Coiled tubing drag-type mechanical variable slot staged fracturing process

Abstract

The present application provides a coiled tubing drag type mechanical variable segment fracturing process, relates to the oil field production engineering technical field. The coiled tubing drag type mechanical variable segment fractuating device, including casing, characterized by: the inside of the casing is provided with coiled tubing, the coiled tubing is sequentially connected with mechanical fracturing packer, first stage jetting and sealing integrated packer, second stage jetting and sealing integrated packer, third stage jetting and sealing integrated packer, hydraulic anchor and safety joint from bottom to top, the lower part outside of the casing is provided with lower anchoring mechanism. Through the integrated design of sand blaster and packer, the card distance conversion is started by the ball throwing mode, the whole is easy to implement, the operability is strong, and the whole pipe string can meet the different card distance change demand of the whole well, the effectiveness and pertinence of single pipe string fracturing are improved, it is a kind of fine, environmental protection, efficient fracturing technology.

Description

Technical Field

[0001] This invention relates to the field of oilfield production engineering technology, specifically to a continuous tubing-driven mechanical variable-distance segmented fracturing process. Background Technology

[0002] With the large-scale development and utilization of unconventional gas resources and marginal oil and gas reservoirs, the demands on equipment and the level of sophistication of technology in modern extraction are constantly increasing. In particular, my country's unconventional gas resources such as shale gas, coalbed methane, and tight sandstone gas have reached the basic conditions for commercial development. In the process of gas resource extraction, reservoir fracturing is one of the essential means of extracting gas resources. As a relatively new reservoir stimulation measure in China, coiled tubing fracturing technology can achieve unlimited-level stimulation of the reservoir as long as the casing is free of perforations and has sufficient strength. Moreover, it has a fast single-layer stimulation speed and the wellbore is fully vented after stimulation, which has significant technical advantages.

[0003] Potential targets for fracturing in onshore oilfields are generally classified into Class II and III thin-layer reservoirs, the top of thick oil layers, and isolated sand bodies with incomplete injection and production. Due to their large remaining reserves, highly dispersed remaining oil, and severe heterogeneity, fracturing reservoir stimulation measures are difficult. Furthermore, the reservoir development characteristics are 40 to 100 oil-bearing sandstones with oil layer thicknesses ranging from 0.2 to 20 meters. Conventional fracturing techniques can only achieve balanced stimulation by fracturing 5 to 10 stages, with each stage fracturing 3 to 5 small layers. At the same time, conventional drag fracturing techniques have a single fracturing spacing, making well and layer selection difficult, with poor adaptability and low efficiency. Therefore, a coiled tubing drag mechanical variable spacing staged fracturing technology is needed, which allows for changes in the tubing spacing according to the reservoir stimulation requirements in the well, thereby meeting the needs of precise, environmentally friendly, and efficient operation in thin-layer reservoirs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a continuous tubing-driven mechanical variable-distance segmented fracturing process, which solves the problems of conventional driven fracturing processes having a single fracturing distance and low operational targeting.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a coiled tubing-driven mechanical variable-distance segmented fracturing device, comprising a casing, wherein a coiled tubing is provided inside the casing, and the coiled tubing is connected sequentially from bottom to top to a mechanical fracturing packer, a first-stage spray-seal integrated packer, a second-stage spray-seal integrated packer, a third-stage spray-seal integrated packer, a hydraulic anchor, and a safety joint, wherein a lower anchoring mechanism is provided on the lower outer side of the casing.

[0006] Preferably, the lower anchoring mechanism includes a lower slip, a hoop is provided on the lower outer side of the lower slip, a lower slip seat is fixedly connected to the lower part of the lower slip, friction blocks are fixedly connected to the left and right sides of the lower slip seat, a protective ring is fixedly connected to the bottom end of the lower slip seat, control pins are provided on the front and rear sides of the protective ring, and a lower connector is fixedly connected to the bottom end of the control pin.

[0007] Preferably, a mechanical fracturing packer is provided on the lower inner wall of the casing.

[0008] A coiled tubing-driven mechanically variable clamping distance staged fracturing process includes the following steps: S1. First, connect the mechanical fracturing packer, the first-stage spray-sealing integrated packer, the second-stage spray-sealing integrated packer, the third-stage spray-sealing integrated packer, the hydraulic anchor, the safety joint, and the coiled tubing, and lower them into the casing to the pre-set depth. S2. By lifting and lowering the packer, the bottom mechanical fracturing packer is set, the pressure is increased and the construction flow rate is increased, the first-stage spray-sealed integrated packer double-clamp layer is set, and then the pressure is continued to complete the first-stage fracturing construction of the first-stage clamping distance. S3. Depressurize and lift the tubing string to complete the release of the first-stage spray-sealed integrated packer and the mechanical fracturing packer; S4. Repeat steps S2 and S3 to complete the fracturing construction of all layers in the first-gap clamping distance. S5. When increasing the clamping distance, first lift and lower the bottom mechanical fracturing packer to set it, then drop a ball at the wellhead to start the second-stage spray-sealing integrated packer, and at the same time seal the first-stage spray-sealing integrated packer. Pressurize and increase the construction displacement to set the second-stage spray-sealing integrated packer in the double clamping layer, and then continue to pressurize to complete the fracturing construction of the first layer of the second clamping distance. S6. Depressurize and lift the tubing string to complete the release of the second-stage spray-sealed integrated packer and the mechanical fracturing packer; S7. Repeat steps S5 and S6 to complete the fracturing construction of all layers in the second-gap clamping distance. S8. When continuing to increase the clamping distance, first lift and lower the bottom mechanical fracturing packer to set it, then drop a ball at the wellhead to start the third-stage spray-sealing integrated packer, and at the same time seal the second-stage spray-sealing integrated packer. Pressurize and increase the construction displacement to set the third-stage spray-sealing integrated packer in the double clamping layer, and then continue to pressurize to complete the fracturing construction of the first layer of the three clamping distance. S9. Depressurize and lift the tubing string to complete the release of the third-stage spray-sealed integrated packer and the mechanical fracturing packer; S10. Repeat steps S8 and S9 to complete the fracturing operation for all layers with three clamping distances until the entire fracturing operation process is completed.

[0009] Preferably, in step S1, the first-stage spray-sealing integrated packer, the second-stage spray-sealing integrated packer, and the third-stage spray-sealing integrated packer are all designed and manufactured as an integrated unit of the sandblaster and the packer.

[0010] Preferably, in step S1, the tube body inspection method for assembled sleeve 1 is as follows: the straightness, diameter, wall thickness, integrity of threads, and wear condition of the wear-resistant band of the tube body are checked by using a caliper, dial indicator, and lamp. If obvious wear and dents or indentations are found, the tube body needs to be replaced and reported. At the same time, ultrasonic non-destructive testing can also be used to detect the damage status of the tube body.

[0011] Preferably, in step S2, the construction discharge rate is controlled between 3 and 3.5 m³. 3 / min, mainly to avoid excessively high cracks that could affect oil layer stimulation.

[0012] This invention provides a coiled tubing-driven mechanically variable clamping distance staged fracturing process. It has the following beneficial effects: 1. This invention integrates the sandblaster and packer into a single design, creating a combined sandblasting and packer. It employs a three-level classification system, combined with a mechanical fracturing packer, hydraulic anchor, safety joint, and coiled tubing. The casing is run to a preset depth, allowing for adjustable clamping distances downhole via ball dropping. The device boasts a simple and stable overall structure, ease of implementation, and strong operability. Furthermore, a single tubing string can meet the varying clamping distance requirements for reservoir stimulation throughout the well, improving the effectiveness and targeting of single-string fracturing and fulfilling the requirements for precise, environmentally friendly, and efficient operations in thin, poor-quality wells.

[0013] 2. This invention completes the assembly by sequentially connecting and combining a fracturing packer, a first-stage spray-sealing integrated packer, a second-stage spray-sealing integrated packer, a third-stage spray-sealing integrated packer, a hydraulic anchor, a safety joint, and coiled tubing, and then lowering the casing to the set depth. The overall connection method of the device is simple and quick, with strong sealing performance, and each part is easy to disassemble and replace, which helps to improve construction efficiency and maintenance speed. Secondly, the setting structure is simple and easy to implement. When used in conjunction with the construction steps, it reduces the number of times the tubing string is pulled up and down, saves fracturing time, improves the work efficiency of fracturing construction, and further reduces costs. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the internal structure of the sleeve of the present invention; Figure 2 This is a schematic diagram of the internal structure of the fracturing casing with a single-stage clamping distance according to the present invention; Figure 3 This is a schematic diagram of the internal structure of the two-stage clamping distance fracturing casing of the present invention; Figure 4This is a schematic diagram of the internal structure of the three-stage clamping distance fracturing casing of the present invention.

[0015] Among them, 1. casing; 2. coiled tubing; 3. safety joint; 4. hydraulic anchor; 5. third-stage spray-sealing integrated packer; 6. second-stage spray-sealing integrated packer; 7. first-stage spray-sealing integrated packer; 8. mechanical fracturing packer; 9. lower anchoring mechanism; 901. lower slip; 902. clamp ring; 903. lower slip seat; 904. friction block; 905. protective ring; 906. control pin; 907. lower joint. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0017] This embodiment provides a coiled tubing-driven mechanical variable-distance segmented fracturing device and process.

[0018] According to one aspect of the invention, such as Figure 1-4 As shown, this embodiment of the invention provides a coiled tubing-driven mechanical variable-distance segmented fracturing device, including a casing 1, with a coiled tubing 2 inside the casing 1. The coiled tubing 2 is connected from bottom to top to a mechanical fracturing packer 8, a first-stage spray-sealing integrated packer 7, a second-stage spray-sealing integrated packer 6, a third-stage spray-sealing integrated packer 5, a hydraulic anchor 4, and a safety joint 3. A lower anchoring mechanism 9 is provided on the lower outer side of the casing 1.

[0019] This invention, through the aforementioned structure, enables rapid activation and adjustment of the clamping distance of the mechanical fracturing packer 8 and different levels of integrated spray-sealing packers downhole via ball dropping. The overall structure of the device is simple and stable. Furthermore, the components installed within the device provide excellent overall sealing with a simple sealing method. Additionally, the components are easy to disassemble and replace, which improves construction efficiency and maintenance speed. Overall, it solves the problem of a single clamping distance in conventional coiled tubing fracturing processes. Moreover, it allows for changes in the tubing clamping distance based on the reservoir stimulation requirements, meeting the requirements for precise, environmentally friendly, and efficient construction operations in thin, poor-quality wells.

[0020] For further details, please refer to Figure 1The lower anchoring mechanism 9 includes a lower slip 901, a hoop 902 is provided on the lower outer side of the lower slip 901, a lower slip seat 903 is fixedly connected to the lower part of the lower slip 901, friction blocks 904 are fixedly connected to the left and right sides of the lower slip seat 903, a protective ring 905 is fixedly connected to the bottom end of the lower slip seat 903, control pins 906 are provided on the front and rear sides of the protective ring 905, and a lower connector 907 is fixedly connected to the bottom end of the control pin 906.

[0021] To ensure the normal operation of the upper clamping distance adjustment and the accurate and stable positioning of the sleeve 1, a lower anchoring mechanism 9 is adopted, which can effectively locate the lower position of the sleeve 1 and improve the accuracy of deployment.

[0022] For further details, please refer to Figure 1-4 A mechanical fracturing packer 8 is installed on the lower inner wall of the casing 1. This is the preset depth of the casing 1, which makes it easy to fix the mechanical fracturing packer 8 at a suitable depth for subsequent construction operations.

[0023] According to another aspect of the present invention, the present invention also provides a coiled tubing-driven mechanically variable clamping distance staged fracturing process, comprising the following steps: S1. First, connect the mechanical fracturing packer 8, the first-stage spray-sealing integrated packer 7, the second-stage spray-sealing integrated packer 6, the third-stage spray-sealing integrated packer 5, the hydraulic anchor 4, and the safety joint 3 to the coiled tubing 2, and lower them into the casing 1 to the preset depth. S2. By lifting and lowering the packer, the bottom mechanical fracturing packer 8 is set, the pressure is increased and the construction flow rate is increased, the first-stage spray-sealed integrated packer 7 double-clamp layer is set, and then the pressure is continued to complete the first-stage fracturing construction of the first-stage clamping distance. S3. Depressurize and lift the tubing string to complete the release of the first-stage spray-sealed integrated packer 7 and the mechanical fracturing packer 8; S4. Repeat steps S2 and S3 to complete the fracturing construction of all layers in the first-gap clamping distance. S5. When increasing the clamping distance, first lift and lower the bottom mechanical fracturing packer 8 to set it, then drop a ball at the wellhead to start the second-stage spray-sealing integrated packer 6, and at the same time seal the first-stage spray-sealing integrated packer 7. Pressurize and increase the construction displacement to set the second-stage spray-sealing integrated packer 6 in the double clamping layer, and then continue to pressurize to complete the fracturing construction of the first layer of the second clamping distance. S6. Depressurize and lift the tubing string to complete the release of the second-stage spray-sealed integrated packer 6 and the mechanical fracturing packer 8; S7. Repeat steps S5 and S6 to complete the fracturing construction of all layers in the second-gap clamping distance. S8. When the clamping distance is further increased, the bottom mechanical fracturing packer 8 is set by first lifting and lowering it, the third-stage spray-sealing integrated packer 5 is started by dropping a ball at the wellhead, and the second-stage spray-sealing integrated packer 6 is sealed at the same time. The third-stage spray-sealing integrated packer 5 is set in the double clamping layer by pressurizing and increasing the construction displacement. Then pressurizing is continued to complete the fracturing construction of the first layer of the three clamping distance. S9. Depressurize and lift the tubing string to complete the release of the third-stage spray-sealed integrated packer 5 and the mechanical fracturing packer 8; S10. Repeat steps S8 and S9 to complete the fracturing operation for all layers with three clamping distances until the entire fracturing operation process is completed.

[0024] In step S1, the first-stage spray-sealing integrated packer 7, the second-stage spray-sealing integrated packer 6, and the third-stage spray-sealing integrated packer 5 are all designed and manufactured as an integrated unit of the sandblaster and the packer.

[0025] In step S1, the assembly sleeve 1 tube body inspection method is as follows: the straightness, diameter, wall thickness, thread integrity, and wear condition of the tube body are checked by using calipers, dial indicators, and lamps. If obvious wear and dents or indentations are found, the tube body needs to be replaced and reported. At the same time, ultrasonic non-destructive testing can also be used to detect the damage status of the tube body.

[0026] In step S2, the construction displacement should be controlled between 3 and 3.5 m³. 3 / min, mainly to avoid excessively high cracks that could affect oil layer stimulation.

[0027] Specifically, the present invention, through the above steps, has the following effects: 1. By launching balls at the wellhead, different levels of integrated spray-sealing packers can be activated, thereby enabling a single tubing string to meet the varying clamping distance requirements throughout the well. The structure is simple, stable, and highly adaptable to the downhole working environment, solving the problems of single clamping distance and low construction targeting in conventional drag fracturing processes.

[0028] 2. Through the cooperation of the first-stage spray-sealing integrated packer 7, the second-stage spray-sealing integrated packer 6, the third-stage spray-sealing integrated packer 5 and the mechanical fracturing packer 8, the tubing string clamping distance can be quickly adjusted. At the same time, through the control of wellhead ball dropping, the purpose of accurately and efficiently controlling the tubing string clamping distance adjustment to different depths can be achieved.

[0029] 3. The internal structure of this coiled tubing-driven mechanical fracturing device consists of a mechanical fracturing packer 8, a first-stage spray-sealing integrated packer 7, a second-stage spray-sealing integrated packer 6, a third-stage spray-sealing integrated packer 5, a hydraulic anchor 4, a safety joint 3, and coiled tubing 2 connected in sequence. The casing 1 is then lowered to the designated depth. The overall sealing and connection methods are simple and quick, allowing for sealing and unsealing at any time. The setting structure is simple and easy to implement. The aforementioned construction steps, when used with this device, effectively solve the problem of a single fracturing clamping distance in conventional drag-type fracturing processes. This reduces the number of times tubing is pulled in and out, saves fracturing time, improves construction efficiency, and further reduces costs.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A coiled tubing-driven mechanical variable-spacing segmented fracturing device, comprising casing (1), characterized in that: The casing (1) is provided with a continuous tubing (2) inside. The continuous tubing (2) is connected from bottom to top to a mechanical fracturing packer (8), a first-stage spray-sealing integrated packer (7), a second-stage spray-sealing integrated packer (6), a third-stage spray-sealing integrated packer (5), a hydraulic anchor (4), and a safety joint (3). The lower outer side of the casing (1) is provided with a lower anchoring mechanism (9).

2. The coiled tubing-driven mechanical variable-distance segmented fracturing device according to claim 1, characterized in that: The lower anchoring mechanism (9) includes a lower slip (901), a hoop (902) is provided on the lower outer side of the lower slip (901), a lower slip seat (903) is fixedly connected to the lower part of the lower slip (901), friction blocks (904) are fixedly connected to the left and right sides of the lower slip seat (903), a protective ring (905) is fixedly connected to the bottom end of the lower slip seat (903), a control pin (906) is provided on the front and rear sides of the protective ring (905), and a lower connector (907) is fixedly connected to the bottom end of the control pin (906).

3. The coiled tubing-driven mechanical variable-distance segmented fracturing device according to claim 1, characterized in that: A mechanical fracturing packer (8) is provided on the lower inner wall of the casing (1).

4. A coiled tubing-driven mechanically variable clamping distance staged fracturing process, characterized in that: Using the coiled tubing-driven mechanical variable-distance segmented fracturing device as described in claim 1 includes the following steps: S1. First, connect the mechanical fracturing packer (8), the first-stage spray-sealing integrated packer (7), the second-stage spray-sealing integrated packer (6), the third-stage spray-sealing integrated packer (5), the hydraulic anchor (4), and the safety joint (3) to the coiled tubing (2), and lower them into the casing (1) to the preset depth. S2. By lifting and lowering, the bottom mechanical fracturing packer (8) is set, the pressure is increased and the construction flow rate is increased, the first-stage spray-sealed integrated packer (7) double-target layer is set, and then the pressure is continued to complete the first-stage fracturing construction of the first layer with a first-stage spacing. S3. Depressurize and lift the tubing to complete the unsealing of the first-stage spray-sealed integrated packer (7) and the mechanical fracturing packer (8); S4. Repeat steps S2 and S3 to complete the fracturing construction of all layers in the first-gap clamping distance. S5. When increasing the clamping distance, first lift and lower the bottom mechanical fracturing packer (8) to set, then drop a ball at the wellhead to start the second-stage spray-sealing integrated packer (6), and at the same time seal the first-stage spray-sealing integrated packer (7), pressurize and increase the construction displacement to set the second-stage spray-sealing integrated packer (6) to the double clamping layer, and then continue to pressurize to complete the fracturing construction of the first layer of the second clamping distance. S6. Depressurize and lift the tubing string to complete the unsealing of the second-stage spray-sealed integrated packer (6) and the mechanical fracturing packer (8); S7. Repeat steps S5 and S6 to complete the fracturing construction of all layers in the second-gap clamping distance. S8. When the clamping distance is further increased, the bottom mechanical fracturing packer (8) is first lifted and lowered to set, the ball is dropped at the wellhead to start the third-stage spray-sealing integrated packer (5), and the second-stage spray-sealing integrated packer (6) is sealed at the same time. The pressure is increased and the construction displacement is increased to set the third-stage spray-sealing integrated packer (5) in the double clamping layer. Then the pressure is continued to complete the fracturing construction of the first layer of the three clamping distance. S9. Depressurize and lift the tubing to complete the unsealing of the third-stage spray-sealed integrated packer (5) and the mechanical fracturing packer (8); S10. Repeat steps S8 and S9 to complete the fracturing operation for all layers with three clamping distances until the entire fracturing operation process is completed.

5. The coiled tubing-driven mechanical variable-distance staged fracturing process according to claim 4, characterized in that: In step S1, the first-stage spray-sealing integrated packer (7), the second-stage spray-sealing integrated packer (6), and the third-stage spray-sealing integrated packer (5) are all designed and manufactured as an integrated sandblaster and packer.

6. The coiled tubing-driven mechanical variable-distance staged fracturing process according to claim 4, characterized in that: In step S1, the assembly sleeve (1) tube body inspection method: the straightness, diameter, wall thickness, integrity of the thread, and wear of the wear-resistant band of the tube body are checked by caliper, dial indicator, and lamp. If there is obvious wear and dents, it needs to be replaced and reported. At the same time, ultrasonic non-destructive testing can be used to detect the damage status of the tube body.

7. The coiled tubing-driven mechanical variable-distance staged fracturing process according to claim 4, characterized in that: In step S2, the construction discharge rate is controlled between 3 and 3.5 m³. 3 / min, mainly to avoid excessively high cracks that could affect oil layer stimulation.

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