An emergency releaseable pipe scraper

Abstract

The application discloses an emergency release type pipe scraper, which comprises a rotating shaft, a rotating scraper, a locking shaft, a locking steel ball, a locking spring and a lower joint. The locking steel ball is installed at the lower part of the rotating shaft, the locking spring is used to limit the locking shaft upwardly, the locking steel ball is positioned, the rotating shaft and the lower joint form an integral whole, the rotating scraper can normally work during the pipe scraping operation, and the rotating shaft, the locking steel ball, the locking spring, the locking shaft and the lower joint form an emergency unlocking assembly. When the pipe scraper needs to be released in an emergency, the release steel ball is only needed to be put in, the release steel ball is located at the step inside the locking shaft to realize hydraulic flow interception, internal pressure is formed, the locking shaft is pushed to overcome the action force of the locking spring and to go down into the release position, the positioning of the locking steel ball is cancelled, the locking steel ball moves inwardly into the release space, the locking between the rotating shaft and the lower joint is cancelled immediately, and the emergency release is realized.

Description

Technical Field

[0001] This invention belongs to the field of oil extraction equipment technology, and in particular relates to an emergency-release scraper. Background Technology

[0002] As the core flow channel in oil and gas wells, the inner wall of the casing is prone to the accumulation of impurities such as wax, crude oil residue, and scale during long-term use. This leads to a reduction in the inner diameter of the casing, obstruction of oil and gas flow, and impacts normal oil and gas production. Therefore, it is necessary to periodically run a scraper to clean and maintain the inner wall of the casing.

[0003] Traditional scrapers typically rely on an anchoring mechanism to adhere to the casing wall and perform scraping operations via surface tubing traction or downhole power. However, in complex conditions such as deep wells, high pressure (wellhead pressure can reach over 30 MPa), uneven wax deposition on the inner wall, and localized casing deformation, scrapers are prone to jamming. Once jammed, traditional scrapers lack effective emergency unlocking mechanisms, often requiring forced traction of the tubing string or the deployment of retrieval tools. Such operations are not only high-risk, easily causing casing damage, cable breakage, and other accidents, but also lead to the cessation of well workover operations, resulting in daily economic losses of hundreds of thousands of yuan. In severe cases, it may even necessitate the abandonment of the wellbore, causing a huge waste of resources.

[0004] Therefore, there is an urgent need for a scraper that can efficiently scrape while having a reliable emergency release function, in order to cope with complex downhole working conditions and improve operational safety and economy. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a scraper that can be released in an emergency, which is especially suitable for cleaning and emergency treatment of the inner wall of casing under deep well and high pressure conditions. It overcomes the problem that scrapers in the prior art are prone to jamming and difficult to unscramble under deep well and high pressure conditions, and realizes a functional closed loop of "high pressure stable cleaning - multi-dimensional jamming detection - emergency safety unlocking - repeated use".

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an emergency-releaseable scraper, comprising a rotating mandrel, the rotating mandrel being a tubular shaft, the lower part of the rotating mandrel having several radial through holes, each through hole containing a locking steel ball, a lower connector sleeved on the lower outer surface of the rotating mandrel, the inner wall of the lower connector having an annular positioning groove, and a locking mandrel on the inner surface of the connection between the rotating mandrel and the lower connector, the locking mandrel enabling the rotating mandrel and the lower connector to have two states. Under normal operating conditions, the locking mandrel is positioned at the top, and several locking steel balls are placed in the annular positioning groove through the through hole. The rotating mandrel is axially interlocked with the lower connector. In the emergency release state, the locking mandrel is positioned at the bottom, and several locking steel balls disengage from the annular positioning groove, releasing the axial lock between the rotating mandrel and the lower connector.

[0007] Furthermore, the upper outer wall of the locking mandrel is stepped, and the diameter of the lower part of the locking mandrel is larger than the diameter of the top part of the locking mandrel. When the locking mandrel is placed at the top, the large-diameter outer cylindrical surface of the lower part of the locking mandrel pushes the locking steel ball into the annular positioning groove; when the locking mandrel is placed at the bottom, the small-diameter outer cylindrical surface of the top of the locking mandrel is placed inside the locking steel ball, giving the locking steel ball space to contract inward, and the locking steel ball disengages from the annular positioning groove.

[0008] Furthermore, a receiving space is formed between the lower outer cylindrical surface of the locking mandrel and the inner cylindrical surface of the lower connector, and a locking spring is provided in the receiving space. Under normal operating conditions, the locking spring is in a compressed state.

[0009] Furthermore, the locking mandrel has an axial flow channel at its center, and a pressure-bearing step with a reduced inner diameter is provided in the middle of the axial flow channel. In the emergency release state, a release steel ball is inserted into the axial flow channel. The diameter of the release steel ball is smaller than the diameter of the axial flow channel, and the diameter of the release steel ball is larger than the diameter of the pressure-bearing step.

[0010] Furthermore, the outer cylindrical surface of the rotating mandrel is provided with a rotating scraper. The rotating scraper 2 is rotatably mounted on the outer annular area of ​​the rotating mandrel 1 and the lower connector 3 via a bearing or bushing. The outer edge of the rotating scraper 2 is provided with scraping blades or hard alloy blocks for scraping off scale from the inner wall of the sleeve.

[0011] Furthermore, the top of the rotating mandrel is provided with an upper connecting thread, which is connected to the downhole working string.

[0012] Furthermore, the bottom end of the lower connector is provided with a lower connecting thread 9, which is connected to a subsequent tool string.

[0013] Furthermore, the number of through holes and locking steel balls is the same, with multiple locking steel balls and multiple through holes corresponding one-to-one and evenly distributed circumferentially.

[0014] The advantages and positive effects of this invention are: 1. This invention solves the problem of traditional oil casing scrapers being difficult to remove when stuck in the well (e.g., due to wax buildup or casing deformation), thus halting well workover operations, by adding an emergency unlocking component between the rotating mandrel and the lower connector. This scraper can efficiently remove wax and scale inside the oil casing, and when stuck, it can be released in an emergency by dropping a ball. It is suitable for high-pressure and deep well conditions in oil casing, significantly improving the efficiency and safety of well workover operations.

[0015] 2. High safety and reliability: The present invention adopts a ball-throwing hydraulic triggering mechanism, which makes the unlocking process controllable, effectively avoiding the risk of accidental release downhole and significantly improving the safety of well workover operations.

[0016] 3. Economic efficiency: The emergency release process of this invention can be completed within 1 hour, which greatly shortens non-operation time and reduces well repair costs; the scraper is replaceable and the main body is reusable, increasing the overall utilization rate of the equipment by more than 60%.

[0017] 4. Strong adaptability: This invention is particularly suitable for complex working conditions such as deep wells, high pressure, uneven wax deposition, and local deformation of casing. While achieving efficient cleaning, it also has the ability to quickly unstick the casing.

[0018] 5. Simple structure: The unlocking component of this invention is integrated inside the scraper, eliminating the need for additional complex mechanisms and facilitating on-site operation and maintenance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the overall release state in an embodiment of the present invention.

[0021] In the picture: 1. Rotary mandrel; 1-1. Through hole; 1-2. Upper connecting thread; 2. Rotary scraper; 3. Lower connector; 3-1. Annular positioning groove; 3-2. Lower connecting thread; 4. Lock the steel ball; 5. Locking mandrel; 5-1. Locking section; 5-2. Release section; 5-3. Pressure-bearing step; 5-4. Axial flow channel; 6. Locking spring; 7. Release the steel ball. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0023] The embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 1As shown, the present invention provides an emergency-release scraper, comprising a rotating spindle 1, a rotating scraper 2, a lower connector 3, a locking steel ball 4, a locking spindle 5, a locking spring 6, and a release steel ball 7. The rotating spindle 1 is a tubular shaft, with several radial through holes 1-1 at its lower part. The locking steel ball 4 is installed in each through hole 1-1. The lower connector 3 is fitted onto the lower outer surface of the rotating spindle 1. The inner wall of the lower connector 3 is provided with an annular positioning groove 3-1. The inner surface of the connection between the rotating spindle 1 and the lower connector 3 is provided with a locking spindle 5. The locking spindle 5 allows the rotating spindle 1 and the lower connector 3 to have two states.

[0024] Under normal operating conditions, the locking mandrel 5 is placed on top, and several locking steel balls 4 are placed in the annular positioning groove 3-1 through the through hole 1-1, so that the rotating mandrel 1 and the lower connector 3 are axially interlocked.

[0025] In the emergency release state, the locking mandrel 5 is placed at the bottom, and several locking steel balls 4 are disengaged from the annular positioning groove 3-1, releasing the axial lock between the rotating mandrel 1 and the lower connector 3.

[0026] Specifically, the rotating mandrel 1 is a tubular shaft with an upper connecting thread 1-2 machined at its top for connecting to the downhole working string. The lower wall of the rotating mandrel 1 has multiple radial through holes 1-1 evenly spaced circumferentially to accommodate locking steel balls 4. The locking steel balls 4 can move freely up and down within the radial holes, enabling the connection and disconnection of the rotating mandrel 1 from the lower connector 3.

[0027] The rotary scraper 2 is rotatably mounted on the outer annular area of ​​the rotary spindle 1 and the lower connector 3 via a bearing or bushing structure. The rotary scraper 2 is easy to replace, and the rotary spindle 1 can be reused. The outer edge of the rotary scraper 2 is equipped with scraping blades or carbide blocks for scraping away scale from the inner wall of the sleeve.

[0028] The lower connector 3 is located on the lower outer side of the rotating spindle 1, and its inner wall has an annular positioning groove 3-1 machined at the position corresponding to the locking steel ball 4. After the locking steel ball 4 enters, it cannot move in the axial direction, thus achieving axial limitation. The bottom end of the lower connector 3 has a lower connecting thread 3-2 for connecting to the subsequent tool string.

[0029] There are multiple locking steel balls 4, the number of which matches the number of radial through holes 1-1 on the rotating spindle 1, and they are installed in each through hole 1-1. Both are evenly distributed circumferentially.

[0030] The locking mandrel 5 is coaxially mounted within the internal cavity of the rotating mandrel 1 and is the core component of the emergency unlocking function. Its outer wall has a crucial stepped structure at its top: the lower part has a larger outer diameter, forming the locking section 5-1; the upper part has a smaller outer diameter, forming the release section 5-2. When the locking mandrel 5 is positioned at the top, the large-diameter outer cylindrical surface at the bottom of the locking mandrel 5 pushes the locking steel ball 4 into the annular positioning groove 3-1. When the locking steel ball 4 is in the locking section 5-1, it cannot move, allowing the tool to operate as a whole. When the locking mandrel 5 is positioned at the bottom, the small-diameter outer cylindrical surface at the top of the locking mandrel 5 is positioned inside the locking steel ball 4, allowing the locking steel ball 4 to retract inwards. The locking steel ball 4 moves inwards, disengaging from the annular positioning groove 3-1, thus releasing the tool. The center of the locking mandrel 5 is provided with an axial flow channel 5-4. A pressure-bearing step 5-3 with a reduced inner diameter is formed in the middle of the axial flow channel 5-4. In the emergency release state, a release steel ball 7 is inserted into the axial flow channel 5-4. The diameter of the release steel ball 7 is smaller than the diameter of the axial flow channel 5-4 and larger than the diameter of the pressure-bearing step 5-3.

[0031] The locking spring 6 is a compression spring, installed between the lower outer cylindrical surface of the locking mandrel 5 and the inner cylindrical surface of the lower connector 3 to form a receiving space. Specifically, the outer wall of the locking mandrel 5 has a lower shoulder, and the inner wall of the lower connector 3 has a corresponding upper shoulder. Under normal operating conditions, the locking spring 6 is pre-compressed and installed between the two shoulders, limiting the locking mandrel 5 to be in the locking section 5-1 under normal conditions, thus providing a continuous upward preload force to the locking mandrel 5. This ensures that the locking mandrel 5 maintains its restraint on the locking steel ball 4 when no external force is applied.

[0032] The release steel ball 7 is an independent component, and its diameter is designed to be slightly larger than the inner diameter of the pressure-bearing step 5-3 of the axial flow channel 5-4 inside the locking mandrel 5. It is used to engage and set the lock during emergency unlocking.

[0033] The working process of this invention is as follows: During normal cleaning operations, under the preload of the locking spring 6, the locking mandrel 5 is pushed to its upper limit position. At this time, the lower locking section 5-1, with its larger outer diameter, pushes the locking steel ball 4 outward, causing it to engage with the annular positioning groove 3-1 of the lower connector 3, thereby achieving axial interlocking between the rotating mandrel 1 and the lower connector 3, forming a rigid whole. At this point, driven by the tubing column, the rotating scraper 2 can rotate freely to clean the sleeve.

[0034] When the tool becomes stuck and requires emergency release, the operator inserts the release steel ball 7 from the wellhead. The ball falls and sets at the pressure-bearing step 5-3 inside the locking mandrel 5. Subsequently, hydraulic pressure is applied from the wellhead, pushing the locking mandrel 5 downwards against the preload of the locking spring 6. As the locking mandrel 5 descends, its smaller outer diameter upper release section 5-2 moves to the inside of the locking steel ball 4, creating space for the locking steel ball 4 to retract inwards. The locking steel ball 4 then disengages from the annular positioning groove 3-1 of the lower connector 3, and the axial lock between the rotating mandrel 1 and the lower connector 3 is immediately released. At this point, the tubing string can be lifted, and the rotating mandrel 1 and its connected parts can be safely removed from the wellhead, completing the emergency release. Figure 2 As shown, a is a schematic diagram of removing the locking mandrel 5, and b is a schematic diagram of the discarded part.

[0035] The advantages and positive effects of this invention are: 1. This invention solves the problem of traditional oil casing scrapers being difficult to remove when stuck in the well (e.g., due to wax buildup or casing deformation), thus halting well workover operations, by adding an emergency unlocking component between the rotating mandrel and the lower connector. This scraper can efficiently remove wax and scale inside the oil casing, and when stuck, it can be released in an emergency by dropping a ball. It is suitable for high-pressure and deep well conditions in oil casing, significantly improving the efficiency and safety of well workover operations.

[0036] 2. High safety and reliability: The present invention adopts a ball-throwing hydraulic triggering mechanism, which makes the unlocking process controllable, effectively avoiding the risk of accidental release downhole and significantly improving the safety of well workover operations.

[0037] 3. Economic efficiency: The emergency release process of this invention can be completed within 1 hour, which greatly shortens non-operation time and reduces well repair costs; the scraper is replaceable and the main body is reusable, increasing the overall utilization rate of the equipment by more than 60%.

[0038] 4. Strong adaptability: This invention is particularly suitable for complex working conditions such as deep wells, high pressure, uneven wax deposition, and local deformation of casing. While achieving efficient cleaning, it also has the ability to quickly unstick the casing.

[0039] 5. Simple structure: The unlocking component of this invention is integrated inside the scraper, eliminating the need for additional complex mechanisms and facilitating on-site operation and maintenance.

[0040] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. An emergency-releaseable tube scraper, characterized in that: The device includes a rotating mandrel, which is a tubular shaft. The lower part of the rotating mandrel has several radial through holes, each containing a locking steel ball. A lower connector is fitted onto the lower outer surface of the rotating mandrel. The inner wall of the lower connector has an annular positioning groove. A locking mandrel is provided on the inner surface of the connection between the rotating mandrel and the lower connector. This locking mandrel allows the rotating mandrel and the lower connector to have two states. Under normal operating conditions, the locking mandrel is positioned at the top, and several locking steel balls are placed in the annular positioning groove through the through hole. The rotating mandrel is axially interlocked with the lower connector. In the emergency release state, the locking mandrel is positioned at the bottom, and several locking steel balls disengage from the annular positioning groove, releasing the axial lock between the rotating mandrel and the lower connector.

2. The emergency-releaseable scraper according to claim 1, characterized in that: The upper outer wall of the locking mandrel is stepped, and the diameter of the lower part of the locking mandrel is larger than the diameter of the top part of the locking mandrel. When the locking mandrel is placed at the top, the large-diameter outer cylindrical surface of the lower part of the locking mandrel pushes the locking steel ball into the annular positioning groove. When the locking mandrel is placed at the bottom, the small-diameter outer cylindrical surface of the top of the locking mandrel is placed inside the locking steel ball, giving the locking steel ball space to retract inward, and the locking steel ball disengages from the annular positioning groove.

3. The emergency-releaseable scraper according to claim 2, characterized in that: A receiving space is formed between the lower outer cylindrical surface of the locking mandrel and the inner cylindrical surface of the lower connector. A locking spring is provided in the receiving space. Under normal operating conditions, the locking spring is in a compressed state.

4. The emergency-releaseable scraper according to claim 3, characterized in that: The locking mandrel has an axial flow channel at its center, and a pressure-bearing step with a reduced inner diameter is provided in the middle of the axial flow channel. In the emergency release state, a release steel ball is inserted into the axial flow channel. The diameter of the release steel ball is smaller than the diameter of the axial flow channel, and the diameter of the release steel ball is larger than the diameter of the pressure-bearing step.

5. An emergency-release scraper according to any one of claims 1 to 4, characterized in that: The outer cylindrical surface of the rotating mandrel is provided with a rotating scraper. The rotating scraper 2 is rotatably mounted on the outer annular area of ​​the rotating mandrel 1 and the lower connector 3 via a bearing or bushing. The outer edge of the rotating scraper 2 is provided with scraping blades or hard alloy blocks for scraping off scale from the inner wall of the sleeve.

6. An emergency-release scraper according to any one of claims 1 to 4, characterized in that: The top of the rotating mandrel is provided with an upper connecting thread, which is connected to the downhole working string.

7. An emergency-release scraper according to any one of claims 1 to 4, characterized in that: The lower connector has a lower connecting thread 9 at its bottom end, which connects to a subsequent tool string.

8. An emergency-release scraper according to any one of claims 1 to 4, characterized in that: The number of through holes and the number of locking steel balls are the same, and the multiple locking steel balls and the multiple through holes correspond one-to-one and are evenly distributed in the circumferential direction.

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