Coal bed gas well testing pressure testing device

Abstract

The utility model relates to a coal bed gas well testing pressure testing device which comprises a tubular column string. The wellhead cover is connected to the upper end opening of the tubular column string through threads, through holes are formed in the wellhead cover and comprise a connecting hole and a circular truncated cone hole, and the diameter of the circular truncated cone hole is gradually reduced from top to bottom; the elastic sealing plug is provided with a first threading hole and is arranged in the through hole; the connecting piece is provided with a second threading hole, the connecting piece is in threaded connection with the connecting hole, and the elastic sealing plug is located on the lower side of the connecting piece; the pressure detection assembly comprises a connecting line and a pressure detection unit connected with the connecting line, and the connecting line penetrates through the second threading hole and the first threading hole; the connecting piece can extrude the elastic sealing plug, so that the elastic sealing plug is at least partially located in the circular truncated cone hole to seal the circular truncated cone hole and the first threading hole. According to the pressure testing device for the coal bed gas well test, the pressure detection assembly is convenient to replace, the sealing performance is good, the pressure intensity of dozens of MPa in a tubular column string can be borne without being damaged, repeated use can be achieved, and the cost is low.

Description

Technical Field

[0001] This utility model relates to the field of coalbed methane extraction technology, and in particular to a coalbed methane well test pressure testing device. Background Technology

[0002] Coal seams contain combustible coalbed methane. Generally, coalbed methane is extracted before coal mining to make full use of the energy.

[0003] Well testing is a specialized test conducted on a well to determine its production capacity and to study reservoir parameters and dynamics. Tests in well testing include injection pressure drop testing and in-situ stress testing. Both of these tests require the detection of coal seam pressure, which is approximately tens of megapascals.

[0004] In the existing technology, a well casing is installed in the hole drilled in the ground, and the pressure sensor is installed in the well casing. The well casing is then sealed with a sealing cover. However, if the pressure sensor fails, the well casing needs to be removed and replaced with a new well casing with the pressure sensor installed, or the pressure sensor in the well casing needs to be replaced, which results in high cost and complicated operation. Utility Model Content

[0005] The purpose of this invention is to provide a coalbed methane well test pressure testing device to at least solve one of the above-mentioned technical problems.

[0006] To achieve the above objectives, this utility model provides a coalbed methane well test pressure testing device, comprising:

[0007] A string of tubing is inserted into a borehole in the formation, and the string of tubing is in communication with the space where the pressure to be measured is located.

[0008] The wellhead cover is threaded to the upper end of the tubing string. The wellhead cover has a through hole, which includes a connecting hole and a frustum hole arranged sequentially from top to bottom. The diameter of the frustum hole gradually decreases from top to bottom.

[0009] An elastic sealing plug has a first thread hole and is disposed in the through hole, wherein the minimum diameter of the frustum hole is smaller than the outer diameter of the elastic sealing plug;

[0010] The connector has a second through hole, and the connector is threaded to the through hole. The elastic sealing plug is located on the lower side of the connector.

[0011] A pressure detection assembly includes a connecting wire and a pressure detection unit. One end of the connecting wire is connected to the pressure detection unit. The connecting wire passes through the second wire hole and the first wire hole, and the other end of the connecting wire is located outside the wellhead cover.

[0012] The connector can compress the elastic sealing plug so that the elastic sealing plug is at least partially located in the frustum hole to seal the frustum hole and the first through hole.

[0013] Optionally, the outer diameter of the resilient sealing plug is 0.9-1.1 times the maximum diameter of the frustum-shaped hole, and / or

[0014] The diameter of the first threading hole is 0.9-1.2 times the diameter of the connecting wire.

[0015] Optionally, the through hole further includes a stop-through hole located below the frustum hole, wherein the diameter of the stop-through hole is not greater than the minimum diameter of the frustum hole.

[0016] Optionally, the through hole further includes a clearance hole located at the lower end of the stop material passage hole.

[0017] Optionally, the resilient sealing plug is made of rubber.

[0018] Optionally, a sealing ring is provided between the wellhead cover and the tubing string.

[0019] Optionally, the wellhead cover has an annular groove, and the sealing ring is disposed in the annular groove.

[0020] Optionally, the wellhead cover includes an insertion part and a positioning part. The insertion part is located inside the tubing string and is threadedly connected to the tubing string. The positioning part is connected to the upper end of the insertion part, and the lower surface of the positioning part can abut against the upper surface of the wellhead cover.

[0021] Optionally, the upper end of the tubular string is provided with an internal thread, and the insertion part is provided with an external thread that is threadedly connected to the internal thread.

[0022] Optionally, the pressure detection assembly further includes a display unit for displaying the pressure value detected by the pressure detection unit, and the connecting line is a cable; or

[0023] The connecting wire is a metal wire.

[0024] As can be seen from the above, the technical solution provided by this utility model requires that when detecting the pressure inside the coal seam, the connecting wire is passed through the second through hole of the connector, the first through hole of the elastic sealing plug, and the through hole of the wellhead cover. Then, the connecting wire is connected to the pressure detection unit, the pressure detection unit is placed in the tubing string, and the wellhead cover is threaded to the upper end of the tubing string. Subsequently, the pressure detection unit is continuously lowered until it reaches the designated position. Afterward, the elastic sealing plug is inserted into the connecting hole, the connector is inserted into the connecting hole, and the connector is gradually tightened. Under the force of the connector, the elastic sealing plug is at least partially pushed into the frustum hole. Under the action of the frustum hole, the elastic sealing plug is squeezed. Since the diameter of the frustum hole gradually decreases from top to bottom, the diameter of the first through hole of the elastic sealing plug gradually decreases from bottom to top. At least the connecting wire located at the upper end of the first through hole is sealed and wrapped by the elastic sealing plug, thereby achieving a seal between the first through hole and the connecting wire. At the same time, the connector is fixed. In addition, the outer side of the elastic sealing plug abuts against the wall of the frustum hole to achieve a seal between the frustum hole and the elastic sealing plug, thereby achieving a seal between the elastic sealing plug and the through hole, that is, to achieve a seal at the open end of the tubing string, ensuring the accuracy of the pressure detection unit.

[0025] When the pressure detection component needs to be replaced, the wellhead cover or connector can be unscrewed to remove the pressure detection component, thus enabling replacement. The pressure detection component replacement is simple, low-cost, and easy to operate.

[0026] The pressure testing device for coalbed methane well testing features easily replaceable pressure detection components, good sealing performance, and can withstand pressures of tens of megapascals within the tubing string without damage. It is reusable and cost-effective. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of the coalbed methane well test pressure testing device provided in this embodiment of the utility model;

[0028] Figure 2 This is a cross-sectional view of the connector provided in an embodiment of this utility model;

[0029] Figure 3 This is a cross-sectional view of the elastic sealing plug provided in an embodiment of this utility model;

[0030] Figure 4 This is a cross-sectional view of the well cover provided in this embodiment of the utility model;

[0031] Figure 5 This is a schematic diagram of another pressure detection component provided in an embodiment of the present invention.

[0032] In the picture:

[0033] 1. Tube string;

[0034] 2. Wellhead cover; 21. Connecting hole; 22. Frustum hole; 23. Stop and material passage hole; 24. Clearance hole; 26. Insertion part; 27. Positioning part; 28. Reinforcing protrusion; 29. ​​Annular groove;

[0035] 3. Elastic sealing plug; 31. First threading hole;

[0036] 4. Connector; 41. Second wire hole;

[0037] 5. Pressure detection assembly; 51. Connecting wire; 511. Metal wire; 512. Cable; 52. Pressure detection unit; 53. Display unit;

[0038] 6. Sealing ring. Detailed Implementation

[0039] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining this utility model and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this utility model are shown in the accompanying drawings, not all of them.

[0040] This utility model defines certain directional terms. Unless otherwise stated, the directional terms used, such as "up", "down", "left", "right", "inner", and "outer", are used for ease of understanding and therefore do not constitute a limitation on the scope of protection of this utility model.

[0041] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] This embodiment provides a coalbed methane well test pressure testing device for use in coalbed methane well test, which reduces costs and simplifies the test operation.

[0044] like Figures 1-3 As shown, the coalbed methane well test pressure testing device provided in this embodiment includes a tubing string 1, a wellhead cover 2, an elastic sealing plug 3, a connector 4, and a pressure detection component 5. The tubing string 1 is inserted into a borehole in the formation and is connected to the space where the pressure is to be measured, allowing the pressure detection component 5 to enter this space, which can be a coal seam, etc. For example, the lower end of the tubing string 1 can be connected to a packer, and the pressure detection component 5 passes through the tubing string 1 and the packer to enter the coal seam for pressure detection. The tubing string 1 is formed by connecting multiple pipes; this is prior art and will not be described further here.

[0045] like Figure 1 and Figure 2 As shown, the wellhead cover 2 is threaded to the upper end of the tubing string 1. The wellhead cover 2 has a through hole, which includes a connecting hole 21 and a frustum-shaped hole 22 arranged sequentially from top to bottom. The diameter of the frustum-shaped hole 22 gradually decreases from top to bottom. The elastic sealing plug 3 has a first threaded hole 31 and is located in the through hole. The connector 4 has a second threaded hole 41 and is threaded to the connecting hole 21. Specifically, the connecting hole 21 has an internal thread, and the connector 4 has an external thread that is screwed into the internal thread.

[0046] The pressure detection assembly 5 includes a connecting wire 51 and a pressure detection unit 52. One end of the connecting wire 51 is connected to the pressure detection unit 52. The connecting wire 51 passes through the second through hole 41 and the first through hole 31, so that the pressure detection unit 52 is located inside the tubing string 1. The other end of the connecting wire 51 is located outside the wellhead cover 2. The connector 4 can compress the elastic sealing plug 3, so that the elastic sealing plug 3 is at least partially located in the frustum hole 22, thereby sealing the frustum hole 22 and the first through hole 31. It is understood that the maximum diameter of the frustum hole 22 is the diameter at its uppermost end, and the minimum diameter of the frustum hole 22 is the diameter at its lowermost end.

[0047] When it is necessary to detect the pressure inside the coal seam, the connecting wire 51 is passed through the second through hole 41 of the connector 4, the first through hole 31 of the elastic sealing plug 3, and the through hole of the wellhead cover 2. Then the connecting wire 51 is connected to the pressure detection unit 52, the pressure detection unit 52 is placed in the tubing string 1, and the wellhead cover 2 is threaded to the upper port of the tubing string 1. Then the pressure detection unit 52 is continuously lowered until the pressure detection unit 52 reaches the designated position. Next, the elastic sealing plug 3 is inserted into the connecting hole 21, and the connector 4 is inserted into the connecting hole 21. The connector 4 is then gradually tightened. Under the force of the connector 4, the elastic sealing plug 3 is at least partially pushed into the frustum hole 22. Under the action of the frustum hole 22, the elastic sealing plug 3 is compressed. Since the diameter of the frustum hole 22 gradually decreases from top to bottom, the diameter of the first wire hole 31 of the elastic sealing plug 3 gradually decreases from bottom to top. At least the connecting wire 51 located at the upper end of the first wire hole 31 is sealed and wrapped by the elastic sealing plug 3, thereby achieving a seal between the first wire hole 31 and the connecting wire 51. At the same time, the connector 4 is fixed. In addition, the outer side of the elastic sealing plug 3 abuts against the hole wall of the frustum hole 22, achieving a seal between the frustum hole 22 and the elastic sealing plug 3, and further achieving a seal between the elastic sealing plug 3 and the through hole, that is, achieving a seal at the open end of the tubing string 1, ensuring the accuracy of the pressure detection unit 52.

[0048] When it is necessary to replace the pressure detection component 5, the wellhead cover 2 or the connector 4 can be unscrewed to remove the pressure detection component 5, thus replacing the pressure detection component 5. The replacement of the pressure detection component 5 is simple, low-cost, and easy to operate.

[0049] The pressure detection component 5 of the coalbed methane well test pressure testing device provided in this embodiment is easy to replace, has good sealing performance, can withstand the pressure of tens of megapascals in the tubing string 1 without damage, can be reused, and has low cost.

[0050] like Figure 2 As shown, the connector 4 can be a bolt, and a second through hole 41 is opened along the axial direction of the bolt.

[0051] like Figure 3 As shown, the outer diameter of the elastic sealing plug 3 can be 0.9-1.1 times the maximum diameter of the frustum hole 22. This allows the elastic sealing plug 3 to easily enter the frustum hole 22, thereby sealing the frustum hole 22, preventing air leakage between the frustum hole 22 and the elastic sealing plug 3, and ensuring the accuracy of pressure detection.

[0052] The diameter of the first through hole 31 is 0.9-1.2 times the diameter of the connecting wire 51. The first through hole 31 facilitates the passage of the connecting wire 51, and when the elastic sealing plug 3 is squeezed by the connecting piece 4 and the wall of the frustum hole 22, it also facilitates the sealing of the first through hole 31, preventing air leakage from the tubing string 1 and ensuring the accuracy of pressure detection.

[0053] Optionally, the elastic sealing plug 3 is made of rubber, which is elastic and has high strength.

[0054] like Figure 4 As shown, the wellhead cover 2 includes an insertion part 26 and a positioning part 27. A through hole passes through the insertion part 26 and the positioning part 27. The insertion part 26 is located inside the tubing string 1 and is threadedly connected to the tubing string 1. The positioning part 27 is connected to the upper end of the insertion part 26, and the lower surface of the positioning part 27 can abut against the upper end face of the wellhead cover 2. The positioning part 27 can determine whether the wellhead cover 2 is connected in place, ensuring the connection strength of the wellhead cover 2. When installing or removing the wellhead cover 2, the operator can hold the positioning part 27 to rotate the wellhead cover 2 for easy installation and removal.

[0055] The upper end of the positioning part 27 can also be connected to the reinforcing protrusion 28, and the connecting hole 21 passes through the reinforcing protrusion 28.

[0056] Specifically, the upper end of the tubing string 1 may be provided with an internal thread, and the insertion part 26 is provided with an external thread that is threaded to the internal thread, thereby connecting the wellhead cover 2 to the tubing string 1.

[0057] like Figure 1 and Figure 4 As shown, a sealing ring 6 is provided between the wellhead cover 2 and the tubing string 1 to further ensure the sealing between the wellhead cover 2 and the tubing string 1.

[0058] The wellhead cover 2 has an annular groove 29, and the sealing ring 6 is disposed in the annular groove 29. The annular groove 29 can prevent the sealing ring 6 from shifting, ensuring the sealing stability of the sealing ring 6. Optionally, there are multiple annular grooves 29, which are spaced apart in the vertical direction, and each annular groove 29 is provided with a sealing ring 6, thereby improving the sealing reliability. In this embodiment, three annular grooves 29 are provided.

[0059] Optionally, the through hole also includes a stop-through hole 23 located below the frustum-shaped hole 22, the diameter of which is not greater than the minimum diameter of the frustum-shaped hole 22. When the elastic sealing plug 3 is subjected to excessive force and partially dislodged from the frustum-shaped hole 22, the stop-through hole 23 can prevent the elastic sealing plug 3 from dislodging from the through hole, thereby ensuring the safety of the pressure detection assembly 5.

[0060] Preferably, the diameter of the stop through hole 23 is equal to the minimum diameter of the frustum hole 22, which facilitates the machining of the through hole 23.

[0061] The maximum diameter of the frustum hole 22 can be equal to the diameter of the connecting hole 21, which makes it easier to machine the frustum hole 22.

[0062] When the length of the insertion part 26 is relatively long, the through hole may also include a clearance hole 24. The clearance hole 24 is located at the lower end of the stop material passage hole 23. The diameter of the clearance hole 24 is larger than the diameter of the stop material passage hole 23, so as to facilitate the passage of the pressure detection component 5 and facilitate the processing of the stop material passage hole 23.

[0063] In this embodiment, the connecting wire 51 can be a metal wire 511, such as a steel wire. One end of the steel wire can be wrapped around the outer shell of the pressure detection unit 52 to fix the pressure detection unit 52 in place, preventing the pressure detection unit 52 from falling off. Furthermore, the metal wire 511 has high strength and is not easily damaged when subjected to the pressure of the elastic sealing plug 3. The pressure detection unit 52 is a storage-type pressure detection unit 52. When it is necessary to read the value of the pressure detection unit 52, the wellhead cover 2 is unscrewed, and the connecting wire 51 and the pressure detection unit 52 are pulled out of the tubing string 1 for reading.

[0064] like Figure 5 As shown, in other optional embodiments, the connecting line 51 can be a cable 512, and the pressure detection assembly 5 also includes a display unit 53, which is used to display the pressure value detected by the pressure detection unit 52. The display unit 53 is located outside the tubing string 1, and the pressure can be directly measured when detecting pressure.

[0065] Optionally, the pressure detection unit 52 can be an OTKJ-SC1BBF-M type direct-reading downhole pressure gauge. The OTKJ-SC1BBF-M type direct-reading downhole pressure gauge can be connected to the cable 512 and the display unit 53 to read the data directly outside the well, or it can store the data and read the data after the pressure detection unit 52 is taken out of the tubing string 1.

[0066] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A coal bed methane well testing pressure testing device, characterized in that, The utility model relates to a kind of wellhead pressure detection device, including: Pipe string (1) is inserted in the hole of stratum, the pipe string (1) is communicated with the space of pressure to be measured; Wellhead cover (2) is connected by thread to the upper port of the pipe string (1), the wellhead cover (2) is provided with through hole, the through hole includes connection hole (21) and circular truncated cone hole (22) sequentially arranged from top to bottom, the diameter of the circular truncated cone hole (22) gradually decreases from top to bottom; Elastic sealing plug (3) is provided with first threading hole (31), and is arranged in the through hole, the minimum diameter of the circular truncated cone hole (22) is less than the outer diameter of the elastic sealing plug (3); Connecting piece (4) is provided with second threading hole (41), the connecting piece (4) is connected with the connection hole (21) by thread, and the elastic sealing plug (3) is located at the lower side of the connecting piece (4); Pressure detection assembly (5) includes connecting wire (51) and pressure detection unit (52), one end of the connecting wire (51) is connected with the pressure detection unit (52), the connecting wire (51) is threaded in the second threading hole (41) and the first threading hole (31), and the other end of the connecting wire (51) is located outside the wellhead cover (2); The connecting piece (4) can extrude the elastic sealing plug (3), so that the elastic sealing plug (3) is at least partially located in the circular truncated cone hole (22), to seal the circular truncated cone hole (22) and the first threading hole (31).

2. The coal bed gas well testing pressure testing device of claim 1, wherein, The outer diameter of the elastic sealing plug (3) is 0.9-1.1 times of the maximum diameter of the circular truncated cone hole (22), and / or The diameter of the first threading hole (31) is 0.9-1.2 times of the diameter of the connecting wire (51).

3. The coal bed gas well testing pressure testing device of claim 1, wherein, The through hole further includes stop hole (23) located at the lower side of the circular truncated cone hole (22), and the diameter of the stop hole (23) is not greater than the minimum diameter of the circular truncated cone hole (22).

4. The coal bed gas well testing pressure testing device of claim 3, wherein, The through hole further includes avoiding hole (24), and the avoiding hole (24) is located at the lower end of the stop hole (23).

5. The coal bed gas well testing pressure testing device of claim 1, wherein, The elastic sealing plug (3) is made of rubber.

6. The coal bed gas well testing pressure testing device of claim 1, wherein, The wellhead cover (2) and the pipe string (1) are provided with sealing ring (6).

7. The coal bed gas well testing pressure testing device of claim 6, wherein, The wellhead cover (2) is provided with annular groove (29), and the sealing ring (6) is arranged in the annular groove (29).

8. The coal bed gas well testing pressure testing device of claim 1, wherein, The wellhead cover (2) includes insertion part (26) and positioning part (27), the insertion part (26) is located in the pipe string (1) and is connected with the pipe string (1) by thread, the positioning part (27) is connected to the upper end of the insertion part (26), and the lower surface of the positioning part (27) can abut on the upper end surface of the wellhead cover (2).

9. The coal bed gas well testing pressure testing device of claim 8, wherein, The upper end of the pipe string (1) is provided with internal thread, and the insertion part (26) is provided with external thread which is connected with the internal thread by thread.

10. The coal bed gas well testing pressure testing device of claim 1, wherein, The pressure detection assembly (5) further includes display unit (53), the display unit (53) is used to display the pressure value detected by the pressure detection unit (52), and the connecting wire (51) is electric cable (512);Or The connecting wire (51) is metal wire (511).

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