage head; 72, leather cup. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0024] The specific implementation of the present utility model is described in detail below in conjunction with specific embodiments.

[0025] See also Figures 1 to 5 The embodiment of the utility model provides a returnable leak detection device for a downhole oil pipe, and the returnable leak detection device for a downhole oil pipe comprises a leak detection seat 1, a middle link rod 2, an abutment ball 3 and an elastic airbag 4.

[0026] In the embodiments of the present invention, please refer to Figures 1 to 5 , an expansion cavity 1a with a decreasing inner diameter from top to bottom is provided at the top of the leak test seat 1, and an arc-shaped protrusion 11 for connecting with the abutting ball 3 is provided in the leak test seat 1 below the expansion cavity 1a, an abutting ball 3 is fixedly fitted at the bottom of the middle link rod 2, and an elastic airbag 4 is coated on the abutting ball 3, and the elastic airbag 4 is attached to the abutting ball 3 when it is not expanded, an air storage cavity 3a is provided in the abutting ball 3, and a plurality of annularly distributed air guide holes 3b connected with the elastic airbag 4 are provided on the side wall of the air storage cavity 3a near the bottom, and a micro cylinder 5 is fixedly fitted in the middle link rod 2, and the output end of the micro cylinder 5 extends into the air storage cavity 3a and is fixedly installed with a piston 6, and the piston 6 is slidably connected with the air storage cavity 3a;

[0027] A threaded mounting rod 7 is mounted on the middle link rod 2 , and a fishing head 71 is fixedly mounted on the top of the mounting rod 7 . A plurality of leather cups 72 equidistantly distributed vertically are fixedly sleeved on the mounting rod 7 .

[0028] The specific operation of downhole oil pipe leak detection is as follows:

[0029] 1. First, connect the leak detection seat 1 to the bottom of the oil pipe string and lower it into the well.

[0030] Second, the middle link rod 2 and the mounting rod 7 are threadedly connected to form a leak detection rod structure, and then the leak detection rod structure is put into the oil pipe at the wellhead and falls onto the leak detection seat 1 at the bottom of the pipe string (keeping the abutting ball 3 at the bottom);

[0031] 3. When the abutting ball 3 falls to the arc-shaped protrusion 11 in the leak detection seat 1, the controller turns on the micro-cylinder 5 to drive the piston 6 to discharge the gas in the gas storage chamber 3a into the elastic airbag 4 through the air guide hole 3b, so that the elastic airbag 4 expands, and the expanded elastic airbag 4 quickly fills the gap between the abutting ball 3 and the arc-shaped protrusion 11, thereby enhancing the firmness of the engagement between the abutting ball 3 and the arc-shaped protrusion 11 in the leak detection seat 1 and the sealing performance of the elastic airbag 4 on the gap between the abutting ball 3 and the arc-shaped protrusion 11. At this time, the expanded elastic airbag 4 cooperates with the abutting ball 3 to seal the upper column;

[0032] 4. Use a cement truck to pump liquid into the tubing string to check if the upper tubing is leaking;

[0033] A. If the pressure test is normal, it means that the oil pipe is well sealed. Then, the micro cylinder 5 is opened to drive the piston 6 to slide back along the air storage chamber 3a. At this time, the air storage chamber 3a generates negative pressure, so the gas in the elastic airbag 4 can flow back into the air storage chamber 3a, so that a gap is generated between the contact ball 3 and the arc-shaped protrusion 11. Then, a catcher can be installed on the upper part of the pipe string and a large-displacement reverse circulation pump truck can be used to wash the well. At this time, the leather cup 72 on the mounting rod 7 is expanded by the hydraulic pressure from below and sealed with the inner wall of the oil pipe. When the hydraulic pressure is large enough, the leather cup 72 drives the leak detection rod structure to slide toward the wellhead. After reaching the wellhead, the fishing head 71 knocks open the locking claw of the catcher, and the leak detection rod structure is fished out, and the next construction can be carried out;

[0034] B. If the pressure test is abnormal, it means that the oil pipe is not sealed well and the staff will need to seal the leak later.

[0035] In this embodiment, the elastic airbag 4 is flexibly inflated or exhausted to change the connection strength with the leak detection seat 1, so that the leak detection rod structure is easy to be fixedly connected and separated from the leak detection seat 1, which is convenient for recycling the leak detection rod structure.

[0036] In addition, in order to facilitate the smooth sliding of the middle link rod 2 along the oil pipe, a cone head 31 is fixedly embedded at the bottom of the abutment ball 3. The cone head 31 can reduce the slurry breaking process of the middle link rod 2 sliding down along the oil pipe to reduce its resistance.

[0037] Furthermore, the upper bag body of the elastic airbag 4 is provided with a through cavity for sleeve-connecting the middle link 2, and the lower bag body of the elastic airbag 4 is provided with a through cavity for sleeve-connecting the root of the cone head 31. A sealing ring is installed on the through cavity provided by the elastic airbag 4, so that the elastic airbag 4 can cover the abutting ball 3 while being fixed between the middle link 2 and the cone head 31. The provided sealing ring seals the elastic airbag 4 and the abutting ball 3 to prevent gas from leaking out of the elastic airbag 4.

[0038] Furthermore, the upper rod section of the center link rod 2 is provided with an external threaded section 21, and the bottom of the mounting rod 7 is provided with an internal threaded hole 7a, the external threaded section 21 is adapted to the internal threaded hole 7a, and the center link rod 2 and the mounting rod 7 are connected in a threaded detachable manner, so that when the center link rod 2 or the mounting rod 7 is damaged, a new part can be replaced without completely replacing the center link rod 2 or the mounting rod 7, thereby reducing waste of resources.

[0039] The circuits and controls involved in the present invention are all prior art and will not be described in detail here.

[0040] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A returnable downhole oil pipe leak detection device, comprising a leak detection seat (1) and a middle link rod (2) inserted into the leak detection seat (1), characterized in that: A contact ball (3) is fixedly embedded at the bottom of the middle link rod (2), and an elastic air bag (4) is coated on the contact ball (3). An air storage cavity (3a) is provided in the contact ball (3), and a plurality of air guide holes (3b) are arranged in an annular pattern and communicated with the elastic air bag (4) on the side wall of the air storage cavity (3a) near the bottom; A micro cylinder (5) is fixedly embedded in the middle link rod (2), and the output end of the micro cylinder (5) extends into the air storage chamber (3a) and is fixedly mounted with a piston (6), and the piston (6) is slidably connected to the air storage chamber (3a); A threaded mounting rod (7) is mounted on the middle link rod (2), a fishing head (71) is fixedly mounted on the top of the mounting rod (7), and a plurality of leather cups (72) equidistantly distributed vertically are fixedly sleeved on the mounting rod (7).

2. The downhole oil pipe returnable leak detection device according to claim 1, characterized in that: A cone head (31) is fixedly embedded in the bottom of the abutment ball (3).

3. The downhole oil pipe returnable leak detection device according to claim 2, characterized in that: The upper bag body of the elastic airbag (4) is provided with a through cavity for sleeve-connecting the middle link rod (2), and the lower bag body of the elastic airbag (4) is provided with a through cavity for sleeve-connecting the root of the cone head (31), and a sealing ring is installed on the through cavity provided by the elastic airbag (4).

4. The downhole oil pipe returnable leak detection device according to claim 1, characterized in that: The upper rod section of the middle link rod (2) is provided with an external thread section (21), the bottom of the mounting rod (7) is provided with an internal thread hole (7a), and the external thread section (21) is adapted to fit the internal thread hole (7a).

5. The downhole oil pipe returnable leak detection device according to claim 1, characterized in that: The leak test seat (1) has an expansion cavity (1a) at the top of the tube mouth, the inner diameter of which decreases from top to bottom, and an arc-shaped protrusion (11) for connecting with the abutment ball (3) is provided in the leak test seat (1) below the expansion cavity (1a).

6. The downhole oil pipe returnable leak detection device according to claim 1, characterized in that: The elastic airbag (4) is attached to the abutment ball (3) when not inflated.

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