Geothermal butt joint well connecting point casing combination and its completion process method

Abstract

This application relates to the field of geothermal docking well technology, and discloses a geothermal docking well connection point casing assembly and its completion process. The geothermal docking well connection point casing assembly includes a pipeline, and a cementing device assembly, a sealing assembly, and a live blind flange assembly arranged sequentially along a first direction. The cementing device assembly includes an inner tube and a first fixing member, which is connected between the inner tube and the pipeline. The sealing assembly includes a second fixing member and a piston component, with the second fixing member fixedly connected between the piston component and the pipeline. The live blind flange assembly includes a ball seat and a third fixing member, with the third fixing member fixedly connected between the ball seat and the pipeline. The shear pressure of the first fixing member is greater than that of the second fixing member, which is also greater than that of the third fixing member. By setting different shear pressures for the first, second, and third fixing members, the cementing device assembly, sealing assembly, and live blind flange assembly can be activated sequentially as needed, improving the reliability and controllability of the geothermal docking well connection point casing assembly operation.

Description

Technical Field

[0001] This application relates to the field of geothermal docking well technology, and in particular to a casing assembly for the connection point of a geothermal docking well and its completion process. Background Technology

[0002] The main drawback of the existing "heat extraction without water extraction" heat exchange mode is its low heat exchange performance. In contrast, geothermal docking wells do not require heat exchange inner tubes, and the circulation rate of a single well can easily reach 80-120 m³ / h. The depth of the heat exchange well is no longer limited to 2700 m, and the heat extraction capacity is 4-5 times that of traditional coaxial casing wells. They have the characteristics of large heat extraction, strong recovery ability, and land saving. However, geothermal docking wells need to meet the requirements of water injection on one side and water output on the other side, and the well bottom must be completely sealed to meet the pressure holding requirements in order to operate normally. However, the current geothermal docking wells have poor sealing effect and poor internal pressure holding, which leads to leakage of geothermal fluid used for heat exchange and affects heat exchange efficiency.

[0003] Based on the characteristics of the relevant technologies, the existing geothermal connection wells have technical problems such as poor sealing leading to geothermal fluid leakage. Summary of the Invention

[0004] This application provides a casing assembly for a geothermal well connection point and a well completion process method thereof, in order to at least partially solve the above-mentioned technical problems.

[0005] Firstly, this application provides a geothermal well connection point casing assembly, comprising: The pipeline is provided with a first cement injection hole, a first limiting block, a liquid inlet and a guide shoe in sequence along a first direction; and a cement injection device assembly, a sealing assembly and a movable blind plate assembly are arranged in sequence along the first direction. The cement injector assembly is disposed inside the pipeline. The cement injector assembly includes an inner tube and a first fixing member. The first fixing member is connected between the inner tube and the pipeline. The inner tube is fixed at a first position and blocks the first cement injection hole. The sealing assembly is disposed on the outside of the pipeline. The sealing assembly includes a sealing element, a hydraulic cylinder sleeve, a second fixing element, and a piston component. The second fixing element is fixedly connected between the piston component and the pipeline. The hydraulic cylinder sleeve and the pipeline form a cavity around each other. The cavity communicates with the liquid inlet. The piston component is at least partially disposed in the cavity. Along the first direction, one end of the sealing element abuts against the first limiting block, and the other end of the sealing element abuts against one end of the hydraulic cylinder sleeve. The piston component abuts against the other end of the hydraulic cylinder sleeve. The movable blind flange assembly is disposed on the inner side of the pipeline. The movable blind flange assembly includes a ball seat, a third fixing member, and a supporting member. The third fixing member is fixedly connected between the ball seat and the pipeline. The ball seat has a hole formed around it. The supporting member is located on one side of the ball seat in the first direction and is connected to the inner wall of the pipeline. The shearing pressure of the first fixing member is greater than that of the second fixing member, and the shearing pressure of the second fixing member is greater than that of the third fixing member.

[0006] By adopting the above technical solution, the operation sequence of "closing the blind flange assembly → opening the sealing assembly → opening the cement injector assembly" is ensured, avoiding functional failures caused by pressure disturbances and improving the reliability and controllability of the casing assembly operation at the geothermal docking well connection point.

[0007] Optionally, the pipeline further includes a second limiting block and a first rubber stopper seat. The first rubber stopper seat is fixed to the inner wall of the pipeline, and the second limiting block is used to limit the inner tube in the first direction. When the first fixing member breaks, the inner tube abuts against the second limiting block to expose the first cement injection hole.

[0008] By adopting the above technical solution, excessive movement or even detachment of the inner tube is prevented, ensuring the accuracy of the opening position of the cement injector assembly, thereby ensuring the smooth progress of the cement injection operation.

[0009] Optionally, a second cement injection hole is also formed on the inner tube. The cement injection assembly further includes a movable piston and a fixed piston. The movable piston is disposed on the inner tube, and the fixed piston is disposed on the inner wall of the pipeline. The fixed piston is located on one side of the movable piston along the first direction. When the inner tube is in the first position, the movable piston is used to block the first cement injection hole together with the inner tube. When the first fixing member breaks, the movable piston moves toward the fixed piston.

[0010] By adopting the above technical solution, the pressure within the pipeline can be stabilized, preventing sudden pressure drops during cement injection. The addition of a second cement injection hole further increases the flow area for cement injection, improving injection efficiency.

[0011] Optionally, the piston component includes a piston, a piston rod, and a limiting member. The piston rod is connected between the piston and the limiting member. The piston and at least a portion of the piston rod are disposed within the cavity. The pipeline is further provided with a third limiting block, which is used to limit the limiting member along the first direction.

[0012] By adopting the above technical solution, the sealing pressure between the seal and the well wall is guaranteed, while preventing excessive compression that could damage or extrude the seal. This structure makes the operation of the sealing assembly precise and controllable, ensuring a reliable sealing effect.

[0013] Optionally, the seal includes a glue barrel and a sealing rubber, the glue barrel being disposed around the outside of the pipeline and covering at least a portion of the sidewall of the first limiting block, the sealing rubber being disposed around the outside of the glue barrel, wherein, along the first direction, the glue barrel is connected between the sealing rubber and the first limiting block.

[0014] By adopting the above technical solution, when the seal expands, a portion of the rubber barrel can wrap around the limiting block, thereby enhancing the stability and reliability of the seal.

[0015] Optionally, the support component includes a support plate and a center plate. The center plate is disposed on a side surface of the support plate opposite to the first direction. The center plate is disposed opposite to the hole. The shape of the center plate is complementary to the shape of the hole on the ball seat. When the third fixing member breaks, the hole of the ball seat and the center plate interlock to block the pipeline.

[0016] By adopting the above technical solution, the reliability of bottom sealing has been improved.

[0017] Optionally, the geothermal docking well connection point casing assembly further includes a rubber plug short connector assembly. The rubber plug short connector assembly is located on the side of the cement injector assembly opposite to the first direction. The rubber plug short connector assembly is disposed inside the pipeline. The rubber plug short connector assembly includes at least a second rubber plug seat and a fourth fixing member. The fourth fixing member is fixedly connected between the second rubber plug seat and the pipeline.

[0018] By adopting the above technical solution, in conjunction with the subsequently installed drill pipe rubber plugs, multi-stage sealing of the pipe channel was achieved after cement injection.

[0019] Optionally, the pipeline is further provided with a screen tube assembly, which is disposed on one side of the live blind plate assembly along the first direction. Along the first direction, the screen tube assembly includes multiple parallel rows of screen tubes, and the screen tubes of adjacent rows of screen tubes are arranged in an alternating manner.

[0020] By adopting the above technical solutions, the flow area is increased, the flow resistance of the pipeline is reduced, and the extraction efficiency is improved.

[0021] Secondly, this application provides a completion process method for a geothermal docking well, employing a geothermal docking well connection point casing assembly as described in any of the above embodiments, including: The casing assembly for the connection point of the geothermal docking well is placed in the inclined shaft of the unfinished geothermal docking well along the first direction. The casing assembly at the connection point of the geothermal docking well is filled with a medium and a ball. When the ball reaches the ball seat, the pipeline is subjected to a first preset pressure, causing the third fixing component to break. The ball seat and the supporting component are partially embedded and jointly block the flow path in the pipeline. Increasing the pumping rate of the medium causes the pipeline to have a second preset pressure, which is greater than the first preset pressure, causing the second fixing member to break. The piston component pushes the hydraulic cylinder sleeve to squeeze the seal, and the seal expands radially along the pipeline. The seal is used to seal the gap between the pipeline and the inner wall of the inclined well. Increasing the pumping rate of the medium causes the pipeline to have a third preset pressure, which is greater than the second preset pressure, causing the first fixing member to break. The inner tube moves along the first direction and exposes the first cement injection hole, and the medium is pumped into the gap through the first cement injection hole. After the medium is pumped in, a drill pipe rubber plug is placed into the pipeline, and a post-filled liquid is pumped in to create a fourth preset pressure in the pipeline. The post-filled liquid carries the drill pipe rubber plug to the second rubber plug seat, causing the fourth fixing component to break. The drill pipe rubber plug and the second rubber plug seat are then moved to the first rubber plug seat by the push of the post-filled liquid. The drill pipe rubber plug, the second rubber plug seat, and the first rubber plug seat together seal the pipeline. The pressure is increased to a fifth preset pressure, the geothermal docking well is closed, and the process waits for the medium to solidify. Remove the residual medium, post-filled fluid, live blind flange assembly, cement injector assembly, and rubber plug short connector assembly from the pipeline, so that the flow paths within the pipeline of the geothermal docking well connection point casing assembly are interconnected.

[0022] Optionally, the first preset pressure ranges from 10 MPa to 11 MPa, the second preset pressure ranges from 14 MPa to 15 MPa, and the third preset pressure ranges from 17 MPa to 18 MPa.

[0023] By adopting the above technical solution and setting specific and gradient pressure ranges, it is ensured that the blind flange assembly, sealing assembly, and cement injection assembly can be activated sequentially.

[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. This application improves the reliability and controllability of the casing assembly operation at the geothermal docking well connection point by making the shear pressure of the first fixing member greater than that of the second fixing member greater than that of the third fixing member.

[0025] 2. This application provides a ball seat and a center plate with complementary shapes in the live blind flange assembly. When the ball seat falls and engages with the center plate, the ball seat, center plate and support plate together form a multi-layer sealing barrier, providing a stable pressure environment for the opening of the sealing assembly and cement injection assembly in subsequent steps.

[0026] 3. This application achieves multi-stage sealing of the casing channel after cement injection by setting up a rubber plug short joint assembly and using it in conjunction with the drill pipe rubber plug, effectively preventing backflow of the medium during cement slurry solidification.

[0027] 4. This application increases the flow area and reduces the flow resistance by setting a staggered screen pipe group at the bottom of the casing assembly at the connection point of the geothermal docking well.

[0028] 5. The well completion process provided in this application completes a series of complex operations such as bottom sealing of the casing assembly at the geothermal docking point, sealing of the annular gap, and cementing at a depth of several thousand meters by gradually increasing the pressure. This simplifies the well completion process and reduces the difficulty and cost of construction.

[0029] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0033] Figure 1 This is a schematic diagram of the overall structure of the casing assembly for the geothermal docking well connection point provided in an exemplary embodiment of this disclosure; Figure 2 This is a schematic diagram of the cement injector assembly in the geothermal docking well connection point casing assembly provided in an exemplary embodiment of this disclosure; Figure 3 This is a schematic diagram of the sealing component in the geothermal docking well connection point casing assembly provided in an exemplary embodiment of this disclosure; Figure 4 This is a schematic diagram of the structure of the live blind flange assembly in the geothermal docking well connection point casing assembly provided in the exemplary embodiments of this disclosure; Figure 5 This is a schematic diagram of the structure of the rubber plug short joint assembly in the geothermal docking well connection point casing assembly provided in the exemplary embodiments of this disclosure; Figure 6 This is a first state structure diagram in the completion process method of the geothermal docking well provided in the exemplary embodiments of this disclosure; Figure 7 This is a second state structure diagram in the well completion process method of the geothermal docking well provided in the exemplary embodiments of this disclosure; Figure 8 This is a third state structure diagram in the completion process method of the geothermal docking well provided in the exemplary embodiments of this disclosure; Figure 9 This is a fourth state structure diagram in the completion process method of the geothermal docking well provided in the exemplary embodiments of this disclosure; Figure 10 This is a fifth state structure diagram in the well completion process method for geothermal docking wells provided in the exemplary embodiments of this disclosure; Figure 11 This is a sixth state structure diagram in the well completion process method for geothermal docking wells provided in the exemplary embodiments of this disclosure; Figure 12 This is a flowchart of the completion process method for a geothermal docking well provided in an exemplary embodiment of this disclosure.

[0034] Explanation of reference numerals in the attached figures: 1. Pipeline; 11. First cement injection hole; 12. First limit stop; 13. Liquid inlet; 14. Guide shoe; 15. Second limit stop; 16. First rubber stop; 17. Third limit stop; 2. Cement injector assembly; 21. Inner tube; 22. First fixing component; 23. Second cement injection hole; 24. Movable piston; 25. Fixed piston; 3. Sealing assembly; 31. Sealing component; 311. Rubber tank; 312. Sealing rubber; 32. Cylinder liner; 33. Second fixed piston. 34. Piston assembly; 341. Piston; 342. Piston rod; 343. Limiting component; 35. Cavity; 4. Live blind flange assembly; 41. Ball seat; 42. Third fixing component; 43. Support component; 431. Center plate; 432. Support plate; 44. Ball; 5. First direction; 6. Rubber plug short connector assembly; 61. Second rubber plug seat; 62. Fourth fixing component; 63. Drill pipe rubber plug; 7. Screen pipe assembly; 8. Annular gap; 9. Inclined well; 10. Vertical well. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0036] Firstly, please refer to Figure 1 The geothermal well connection point casing assembly provided in this disclosure includes a pipeline 1, a cementing device assembly 2, a sealing assembly 3, and a movable blind flange assembly 4 arranged sequentially along a first direction 5. The pipeline 1 is sequentially provided with a first cementing hole 11, a first limiting block 12, a liquid inlet 13, and a guide shoe 14 along the first direction 5. The cementing device assembly 2 is located inside the pipeline 1 and includes an inner tube 21 and a first fixing member 22. The first fixing member 22 connects the inner tube 21 and the pipeline 1, and the inner tube 21 is fixed at a first position and seals the first cementing hole 11. The sealing assembly 3 is located outside the pipeline 1 and includes a sealing member 31, a hydraulic cylinder sleeve 32, a second fixing member 33, and a piston component 34. The second fixing member 33 is fixedly connected between the piston component 34 and the pipeline 1, and the hydraulic cylinder sleeve 32 and the pipeline 1 form a cavity around each other. 35. Cavity 35 is connected to inlet 13. Piston component 34 is at least partially disposed in cavity 35. Along the first direction 5, one end of seal 31 abuts against first limiting block 12, and the other end of seal 31 abuts against one end of cylinder sleeve 32. Piston component 34 abuts against the other end of cylinder sleeve 32. Live blind flange assembly 4 is disposed inside pipeline 1. Live blind flange assembly 4 includes ball seat 41, third fixing member 42 and support member 43. Third fixing member 42 is fixedly connected between ball seat 41 and pipeline 1. Ball seat 41 is surrounded by a hole. Support member 43 is located on one side of ball seat 41 in the first direction 5. Support member 43 is connected between the inner walls of pipeline 1. The shearing pressure of first fixing member 22 is greater than the shearing pressure of second fixing member 33. The shearing pressure of second fixing member 33 is greater than the shearing pressure of third fixing member 42.

[0037] The first limiting block 12 is used to limit the sealing element 31 along the first direction 5, which is the axial direction of the geothermal docking well connection point casing assembly toward the guide shoe 14. The liquid inlet 13 is used to allow the medium to enter the cavity 35 and provide a driving force for the piston component 34. The guide shoe 14 is used to guide the geothermal docking well connection point casing assembly into the inclined well 9.

[0038] When the geothermal well connection point casing assembly is placed downhole, an annular gap 8 is formed between the geothermal well connection point casing assembly and the well wall. The sealing element 31 is used to seal the annular gap 8. The hydraulic cylinder sleeve 32 is used to form a cavity 35 around the pipeline 1. The piston component 34 is used to push the hydraulic cylinder sleeve 32 to squeeze the sealing element 31. The second fixing element 33 is used to fix the piston component 34 and the pipeline 1.

[0039] When the casing assembly of the local thermal connection well is placed in the inclined well 9, a ball 44 is placed into the pipeline 1 and filled with medium. The ball seat 41 is used to cooperate with the ball 44. The third fixing member 42 is used to fix the ball seat 41. The support member 43 is used to support the ball seat 41 after it breaks and to block the flow channel in the pipeline 1.

[0040] It is understandable that the cavity 35 is connected to the inside of the pipeline 1 through the liquid inlet 13. When the medium is filled into the pipeline 1, the medium flows into the cavity 35 through the liquid inlet 13. The medium provides hydraulic pressure to push the piston component 34, so that the piston component 34 squeezes the seal 31. The seal 31 expands radially to seal the annular gap 8.

[0041] It should be noted that the shear pressure is set as follows: first fixing member 22 > second fixing member 33 > third fixing member 42. This design causes the third fixing member 42 to disconnect first under the hydraulic pressure of the medium, and the live blind flange assembly 4 to be activated first. Then, by increasing the hydraulic pressure of the medium, the second fixing member 33 disconnects, at which point the sealing assembly 3 is activated. Finally, by continuing to increase the hydraulic pressure, the first fixing member 22 disconnects, thereby activating the cement injector assembly 2.

[0042] In one embodiment, please refer to Figure 1 The pipeline 1 also includes a second limiting block 15 and a first rubber stopper seat 16. The first rubber stopper seat 16 is fixed to the inner wall of the pipeline 1. The second limiting block 15 is used to limit the inner tube 21 in the first direction 5. When the first fixing member 22 breaks, the inner tube 21 abuts against the second limiting block 15 to expose the first cement injection hole 11.

[0043] The first rubber plug seat 16 is used to cooperate with the drill pipe rubber plug 63 to achieve the final sealing of the inside of the pipeline 1.

[0044] When the first fixing member 22 breaks, the inner tube 21 moves along the first direction 5 under the push of the medium to expose the first cement injection hole 11. To prevent the inner tube 21 from moving excessively or even falling off, a second limiting block 15 is added. The second limiting block 15 is fixed to the inner wall of the pipeline 1 and is located on one side of the inner tube 21 along the first direction 5. When the inner tube 21 moves to abut against the second limiting block 15, it reaches the end of the travel of the inner tube 21, that is, the inner tube 21 reaches the second position.

[0045] In one embodiment, please refer to Figure 2 The inner tube 21 also has a second cement injection hole 23. The cement injection assembly 2 also includes a movable piston 24 and a fixed piston 25. The movable piston 24 is disposed on the inner tube 21, and the fixed piston 25 is disposed on the inner wall of the pipeline 1. The fixed piston 25 is located on one side of the movable piston 24 along the first direction 5. When the inner tube 21 is in the first position, the movable piston 24 is used to block the first cement injection hole 11 together with the inner tube 21. When the first fixing member 22 breaks, the movable piston 24 moves toward the fixed piston 25.

[0046] The movable piston 24 is fixed to the inner tube 21 and can move together with the inner tube 21; the fixed piston 25 is fixed to the inner wall of the pipeline 1 and is located on the side of the movable piston 24 along the first direction 5. The fixed piston will not move relative to the pipeline.

[0047] When the inner tube 21 is in the first position, the movable piston 24 and the inner tube 21 work together to block the first cement injection hole 11, ensuring that the first cement injection hole 11 is in a closed state. When the medium enters the cavity formed by the inner tube 21 through the second cement injection hole 23, the first fixing member 22 breaks due to the hydraulic pressure of the medium. When the inner tube 21 moves along the first direction 5 under the action of hydraulic pressure and gravity, the movable piston 24 moves with the inner tube 21. When the inner tube 21 moves to the second position, the movable piston 24 abuts against the fixed piston 25 and opens the first cement injection hole 11 to start the cement injector assembly 2.

[0048] Understandably, the movable piston 24 and the fixed piston 25 are arranged in abutment to improve the sealing effect, help stabilize the pressure in the pipeline 1, and avoid pressure leakage in the pipeline during the injection of cement slurry into the first cement injection hole 11, which would affect the injection efficiency. At the same time, when the cement injector assembly 2 is opened, the second cement injection hole 23 is arranged opposite to the first cement injection hole 11. The second cement injection hole 23 can also guide the cement slurry, guiding the cement slurry to be injected in the direction of the first cement injection hole 11.

[0049] In one embodiment, please refer to Figure 3 The piston component 34 includes a piston 341, a piston rod 342, and a limiting member 343. The piston rod 342 is connected between the piston 341 and the limiting member 343. The piston 341 and at least part of the piston rod 342 are disposed in the cavity 35. The pipeline 1 is also provided with a third limiting block 17, which is used to limit the limiting member 343 along the first direction 5.

[0050] The piston rod 342 is connected between the piston 341 and the limiting member 343, so that the piston 341, the piston rod 342 and the limiting member 343 form a linked whole. The piston 341 and at least part of the piston rod 342 are disposed in the cavity 35 formed by the hydraulic cylinder liner 32 and the pipeline 1, so that the piston 341 can be directly moved by the hydraulic pressure of the medium in the cavity 35.

[0051] The outer wall of the pipeline 1 is also provided with a third limiting block 17. When the second fixing member 33 breaks, the piston 341 moves and drives the limiting member 343 to move accordingly. The limiting member 343 has a serrated protrusion. The serrated protrusion contacts the third limiting block 17 in a specific direction. When the piston 341 pushes the hydraulic cylinder liner 32 to squeeze the seal 31, the serrated protrusion will not restrict the movement of the limiting member 343. The contact between the serrated protrusion and the third limiting block 17 is only used to restrict the movement of the limiting member 343 toward the first direction 5.

[0052] Understandably, setting the third limit block 17 makes the operation of the sealing component 3 precise and controllable. After the sealing component 31 is squeezed and expanded, it will not fall naturally under gravity and cause the seal to fail, thereby improving the reliability of the sealing effect.

[0053] In one embodiment, please refer to Figure 3 The sealing element 31 includes a glue barrel 311 and a sealing rubber 312. The glue barrel 311 is arranged around the outside of the pipeline 1 and covers at least part of the side wall of the first limiting block 12. The sealing rubber 312 is arranged around the outside of the glue barrel 311. Along the first direction 5, the glue barrel 311 is connected between the sealing rubber 312 and the first limiting block 12.

[0054] Understandably, when the cylinder liner 32 is pushed by the piston component 34 to compress the seal 31, the upper end of the rubber barrel 311 is limited by the first limiting block 12, and the rubber barrel 311 and the sealing rubber 312 on its outer side are forced to expand radially outward. The rubber barrel 311 is mainly used to provide elastic deformation capacity so that the seal 31 has sufficient expansion. The sealing rubber 312 is used to fit with the well wall to achieve a seal. The flexibility of the sealing rubber 312 is greater than that of the rubber barrel 311, which can adapt to the irregular well wall surface and further enhance the stability and reliability of the seal.

[0055] In one embodiment, please refer to Figure 4 The support component 43 includes a support plate 432 and a center plate 431. The center plate 431 is disposed on the side surface of the support plate 432 away from the first direction 5. The center plate 431 is disposed opposite to the hole. The shape of the center plate 431 is complementary to the shape of the hole on the ball seat 41. When the third fixing member 42 breaks, the hole of the ball seat 41 and the center plate 431 fit together to block the pipeline 1.

[0056] Among them, the diameter of the ball 44 is larger than the diameter of the hole; the larger diameter of the ball 44 allows it to be stuck on the ball seat 41, and under the action of the medium liquid pressure, it can exert pressure on the ball seat 41, thereby causing the third fixing member 42 that fixes the ball seat 41 to break.

[0057] The support plate 432 can be fixed to the inner wall of the pipe 1 by welding or other means. The center plate 431 is set on the upper surface of the support plate 432 on the side away from the first direction 5, and the position of the center plate 431 is opposite to the position of the hole on the ball seat 41, so that the ball seat 41 can be interlocked with the center plate 431 after it breaks.

[0058] Understandably, when the ball seat 41 is fixed by the third fixing member 42, the hole of the ball seat 41 is open and allows the medium to flow through. When the third fixing member 42 breaks, the ball seat 41 moves along the first direction 5 under the action of the medium thrust and gravity until it contacts the support plate 432. The hole on the ball seat 41 will interlock with the center plate 431 on the support plate 432 to form a complete sealing surface, thereby completely blocking the pipeline 1.

[0059] It should be noted that this interlocking sealing method has a better sealing effect than the planar contact sealing method. In this embodiment, the multi-layer sealing structure composed of "sphere 44 + sphere seat 41 + center plate 431 + support plate 432" can improve the reliability of the sealing.

[0060] In one embodiment, please refer to Figure 5 The geothermal docking well connection point casing assembly also includes a rubber plug short connector assembly 6. The rubber plug short connector assembly 6 is located on the side of the cement injector assembly 2 away from the first direction 5. The rubber plug short connector assembly 6 is disposed inside the pipeline 1. The rubber plug short connector assembly 6 includes at least a second rubber plug seat 61 and a fourth fixing member 62. The fourth fixing member 62 is fixedly connected between the second rubber plug seat 61 and the pipeline 1.

[0061] The main function of the rubber plug short connector assembly 6 is as follows: After the cementing operation is completed, the drill pipe rubber plug 63 needs to be put into the wellhead and the post-fluid needs to be pumped in. The drill pipe rubber plug 63 first reaches the second rubber plug seat 61. Under pressure, the fourth fixing member 62 breaks. Then the drill pipe rubber plug 63 together with the second rubber plug seat 61 is pushed downward by the post-fluid until it reaches the first rubber plug seat 16 below. The drill pipe rubber plug 63, the second rubber plug seat 61 and the first rubber plug seat 16 together achieve the sealing inside the pipe.

[0062] Understandably, the combined use of the second rubber stopper seat 61 and the first rubber stopper seat 16 forms a double sealing barrier, ensuring the reliability of the pipe sealing.

[0063] In one embodiment, please refer to Figure 1 The pipeline 1 is also provided with a screen tube group 7, which is located on one side of the live blind plate assembly 4 along the first direction 5. Along the first direction 5, the screen tube group 7 includes multiple parallel rows of screen tubes, and the screen tubes of adjacent rows of screen tubes are arranged in an alternating manner.

[0064] Each screen tube row includes 8 screen tubes, and along the first direction 5, the screen tube group 7 is arranged with multiple rows of screen tubes in a manner of 20 rows / meter.

[0065] The staggered arrangement refers to the following: along the first direction 5, any screen tube in one of the two adjacent screen tube rows is staggered from the screen tube in the other screen tube row by a certain angle in the circumferential direction, so that more screen tubes can be arranged along the same pipe length 1, thereby further increasing the flow rate of geothermal fluid through the screen tubes.

[0066] Among them, the screen tube group 7 is set on one side of the live blind plate assembly 4 along the first direction 5. The screen tube group 7 is used to connect with the pipeline 1 in the vertical well 10 in the well. The screen tube group 7 is distributed circumferentially on the pipeline 1 and the screen tube is a through hole.

[0067] In this embodiment, the increased flow rate of geothermal fluid through the screen tube reduces the resistance to geothermal fluid flow and improves the extraction efficiency of geothermal fluid.

[0068] Secondly, please refer to Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 This application provides a completion process method for a geothermal docking well, employing a casing assembly for the geothermal docking well connection point as described in any of the above embodiments. The completion process method includes: S1: Place the casing assembly of the geothermal docking well connection point along the first direction 5 into the inclined shaft 9 of the unfinished geothermal docking well.

[0069] S2: Please refer to Figure 6 and Figure 7 The medium and ball 44 are filled into the casing assembly of the geothermal docking well connection point. When the ball 44 reaches the ball seat 41, the pipeline 1 has a first preset pressure, causing the third fixing member 42 to break. The ball seat 41 and the supporting member 43 are partially embedded and jointly block the flow path in the pipeline 1.

[0070] S3: Please refer to Figure 8The increased pumping volume of the medium causes the pipeline 1 to have a second preset pressure. The second preset pressure is greater than the first preset pressure, causing the second fixing member 33 to break. The piston component 34 pushes the hydraulic cylinder sleeve 32 to squeeze the seal 31. The seal 31 expands radially along the pipeline 1. The seal 31 is used to seal the gap between the pipeline 1 and the inner wall of the inclined well 9.

[0071] S4: Please refer to Figure 9 The increased pumping volume of the medium causes the pipeline 1 to have a third preset pressure. The third preset pressure is greater than the second preset pressure, causing the first fixing member 22 to break. The inner tube 21 moves along the first direction 5 and exposes the first cement injection hole 11. The medium is pumped into the gap through the first cement injection hole 11.

[0072] S5: Please refer to Figure 10 After the medium is pumped in, the drill pipe rubber plug 63 is placed into the pipeline 1, and the post-fluid is pumped in, so that the pipeline 1 has a fourth preset pressure. The post-fluid drives the drill pipe rubber plug 63 to the second rubber plug seat 61 first, causing the fourth fixing member 62 to break. The drill pipe rubber plug 63 and the second rubber plug seat 61 move to the first rubber plug seat 16 under the push of the post-fluid. The drill pipe rubber plug 63, the second rubber plug seat 61 and the first rubber plug seat 16 together seal the pipeline 1, pressurize to the fifth preset pressure, close the geothermal docking well and wait for the first time for the medium to solidify.

[0073] S6: Please refer to Figure 11 Remove residual medium, post-filled fluid, blind flange assembly 4, cement injector assembly 2, and rubber plug short joint assembly 6 from pipeline 1, so that the flow paths in pipeline 1 of the geothermal docking well connection point casing assembly are interconnected.

[0074] In this process, step S2 is used to close the live blind flange assembly 4, step S3 is used to open the sealing assembly 3, and step S4 is used to open the cement injector assembly 2.

[0075] Furthermore, the purpose of closing the blind flange assembly 4 is to block the flow path within the pipeline 1, providing a stable pressure environment for subsequent steps; the purpose of opening the sealing assembly 3 is to seal the annular gap 8 between the geothermal docking well connection point casing assembly and the well wall, specifically, to seal the annular gap 8 on the side of the sealing assembly 3 facing away from the first direction 5; the purpose of opening the cement injector assembly 2 is to inject cement slurry into the annular gap 8 sealed by the sealing assembly 3. After the cement slurry solidifies, the solidified cement slurry and the sealing assembly 3 together seal the fluid flowing through the pipeline 1 for heat exchange, avoiding the technical problem of low energy efficiency caused by the leakage of this fluid.

[0076] Understandably, the ball seat 41 breaks under the action of the ball 44 and fits into the support component 43 to seal the pipeline 1, establishing a closed pressure system within the pipeline 1, providing a pressure environment and foundation for subsequent hydraulic operations; the sealing assembly 3 is activated, and the seal 31 expands radially to seal the annular gap 8; the cement injector assembly 2 is opened and cement slurry is injected, and the cement slurry is pumped into the annular gap 8 as the inner tube 21 moves to expose the first cement injection hole 11.

[0077] It should be noted that after the cement slurry is injected, the drill pipe plug 63 needs to be inserted and the post-filled fluid needs to be pumped in. The second plug seat 61, the first plug seat 16, and the drill pipe plug 63 are used to form a multi-layer seal in the pipeline 1 to prevent backflow of cement slurry and facilitate subsequent cleaning operations. After the cement slurry solidifies, the excess tools and media in the pipeline 1 are removed, and the pipeline 1 is restored to openness. Geothermal fluid can enter the pipeline 1 from the stratum through the bottom screen tube group 7 to realize the collection and conversion of geothermal energy. Since the sealing component 3 is located on the outside of the pipeline 1, it does not affect the openness of the pipeline 1. The sealing component 3 is retained to enhance the sealing effect on the geothermal fluid.

[0078] In one embodiment, the first preset pressure ranges from 10 MPa to 11 MPa, the second preset pressure ranges from 14 MPa to 15 MPa, and the third preset pressure ranges from 17 MPa to 18 MPa.

[0079] The fourth preset pressure is 10 MPa, and the fifth preset pressure ranges from 13 MPa to 15 MPa.

[0080] The first preset pressure can be any one of 10 MPa, 10.5 MPa, or 11 MPa; the first preset pressure can be any one of 14 MPa, 14.5 MPa, or 15 MPa; or the first preset pressure can be any one of 17 MPa, 17.5 MPa, or 18 MPa.

[0081] It is understandable that the difference between the first preset pressure, the second preset pressure, and the third preset pressure is at least greater than or equal to 2 MPa, so that the working sequence of each component in the geothermal docking well connection point casing assembly is controllable and sufficient safety margin is left to ensure that each fastener breaks reliably within its respective preset pressure range, and to avoid other fasteners being accidentally cut off when one fastener is cut off due to pressure fluctuations.

[0082] In one embodiment, the medium includes at least one of circulating cement, pre-fluid, and high-temperature resistant cement.

[0083] Among them, recycled cement refers to cement slurry that can be recycled or has a specific fluidity and is suitable for cementing operations; high-temperature resistant cement is used in the high-temperature environment design of geothermal docking wells and can maintain stable mechanical properties and sealing performance under high-temperature conditions.

[0084] Among them, the pre-fluid is a special fluid pumped in before the cement slurry is injected, and the pre-fluid plays the role of cleaning the well wall.

[0085] Thirdly, this application provides a geothermal docking well, including a geothermal docking well connection point casing assembly as described in any of the above embodiments, or prepared using the well completion process method as described in any of the above embodiments.

[0086] Since the geothermal docking well adopts the geothermal docking well connection point casing combination or well completion process method in the above embodiments of this application, it necessarily possesses all the beneficial effects brought about by the geothermal docking well connection point casing combination and its well completion process method.

[0087] Specifically, the geothermal docking well features reliable sealing of the annular gap 8, uniform distribution and good bonding of the cement sheath, and a large flow area of ​​the bottom screen tube group 7; which gives the geothermal docking well the advantages of high development efficiency, long service life and low operation and maintenance costs.

[0088] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0089] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0090] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0091] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A casing assembly for a geothermal well connection point, characterized in that, include: The pipeline (1) is provided with a first cement injection hole (11), a first limiting block (12), a liquid inlet (13), and a guide shoe (14) in sequence along the first direction (5); and The cement injection assembly (2), the sealing assembly (3) and the live blind plate assembly (4) are arranged sequentially along the first direction (5). The cement injection assembly (2) is disposed inside the pipeline (1). The cement injection assembly (2) includes an inner tube (21) and a first fixing member (22). The first fixing member (22) is connected between the inner tube (21) and the pipeline (1). The inner tube (21) is fixed in a first position and blocks the first cement injection hole (11). The sealing assembly (3) is disposed on the outside of the pipeline (1). The sealing assembly (3) includes a sealing element (31), a hydraulic cylinder sleeve (32), a second fixing element (33), and a piston component (34). The second fixing element (33) is fixedly connected between the piston component (34) and the pipeline (1). The hydraulic cylinder sleeve (32) and the pipeline (1) form a cavity (35) around each other. The cavity (35) is connected to the liquid inlet (13). The piston component (34) is at least partially disposed in the cavity (35). Along the first direction (5), one end of the sealing element (31) abuts against the first limiting block (12), and the other end of the sealing element (31) abuts against one end of the hydraulic cylinder sleeve (32). The piston component (34) abuts against the other end of the hydraulic cylinder sleeve (32). The movable blind flange assembly (4) is disposed inside the pipeline (1). The movable blind flange assembly (4) includes a ball seat (41), a third fixing member (42), and a support member (43). The third fixing member (42) is fixedly connected between the ball seat (41) and the pipeline (1). The ball seat (41) has a hole formed around it. The support member (43) is located on the first direction (5) side of the ball seat (41). The support member (43) is connected between the inner walls of the pipeline (1). The shearing pressure of the first fastener (22) is greater than that of the second fastener (33), and the shearing pressure of the second fastener (33) is greater than that of the third fastener (42).

2. The casing assembly for the geothermal connection well connection point according to claim 1, characterized in that, The pipeline (1) further includes a second limiting block (15) and a first rubber stopper seat (16). The first rubber stopper seat (16) is fixed to the inner wall of the pipeline (1). The second limiting block (15) is used to limit the inner tube (21) in the first direction (5). When the first fixing member (22) breaks, the inner tube (21) abuts against the second limiting block (15) to expose the first cement injection hole (11).

3. The casing assembly for the geothermal connection well connection point according to claim 2, characterized in that, A second cement injection hole (23) is also formed on the inner tube (21). The cement injection assembly (2) also includes a movable piston (24) and a fixed piston (25). The movable piston (24) is disposed on the inner tube (21), and the fixed piston (25) is disposed on the inner wall of the pipeline (1). The fixed piston (25) is located on one side of the movable piston (24) along the first direction (5). When the inner tube (21) is in the first position, the movable piston (24) is used to block the first cement injection hole (11) together with the inner tube (21). When the first fixing member (22) breaks, the movable piston (24) moves toward the fixed piston (25).

4. The casing assembly for the geothermal connection well connection point according to claim 1, characterized in that, The piston component (34) includes a piston (341), a piston rod (342), and a limiting member (343). The piston rod (342) is connected between the piston (341) and the limiting member (343). The piston (341) and at least part of the piston rod (342) are disposed in the cavity (35). The pipeline (1) is also provided with a third limiting block (17), which is used to limit the limiting member (343) along the first direction (5).

5. The casing assembly for the geothermal connection well connection point according to claim 4, characterized in that, The sealing element (31) includes a rubber barrel (311) and a sealing rubber (312). The rubber barrel (311) is disposed around the outside of the pipeline (1) and covers at least a portion of the sidewall of the first limiting block (12). The sealing rubber (312) is disposed around the outside of the rubber barrel (311). Along the first direction (5), the rubber barrel (311) is connected between the sealing rubber (312) and the first limiting block (12).

6. The casing assembly for the geothermal connection well connection point according to claim 1, characterized in that, The support component (43) includes a support plate (432) and a center plate (431). The center plate (431) is disposed on the side surface of the support plate (432) away from the first direction (5). The center plate (431) is disposed opposite to the hole. The shape of the center plate (431) is complementary to the shape of the hole on the ball seat (41). When the third fixing member (42) breaks, the hole of the ball seat (41) and the center plate (431) fit together to block the pipeline (1).

7. The geothermal well connection point casing assembly according to any one of claims 1 to 6, characterized in that, The geothermal docking well connection point casing assembly also includes a rubber plug short connector assembly (6), which is located on the side of the cement injection unit assembly (2) away from the first direction (5). The rubber plug short connector assembly (6) is disposed inside the pipeline (1). The rubber plug short connector assembly (6) includes at least a second rubber plug seat (61) and a fourth fixing member (62). The fourth fixing member (62) is fixedly connected between the second rubber plug seat (61) and the pipeline (1).

8. The geothermal well connection point casing assembly according to any one of claims 1 to 6, characterized in that, The pipeline (1) is also provided with a screen tube group (7), which is located on one side of the live blind plate assembly (4) along the first direction (5). Along the first direction (5), the screen tube group (7) includes a plurality of screen tube rows arranged in parallel, and the screen tubes of adjacent screen tube rows are staggered.

9. A completion process for a geothermal docking well, comprising the use of the geothermal docking well connection point casing assembly as described in any one of claims 1 to 8, characterized in that, include: The casing assembly of the geothermal docking well connection point is placed in the inclined shaft (9) of the unfinished geothermal docking well along the first direction (5); The medium and sphere are filled into the casing assembly of the geothermal docking well connection point. When the sphere reaches the ball seat (41), the pipeline (1) has a first preset pressure, causing the third fixing member (42) to break. The ball seat (41) and the supporting member (43) are partially embedded and jointly block the flow path in the pipeline (1). Increasing the pumping volume of the medium causes the pipeline (1) to have a second preset pressure, which is greater than the first preset pressure, causing the second fixing member (33) to break. The piston component (34) pushes the hydraulic cylinder sleeve (32) to squeeze the seal (31). The seal (31) expands radially along the pipeline (1). The seal (31) is used to seal the gap between the pipeline (1) and the inner wall of the inclined well (9). Increasing the pumping volume of the medium causes the pipeline (1) to have a third preset pressure, which is greater than the second preset pressure, causing the first fixing member (22) to break, the inner tube (21) to move along the first direction (5) and expose the first cement injection hole (11), and the medium is pumped into the gap through the first cement injection hole (11). After the medium is pumped in, a drill pipe plug is placed into the pipeline (1), and a post-filling liquid is pumped in to give the pipeline (1) a fourth preset pressure. The post-filling liquid drives the drill pipe plug to the second plug seat (61) first, causing the fourth fixing member (62) to break. The drill pipe plug and the second plug seat (61) move to the first plug seat (16) under the push of the post-filling liquid. The drill pipe plug, the second plug seat (61) and the first plug seat (16) together block the pipeline (1), pressurize to the fifth preset pressure, close the geothermal docking well and wait for the first time for the medium to solidify. Remove the residual medium, post-filled fluid, live blind plate assembly (4), cement injector assembly (2) and rubber plug short joint assembly (6) from the pipeline (1) so that the flow paths in the pipeline (1) of the geothermal docking well connection point casing assembly are interconnected.

10. The completion process method for geothermal docking wells according to claim 9, characterized in that, The first preset pressure ranges from 10 MPa to 11 MPa, the second preset pressure ranges from 14 MPa to 15 MPa, and the third preset pressure ranges from 17 MPa to 18 MPa.

Images