A precise leak detection device and method for accurate positioning of the entire wellbore in oil and gas wells

Abstract

This invention relates to the technical field of oilfield production engineering, and particularly to a device and method for accurate positioning and precision leak testing of the entire wellbore in oil and gas wells. The device includes: a guide head, the upper end of which is sequentially connected to a locator, a packer, a check valve, and coiled tubing; the locator includes a central tube, an outer fixed-position sleeve, and the outer locating sleeve is connected to a locator limiting sleeve; the packer includes a central connecting tube, which connects to a rubber sleeve, a cone-shaped body, an inner packer sleeve, an outer packer sleeve, and a track sleeve, the inner packer sleeve is connected to a card mechanism, the card mechanism is connected to a fixing plate mechanism, and the track sleeve; the check valve includes an upper connector, which connects to a check valve limiting sleeve and an inner check valve sleeve, the inner check valve sleeve is connected to an outer check valve sleeve, the inner check valve sleeve is connected to a T-type packing mechanism, and the T-type packing mechanism is connected to a pressure ring mechanism. The device and method for accurate positioning and precision leak testing of the entire wellbore in oil and gas wells provided by this invention accurately positions the well and enables continuous and rapid precision leak testing of the entire well.

Description

Technical Field

[0001] This invention relates to the technical field of oilfield production engineering, and in particular to a precision leak detection device and method for accurate positioning of the entire wellbore of an oil and gas well. Background Technology

[0002] In the oilfield sector, all types of wells are crucial. Whether oil / gas or water wells, leakage can have devastating consequences, with oil / gas well leakage being particularly severe. Generally, wells with good leakage potential can still be operated on after repairs or fracturing; however, wells with severe leakage often require abandonment, resulting in significant economic and labor losses. While leakage can be addressed through repairs, early leak detection is far more important than reactive measures. In fact, many wells lack the equipment and methods for quickly and accurately locating and precisely detecting leaks, preventing workers from tapping into their potential and severely impacting production and profitability. Therefore, to address these shortcomings, a precise leak detection device and method for accurate positioning throughout the entire wellbore of oil / gas wells is proposed. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] This invention provides a device and method for accurate positioning and precision leak detection of the entire wellbore of oil and gas wells. It avoids the problems of existing methods, such as the inability to quickly detect leaks, the inability to accurately locate and precisely detect leaks, which leads to low leak detection efficiency in oilfield seepage wells and causes unexplained seepage throughout the wellbore of oil and gas wells, affecting production and efficiency.

[0005] (II) Technical Solution

[0006] To address the above problems, this invention provides a precision leak detection device for accurate positioning of the entire wellbore in oil and gas wells, comprising:

[0007] A guide head, the upper end of which is sequentially connected to a positioner, a packer, a check valve, and a continuous tubing;

[0008] The positioner includes a central tube, and a positioning sleeve is fixed to the outside of the central tube by a positioner pin. The outer side of the positioning sleeve is provided with a protrusion, and a positioner limiting sleeve is connected to the bottom of the positioning sleeve by a thread.

[0009] The packer includes a central connecting tube, to which a rubber sleeve, a cone-shaped body, a packer inner sleeve, a packer outer sleeve, and a track sleeve are connected. The rubber sleeve and the cone-shaped body are connected, and the cone-shaped body and the central connecting tube are sealed by a sealing rubber ring. The sealing rubber ring is connected to a gasket. The outer side of the packer inner sleeve is connected to a card mechanism. The card mechanism is connected to a fixing plate mechanism by a locking ring. The outer side of the fixing plate mechanism is connected to the packer outer sleeve, and the bottom end of the card mechanism is connected to the track sleeve.

[0010] The check valve includes an upper connector, a check valve limiting sleeve connected to the outer side of the upper connector, a check valve inner sleeve connected to the bottom end of the upper connector, a check valve outer sleeve connected to the outer side of the inner sleeve, a check valve limiting sleeve connected to the outer sleeve, a T-shaped packing mechanism connected to the outer side of the lower end of the inner sleeve, and a pressure ring mechanism connected to the T-shaped packing mechanism.

[0011] Preferably, the card mechanism includes a card sleeve, a card, and a card spring, wherein the two ends of the card sleeve are the card and a locking ring, respectively, and the card is provided with a card spring.

[0012] Preferably, the fixing plate mechanism includes a fixing plate and fixing plate springs. The upper end of the fixing plate is a locking ring, and two fixing plate springs are provided on the fixing plate. The outer side of the fixing plate is connected to the packer sleeve through a packer pin, and the bottom end of the fixing plate is connected to the track sleeve through a track pin.

[0013] Preferably, the T-shaped packing mechanism includes two T-shaped packings, the pressure ring mechanism includes a pressure ring and a pressure cap, the two T-shaped packings are connected, the pressure ring is between the two T-shaped packings, and the pressure cap is connected to the T-shaped packing at the tail end.

[0014] Preferably, the check valve limiting sleeve and the upper connector are sealed by a sealing ring, the check valve limiting sleeve is connected to the check valve outer sleeve by a check valve pin, and the check valve inner sleeve is connected to the upper connector by a check valve pin.

[0015] Preferably, the coiled tubing is equipped with a monitoring meter and a counter. The monitoring meter monitors the changes in the suspended weight of the coiled tubing during the running-in process in real time, and the counter measures the running-in depth of the coiled tubing in real time.

[0016] This invention also provides a method for a precision leak detection device based on accurate positioning of the entire wellbore of an oil and gas well, comprising:

[0017] Step S1: Complete the connection of the leak detection device and lower the connected leak detection device to the bottom of the well;

[0018] Step S2: Raise the fracturing tubing string, determine the short casing depth using the locator, and verify the obtained short casing depth based on the short casing depth and length data in the acoustic amplitude logging data after well completion. Calculate the error value between the running depth of the coiled tubing and the logging depth, and preliminarily determine the location of the leakage point based on the error value.

[0019] Step S3: Based on the preliminary location of the leak point obtained in step S2, the packer is set by lifting and lowering the coiled tubing, while the check valve is closed to seal the coiled tubing, reduce pressure backflow, minimize leakage, and reduce leak detection error. After setting, the hanging weight of the monitoring gauge returns to 0. By pressing down the coiled tubing, the hanging weight range of the monitoring gauge is displayed as 20-30kN.

[0020] Step S4: Pressurize the casing inside the wellhead and monitor the pressure gauge changes to determine if leakage has occurred at the current well depth;

[0021] Step S5: If there is no leak at the depth monitored in step S4, raise the tubing string to half the depth between the wellhead and the current depth. Repeat steps S3 and S4 in this manner until the leak point is found.

[0022] Step S6: After identifying the leak point, end the test, depressurize the casing, and disassemble the device. Then, repair the leak point.

[0023] Preferably, in step S2, the suspended weight monitored by the monitoring meter increases by 10-20 kN for each sleeve coupling the positioner passes, and the number of sleeve couplings passed is determined by the suspended weight.

[0024] Preferably, in step S2, the error value is the difference between the downhole depth and the logging depth, and the preliminary location of the leakage point is the difference between the downhole depth and the error value.

[0025] Preferably, in step S5, if the pressure value of the pressure gauge remains stable, it indicates that there is no leakage up to this depth from the wellhead; if the pressure value of the pressure gauge continues to drop, it indicates that leakage has occurred in this section.

[0026] (III) Beneficial Effects

[0027] The invention provides an accurate positioning and precision leak detection device and method for the entire wellbore of oil and gas wells. It accurately positions the leaks and enables continuous and rapid precision leak detection throughout the well, effectively solving problems such as unexplained leakage in the entire wellbore of oil and gas wells, inability to quickly detect leaks, and inability to accurately locate and precisely detect leaks. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the precise leak detection device for accurate positioning of the entire wellbore in an oil and gas well, according to an embodiment of the present invention.

[0029] Figure 2This is a schematic diagram of the locator in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the packer structure according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the check valve structure according to an embodiment of the present invention;

[0032] Figure 5 This is an application diagram of the check valve in an embodiment of the present invention.

[0033] Wherein: 1-Guide head; 2-Positioner; 3-Packer; 4-Check valve; 5-Continuous tubing;

[0034] 21-Center tube; 22-Positioning sleeve; 23-Positioner pin; 24-Positioner limit sleeve;

[0035] 31-Center connecting pipe; 32-Glue sleeve; 33-Sealing rubber ring; 34-Washer; 35-Conical body; 36-Card; 37-Card spring; 38-Packer inner sleeve; 39-Card sleeve; 310-Locking ring; 311-Fixing plate; 312-Fixing plate spring; 313-Packer pin; 314-Packer outer sleeve; 315-Railway sleeve; 316-Railway pin;

[0036] 41-Upper connector; 42-Sealing ring; 43-Check valve pin; 44-Check valve limit sleeve; 45-Check valve inner sleeve; 46-Check valve outer sleeve; 47-T-type packing; 48-Pressure ring; 49-Pressure cap. Implementation

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] Figure 1 This is a schematic diagram of the precise leak detection device for accurate positioning of the entire wellbore in an oil and gas well, as described in an embodiment of the present invention. Figure 1 As shown, the present invention provides a precision leak detection device for accurate positioning of the entire wellbore of an oil and gas well, comprising:

[0039] Guide head 1, the upper end of guide head 1 is connected to positioner 2, positioner 2 is connected to packer 3, packer is connected to check valve 4, and the upper end of check valve 4 is connected to continuous oil pipe 5.

[0040] Figure 2 This is a schematic diagram of the locator in an embodiment of the present invention, as shown below. Figure 2As shown, the positioner 2 includes a central tube 21. The outer side of the central tube 21 is connected to the positioning sleeve 22 by the positioner pin 23. The outer side of the positioning sleeve 22 is provided with a protrusion. The lower part of the positioning sleeve 22 is connected to the positioner limiting sleeve 24 by a thread.

[0041] In practical applications, the positioning sleeve 22 is hung on the outer wall of the central tube 21. When the tube string is lifted, the protrusion of the positioning sleeve 22 passes through the gap of the casing coupling, the weight of the coiled tubing increases, which can determine the lowering position of the device.

[0042] Figure 3 This is a schematic diagram of the packer structure according to an embodiment of the present invention, as shown below. Figure 3 As shown, the packer 3 includes a central connecting tube 31. The outer side of the central connecting tube 31 is connected to a rubber sleeve 32, a cone-shaped body 35, a packer inner sleeve 38, a packer outer sleeve 314, and a track sleeve 315. The rubber sleeve 32 and the cone-shaped body 35 are connected. The outer side of the packer inner sleeve 38 is connected to a card mechanism. The card mechanism is connected to a fixing plate mechanism. The outer side of the fixing plate mechanism is connected to the packer outer sleeve 314. The bottom end of the card mechanism is connected to the track sleeve 315.

[0043] Figure 4 This is a schematic diagram of the check valve structure according to an embodiment of the present invention. Figure 5 This is an application diagram of the check valve according to an embodiment of the present invention, as shown below. Figure 4 and Figure 5 As shown, the check valve 4 includes an upper connector 41, the outer side of which is connected to a check valve limiting sleeve 44, the bottom end of which is connected to a check valve inner sleeve 45, the outer side of which is connected to a check valve outer sleeve 46, the check valve limiting sleeve 44 is connected to the check valve outer sleeve 46, the outer side of the lower end of the check valve inner sleeve 45 is connected to a T-type packing mechanism, and the T-type packing mechanism is connected to a pressure ring mechanism.

[0044] In practical applications, the cone-shaped body 35 and the central connecting tube 31 are sealed by a sealing ring 33, which is connected to a gasket 34. The card mechanism is connected to the fixing plate mechanism by a locking ring 310.

[0045] It should be noted that the card mechanism includes a card sleeve 39, a card 36, and a card spring 37. The two ends of the card sleeve 39 are the card 36 and the locking ring 310, respectively. The card 36 is provided with a card spring 37. In addition, the fixing plate mechanism includes a fixing plate 311 and a fixing plate spring 312. The upper end of the fixing plate 311 is the locking ring 310. The fixing plate 311 is provided with two fixing plate springs 32. The outer side of the fixing plate 311 is connected to the packer outer sleeve 314 through the packer pin 313. The bottom end of the fixing plate 311 is connected to the track sleeve 315 through the track pin 316.

[0046] In this leak detection device, the rubber tube 32, the card 33, the fixing plate 311, and the packer outer sleeve 314 are all hung on the outer wall of the central connecting pipe 31. By lifting and lowering the central connecting pipe 31, the track of the central connecting pipe 31 is changed, the card 36 is dismounted, and the rubber tube 32 is set.

[0047] In practical applications, the check valve limiting sleeve 44 and the upper connector 41 are sealed by a sealing ring 42. The check valve limiting sleeve 44 is connected to the check valve outer sleeve 46 by the check valve pin 43. The check valve inner sleeve 45 is connected to the upper connector 41 by the check valve pin 43. In addition, the T-type packing mechanism includes two T-type packings 47, and the pressure ring mechanism includes a pressure ring 48 and a pressure cap 49. The two T-type packings 47 are connected, and the pressure ring 48 is between the two T-type packings 47. The T-type packings 47 at the tail end are connected to the pressure cap 49.

[0048] In this leak detection device, a sealing ring 42 is installed in the check valve limiting sleeve 44, the check valve limiting sleeve 44 is fitted into the upper connector 41, the T-shaped packing 47 is fitted into the check valve inner sleeve 45, the pressure cap 49 is pressed on, the pressure ring 48 is tightened, the check valve inner sleeve 45 is threadedly connected to the upper connector 41, and the check valve outer sleeve 46 is threadedly connected to the check valve limiting sleeve 44. When it is necessary to seal the check valve 4, the upper connector 41 is pressed down, which moves the T-shaped packing 47 to the check valve outer sleeve 46 to form a seal and prevent backflow.

[0049] In addition, the coiled tubing 5 is equipped with a monitoring meter and a counter. The monitoring meter monitors the changes in the suspended weight during the running of the coiled tubing into the well in real time, and the counter measures the running depth of the coiled tubing into the well in real time.

[0050] This invention also provides a method for a precision leak detection device based on accurate positioning of the entire wellbore of an oil and gas well, comprising:

[0051] Step S1: Complete the connection of the leak detection device and lower the connected leak detection device to the bottom of the well;

[0052] Step S2: Raise the fracturing tubing string, determine the short casing depth using the locator, and verify the obtained short casing depth based on the short casing depth and length data in the acoustic amplitude logging data after well completion. Calculate the error value between the running depth of the coiled tubing and the logging depth, and preliminarily determine the location of the leakage point based on the error value.

[0053] Step S3: Based on the preliminary location of the leak point obtained in step S2, the packer is set by lifting and lowering the coiled tubing, while the check valve is closed to seal the coiled tubing, reduce pressure backflow, minimize leakage, and reduce leak detection error. After setting, the hanging weight of the monitoring gauge returns to 0. By pressing down the coiled tubing, the hanging weight range of the monitoring gauge is displayed as 20-30kN.

[0054] Step S4: Pressurize the casing inside the wellhead and monitor the pressure gauge changes to determine if leakage has occurred at the current well depth;

[0055] Step S5: If there is no leak at the depth monitored in step S4, raise the tubing string to half the depth between the wellhead and the current depth. Repeat steps S3 and S4 in this manner until the leak point is found.

[0056] Step S6: After identifying the leak point, end the test, depressurize the casing, and disassemble the device. Then, repair the leak point.

[0057] In practical applications, the suspended weight monitored by the positioner 2 increases by 10-20kN for each casing coupling it passes. The number of casing couplings passed is determined by the suspended weight, and the depth of the casing coupling is obtained by the number of casing couplings.

[0058] In this leak detection method, the error value is the difference between the well depth and the logging depth. The initial location of the leak point is the difference between the well depth and the error value. In practical applications, if the pressure value of the pressure gauge remains stable, it indicates that there is no leakage up to this depth from the wellhead. If the pressure value of the pressure gauge continues to drop, it indicates that leakage has occurred in this section.

[0059] Daqing Oilfield currently has over 10,000 leaking wells of various types, of which more than 2,000 have good potential and require subsequent downhole operations such as repair and fracturing. However, to date, there is no technology for quickly and accurately locating leak points and performing precise leak testing, which prevents these wells from being fully exploited and seriously affects production and efficiency. The following describes in detail the practical application process of this precision leak testing device based on accurate positioning of the entire wellbore in oil and gas wells:

[0060] Step 1: Complete the connection of the leak detection device and lower the connected leak detection device to the bottom of the well.

[0061] In this embodiment, the upper end of the guide head 1 is connected to the positioner 2, the positioner 2 is connected to the packer 3, the packer is connected to the check valve 4, and the upper end of the check valve 4 is connected to the continuous tubing 5.

[0062] Step 2: Raise the fracturing string and determine the short casing depth using the locator. Based on the short casing depth and length data from the post-completion acoustic amplitude logging data, verify the obtained short casing depth and calculate the error value between the running depth of the coiled tubing and the logging depth. Use the error value to preliminarily determine the location of the leakage point.

[0063] In this embodiment, when the lifting tubing passes through the casing coupling, the protruding part of the positioning sleeve 22 enters the casing coupling gap. At this time, the suspended weight displayed on the monitoring meter of the coiled tubing 5 increases. For each casing coupling that the positioner 2 passes through, the suspended weight monitored by its monitoring meter increases by 10-20kN. The number of casing couplings passed through is determined by the change in suspended weight, thereby determining the lowering position of the leak detection device.

[0064] In practical applications, the short casing depth is checked based on the short casing depth and length data in the acoustic amplitude logging data after well completion, the error value is calculated, and the location of the leakage point is preliminarily determined through the error value.

[0065] Step 3: Based on the preliminary location of the leak point obtained in Step 2, the packer is set by lifting and lowering the coiled tubing, while the check valve is closed to seal the coiled tubing, reduce pressure backflow, minimize leakage, and reduce leak detection error. After setting, the suspended weight of the monitoring gauge returns to 0. By pressing down the coiled tubing, the suspended weight range of the monitoring gauge is made to display 20-30 kN.

[0066] In this embodiment, the rubber sleeve 32 is fitted onto the central connecting pipe 31, and a conical body 35 is installed below the central connecting pipe 31. The sealing rubber ring 33 and the washer 36 are embedded in the conical body 35. The packer inner sleeve 38 is fitted onto the central connecting pipe 31. The card 36 and the card spring 37 are fixed onto the packer inner sleeve 38 through the card sleeve 39. The fixing plate 311 and the fixing plate spring 312 are embedded into the packer outer sleeve 314 through the packer pin 313. The packer outer sleeve 39 is fitted onto the central connecting pipe 31 and is limited by the locking ring 310. In addition, the track pin 316 is embedded into the track sleeve 315 and then into the outer sleeve 39.

[0067] In practical applications, the central connecting pipe 31 is raised and lowered, the track is changed, the card 36 is dispensing, the sealing tube 32 is set, and the sealing sleeve is sealed.

[0068] In this embodiment, a sealing ring 42 is installed in the check valve limiting sleeve 44, and the upper connector 4.1 is fitted in. The T-shaped packing 47 is fitted in the check valve inner sleeve 45, the pressure cap 49 is pressed on, and the pressure ring 48 is tightened. The check valve inner sleeve 45 is threadedly connected to the upper connector 41, and the check valve outer sleeve 46 is threadedly connected to the check valve limiting sleeve 44.

[0069] By pressing down the upper connector 41, the T-shaped packing 47 is driven to the outer sleeve 46 to form a seal, close the check valve 4, prevent back pressure, reduce leakage, and minimize leak detection errors.

[0070] Step 4: Pressurize the casing inside the wellhead and monitor the pressure gauge changes to determine if leakage has occurred at the current well depth.

[0071] In practical applications, after sealing the casing, the casing is pressurized at the wellhead, and the well section is inspected. The pressure gauge at the wellhead is observed to determine the leakage situation in the well section.

[0072] Step 5: If there is no leak at the depth monitored in Step 4, raise the tubing string to half the depth between the wellhead and the current depth. Repeat Steps 3 and 4 in this manner until the leak point is found.

[0073] Step Six: After identifying the leak point, end the test, depressurize the casing, disassemble the device, and repair the leak point after confirming its location.

[0074] In practical applications, once the leak point is located, the test can be ended, the leak detection device can be disassembled, and the foundation can be laid for subsequent repair work on the leak point.

[0075] In this embodiment, after the test is completed, the sleeve is depressurized, the tubing is lifted to change the track of the central connecting pipe 31, the card 36 is retrieved, and the rubber tube 32 is unsealed; at the same time, the lifting of the tubing drives the upper connector 41 to move upward, opening the check valve 4 and balancing the pressure.

[0076] The invention provides an accurate positioning and precision leak detection device and method for the entire wellbore of oil and gas wells. It accurately positions the leaks and enables continuous and rapid precision leak detection throughout the well, effectively solving problems such as unexplained leakage in the entire wellbore of oil and gas wells, inability to quickly detect leaks, and inability to accurately locate and precisely detect leaks.

[0077] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A precision leak detection device for accurate positioning of the entire wellbore of an oil and gas well, characterized in that, include: Guide head (1), the upper end of which is connected in sequence to positioner (2), packer (3), check valve (4) and coiled tubing (5); The locator (2) includes a central tube (21), and the outer side of the central tube (21) is fixed with a locator sleeve (22) by a locator pin (23). The outer side of the locator sleeve (22) is provided with a protrusion, and the lower part of the locator sleeve (22) is connected to a locator limiting sleeve (24) by a thread. The packer (3) includes a central connecting tube (31), and the outer side of the central connecting tube (31) is connected to a rubber sleeve (32), a cone-shaped body (35), a packer inner sleeve (38), a packer outer sleeve (314), and a track sleeve (315). The rubber sleeve (32) and the cone-shaped body (35) are connected. The cone-shaped body (35) and the central connecting tube (31) are sealed by a sealing rubber ring (33). The sealing rubber ring (33) is connected to a gasket (34). The outer side of the packer inner sleeve (38) is connected to a card mechanism. The card mechanism is connected to a fixing plate mechanism through a locking ring (310). The outer side of the fixing plate mechanism is connected to the packer outer sleeve (314). The bottom end of the card mechanism is connected to the track sleeve (315). The check valve (4) includes an upper connector (41), the outer side of which is connected to a check valve limiting sleeve (44), the bottom end of which is connected to a check valve inner sleeve (45), the outer side of which is connected to a check valve outer sleeve (46), the check valve limiting sleeve (44) is connected to the check valve outer sleeve (46), the outer side of the lower end of the check valve inner sleeve (45) is connected to a T-type packing mechanism, and the T-type packing mechanism is connected to a pressure ring mechanism. The coiled tubing (5) is equipped with a monitoring table and a counter. The monitoring table monitors the change in suspended weight during the running of the coiled tubing into the well in real time, and the counter measures the running depth of the coiled tubing into the well in real time.

2. The precision leak detection device for accurate positioning of the entire wellbore of oil and gas wells according to claim 1, characterized in that, The card mechanism includes a card sleeve (39), a card (36) and a card spring (37). The two ends of the card sleeve (39) are the card (36) and the locking ring (310), respectively. The card (36) is provided with a card spring (37).

3. The precision leak detection device for accurate positioning of the entire wellbore of oil and gas wells according to claim 1, characterized in that, The fixing plate mechanism includes a fixing plate (311) and a fixing spring (312). The upper end of the fixing plate (311) is a locking ring (310). Two fixing springs (312) are provided on the fixing plate (311). The outer side of the fixing plate (311) is connected to the packer outer sleeve (314) through the packer pin (313). The bottom end of the fixing plate (311) is connected to the track sleeve (315) through the track pin (316).

4. The precision leak detection device for accurate positioning of the entire wellbore of oil and gas wells according to claim 1, characterized in that, The T-type packing mechanism includes two T-type packings (47), and the pressure ring mechanism includes a pressure ring (48) and a pressure cap (49). The two T-type packings (47) are connected, and the pressure ring (48) is between the two T-type packings (47). The T-type packings (47) at the tail end are connected to the pressure cap (49).

5. The precision leak detection device for accurate positioning of the entire wellbore of oil and gas wells according to claim 4, characterized in that, The check valve limiting sleeve (44) and the upper connector (41) are sealed by a sealing ring (42). The check valve limiting sleeve (44) is connected to the check valve outer sleeve (46) by a check valve pin (43). The check valve inner sleeve (45) is connected to the upper connector (41) by a check valve pin (43).

6. A method for accurate positioning and precision leak detection of the entire wellbore of an oil and gas well based on the precision leak detection device for accurate positioning of the entire wellbore according to any one of claims 1-5, characterized in that, include: Step S1: Complete the connection of the leak detection device and lower the connected leak detection device to the bottom of the well; Step S2: Raise the fracturing string and measure the short casing depth using the locator (2). Based on the data of the short casing depth and length in the acoustic amplitude logging data after well completion, check the obtained short casing depth and calculate the error value between the running depth of the coiled tubing (5) and the logging depth. The location of the leakage point is initially determined by the error value. Step S3: Based on the preliminary location of the leak point obtained in step S2, the packer (3) is set by lifting and lowering the coiled tubing (5), while simultaneously closing the check valve (4) to seal the coiled tubing (5), thereby preventing pressure backflow and reducing leakage. To reduce the leak detection error, after setting the seal, the suspended weight of the monitoring gauge is returned to 0. By pressing down the continuous tubing (5), the suspended weight range of the monitoring gauge is displayed as 20-30kN. Step S4: Pressurize the casing inside the wellhead and monitor the pressure gauge changes to determine if leakage has occurred at the current well depth; Step S5: If there is no leak at the depth monitored in step S4, raise the tubing string to half the depth between the wellhead and the current depth. Repeat steps S3 and S4 in this manner until the leak point is found. Step S6: After identifying the leak point, end the test, depressurize the casing, and disassemble the device. Then, repair the leak point.

7. The method for accurate positioning and precision leak detection of the entire wellbore of oil and gas wells according to claim 6, characterized in that, In step S2, the positioner (2) increases the suspended weight monitored by the monitoring table by 10-20kN each time it passes a sleeve coupling. The number of sleeve couplings passed is determined by the suspended weight.

8. The method for accurate positioning and precision leak detection of the entire wellbore of an oil and gas well according to claim 6, characterized in that, In step S2, the error value is the difference between the well depth and the logging depth, and the preliminary location of the leakage point is the difference between the well depth and the error value.

9. The method for accurate positioning and precision leak detection of the entire wellbore of an oil and gas well according to claim 6, characterized in that, In step S5, if the pressure value of the pressure gauge remains stable, it indicates that there is no leakage up to this depth of the wellhead. If the pressure value of the pressure gauge continues to drop, it indicates that leakage has occurred in this section.

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