A large borehole wall scraper

Abstract

The application discloses a large-size wellbore wall scraping device and relates to the technical field of oil and gas well equipment. The wellbore wall scraping device comprises a wall scraping module, the wall scraping module comprises a driving mechanism, a guide locking mechanism and an executing mechanism, the guide locking mechanism comprises a transposition shaft and a fixed top pin, a guide sliding groove is arranged on the outer ring of the transposition shaft, a plurality of groups of first locking grooves are arranged in the circumferential direction of the guide sliding groove, two second locking grooves are symmetrically arranged between two first locking grooves, a third locking groove is arranged between the two second locking grooves, the first locking groove and the third locking groove are located on the same side of the guide sliding groove, and the second locking groove is located on the other side of the guide sliding groove. The application realizes the multiple activation and recovery of the cutter by adjusting the drilling fluid displacement, does not need to change the tool by tripping, improves the operation efficiency, ensures that the unfolded cutter is locked by the guide locking mechanism, maintains the constant scraping diameter, guarantees the uniformity and stability of the well wall treatment quality, and continuously flushes the cutter by the cleaning mechanism, thereby avoiding the mud ball problem caused by the rock debris accumulation.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well equipment technology, specifically a large-size wellbore scraper. Background Technology

[0002] Scraper blades are used in oilfield downhole operations to clean and scrape away residual cement blocks, salt crystals, or deposits from the inner wall of the casing. Traditional scraper blade technology suffers from two major drawbacks due to limitations in mechanical structure design and control methods: First, in non-operating conditions, the blades remain in constant contact and friction with the casing wall. Especially in large-diameter wells, this continuous, ineffective friction not only leads to premature wear of the cutting edges, reducing efficiency after reaching the target formation, but also easily causes scratches on the casing inner wall at non-target formations, affecting well completion quality. Second, under low return velocity conditions, cement fragments, formation sand, and other deposits easily accumulate in the gap between the blades and the casing. Especially in multi-spring floating structures, deposits entering the spring chambers can cause "sand jamming" or "mud buildup," causing the blades to lose their radial compensation and retraction functions, thereby increasing tripping resistance and worsening the bottomhole flow field. These two technical bottlenecks severely impact drilling efficiency and wellbore integrity.

[0003] In existing technologies, the latest solutions mostly employ wall scraping tools derived from the principle of drilling reaming, primarily activating the cutter wings through surface ball dropping or using fixed-size cutting wings. While existing technologies have addressed the main challenges of wall scraping, significant problems remain. First, once activated, the tool often cannot be retrieved or re-deployed downhole, requiring repeated tripping for activation and increasing construction costs. Second, fixed tools continuously wear down the casing during drilling, reducing casing life. Third, in large-diameter wells, due to limited cuttings transport efficiency, the tool is prone to forming mud pockets during cutting, leading to scraping failure or even stuck pipe. Summary of the Invention

[0004] The purpose of this invention is to provide a large-size wellbore scraper to solve the problems in the prior art where the cutter blades continuously scrape the casing during tripping and cutting, and where the cutter blades get stuck and scraping fails during cutting.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A large-size wellbore scraper, the wellbore scraper including a scraping module; The wall scraping module includes a drive mechanism, a guide locking mechanism, and an actuator. The guide locking mechanism includes a shifting shaft and a fixed ejector pin; The outer ring of the shifting shaft is provided with a guide groove, and several sets of first locking grooves are provided in the circumferential direction of the guide groove. Two second locking grooves are symmetrically provided between two first locking grooves, and a third locking groove is provided between two second locking grooves. The first locking grooves and the third locking grooves are located on the same side of the guide groove, and the second locking grooves are located on the other side of the guide groove. The guide groove is provided with several protrusions; The actuator includes a sliding sleeve, and the outer circumference of the sliding sleeve is provided with several sets of cutting tools. The sliding sleeve and the cutting tools are slidably connected. Several protrusions are respectively eccentrically arranged on the same side as the first locking groove, the second locking groove and the third locking groove. The fixed ejector pin is slidably connected to the guide slide, the first locking groove, the second locking groove and the third locking groove. The drive mechanism is rotatably connected to the shifting shaft. The drive mechanism drives the shifting shaft to move axially and rotate radially and drives the tool to extend and retract.

[0007] When the wall scraping operation mode needs to be activated, the drilling fluid flow rate is increased to the preset activation flow rate via the surface pump unit. The increased flow rate generates sufficient hydraulic pressure within the drive mechanism, pushing the sliding sleeve axially. The sliding sleeve interacts with the cutter on its outer ring, driving the cutter to radially unfold from within the housing, completing the initial preparation for the wall scraping operation. After the cutter unfolds, the drilling fluid flow rate is reduced to the normal working flow rate. At this point, the axial driving force decreases, and the shifting shaft rotates under the constraint of the fixed ejector pin. Ultimately, the fixed ejector pin slides through the guide groove into the third locking groove on the shifting shaft. This process achieves mechanical locking of the cutter in the unfolded state, and the wall scraper enters a stable wall scraping operation mode, effectively cleaning the well wall. When the scraping operation is stopped and the cutting tool is retrieved, the drilling fluid flow rate is increased to the activated flow rate again. The hydraulic pressure drives the sliding sleeve forward, and the rotation of the shifting shaft causes the fixed ejector pin to slide out of the third locking groove. Due to the eccentric setting of the protrusion, the shifting shaft can only rotate in a directional manner, so when the fixed ejector pin slides out, it can only slide in a directional manner to the second locking groove to release the mechanical lock. Then, the flow rate is immediately reduced to the normal working flow rate, the sliding sleeve retracts, the cutting tool retracts, the shifting shaft continues to rotate in a directional manner, and the fixed ejector pin moves to the first locking groove. The scraper returns to the normal drilling standby state. The guide locking mechanism can ensure that the cutting tool remains mechanically locked after being deployed, effectively maintaining a constant scraping diameter, thereby ensuring the uniformity and stability of the well wall treatment quality.

[0008] Furthermore, the guide locking mechanism also includes a guide housing, on which a fixing pin is provided, and the fixing pin passes through the guide housing; The guide housing also includes an initial slot and an insertion slot; The outer ring of the shifting shaft is also provided with a strip-shaped boss in the circumferential direction, and the strip-shaped boss is located on one side of the first locking groove; The strip-shaped bosses are slidably connected to the initial slot and the insertion slot, respectively.

[0009] The guide housing is slidably connected to the strip-shaped boss on the outer ring of the transposition shaft via an initial groove, ensuring precise guidance of the relative movement between the guide housing and the transposition shaft. During drilling fluid hydraulic drive, the strip-shaped boss first slides out along the initial groove. When the fixed ejector pin slides to the third locking groove, the strip-shaped boss slides into the insertion groove, achieving double locking and keeping the tool in the deployed state. During tool retraction, the strip-shaped boss slides out of the insertion groove and slides back into the initial groove as the transposition shaft rotates. The fixed ejector pin passes through the guide housing, further enhancing the stability of the entire guide locking mechanism.

[0010] Furthermore, the outer ring of the sliding sleeve is provided with several sets of sliding tracks in the circumferential direction, and the several sets of sliding tracks are arranged at an incline. The cutting tool has a sliding groove on the side near the sliding sleeve, and the sliding groove is arranged at an angle; The sliding track and sliding groove are slidably connected.

[0011] The inclined arrangement of the sliding track and sliding groove allows the sliding sleeve to effectively transmit force to the tool when it moves axially, thereby realizing the radial expansion or contraction of the tool. When the sliding sleeve moves forward under hydraulic drive, the cooperation of the sliding track and sliding groove causes the tool to expand outward radially until the predetermined scraping diameter is reached. When the sliding sleeve retracts, the tool retracts inward along the sliding track through the sliding groove and returns to the initial state.

[0012] Furthermore, the wellbore scraper also includes a cleaning mechanism; The wall scraping module also includes a transmission mechanism; The drive mechanism includes a fixed housing, and a piston is installed inside the fixed housing; The cleaning system includes a flushing system; The inner ring of the fixed outer shell is rotatably connected to the shifting shaft. One end of the shifting shaft is rotatably connected to the piston, and the other end of the shifting shaft is equipped with a transmission mechanism. One end of the transmission mechanism is equipped with a punch tube, which passes through the sliding sleeve and is slidably connected to the sliding sleeve.

[0013] The flushing tube moves axially under hydraulic drive, and its movement is transmitted to the sliding sleeve through the transmission mechanism, thereby driving the cutter to extend. The fixed housing provides a stable operating environment for the piston. When the flushing tube moves forward, the relative sliding between it and the sliding sleeve not only realizes the unfolding of the cutter, but also simultaneously triggers the cleaning mechanism to form a high-pressure jet to clean the cutter in real time, avoiding the problem of tool jamming caused by debris accumulation, and further improving the adaptability and reliability of the scraper under complex well conditions.

[0014] Furthermore, the actuator also includes a return spring and a sliding sleeve housing; The inner ring of the sliding sleeve housing is provided with an annular boss, and the sliding sleeve housing is provided with several tool grooves in the circumferential direction. An annular boss is placed between the sliding sleeve and the punch tube. A return spring is provided on one side of the annular boss. The return spring is placed between the annular boss and the punch tube. A guide shell is fitted on the outer ring of one side of the sliding sleeve housing. The cutting tool passes through the cutting groove, and the cutting tool and the cutting groove are slidably connected.

[0015] The return spring plays a crucial role in the tool retraction process. When the drilling fluid flow rate decreases, the axial force applied to the piston decreases. Under the action of the restoring force, the return spring pushes the punch pipe back, thereby causing the sliding sleeve to retract, ensuring that the tool can retract into the sliding sleeve housing in a timely and smooth manner. The annular boss not only provides a stable support point for the return spring but also limits the axial movement range of the sliding sleeve through its cooperation with the punch pipe, preventing the mechanism from jamming or being damaged due to excessive movement. In addition, the tool discharge groove on the sliding sleeve housing provides a precise guide path for the radial movement of the tool, ensuring that the tool maintains a stable movement trajectory during deployment and retraction, further improving the reliability and safety of the wall scraping operation.

[0016] Furthermore, the transmission mechanism includes a shifting key, a sliding sleeve key, and a rolling bearing. The rolling bearing is provided between the shifting key and the sliding sleeve key, and the shifting key and the sliding sleeve key are rotatably connected. A punch is provided on one side of the shifting key, a sliding sleeve housing is provided on the outer ring of one side of the shifting key, a shifting shaft is provided on one side of the sliding sleeve key, and the outer ring of one side of the sliding sleeve key is rotatably connected to the guide housing.

[0017] The transmission mechanism, through the cooperation of the shifting key and the sliding sleeve key, combined with the use of rolling bearings, achieves smooth and flexible power transmission. The rolling bearings not only reduce frictional losses during transmission but also improve the overall durability of the mechanism. When the punch moves axially under hydraulic drive, its motion is transmitted to the sliding sleeve key via the shifting key, thereby driving the shifting shaft to rotate or move axially.

[0018] Furthermore, the cleaning mechanism also includes a cleaning housing, which is slidably connected to a flushing pipe, with the flushing pipe inserted into the cleaning housing.

[0019] The cleaning mechanism further enhances the overall functionality of the wall scraper. The flushing pipe is placed inside the cleaning shell, and the drilling fluid entering through the flushing pipe can enter the cutting surface and root area of ​​the tool through the cleaning shell, realizing real-time hydraulic cleaning of the tool during the wall scraping operation. This effectively removes debris and attachments generated during scraping, reduces the risk of rock cuttings, cement blocks, etc. accumulating in the gap between the tool and the wall, thereby fundamentally suppressing mud packing or sand jamming, and ensuring the reliability and continuity of the wall scraping operation.

[0020] Furthermore, the flushing pipe has several pressure relief holes circumferentially arranged at one end near the cleaning housing; The cleaning housing has several rinsing holes arranged at an angle along its inner circumference. One end of the flushing hole faces the pressure relief hole, and the other end faces the tool.

[0021] Multiple pressure relief holes are circumferentially opened at the front of the flushing tube, and corresponding flushing holes are provided on the inner wall of the cleaning shell, which are connected to the working area of ​​the cutting tool through an inclined arrangement. When the cutting tool is radially extended, the flushing tube moves forward synchronously, connecting the pressure relief holes and the flushing holes. High-pressure drilling fluid then enters through the pressure relief holes and forms a directional high-speed jet through the flow channels of the inclined flushing holes, continuously acting on the cutting surface and root area of ​​the cutting tool. This achieves real-time hydraulic cleaning of the cutting tool during the wall scraping operation, suppresses mud packing or sand jamming, and ensures the reliability and continuity of the wall scraping operation.

[0022] Compared with existing technologies, the advantages of this invention are as follows: This invention achieves multiple activation and retraction of the cutting tool by adjusting the drilling fluid flow rate, eliminating the need for tool changes during tripping. A single drill string trip can perform multiple scraping tasks, improving operational efficiency. Its built-in guide locking mechanism ensures the cutting tool remains mechanically locked after deployment, effectively maintaining a constant scraping diameter and thus guaranteeing uniform and stable wellbore treatment quality. Furthermore, the cleaning mechanism continuously flushes the cutting tool during operation, fundamentally avoiding mud packing problems caused by cuttings accumulation, ensuring long-term, efficient operation of the scraping tool under large-diameter wellbore conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall internal structure of the present invention; Figure 3 This is a schematic diagram of the guide locking mechanism of the present invention; Figure 4 for Figure 2 A magnified view of part A of the view; Figure 5 This is a schematic diagram of the structure of the guide shell of the present invention; Figure 6 This is a schematic diagram of the structure of the present invention, showing the fixed ejector pin located in the second locking groove; Figure 7 This is a schematic diagram of the structure of the present invention, showing the fixed ejector pin located in the third locking groove; Figure 8 This is a schematic diagram of the structure of the sliding sleeve and the cutting tool of the present invention; Figure 9 for Figure 2 A magnified view of part B in the view; Figure 10 for Figure 2 A magnified view at point C in the view.

[0024] In the diagram: 1. Scraping module; 11. Drive mechanism; 111. Fixed housing; 112. Piston; 12. Guide locking mechanism; 121. Shifting shaft; 1211. Guide groove; 12111. Protrusion; 1212. First locking groove; 1213. Second locking groove; 1214. Third locking groove; 1215. Strip-shaped boss; 122. Fixed ejector pin; 123. Guide housing; 1231. Initial groove; 1232. Insertion 13. Transmission mechanism; 131. Shifting key; 132. Sliding sleeve key; 133. Rolling bearing; 14. Actuator; 141. Sliding sleeve; 1411. Sliding rail; 142. Cutting tool; 1421. Sliding groove; 143. Return spring; 144. Sliding sleeve housing; 1441. Annular boss; 2. Cleaning mechanism; 21. Punching pipe; 211. Pressure relief hole; 22. Cleaning housing; 221. Flushing hole. Detailed Implementation

[0025] 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.

[0026] Example: Figures 1-10 As shown, the present invention provides a technical solution: a large-size wellbore scraper.

[0027] like Figures 1-3 As shown, a large-size wellbore scraper includes a scraping module 1. The wall scraping module 1 includes a drive mechanism 11, a guide locking mechanism 12, and an actuator 14; The guide locking mechanism 12 includes a shifting shaft 121 and a fixed ejector pin 122; The outer ring of the shifting shaft 121 is provided with a guide groove 1211. The guide groove 1211 is provided with several sets of first locking grooves 1212 in the circumferential direction. Two second locking grooves 1213 are symmetrically provided between two first locking grooves 1212. A third locking groove 1214 is provided between two second locking grooves 1213. The first locking grooves 1212 and the third locking grooves 1214 are located on the same side of the guide groove 1211, and the second locking grooves 1213 are located on the other side of the guide groove 1211. The guide groove 1211 is provided with several protrusions 12111; The actuator 14 includes a sliding sleeve 141, and a plurality of cutters 142 are provided around the outer circumference of the sliding sleeve 141. The sliding sleeve 141 and the cutters 142 are slidably connected. Several protrusions 12111 are respectively eccentrically arranged on the same side as the first locking groove 1212, the second locking groove 1213 and the third locking groove 1214. The fixed ejector pin 122 is slidably connected to the guide groove 1211, the first locking groove 1212, the second locking groove 1213 and the third locking groove 1214 respectively. The drive mechanism 11 is rotatably connected to the shifting shaft 121. The drive mechanism 11 drives the shifting shaft 121 to move axially and rotate radially and drives the tool 142 to extend and retract.

[0028] When the wall scraping operation mode needs to be activated, the drilling fluid flow rate is increased to the preset activation flow rate via the surface pump set. The increased flow rate generates sufficient hydraulic pressure within the drive mechanism 11, pushing the sliding sleeve 141 to move axially. The sliding sleeve 141 interacts with the cutter 142 on its outer ring, driving the cutter 142 to expand radially from the housing, completing the initial preparation for the wall scraping operation. After the cutter 142 expands, the drilling fluid flow rate is reduced to the normal working flow rate. At this time, the axial driving force decreases, and the shifting shaft 121 rotates under the limitation of the fixed ejector pin 122, ultimately causing the fixed ejector pin 122 to slide into the third locking groove 1214 on the shifting shaft 121 through the guide groove 1211. This process achieves mechanical locking of the cutter 142 in the expanded state, and the wall scraper enters a stable wall scraping operation mode, which can effectively clean the well wall. When the wall scraping operation is stopped and the cutting tool 142 is retrieved, the drilling fluid flow rate is increased to the activated flow rate again. The hydraulic pressure drives the sliding sleeve 141 to move forward, and through the rotation of the shifting shaft 121, the fixed pin 122 slides out from the third locking groove 1214. Due to the eccentric setting of the protrusion 12111, the shifting shaft 121 can only rotate in a directional manner. Thus, when the fixed pin 122 slides out, it can only slide in a directional manner to the second locking groove 1213, releasing the mechanical lock. Then, the flow rate is immediately reduced to the normal working flow rate, the sliding sleeve 141 retracts, the cutting tool 142 retracts, the shifting shaft 121 continues to rotate in a directional manner, and the fixed pin 122 moves to the first locking groove 1212. The wall scraper re-enters the normal drilling standby state. The guide locking mechanism 12 can ensure that the cutting tool 142 remains in a mechanically locked state after being deployed, effectively maintaining a constant scraping diameter, thereby ensuring the uniformity and stability of the well wall treatment quality.

[0029] like Figures 4-7 As shown, the guide locking mechanism 12 also includes a guide housing 123, on which a fixing pin 122 is provided, and the fixing pin 122 passes through the guide housing 123; The guide housing 123 also includes an initial slot 1231 and an insertion slot 1232; The outer ring of the transposition shaft 121 is also provided with a strip-shaped boss 1215 in the circumferential direction, and the strip-shaped boss 1215 is placed on one side of the first locking groove 1212; The strip-shaped boss 1215 is slidably connected to the initial groove 1231 and the insertion groove 1232 respectively.

[0030] The guide housing 123 is slidably connected to the strip-shaped boss 1215 on the outer ring of the shifting shaft 121 via the initial groove 1231 thereon, ensuring precise guidance of the relative movement between the guide housing 123 and the shifting shaft 121. During drilling fluid hydraulic drive, the strip-shaped boss 1215 first slides out along the initial groove 1231. When the fixed ejector pin 122 slides to the third locking groove 1214, the strip-shaped boss 1215 slides into the insertion groove 1232, thus achieving double locking and keeping the tool 142 in the deployed state. During the retraction of the tool 142, the strip-shaped boss 1215 slides out from the insertion groove 1232 and slides back into the initial groove 1231 as the shifting shaft 121 rotates. The fixed ejector pin 122 passes through the guide housing 123, further enhancing the stability of the entire guide locking mechanism 12.

[0031] like Figure 8 As shown, the outer circumference of the sliding sleeve 141 is provided with several sets of sliding tracks 1411, and the several sets of sliding tracks 1411 are arranged at an angle. The cutting tool 142 is provided with a sliding groove 1421 on the side near the sliding sleeve 141, and the sliding groove 1421 is arranged at an angle. The sliding rail 1411 and the sliding groove 1421 are slidably connected.

[0032] The inclined arrangement of the sliding track 1411 and the sliding groove 1421 enables the sliding sleeve 141 to effectively transmit force to the tool 142 when it moves axially, thereby realizing the radial expansion or contraction of the tool 142. When the sliding sleeve 141 moves forward under hydraulic drive, the cooperation between the sliding track 1411 and the sliding groove 1421 causes the tool 142 to expand radially outward until the predetermined scraping diameter is reached. When the sliding sleeve 141 retracts, the tool 142 retracts inward along the sliding track 1411 through the sliding groove 1421, returning to the initial state.

[0033] like Figure 1 As shown, the wellbore scraper also includes a cleaning mechanism 2; The wall scraping module 1 also includes a transmission mechanism 13; The drive mechanism 11 includes a fixed housing 111, and a piston 112 is provided inside the fixed housing 111; The cleaning mechanism 2 includes a flushing pipe 21; The inner ring of the fixed outer shell 111 is rotatably connected to the shifting shaft 121. One end of the shifting shaft 121 is rotatably connected to the piston 112. The other end of the shifting shaft 121 is provided with a transmission mechanism 13. One end of the transmission mechanism 13 is provided with a punch 21. The punch 21 passes through the sliding sleeve 141 and is slidably connected to the sliding sleeve 141.

[0034] The punch tube 21 moves axially under hydraulic drive, and its movement is transmitted to the sliding sleeve 141 through the transmission mechanism 13, thereby driving the cutter 142 to extend. The fixed housing 111 provides a stable operating environment for the piston 112. When the punch tube 21 moves forward, the relative sliding between it and the sliding sleeve 141 not only realizes the unfolding of the cutter 142, but also simultaneously triggers the cleaning mechanism 2 to form a high-pressure jet to clean the cutter 142 in real time, avoiding the problem of tool jamming caused by debris accumulation, and further improving the adaptability and reliability of the scraper under complex well conditions.

[0035] like Figure 9 As shown, the actuator 14 also includes a return spring 143 and a sliding sleeve housing 144; The inner ring of the sliding sleeve housing 144 is provided with an annular boss 1441, and the sliding sleeve housing 144 is provided with several tool grooves in the circumferential direction. An annular boss 1441 is placed between the sliding sleeve 141 and the punch 21. A return spring 143 is provided on one side of the annular boss 1441. The return spring 143 is placed between the annular boss 1441 and the punch 21. A guide shell 123 is provided on the outer ring of one side of the sliding sleeve shell 144. The cutting tool 142 passes through the cutting groove and is slidably connected to the cutting groove.

[0036] The return spring 143 plays a crucial role in the retraction of the cutting tool 142. When the drilling fluid discharge decreases, the axial force applied to the piston 112 decreases. Under the action of the restoring force, the return spring 143 pushes the punch 21 back, thereby causing the sliding sleeve 141 to retract, ensuring that the cutting tool 142 can retract into the sliding sleeve housing 144 in a timely and smooth manner. The annular boss 1441 not only provides a stable support point for the return spring 143, but also limits the axial movement range of the sliding sleeve 141 through its cooperation with the punch 21, preventing the mechanism from jamming or being damaged due to excessive movement. In addition, the tool groove on the sliding sleeve housing 144 provides a precise guide path for the radial movement of the cutting tool 142, ensuring that the cutting tool 142 maintains a stable movement trajectory during expansion and contraction, further improving the reliability and safety of the wall scraping operation.

[0037] like Figure 2 As shown, the transmission mechanism 13 includes a shifting key 131, a sliding key 132, and a rolling bearing 133. The rolling bearing 133 is provided between the shifting key 131 and the sliding key 132. The shifting key 131 and the sliding key 132 are rotatably connected. A punch 21 is provided on one side of the shifting key 131. A sliding housing 144 is provided on the outer ring of one side of the shifting key 131. A shifting shaft 121 is provided on one side of the sliding key 132. The outer ring of one side of the sliding key 132 is rotatably connected to the guide housing 123.

[0038] The transmission mechanism 13, through the cooperation of the shifting key 131 and the sliding sleeve key 132, combined with the use of the rolling bearing 133, achieves smooth and flexible power transmission. The rolling bearing 133 not only reduces frictional loss during transmission but also improves the overall durability of the mechanism. When the punch 21 moves axially under hydraulic drive, its motion is transmitted to the sliding sleeve key 132 through the shifting key 131, thereby driving the shifting shaft 121 to rotate or move axially.

[0039] like Figure 2 As shown, the cleaning mechanism 2 also includes a cleaning housing 22, which is slidably connected to a flushing pipe 21, with the flushing pipe 21 inserted into the cleaning housing 22.

[0040] The cleaning mechanism 2 further enhances the overall functionality of the wall scraper. The flushing pipe 21 is placed inside the cleaning housing 22. The drilling fluid entering from the flushing pipe 21 can enter the cutting surface and root area of ​​the tool 142 through the cleaning housing 22, realizing real-time hydraulic cleaning of the tool 142 during the wall scraping operation. This effectively removes debris and attachments generated during scraping, reducing the risk of rock cuttings, cement blocks, etc. accumulating in the gap between the tool 142 and the wall surface. This fundamentally suppresses mud packing or sand jamming, ensuring the reliability and continuity of the wall scraping operation.

[0041] like Figure 10 As shown, the flushing pipe 21 has several pressure relief holes 211 circumferentially arranged at one end near the cleaning housing 22; The inner circumference of the cleaning housing 22 is provided with a number of rinsing holes 221, which are arranged at an angle. One end of the flushing hole 221 faces the pressure relief hole 211, and the other end of the flushing hole 221 faces the tool 142.

[0042] Multiple pressure relief holes 211 are circumferentially opened at the front of the flushing pipe 21, and flushing holes 221 are provided at corresponding positions on the inner wall of the cleaning shell 22, which are connected to the working area of ​​the cutter 142 through an inclined arrangement. When the cutter 142 is radially extended, the flushing pipe 21 moves forward synchronously, so that the pressure relief holes 211 and the flushing holes 221 are connected. High-pressure drilling fluid then enters through the pressure relief holes 211 and forms a directional high-speed jet through the flow channel of the inclined flushing holes 221, which continuously acts on the cutting surface and root area of ​​the cutter 142, realizing real-time hydraulic cleaning of the cutter 142 during the wall scraping operation, suppressing mud packing or sand jamming, and ensuring the reliability and continuity of the wall scraping operation.

[0043] Working principle of the invention: When the wall scraping operation mode needs to be activated, the drilling fluid discharge rate is increased to the preset activation discharge rate via the surface pump set. The increased discharge rate generates sufficient hydraulic pressure at the piston 112 inside the wall scraper, pushing the piston 112 to move axially. This movement is transmitted through the transmission mechanism 13, causing the sliding sleeve 141 to move forward. The sliding sleeve 141 interacts with the cutter 142 on its outer ring, driving the cutter 142 to expand radially from the housing, completing the initial preparation for the wall scraping operation.

[0044] After the cutter 142 is deployed, the drilling fluid flow rate is reduced to the normal working flow rate. At this time, the axial force of the piston 112 decreases, and the actuator 14 pushes the flushing tube 21 to partially retract. The retraction of the flushing tube 21 causes the shifting shaft 121 to rotate under the limitation of the fixed ejector pin 122. Finally, the fixed ejector pin 122 slides into the third locking groove 1214 on the shifting shaft 121 through the guide groove 1211. This process achieves mechanical locking of the deployed state of the cutter 142, and the wall scraper enters a stable wall scraping operation mode, which can effectively clean the well wall. When the cutter 142 is radially deployed, the flushing tube 21 moves forward synchronously, making the pressure relief hole 211 connected to the flushing hole 221. The high-pressure drilling fluid then enters through the pressure relief hole 211 and forms a directional high-speed jet through the inclined flushing hole 221 flow channel, continuously acting on the cutting surface and root region of the cutter 142.

[0045] When the wall scraping operation is stopped and the cutting tool 142 is retrieved, the drilling fluid flow rate is increased to the activated flow rate again. The hydraulic pressure drives the piston 112 to move forward, causing the shift shaft 121 to rotate. This causes the fixed ejector pin 122 to slide out into the second locking groove 1213, releasing the mechanical lock. Then, the flow rate is immediately reduced to the normal operating flow rate, causing the flushing pipe 21 to retract the sliding sleeve 141, and the cutting tool 142 to retract. Guided by the fixed ejector pin 122, the shift shaft 121 continues to rotate to the first locking groove 1212. All internal mechanisms of the wall scraper are fully reset, the cutting tool 142 is fully retracted, and the wall scraper re-enters the normal drilling standby state.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A large-size wellbore wall scraper, characterized in that: The wellbore scraper includes a scraping module (1); The scraping module (1) includes a drive mechanism (11), a guide locking mechanism (12), and an actuator (14). The guide locking mechanism (12) includes a shifting shaft (121) and a fixed ejector pin (122). The outer ring of the transposition shaft (121) is provided with a guide groove (1211), and the guide groove (1211) is provided with a plurality of first locking grooves (1212) in the circumferential direction. Two second locking grooves (1213) are symmetrically provided between two first locking grooves (1212), and a third locking groove (1214) is provided between two second locking grooves (1213). The first locking grooves (1212) and the third locking grooves (1214) are located on the same side of the guide groove (1211), and the second locking grooves (1213) are located on the other side of the guide groove (1211). The guide groove (1211) is provided with a plurality of protrusions (12111). The actuator (14) includes a sliding sleeve (141), and the outer circumference of the sliding sleeve (141) is provided with a plurality of sets of cutters (142), and the sliding sleeve (141) and the cutters (142) are slidably connected; Several protrusions (12111) are respectively eccentrically arranged on the same side relative to the first locking groove (1212), the second locking groove (1213) and the third locking groove (1214). The fixed ejector pin (122) is slidably connected to the guide groove (1211), the first locking groove (1212), the second locking groove (1213) and the third locking groove (1214). The drive mechanism (11) is rotatably connected to the shift shaft (121). The drive mechanism (11) drives the shift shaft (121) to move axially and rotate radially and drives the tool (142) to extend and retract.

2. The large-size wellbore scraper according to claim 1, characterized in that: The guide locking mechanism (12) further includes a guide housing (123), on which a fixing pin (122) is provided, and the fixing pin (122) passes through the guide housing (123). The inner ring of the guide housing (123) is alternately provided with an initial groove (1231) and an insertion groove (1232). The outer ring of the transposition shaft (121) is also provided with a strip-shaped boss (1215) in the circumferential direction, and the strip-shaped boss (1215) is located on one side of the first locking groove (1212); The strip-shaped boss (1215) is slidably connected to the initial groove (1231) and the insertion groove (1232) respectively.

3. A large-size wellbore wall scraper according to claim 2, characterized in that: The outer circumference of the sliding sleeve (141) is provided with several sets of sliding tracks (1411), and the several sets of sliding tracks (1411) are arranged at an angle; The cutting tool (142) has a sliding groove (1421) on the side near the sliding sleeve (141), and the sliding groove (1421) is arranged at an angle; The sliding track (1411) and the sliding groove (1421) are slidably connected.

4. A large-size wellbore wall scraper according to claim 3, characterized in that: The wellbore scraper also includes a cleaning mechanism (2); The scraping module (1) also includes a transmission mechanism (13); The drive mechanism (11) includes a fixed housing (111), and a piston (112) is provided inside the fixed housing (111). The cleaning mechanism (2) includes a flushing pipe (21); The inner ring of the fixed outer shell (111) is rotatably connected to the shifting shaft (121). One end of the shifting shaft (121) is rotatably connected to the piston (112). The other end of the shifting shaft (121) is provided with a transmission mechanism (13). One end of the transmission mechanism (13) is provided with a punch (21). The punch (21) passes through the sliding sleeve (141). The punch (21) and the sliding sleeve (141) are slidably connected.

5. A large-size wellbore wall scraper according to claim 4, characterized in that: The actuator (14) also includes a return spring (143) and a sliding sleeve housing (144). The inner ring of the sliding sleeve housing (144) is provided with an annular boss (1441), and the sliding sleeve housing (144) is provided with a plurality of blade grooves in the circumferential direction; The annular boss (1441) is placed between the sliding sleeve (141) and the punch (21). A return spring (143) is provided on one side of the annular boss (1441). The return spring (143) is placed between the annular boss (1441) and the punch (21). A guide shell (123) is provided on the outer ring of one side of the sliding sleeve shell (144). The cutting tool (142) passes through the cutting groove, and the cutting tool (142) and the cutting groove are slidably connected.

6. A large-size wellbore wall scraper according to claim 5, characterized in that: The transmission mechanism (13) includes a shifting key (131), a sliding key (132), and a rolling bearing (133). The rolling bearing (133) is provided between the shifting key (131) and the sliding key (132). The shifting key (131) and the sliding key (132) are rotatably connected. A punch (21) is provided on one side of the shifting key (131). A sliding housing (144) is provided on the outer ring of one side of the shifting key (131). A shifting shaft (121) is provided on one side of the sliding key (132). The outer ring of one side of the sliding key (132) is rotatably connected to the guide housing (123).

7. A large-size wellbore wall scraper according to claim 6, characterized in that: The cleaning mechanism (2) also includes a cleaning housing (22), which is slidably connected to a flushing pipe (21), and the flushing pipe (21) is inserted into the cleaning housing (22).

8. A large-size wellbore wall scraper according to claim 7, characterized in that: The flushing pipe (21) has several pressure relief holes (211) circumferentially arranged at one end near the cleaning shell (22); The cleaning housing (22) has a plurality of rinsing holes (221) arranged in the inner circumferential direction, and the plurality of rinsing holes (221) are arranged at an angle; One end of the flushing hole (221) faces the pressure relief hole (211), and the other end of the flushing hole (221) faces the tool (142).

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