Blockage removing tool and blockage removing system for coal-bed gas well
By using unblocking tools consisting of a central tube and rubber plugs in coalbed methane wells, and clearing the gas production channels with water flow, the problem of coalbed methane well blockage was solved, achieving low-cost and safe unblocking results and significantly increasing gas production.
Patent Information
- Application Number
- CN202520158514.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2035-01-23
AI Technical Summary
Existing coalbed methane wells are prone to blockage during the drainage process, leading to a decrease in gas production. Current unblocking methods, such as nitrogen unblocking and secondary fracturing, are costly and easily damage formation channels, making it difficult to effectively restore gas production.
A deblocking tool consisting of a central tube, rubber plug, upper protective plate, lower protective plate, upper coupling, and lower coupling is used. By reciprocating up and down within the production casing, the deposition state of the blockage is changed, and water flow is used to clear the gas production channel, thus avoiding damage to the proppant.
It achieves safe and low-cost unblocking, significantly increases gas production in a short period of time, reduces construction complexity and equipment requirements, lowers construction costs, and does not damage the formation channels.
Smart Images
Figure CN223647790U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a coalbed methane well unblocking tool and unblocking system, belonging to the technical field of coalbed methane well unblocking tools. Background Technology
[0002] To establish connectivity between the formation and the wellbore, enabling coalbed methane (CBM) to enter and be extracted, CBM wells typically require perforation. During perforation, fracturing sand is injected into the underground rock through high-pressure water or gas flow, creating fractures. These fractures increase the permeability of the gas layer, thereby improving CBM recovery rates. Specifically, fracturing sand acts as a proppant, filling and supporting the fractures to prevent closure, thus ensuring that CBM can smoothly enter the well through the fractures, resulting in increased production.
[0003] During the production process, coalbed methane wells discharge a large amount of coalbed methane and water. Some fracturing sand and coal dust smaller than the perforation diameter are also discharged, while other coal particles larger than the perforation diameter are squeezed and blocked outside the perforation. With long-term discharge, the blockage outside the perforation will block even smaller sand and coal dust, and the blockage will increase. As the discharge time is further extended, the gas production channel will become smaller and smaller or even completely blocked. The coalbed methane well will experience a decrease in gas production or even no gas production. At this time, it is necessary to unblock the coalbed methane well.
[0004] Currently, the commonly used method in the industry is nitrogen deblocking. This involves injecting large volumes of nitrogen into the formation using liquid nitrogen pumps. The high-pressure nitrogen propels the blockage deeper into the formation, followed by rapid venting to return the blockage to the surface. While this method produces a rapid increase in gas production in the short term, production quickly declines after a period of drainage, sometimes failing to recover to previous levels. This is because nitrogen deblocking disrupts the original formation channels, transporting fracturing sand deeper into the formation. After resuming normal drainage, the formation lacks this hard proppant, replaced by coal seam debris. Over time, the formation closes, trapping the coalbed methane within. Regaining production requires repeated deblocking, resulting in high costs.
[0005] Another method is secondary fracturing and plugging, but secondary fracturing requires precise control over fracture formation and propagation, making it technically complex and demanding. Furthermore, secondary fracturing is more expensive and requires more equipment and human resources.
[0006] To address this phenomenon, a process and method are needed that can achieve the purpose of unblocking without damaging the proppant. Utility Model Content
[0007] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a coalbed methane well unblocking tool and unblocking system that is easy to operate, does not damage the proppant, and has low construction cost.
[0008] To achieve the above objectives, this utility model adopts the following technical solution: a coalbed methane well unblocking tool, comprising a central tube, a rubber plug, an upper protective plate, a lower protective plate, an upper coupling, and a lower coupling. The rubber plug is an elastic cylinder with thicker ends and a thinner middle section, and it has an axial through hole. The upper and lower protective plates are both circular plates with a central opening. The outer diameter of the upper and lower protective plates is smaller than the maximum diameter of the rubber plug. The rubber plug, the upper protective plate, and the lower protective plate are all fitted onto the outside of the central tube, with the rubber plug located in the middle. The upper and lower protective plates are located above and below the rubber plug, respectively. The upper and lower ends of the central tube have external threads. The upper coupling is threaded to the upper end of the central tube to press the upper protective plate tightly, and the lower coupling is threaded to the lower end of the central tube to press the lower protective plate tightly.
[0009] Furthermore, the stopper is made of rubber.
[0010] Furthermore, the rubber stopper, upper protective plate, lower protective plate, and central tube are all clearance fit.
[0011] A coalbed methane well unblocking system including the aforementioned coalbed methane well unblocking tool includes a workover truck, a water tanker truck, the original well tubing, and the unblocking tool. The upper end of the original well tubing is hoisted on the workover truck, and the lower end extends into the production casing. The water tanker truck is connected to one end of a drain pipe, and the other end of the drain pipe is connected to the annulus between the original well tubing and the production casing. The upper coupling in the unblocking tool is threadedly connected to the lower end of the original well tubing, and the lower coupling in the unblocking tool is threadedly connected to a plug.
[0012] Furthermore, there are multiple unblocking tools connected in series from top to bottom. A tubing short section is provided between each adjacent unblocking tool. Both ends of the tubing short section have external threads. The upper end of each tubing short section is connected to the lower coupling in the unblocking tool above it, and the lower end is connected to the upper coupling in the unblocking tool below it. The uppermost upper coupling is threaded to the lower end of the original well tubing, and the lowermost lower coupling is threaded to a plug.
[0013] Furthermore, the number of unblocking tools is two or three.
[0014] Furthermore, the spacing between adjacent unblocking tools is 30cm-50cm, where the spacing refers to the distance between the lower end face of the lower guard plate in the upper unblocking tool and the upper end face of the upper guard plate in the lower unblocking tool.
[0015] Compared with the prior art, the present invention has the following beneficial effects.
[0016] 1. This utility model utilizes the reciprocating motion of the unblocking tool within the production casing to continuously alter the deposition state of coal dust, coal debris, and other blockages around the perforated section of the target coal seam under the suction force. Fine particles, coal debris, and coal dust in the reservoir affected by the water flow are partially carried out, thus clearing the gas production channel. Furthermore, during the operation, the amount of water used and the speed of the water flow are insufficient to move the proppant in the gas production channel, and the gas production channel is not damaged.
[0017] 2. Apart from the unblocking tool, all other equipment in this utility model are existing well repair equipment. No other complicated auxiliary equipment is required, resulting in low safety risks during construction. In addition, the construction process is simple and can be completed in 2-3 working days, with a short construction period.
[0018] 3. The unblocking tool in this utility model is simple to manufacture and easy to obtain materials. After the construction of a coalbed methane well is completed, the rubber plug will wear out. After the rubber plug is replaced, it can be reused in multiple wells, resulting in low construction costs.
[0019] 4. In this utility model, all components of the unblocking tool are designed to be detachable. During use, only the rubber plug is worn, making replacement convenient and quick. The rubber plug is an elastic cylinder that is thick at both ends and thin in the middle. Both ends can be used to seal the production casing, resulting in a good sealing effect. It can also reduce the number of unblocking tools connected in series on the original well tubing, further reducing costs. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a structural schematic diagram of Embodiment 1 of the present utility model.
[0022] Figure 2 This is a structural schematic diagram of Embodiment 2 of the present invention.
[0023] Figure 3 for Figure 2 A schematic diagram of a structure in which multiple unblocking tools are connected in series.
[0024] In the diagram: 1 is the central tube, 2 is the rubber plug, 3 is the upper protective plate, 4 is the lower protective plate, 5 is the upper coupling, 6 is the lower coupling, 7 is the workover truck, 8 is the water tanker, 9 is the original well tubing, 10 is the unblocking tool, 11 is the production casing, 12 is the drain pipe, 13 is the plug, 14 is the tubing sub, 15 is the target coal seam, and 16 is the annulus. Detailed Implementation
[0025] The technical solutions of the present utility model will be clearly and completely described in conjunction with the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.
[0026] It should be noted that the structures, proportions, sizes, etc. shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this utility model can be implemented. Therefore, they have no substantial technical significance. Any modification to the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in this utility model, provided that it does not affect the effects and purposes that this utility model can produce. It should be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.
[0027] The present invention provides the following embodiments.
[0028] Example 1
[0029] like Figure 1 As shown, this utility model discloses a coalbed methane well unblocking tool, comprising a central tube 1, a rubber plug 2, an upper protective plate 3, a lower protective plate 4, an upper coupling 5, and a lower coupling 6. The rubber plug 2 is an elastic cylinder with thicker ends and a thinner middle section, and it has an axial through hole. The upper protective plate 3 and the lower protective plate 4 are both circular plates with a central opening. The outer diameter of the upper protective plate 3 and the lower protective plate 4 is smaller than the maximum diameter of the rubber plug 2. The rubber plug 2, the upper protective plate 3, and the lower protective plate 4 are all fitted onto the outside of the central tube 1, with the rubber plug 2 located in the middle. The upper protective plate 3 and the lower protective plate 4 are located above and below the rubber plug 2, respectively. The upper and lower ends of the central tube 1 have external threads. The upper coupling 5 is threadedly connected to the upper end of the central tube 1 to press the upper protective plate 3 tightly, and the lower coupling 6 is threadedly connected to the lower end of the central tube 1 to press the lower protective plate 4 tightly.
[0030] The rubber stopper 2 is made of rubber.
[0031] The rubber stopper 2, upper protective plate 3, lower protective plate 4 and central tube 1 are all clearance fit.
[0032] The thicker parts at both ends and the thinner parts in the middle of the rubber stopper 2 have a smooth arc transition.
[0033] In this embodiment, all components are detachably connected, making it easy and convenient to replace the rubber plug 2 after it wears out. Furthermore, the rubber plug 2 is an elastic cylinder that is thicker at both ends and thinner in the middle; both its upper and lower ends can seal the production casing 9, resulting in a good sealing effect. This also reduces the number of unblocking tools 10 connected in series on the original well tubing in Embodiment Two below, thus lowering costs.
[0034] Example 2
[0035] like Figure 2 , Figure 3 As shown, a coalbed methane well unblocking system includes a workover vehicle 7, a water tanker 8, the original well tubing 9, and an unblocking tool 10. The upper end of the original well tubing 9 is hoisted on the workover vehicle 7, and the lower end extends into the production casing 11. The water tanker 8 is connected to one end of a drain pipe 12, and the other end of the drain pipe 12 is connected to the annulus 16 between the original well tubing 9 and the production casing 11. The upper coupling 5 of the unblocking tool 10 is threadedly connected to the lower end of the original well tubing 9, and the lower coupling 6 of the unblocking tool 10 is threadedly connected to a plug 13.
[0036] To enhance the sealing and pumping effect, multiple unblocking tools 10 are connected in series from top to bottom. A tubing short section 14 is provided between each adjacent unblocking tool 10. Both ends of the tubing short section 14 have external threads. The upper end of each tubing short section 14 is connected to the lower coupling 6 in the unblocking tool 10 above it, and the lower end is connected to the upper coupling 5 in the unblocking tool 10 below it. The uppermost upper coupling 5 is threaded to the lower end of the original well tubing 9, and the lowermost lower coupling 6 is threaded to the plug 13.
[0037] The number of unblocking tools 10 is two or three.
[0038] The distance between adjacent unblocking tools 10 is 30cm-50cm.
[0039] The unblocking tool 10 in this second embodiment is the same as the coalbed methane well unblocking tool in the first embodiment.
[0040] In this second embodiment, the maximum diameter of the rubber plug 2 in the unblocking tool 10 is 2-5 mm smaller than the inner diameter of the production sleeve 11.
[0041] The assembly and operation process of this embodiment two is as follows: After the original well tubing 9 is pulled out, one or more unblocking tools 10 are connected in series to the lower end of the original well tubing 9 to form a tubing string. Then, the tubing string is lowered into the coalbed methane well by the workover vehicle 7 to a position 2m above the roof of the target coal seam 15. Then, 2-3m of water is injected into the annulus 16 between the original well tubing 9 and the production casing 11 by the water tanker 8. 3Then, while maintaining continuous water injection, the tubing string continues downwards until it exceeds the bottom plate of the target coal seam 15 by 0.2m. At this point, the water above the unblocking tool 10 will enter some formations with slight channels. Then, the tubing string is quickly lifted to the highest point by the workover vehicle 7 and held for 1-2 minutes. During the lifting process, under the action of the suction force, the water below the unblocking tool 10 that has entered the formation will be sucked out again. The water above the unblocking tool 10 will further enter the formation under the pressure of rapid lifting. Then, the tubing string is lowered down by free fall. The gravity of the tubing string is transferred to the water column below the unblocking tool 10, squeezing the water into the formation. This lifting and lowering operation is repeated hundreds of times, so that the deposition state of the blockage around the perforation section of the target coal seam 15 is constantly changed. Fine particles, coal dust and coal powder in the area affected by the water flow in the reservoir will be partially carried out, which plays a role in clearing the gas production channel. Finally, water injection is stopped, the tubing string is pulled out, and drainage is resumed.
[0042] During the above construction process, apart from the unblocking tool 10, there are no other complex auxiliary equipment, resulting in low safety risks during construction operations. In addition, the construction process is simple and can be completed in 2-3 working days, with a short construction period, enabling rapid unblocking of coalbed methane wells.
[0043] In the coalbed methane well unblocking and production enhancement test of this coalbed methane enterprise, a total of 45 wells were tested with the unblocking system of this utility model. The average daily gas production of a single well increased by 50% compared with that before the test. This shows that this utility model is practical and effective. It is a more direct and effective equipment and method to solve the problem of coalbed methane wells that do not produce gas after successful drilling and fracturing or have poor drainage effect in a short period of time.
[0044] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.
Claims
1. A tool for unclogging coalbed methane wells, characterized in that: The device includes a central tube (1), a rubber plug (2), an upper protective plate (3), a lower protective plate (4), an upper coupling (5), and a lower coupling (6). The rubber plug (2) is an elastic cylinder that is thick at both ends and thin in the middle, and it has an axial through hole. The upper protective plate (3) and the lower protective plate (4) are both circular plates with a central hole. The outer diameter of the upper protective plate (3) and the lower protective plate (4) is smaller than the maximum diameter of the rubber plug (2). The rubber plug (2), the upper protective plate (3), and the lower protective plate (4) are all fitted on the outside of the central tube (1). The rubber plug (2) is located in the middle. The upper protective plate (3) and the lower protective plate (4) are located above and below the rubber plug (2), respectively. The upper and lower ends of the central tube (1) have external threads. The upper coupling (5) is connected to the upper end of the central tube (1) by threads to press the upper protective plate (3) tightly. The lower coupling (6) is connected to the lower end of the central tube (1) by threads to press the lower protective plate (4) tightly.
2. The coalbed methane well unblocking tool according to claim 1, characterized in that: The rubber stopper (2) is made of rubber.
3. A coalbed methane well unblocking tool according to claim 1 or 2, characterized in that: The rubber stopper (2), upper protective plate (3), lower protective plate (4) and central tube (1) are all clearance fit.
4. A coalbed methane well unblocking system including the coalbed methane well unblocking tool as described in claim 1, characterized in that: The equipment includes a workover truck (7), a water tanker (8), the original well tubing (9), and a plugging tool (10). The upper end of the original well tubing (9) is hoisted on the workover truck (7), and the lower end extends into the production casing (11). The water tanker (8) is connected to one end of the drain pipe (12), and the other end of the drain pipe (12) is connected to the annulus (16) between the original well tubing (9) and the production casing (11). The upper coupling (5) in the plugging tool (10) is threadedly connected to the lower end of the original well tubing (9), and the lower coupling (6) in the plugging tool (10) is threadedly connected to a plug (13).
5. A coalbed methane well unblocking system according to claim 4, characterized in that: There are multiple unblocking tools (10), which are connected in series from top to bottom. A tubing short section (14) is provided between two adjacent unblocking tools (10). The tubing short section (14) has external threads at both ends. The upper end of each tubing short section (14) is connected to the lower coupling (6) in the unblocking tool (10) above it, and the lower end is connected to the upper coupling (5) in the unblocking tool (10) below it. The uppermost upper coupling (5) is threaded to the lower end of the original well tubing (9), and the lowermost lower coupling (6) is threaded to the plug (13).
6. The coalbed methane well unblocking system according to claim 5, characterized in that: The number of unblocking tools (10) is two or three.
7. A coalbed methane well unblocking system according to claim 5 or 6, characterized in that: The distance between adjacent unblocking tools (10) is 30cm-50cm.