Coiled tubing work staged cementing system and method

Abstract

The present application belongs to the technical field of oil and gas field cementing, and particularly relates to a coiled tubing operation staged cementing system and a cementing method. The coiled tubing operation staged cementing system comprises a wellhead injection device, a staged collar, a windowing tool, a primary rubber plug and a secondary rubber plug. The coiled tubing operation staged cementing comprises the following steps: running in the staged collar, installing the wellhead injection device, primary cementing, running in the windowing tool to open the staged collar, secondary cementing and tripping out the windowing tool. The present application uses the coiled tubing to realize the cementing operation. After the cementing operation is completed, the secondary rubber plug is tripped out of the wellhead with the coiled tubing, and does not need to be punched into the well bottom through the pipe column, so that the operation cost is low, the efficiency is high, the staged cementing without drilling is realized for the full-gauge wellbore of the coiled tubing operation, the wellbore integrity is effectively improved, and the cementing quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field cementing technology, and specifically relates to a staged cementing system and cementing method for coiled tubing operations. Background Technology

[0002] Staged cementing involves installing a special staged cementing device on the casing string. During cementing, the cementing operation of a well is divided into two, three, or more stages using the staged cementing device and various matching plugs. In field applications, two-stage cementing is generally the primary method. Staged cementing is often used when conventional single-stage cementing cannot meet the wellbore sealing and casing protection requirements in the following situations: excessive cement volume injected in a single operation; formation inability to withstand excessive hydraulic pressure; sealing of special formations; prevention of annular air leakage after cementing; large temperature difference between the upper and lower sections of the cemented section, making it difficult to adjust the cement slurry properties, etc.

[0003] Currently, cementing stage devices are mainly divided into two categories: conventional and drill-free. Drill-free cementing stage devices are widely used in the field because they do not require the insertion of small drill strings to remove the internal sliding sleeves, rubber plugs, and rubber plug seats of the drilling equipment. Based on the method of opening the circulation port, drill-free cementing stage devices can be further divided into mechanical and hydraulic types. Mechanical cementing stage devices typically involve inserting an opening plug after the first stage of cementing and pressurization. The opening plug then falls automatically to the rubber plug seat to open the circulation port. However, this method makes it difficult to achieve the automatic descent of tools and accessories within the designed borehole diameter of the cementing stage device. Hydraulic cementing stage devices use hydraulic opening of the circulation port. Although the structure is simplified, the design is more complex. After cementing operations are completed, the rubber plugs and rubber plug seats in the drill-free cementing stage device also have two descent methods: Early methods used completion tubing to push the rubber plugs and rubber plug seats to the bottom of the well. The second method involves the shut-in gravity plug, upper rubber plug, and rubber plug seat falling together to the bottom of the well. With the first method, completion logging cannot be performed before running the tubing. The success rate of the second method, which involves lowering the rubber stopper and its seat to the bottom of the well, needs further improvement. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a staged cementing system and method for coiled tubing operations. The system utilizes coiled tubing for cementing operations. After cementing is completed, the secondary rubber plug is pulled out of the wellhead along with the coiled tubing, eliminating the need to push it down to the bottom of the well via the tubing string. This results in low operating costs and high efficiency, enabling drill-free staged cementing of the entire borehole using coiled tubing, effectively improving wellbore integrity and cementing quality.

[0005] The technical solution of this invention is: a staged cementing system for coiled tubing operations, comprising: a wellhead injection device, a stage clamp, a window opening tool, a primary rubber plug, and a secondary rubber plug, wherein:

[0006] The wellhead injection device, from top to bottom, includes a displacement fluid injection plate gate valve, a three-gate blowout preventer, and a cement slurry injection plate gate valve connected in sequence.

[0007] The graded hoop includes an upper connector, a sliding sleeve, a spring, and a lower connector. The lower outer wall of the upper connector is fixedly connected to the upper inner wall of the lower connector. An annular step is provided on the lower inner wall of the lower connector. A spring is provided on the annular step. The sliding sleeve is provided above the spring. The upper end face of the sliding sleeve contacts the lower end face of the upper connector. A variable diameter groove is provided on the inner wall of the sliding sleeve.

[0008] The window opening tool includes, from top to bottom, a continuous oil pipe connector, a cone, a central rod, a window opening tool body, a connector, and a spring claw connected in sequence. A rubber cylinder is provided on the outer side of the central rod, and steel wire shafts are provided on both sides of the lower end of the spring claw. Steel wires are provided on the steel wire shafts, and the steel wires are rotatably connected to the spring claws through the steel wire shafts.

[0009] The primary rubber stopper includes a primary rubber stopper body and a primary rubber stopper skirt located on the side of the primary rubber stopper body. The primary rubber stopper body is solid.

[0010] The secondary rubber plug includes a secondary rubber plug body and a secondary rubber plug skirt located on the side of the secondary rubber plug body. The secondary rubber plug body has a through hole inside, and the diameter of the through hole is the same as the outer diameter of the continuous tubing in operation.

[0011] The lower connector has multiple radial through holes on its central housing, and the centers of the radial through holes are located on the same plane.

[0012] The housing of the sliding sleeve is provided with a number of diversion holes of the same size as the radial through holes. The diversion holes are located above the radial through holes, and a variable diameter groove is provided on the inner wall below the diversion holes.

[0013] Multiple sealing rings are provided between the sliding sleeve and the inner wall of the lower connector.

[0014] The inner diameter of the upper connector is the same as the inner diameter of the sliding sleeve.

[0015] The window opening tool body passes through the spring claw and is fixedly connected to the connector. The continuous oil pipe connector is connected to the cone by a threaded connection, and the center rod is connected to the cone by a shear pin.

[0016] The lower end of the spring claw is provided with protrusions on both sides, and a groove is provided in the middle of the protrusion. The steel wire shaft passes through the groove and is connected to the spring claw. The middle of the steel wire is provided with an overlapping right angle. One end of the steel wire is rotatably connected to the steel wire shaft on one side of the lower end of the spring claw, and the other end is connected to the steel wire shaft on the other side of the lower end of the spring claw through the overlapping right angle and extends out from the groove.

[0017] The primary rubber plug is made of wear-resistant rubber. The outer diameter of the primary rubber plug skirt is larger than the inner diameter of the working casing. The primary rubber plug skirt can retract radially within the wellbore. The secondary rubber plug is also made of wear-resistant rubber. The outer diameter of the secondary rubber plug skirt is larger than the inner diameter of the working casing. The secondary rubber plug skirt can retract radially within the wellbore.

[0018] A staged cementing method for coiled tubing operations, using any of the staged cementing systems described above, is as follows:

[0019] S1: Lower the graded hoop;

[0020] After connecting the staged collar to the designed position on the casing, it is lowered into the open hole;

[0021] S2: Install wellhead injection device;

[0022] S3: First-stage cementing, the specific process is as follows:

[0023] Close the three-gate blowout preventer, place the first-stage rubber plug between the displacement fluid injection plate valve and the three-gate blowout preventer of the wellhead injection device, open the cement slurry injection plate valve to start cement slurry injection, when the cement slurry injection volume is completed, close the cement slurry injection plate valve, open the three-gate blowout preventer, open the displacement fluid injection plate valve to start injecting clean water displacement fluid, the first-stage rubber plug enters the casing with the clean water displacement fluid until the first stage cementing is completed at the bottom of the artificial well;

[0024] S4: Insert the window opening tool to open the graded clamp. The specific process is as follows:

[0025] S41: Pass the working coiled tubing through the secondary rubber plug and the window opening tool, and connect it to the coiled tubing joint by rolling. Then, place the whole coiled tubing into the wellhead injection device. The working coiled tubing and the wellhead injection device are sealed with packing. After the window opening tool passes through the three-gate blowout preventer, the three-gate blowout preventer is partially closed, so that the secondary rubber plug is placed between the three-gate blowout preventer and the displacement fluid injection plate valve of the wellhead injection device. At this time, the cement slurry injection plate valve and the displacement fluid injection plate valve are closed.

[0026] S42: The working coiled tubing delivers the window opening tool to a position below the graded clamp. The working coiled tubing is then lifted, and the two steel wires cross and overlap within the reducing groove of the sliding sleeve, releasing the spring claw into a radially retractable free state. The working coiled tubing is then lowered again, and the spring claw locks into the reducing groove of the sliding sleeve. As the working coiled tubing continues to descend, the sliding sleeve compresses the spring and moves downward, connecting the flow branch hole of the sliding sleeve with the radial through hole of the lower connector, thus completing the window opening process. During this process, the coiled tubing connector, cone, rubber sleeve, center rod, window opening tool body, and connector of the window opening tool move downward relative to the spring claw. The connector firmly supports the spring claw, preventing further radial deformation. The shear pin is cut off, and the cone causes the rubber sleeve to expand radially and seal with the sliding sleeve.

[0027] S5: Secondary cementing, the specific process is as follows:

[0028] Open the cement slurry injection plate gate valve to start cement slurry injection. When the cement slurry injection volume is completed, close the cement slurry injection plate gate valve. The three-gate blowout preventer is fully opened. Open the displacement fluid injection plate gate valve to start injecting water displacement fluid. The secondary rubber plug travels through the working coiled tubing with the water displacement fluid and enters the casing until the stage collar position is reached to complete the secondary cementing.

[0029] S6: Retrieve the window opening tool to complete the staged cementing operation. The specific process is as follows:

[0030] After the cement slurry from the secondary cementing stage solidifies, the coiled tubing is pulled up, the cone separates from the rubber sleeve, and the rubber sleeve retracts radially. At the same time, the coiled tubing connector, cone, rubber sleeve, center rod, window opening tool body, and connector of the window opening tool move upward relative to the spring claw. The spring claw loses its central support and becomes a free state that can deform radially again. The friction of the window opening tool is eliminated, and the secondary rubber plug is pulled out of the wellhead along with the coiled tubing and the window opening tool. After the window opening tool separates from the stage clamp, the spring pushes the sliding sleeve back to its original ground assembly position, so that the flow hole of the sliding sleeve is misaligned with the radial through hole of the lower connector, the stage clamp is closed, and the wellbore is sealed.

[0031] The technical advantages of this invention are as follows: 1. This invention uses coiled tubing to perform cementing operations. After the cementing operation is completed, the secondary rubber plug is pulled out of the wellhead along with the coiled tubing, without needing to be pushed down to the bottom of the well through the tubing string, resulting in low operating costs and high efficiency; 2. This invention uses a stage collar with a diameter exactly the same as the connected casing diameter, eliminating any necking and not affecting the passage of any downhole tools, ensuring good wellbore integrity; 3. This invention uses an elastic claw clamp to fix the variable diameter groove and uses a window opening tool to open the stage collar sliding sleeve, which has a simple structure, is easy to use, and improves cementing efficiency.

[0032] The following will provide further explanation in conjunction with the accompanying drawings. Attached Figure Description

[0033] Figure 1This is a schematic diagram of the wellhead injection device of a staged cementing system for coiled tubing operations according to the present invention.

[0034] Figure 2 This is a schematic diagram of the graded clamp structure of a graded cementing system for coiled tubing operations according to the present invention.

[0035] Figure 3 This is a schematic diagram of the window opening tool structure of a staged cementing system for coiled tubing operations according to the present invention.

[0036] Figure 4 This is a schematic diagram of the first-stage rubber plug structure of a staged cementing system for coiled tubing operations according to the present invention.

[0037] Figure 5 This is a schematic diagram of the two-stage rubber plug structure of a staged cementing system for coiled tubing operations according to the present invention.

[0038] Figure 6 This is a schematic diagram of the spring claw opening tool of a staged cementing system for coiled tubing operations according to the present invention.

[0039] Figure 7 This invention provides a schematic diagram of the window opening tool for a staged cementing system in coiled tubing operations, showing the opening of the stage clamp.

[0040] Reference numerals: 1-Displacement fluid injection plate gate valve, 2-Three-gate blowout preventer, 3-Cement slurry injection plate gate valve, 4-Upper connector, 5-Sliding sleeve, 6-Diverter hole, 7-Sealing ring, 8-Radial through hole, 9-Reducing groove, 10-Spring, 11-Annular step, 12-Lower connector, 13-Continuous tubing connector, 14-Shear pin, 15-Cone, 16-Rubber sleeve, 17-Center rod, 18-Window opening tool body, 19-Connector, 20-Spring claw, 21-Steel wire, 22-Steel wire shaft, 23-First-stage rubber plug body, 24-First-stage rubber plug skirt, 25-Second-stage rubber plug body, 26-Second-stage rubber plug skirt, 27-Through hole, 201-Boss, 202-Slot, 211-Overlapping right angle. Detailed Implementation

[0041] Example 1

[0042] To overcome the problem that existing drill-free grading devices cannot achieve self-lowering of tools and accessories within the designed borehole diameter, and that after cementing operations are completed, the rubber plugs and plug seats inside the device need to be lowered to the bottom of the well with a low success rate, this invention provides... Figures 1-5 The invention discloses a staged cementing system for coiled tubing operations. By using coiled tubing to perform cementing operations, after the cementing operation is completed, the secondary rubber plug is pulled out of the wellhead along with the coiled tubing, without having to be pushed down to the bottom of the well through the tubing string. This results in low operating costs and high efficiency, enabling drill-free staged cementing of the entire borehole using coiled tubing operations, effectively improving wellbore integrity and cementing quality.

[0043] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, a staged cementing system for coiled tubing operations includes: a wellhead injection device, a stage clamp, a window opening tool, a primary rubber plug, and a secondary rubber plug, wherein:

[0044] The wellhead injection device includes, from top to bottom, a displacement fluid injection plate gate valve 1, a three-gate blowout preventer 2, and a cement slurry injection plate gate valve 3 connected in sequence.

[0045] The graded hoop includes an upper connector 4, a sliding sleeve 5, a spring 10, and a lower connector 12. The lower outer wall of the upper connector 4 is fixedly connected to the upper inner wall of the lower connector 12. An annular step 11 is provided on the lower inner wall of the lower connector 12. A spring 10 is provided on the annular step 11. The sliding sleeve 5 is provided above the spring 10. The upper end face of the sliding sleeve 5 contacts the lower end face of the upper connector 4. A variable diameter groove 9 is provided on the inner wall of the sliding sleeve 5.

[0046] The window opening tool includes, from top to bottom, a continuous oil pipe connector 13, a cone 15, a central rod 17, a window opening tool body 18, a connector 19, and a spring claw 20 connected in sequence. A rubber sleeve 16 is provided on the outer side of the central rod 17. A steel wire shaft 22 is provided on both sides of the lower end of the spring claw 20. A steel wire 21 is provided on the steel wire shaft 22. The steel wire 21 is rotatably connected to the spring claw 20 through the steel wire shaft 22.

[0047] The primary rubber stopper includes a primary rubber stopper body 23 and a primary rubber stopper skirt 24 located on the side of the primary rubber stopper body 23. The primary rubber stopper body 23 is solid.

[0048] The secondary rubber plug includes a secondary rubber plug body 25 and a secondary rubber plug skirt 26 located on the side of the secondary rubber plug body 25. The secondary rubber plug body 25 has a through hole 27 inside, and the diameter of the through hole 27 is the same as the outer diameter of the working continuous tubing.

[0049] In use, the displacement fluid injection plate gate valve 1, the three-gate blowout preventer 2, and the cement slurry injection plate gate valve 3 are connected by flanges. After connecting the stage clamp to the designed position of the casing, it is lowered into the open hole, and then the wellhead injection device is installed. The three-gate blowout preventer 2 is closed, and the first-stage rubber plug is placed between the displacement fluid injection plate gate valve 1 and the three-gate blowout preventer 2 of the wellhead injection device. The cement slurry injection plate gate valve 3 is opened to begin injecting cement slurry. When the calculated amount of cement slurry has been injected, the cement slurry injection plate gate valve 3 is closed, the three-gate blowout preventer 2 is opened, and the displacement fluid injection plate gate valve 1 is opened to begin injecting clear water displacement fluid. The first-stage rubber plug is then injected with the clear water displacement fluid. Water displacement fluid enters the casing until the bottom of the artificial well is reached, completing the first stage of cementing. Then, a window-opening tool is lowered to open the stage collar. After the stage collar is open, the cement slurry injection gate valve 3 is opened to begin cement slurry injection. When the calculated amount of cement slurry has been injected, the cement slurry injection gate valve 3 is closed, the three-gate blowout preventer 2 is fully opened, and the displacement fluid injection gate valve 1 is opened to begin injecting clear water displacement fluid. The secondary rubber plug travels with the clear water displacement fluid throughout the entire process, passing through the working coiled tubing and entering the casing until the stage collar position is reached, completing the second stage of cementing. Finally, the window-opening tool is retrieved, and the secondary rubber plug is pulled out of the wellhead along with the working coiled tubing and the window-opening tool, completing the staged cementing operation. This invention uses coiled tubing to achieve cementing operations. After cementing is completed, the secondary rubber plug is pulled out of the wellhead with the coiled tubing, eliminating the need to push it down to the bottom of the well via the tubing string. This results in low operating costs and high efficiency, achieving drill-free staged cementing of the entire borehole using coiled tubing, effectively improving wellbore integrity and cementing quality.

[0050] Example 2

[0051] Preferably, based on Embodiment 1, in this embodiment, the middle housing of the lower connector 12 is provided with a plurality of radial through holes 8, and the centers of the radial through holes 8 are located in the same plane.

[0052] In actual use, the lower connector 12 has multiple radial through holes 8 on its central housing. During the secondary cementing process, after the window opening tool opens the stage collar, the cement slurry can flow from the radial through holes 8 to the outer annulus of the casing.

[0053] Example 3

[0054] Preferably, based on embodiment 2, in this embodiment, the housing of the sliding sleeve 5 is provided with a number of diversion holes 6 of the same size as the radial through holes 8. The diversion holes 6 are located above the radial through holes 8, and a variable diameter groove 9 is provided on the inner wall below the diversion holes 6.

[0055] In actual use, the housing of the sliding sleeve 5 is provided with the same number and size of diversion holes 6 as the radial through holes 8. The diversion holes 6 are located above the radial through holes 8. During the first stage cementing process, the cement slurry is prevented from flowing from the diversion holes 6 and the radial through holes 8 to the outer annulus of the casing. When used for the second stage cementing process, after the window opening tool opens the stage clamp, the cement slurry can flow from the diversion holes 6 and the radial through holes 8 to the outer annulus of the casing.

[0056] Example 4

[0057] Preferably, based on Embodiment 1, in this embodiment, multiple sealing rings 7 are provided between the sliding sleeve 5 and the inner wall of the lower connector 12.

[0058] In actual use, multiple sealing rings 7 are provided between the sliding sleeve 5 and the inner wall of the lower connector 12 to ensure the sealing between the sliding sleeve 5 and the lower connector 12 and prevent cement slurry from leaking into the outer annulus of the casing during cementing.

[0059] Example 5

[0060] Preferably, based on Embodiment 1, in this embodiment, the inner diameter of the upper connector 4 is the same as the inner diameter of the sliding sleeve 5.

[0061] In actual use, the inner diameter of the upper connector 4 is the same as the inner diameter of the sliding sleeve 5, which can realize drilling-free staged cementing of the full-bore wellbore in coiled tubing operations, effectively improving wellbore integrity and cementing quality.

[0062] Example 6

[0063] Preferably, based on Embodiment 1, in this embodiment, the window opening tool body 18 passes through the spring claw 20 and is fixedly connected to the connector 15, the continuous oil pipe connector 13 is connected to the cone 15 by a threaded connection, and the center rod 17 is connected to the cone 15 by a shear pin 14.

[0064] In actual use, the center rod 17 and the cone 15 are connected by shear pins 14. During the process of lowering the window opening tool to open the stage clamp, when the spring claw 20 is locked in the variable diameter groove 9 of the sliding sleeve 5, as the working coiled tubing continues to be lowered, the coiled tubing joint 13, cone 15, rubber sleeve 16, center rod 17, window opening tool body 18, and connector 19 of the window opening tool move down relative to the spring claw 20. The connector 19 supports the spring claw 20 and prevents it from deforming radially. The shear pins 14 are sheared off, and the cone 15 causes the rubber sleeve 16 to expand radially and seal with the sliding sleeve 5, forming an internal seal at the stage clamp, ensuring the smooth progress of the secondary cementing.

[0065] Example 7

[0066] Preferably, based on Example 1, in this example, as Figure 3 , Figure 6 As shown, the lower end of the spring claw 20 is provided with protrusions 201 on both sides, and the middle of the protrusion 201 is provided with a groove 202 in the middle. The steel wire shaft 22 passes through the groove 202 and is connected to the spring claw 20. The middle of the steel wire 21 is provided with an overlapping right angle 211. One end of the steel wire 21 is rotatably connected to the steel wire shaft 22 on one side of the lower end of the spring claw 20, and the other end is connected to the steel wire shaft 22 on the other side of the lower end of the spring claw 20 through the overlapping right angle 211 and extends out from the groove 202.

[0067] In actual use, two steel wires 21 are respectively connected to their corresponding steel wire shafts 22 via overlapping right angles 211. This cross-over overlap achieves radial compression of the spring claw 20, making its radial outer diameter smaller than the inner diameter of the sleeve. After the cross-over overlap, the two steel wires 21 extend from the slots 202, with the distance between the extended ends of the two steel wires 21 greater than the inner diameter of the sleeve. After the steel wires 21 fix the spring claw 20, they can only enter the sleeve downwards. When the sleeve changes diameter, they reverse direction, the overlap between the right angle 211 of the two steel wires 21 and the steel wire shaft 22 is released, and they rotate in the opposite direction, releasing the spring claw 20 into a radially retractable free state.

[0068] Example 8

[0069] Preferably, based on Embodiment 1, in this embodiment, the material of the primary rubber plug is wear-resistant rubber, the outer diameter of the primary rubber plug skirt 24 is larger than the inner diameter of the working casing, and the primary rubber plug skirt 24 can be radially retracted in the wellbore. The material of the secondary rubber plug is wear-resistant rubber, the outer diameter of the secondary rubber plug skirt 26 is larger than the inner diameter of the working casing, and the secondary rubber plug skirt 26 can be radially retracted in the wellbore.

[0070] In practical use, the primary rubber plug is made of wear-resistant rubber. The outer diameter of the primary rubber plug skirt 24 is larger than the inner diameter of the working casing. The primary rubber plug skirt 24 can retract radially within the wellbore, ensuring that during the primary cementing process, the primary rubber plug can enter the casing with the water displacement fluid and displace the cement slurry, returning it from the bottom of the well to the annulus, thus achieving the pressing operation. The secondary rubber plug is also made of wear-resistant rubber. The outer diameter of the secondary rubber plug skirt 26 is larger than the inner diameter of the working casing. The secondary rubber plug skirt 26 can retract radially within the wellbore, ensuring that during the secondary cementing process, the secondary rubber plug can travel through the entire working coiled tubing into the casing with the water displacement fluid, displacing the cement slurry and returning it from the stage collar position to the annulus, thus achieving the pressing operation; completing the secondary cementing.

[0071] Example 9

[0072] A staged cementing method for coiled tubing operations, using any of the staged cementing systems described above, is as follows:

[0073] S1: Lower the graded hoop;

[0074] After connecting the staged collar to the designed position on the casing, it is lowered into the open hole;

[0075] S2: Install wellhead injection device;

[0076] S3: First-stage cementing, the specific process is as follows:

[0077] Close the three-gate blowout preventer 2, place the first-stage rubber plug between the displacement fluid injection plate gate valve 1 and the three-gate blowout preventer 2 of the wellhead injection device, open the cement slurry injection plate gate valve 3 to start cement slurry injection, when the cement slurry injection calculation is completed, close the cement slurry injection plate gate valve 3, open the three-gate blowout preventer 2, open the displacement fluid injection plate gate valve 1 to start injecting clean water displacement fluid, the first-stage rubber plug enters the casing with the clean water displacement fluid until the first stage cementing is completed at the bottom of the artificial well;

[0078] S4: Insert the window opening tool to open the graded clamp. The specific process is as follows:

[0079] S41: Pass the working coiled tubing through the secondary rubber plug and the window opening tool, and connect it to the coiled tubing joint 13 by rolling. Then, place the whole coiled tubing into the wellhead injection device. The working coiled tubing and the wellhead injection device are sealed with packing. After the window opening tool passes through the three-gate blowout preventer 2, the three-gate blowout preventer 2 is partially sealed, so that the secondary rubber plug is placed between the three-gate blowout preventer 2 and the displacement fluid injection plate gate valve 1 of the wellhead injection device. At this time, the cement slurry injection plate gate valve 3 and the displacement fluid injection plate gate valve 1 are closed.

[0080] S42: The working coiled tubing is lowered to below the stage clamp position. The working coiled tubing is then lifted, and the two steel wires 21 interlock within the reducing groove 9 of the sliding sleeve 5, releasing the spring claw 20 into a radially retractable free state. The working coiled tubing is lowered again, and the spring claw 20 locks into the reducing groove 9 of the sliding sleeve 5. As the working coiled tubing continues to descend, the sliding sleeve 5 compresses the spring 10 and moves downward, connecting the flow divider hole 6 of the sliding sleeve 5 with the radial through hole 9 of the lower connector 12. Figure 7 The window opening process is shown in the diagram. During this process, the continuous oil pipe joint 13, cone 15, rubber sleeve 16, center rod 17, window opening tool body 18, and connector 19 of the window opening tool move downward relative to the spring claw 20. The connector 19 supports the spring claw 20 and prevents it from deforming radially. The shear pin 14 is sheared, and the cone 15 causes the rubber sleeve 16 to expand radially and seal with the sliding sleeve 5.

[0081] S5: Secondary cementing, the specific process is as follows:

[0082] Open the cement slurry injection plate gate valve 3 to start cement slurry injection. When the cement slurry injection calculation is completed, close the cement slurry injection plate gate valve. The three-gate blowout preventer 2 is fully opened. Open the displacement fluid injection plate gate valve 1 to start injecting water displacement fluid. The secondary rubber plug travels through the working coiled tubing with the water displacement fluid and enters the casing until the stage collar position is reached to complete the secondary cementing.

[0083] S6: Retrieve the window opening tool to complete the staged cementing operation. The specific process is as follows:

[0084] After the cement slurry from the secondary cementing stage solidifies, the coiled tubing is pulled up, the cone 15 separates from the rubber sleeve 16, and the rubber sleeve 16 retracts radially. At the same time, the coiled tubing connector 13, cone 15, rubber sleeve 16, center rod 17, window opening tool body 18, and connector 19 of the window opening tool move upward relative to the spring claw 20. The spring claw 20 loses its central support and becomes a free state that can deform radially again. The friction of the window opening tool is eliminated, and the secondary rubber plug is pulled out of the wellhead along with the coiled tubing and the window opening tool. After the window opening tool is separated from the stage clamp, the spring 10 pushes the sliding sleeve 5 back to its original ground assembly position, so that the diversion hole 6 of the sliding sleeve 5 is misaligned with the radial through hole 9 of the lower connector 12, the stage clamp is closed, and the wellbore is sealed.

[0085] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A staged cementing system for coiled tubing operations, characterized in that: include: Wellhead injection device, stage clamp, window opening tool, primary rubber plug, secondary rubber plug, including: The wellhead injection device includes, from top to bottom, a displacement fluid injection flat gate valve (1), a three-gate blowout preventer (2), and a cement slurry injection flat gate valve (3) connected in sequence. The graded hoop includes an upper connector (4), a sliding sleeve (5), a spring (10), and a lower connector (12). The lower outer wall of the upper connector (4) is fixedly connected to the upper inner wall of the lower connector (12). An annular step (11) is provided on the lower inner wall of the lower connector (12). A spring (10) is provided on the annular step (11). The sliding sleeve (5) is provided above the spring (10). The upper end face of the sliding sleeve (5) is in contact with the lower end face of the upper connector (4). A variable diameter groove (9) is provided on the inner wall of the sliding sleeve (5). A plurality of radial through holes (8) are provided on the middle shell of the lower connector (12). The centers of the radial through holes (8) are located on the same plane. A number of diversion holes (6) with the same size as the radial through holes (8) are provided on the shell of the sliding sleeve (5). The diversion holes (6) are located above the radial through holes (8). A variable diameter groove (9) is provided on the inner wall below the diversion holes (6). The window opening tool comprises, from top to bottom, a continuous oil pipe connector (13), a cone (15), a central rod (17), a window opening tool body (18), a connector (19), and a spring claw (20). A rubber sleeve (16) is provided on the outside of the central rod (17). A steel wire shaft (22) is provided on both sides of the lower end of the spring claw (20). A steel wire (21) is provided on the steel wire shaft (22). The steel wire (21) is rotatably connected to the spring claw (20) through the steel wire shaft (22). The window opening tool body (18) passes through the spring claw (20) and is fixedly connected to the connector (19). The continuous oil pipe connector (13) is connected to the cone (15) by a threaded connection. The central rod (17) is connected to the cone (15) by a shear pin (14). The primary rubber stopper includes a primary rubber stopper body (23) and a primary rubber stopper skirt (24) located on the side of the primary rubber stopper body (23). The primary rubber stopper body (23) is solid. The secondary rubber plug includes a secondary rubber plug body (25) and a secondary rubber plug skirt (26) located on the side of the secondary rubber plug body (25). The secondary rubber plug body (25) has a through hole (27) inside, and the diameter of the through hole (27) is the same as the outer diameter of the working coiled tubing.

2. The staged cementing system for coiled tubing operations according to claim 1, characterized in that: Multiple sealing rings (7) are provided between the sliding sleeve (5) and the inner wall of the lower connector (12).

3. The staged cementing system for coiled tubing operations according to claim 1, characterized in that: The inner diameter of the upper connector (4) is the same as the inner diameter of the sliding sleeve (5).

4. The staged cementing system for coiled tubing operations according to claim 1, characterized in that: The lower end of the spring claw (20) is provided with protrusions (201) on both sides. The protrusions (201) are provided with a groove (202) in the middle. The steel wire shaft (22) passes through the groove (202) and is connected to the spring claw (20). The steel wire (21) is provided with an overlapping right angle (211) in the middle. One end of the steel wire (21) is rotatably connected to the steel wire shaft (22) on one side of the lower end of the spring claw (20). The other end is connected to the steel wire shaft (22) on the other side of the lower end of the spring claw (20) through the overlapping right angle (211) and extends out from the groove (202).

5. The staged cementing system for coiled tubing operations according to claim 1, characterized in that: The primary rubber plug is made of wear-resistant rubber. The outer diameter of the primary rubber plug skirt (24) is larger than the inner diameter of the working casing. The primary rubber plug skirt (24) can be radially retracted in the wellbore. The secondary rubber plug is made of wear-resistant rubber. The outer diameter of the secondary rubber plug skirt (26) is larger than the inner diameter of the working casing. The secondary rubber plug skirt (26) can be radially retracted in the wellbore.

6. A staged cementing method for coiled tubing operations, using a staged cementing system for coiled tubing operations as described in any one of claims 1-5, characterized in that: Includes the following steps: S1: Lower the graded hoop; After connecting the staged collar to the designed position on the casing, it is lowered into the open hole; S2: Install wellhead injection device; S3: First-stage cementing, the specific process is as follows: Close the three-gate blowout preventer (2), place the first-stage rubber plug between the displacement fluid injection plate gate valve (1) and the three-gate blowout preventer (2) of the wellhead injection device, open the cement slurry injection plate gate valve (3) to start cement slurry injection, when the cement slurry injection calculation is completed, close the cement slurry injection plate gate valve (3), open the three-gate blowout preventer (2), open the displacement fluid injection plate gate valve (1) to start injecting clean water displacement fluid, the first-stage rubber plug enters the casing with the clean water displacement fluid until the first stage cementing is completed at the bottom of the artificial well; S4: Insert the window opening tool to open the graded clamp. The specific process is as follows: S41: Pass the working coiled tubing through the secondary rubber plug and the window opening tool, and connect it to the coiled tubing joint (13) by rolling. Then, put the whole coiled tubing into the wellhead injection device. The working coiled tubing and the wellhead injection device are sealed with packing. After the window opening tool passes through the three-gate blowout preventer (2), the three-gate blowout preventer (2) is partially sealed, so that the secondary rubber plug is placed between the three-gate blowout preventer (2) and the displacement fluid injection plate gate valve (1) of the wellhead injection device. At this time, the cement slurry injection plate gate valve (3) and the displacement fluid injection plate gate valve (1) are closed. S42: The working coiled tubing is used to send the window opening tool to a position below the graded clamp. The working coiled tubing is lifted up, and the two steel wires (21) in the variable diameter groove (9) of the sliding sleeve (5) are released from their cross-connection. The spring claw (20) is released and is in a free state that can be radially retracted. The working coiled tubing is lowered again, and the spring claw (20) is locked in the variable diameter groove (9) of the sliding sleeve (5). As the working coiled tubing continues to be lowered, the sliding sleeve (5) compresses the spring (10) and moves down to realize the diversion hole (6) of the sliding sleeve (5). The radial through hole (8) of the lower connector (12) is connected to realize the window opening process; during this process, the continuous oil pipe connector (13), cone (15), rubber sleeve (16), center rod (17), window opening tool body (18), and connector (19) of the window opening tool move down relative to the spring claw (20), the connector (19) supports the spring claw (20) and prevents it from undergoing radial deformation, the shear pin (14) is sheared, and the cone (15) causes the rubber sleeve (16) to expand radially and seal with the sliding sleeve (5); S5: Secondary cementing, the specific process is as follows: Open the cement slurry injection plate gate valve (3) to start injecting cement slurry. When the cement slurry injection calculation is completed, close the cement slurry injection plate gate valve. The three-gate blowout preventer (2) is fully opened. Open the displacement fluid injection plate gate valve (1) to start injecting water displacement fluid. The secondary rubber plug travels through the working coiled tubing with the water displacement fluid and enters the casing until the stage clamp position is reached to complete the secondary cementing. S6: Retrieve the window opening tool to complete the staged cementing operation. The specific process is as follows: After the cement slurry of the secondary cementing solidifies, the coiled tubing is pulled up, the cone (15) separates from the rubber sleeve (16), the rubber sleeve (16) retracts radially, and at the same time the coiled tubing joint (13), cone (15), rubber sleeve (16), center rod (17), window opening tool body (18), connector (19) move upward relative to the spring claw (20). The spring claw (20) loses its central support and becomes a free state that can be radially deformed again. The friction of the window opening tool is eliminated, and the secondary rubber plug is pulled out of the wellhead along with the coiled tubing and the window opening tool. After the window opening tool is separated from the stage clamp, the spring (10) pushes the sliding sleeve (5) back to the original ground assembly position, so that the diversion hole (6) of the sliding sleeve (5) is staggered from the radial through hole (8) of the lower joint (12), the stage clamp is closed, and the wellbore is sealed.

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