Composite pipe scraping cement retainer

Abstract

The present application belongs to the technical field of downhole tools, and particularly relates to a composite pipe scraping cement retainer for casing well wellbore isolation, which comprises a mandrel assembly, an anchoring sealing assembly, a flow passage control assembly, a pipe scraping and centralizing assembly and a pilot cone. The anchoring sealing assembly is sleeved on the outside of the mandrel assembly and is used for forming axial anchoring and annular sealing with the inner wall of the casing. The flow passage control assembly is arranged inside the mandrel assembly and is used for controlling the on-off of the internal flow passage of the mandrel and bidirectional sealing and isolation of the wellbore. The pipe scraping and centralizing assembly is connected to the lower end of the mandrel assembly and is used for scraping the inner wall of the casing and centrally supporting the tool in the process of lowering the pipe string. The pilot cone is connected to the bottom end of the pipe scraping and centralizing assembly and is used for guiding the lowering of the tool. The device integrates the pipe scraping structure and the cement retainer, realizes the pipe scraping and setting operation by one pipe string, reduces the process of entering the well, realizes the central support of the tool in the whole process by the pipe scraping and centralizing assembly, reduces the wear of the anchoring sealing assembly, and improves the setting reliability.

Description

Technical Field

[0001] This invention belongs to the field of downhole tool technology, specifically relating to a composite scraper cement retainer for wellbore isolation in casing wells. Background Technology

[0002] According to relevant regulations and industry standards for oil and gas fields, cement retainers must be installed for well abandonment operations at the end of oil and gas well production and for casing damage repair operations, and cement slurry must be injected to seal and isolate the wellbore.

[0003] When conventional cement retainers are used in the field, a separate scraper needs to be lowered to clean the inner wall of the casing. This process takes up a lot of drilling time and increases the safety risks of on-site operations.

[0004] Furthermore, conventional cement retainers have poor alignment during well entry, and the slips and sealing sleeve components are prone to friction and wear against the inner wall of the casing, which can easily lead to jamming or premature setting. In addition, the overall structure of cement retainers is relatively complex, making drilling and removal operations difficult and time-consuming. The internal flow channel control of cement retainers is also limited, often employing a unidirectional pressure-bearing structure or a bottom blind plug structure. During drilling, it is impossible to achieve automatic grouting inside the drill string and bottom circulation flushing. The bottom circulation channel often uses a side opening, making it difficult to achieve effective flushing of the entire bottom section.

[0005] To solve the above-mentioned technical problems, the present invention provides a composite scraper cement retainer with integrated scraper function. Summary of the Invention

[0006] One of the technical problems that this application aims to solve is to overcome the technical defects of existing cement retainers, such as the need for separate scraping operations, poor well straightening effect, easy wear of key components, single flow channel control, inability to automatically grout and circulate at the bottom of the well, and difficulty in drilling and removing them.

[0007] To address the aforementioned technical problems, this application provides a composite scraper cement retainer, comprising a mandrel assembly, an anchoring and sealing assembly, a flow channel control assembly, a scraper straightening assembly, and a guide cone; the anchoring and sealing assembly is sleeved on the outside of the mandrel assembly and is used to form axial anchoring and annular sealing with the inner wall of the casing; The flow channel control component is located inside the mandrel assembly and is used to control the opening and closing of the flow channel inside the mandrel and the bidirectional sealing and isolation of the wellbore. The tube scraper and straightening assembly is connected to the lower end of the mandrel assembly and is used to perform tube inner wall scraping and tool radial straightening during the tube string insertion process; The guide cone is connected to the bottom of the scraper straightening assembly and is used to guide the tool downwards.

[0008] In some embodiments, the mandrel assembly includes an upper mandrel and a lower mandrel. The top of the upper mandrel is provided with a reverse-threaded internal thread for connection with a sealing tool, and the inner wall is provided with a sealing surface for sealing and a groove for limiting. The outer wall of the upper mandrel is connected to the upper cone and lower cone of the anchoring sealing assembly respectively by shear pins. The lower mandrel is a stepped tubular structure, with its upper end connected to the flow channel control assembly and its lower end connected to the scraper straightening assembly.

[0009] In some embodiments, the anchoring sealing assembly includes an upper slip, an upper cone, a sealing sleeve assembly, a support ring, a lower slip, and a lower cone; The upper slip and the upper cone, and the lower slip and the lower cone are stacked and fitted together in sequence; the upper cone and the lower cone are configured to drive the corresponding slip to expand radially under the action of axial force, so as to achieve anchoring with the inner wall of the sleeve; The sealing sleeve assembly is configured to expand radially under axial compression to achieve annular sealing; the support ring is used to limit the deformation direction of the sealing sleeve assembly.

[0010] In some embodiments, an anti-rotation locking keyway structure is provided between the upper mandrel and the upper cone. The anti-rotation locking keyway structure is configured to restrict the relative rotation between the upper mandrel and the upper cone during the setting process and to restrict the upper cone from rotating circumferentially with the milling tool during the drilling and grinding process.

[0011] In some embodiments, the flow channel control assembly includes an elastic sliding valve and a sleeve valve joint. The sleeve valve joint is provided with interconnected radial guide grooves and axial guide holes to form a through flow channel. The elastic sliding valve can move axially along the inner wall of the upper mandrel to open or close the guide holes of the sleeve valve joint, so as to realize the conduction and isolation of the mandrel flow channel.

[0012] In some embodiments, the top of the elastic sliding valve is provided with an elastic claw structure, which is configured to form an axial driving engagement with the seat sealing tool insertion tube. The outer wall of the elastic sliding valve is provided with multiple sealing rings, which are configured to block the upper and lower ends of the guide hole respectively when the elastic sliding valve is in the closed position, so as to form a bidirectional sealing barrier. The top of the upper mandrel is provided with a reverse-threaded internal thread for connecting with the seat sealing tool, and the inner wall of the lower end of the upper mandrel is also provided with a groove for engaging with the elastic sliding valve.

[0013] In some embodiments, the pipe straightening assembly includes an elastic scraper cage and a rotary bearing; the elastic scraper cage is composed of multiple spiral scraping ribs, and hollow guide grooves are provided between the scraping ribs for scraping the inner wall of the sleeve and guiding the annular fluid; the rotary bearings are respectively disposed at the upper and lower ends of the elastic scraper cage for allowing the elastic scraper cage to rotate freely circumferentially relative to the lower mandrel.

[0014] In some embodiments, the upper end of the lower mandrel and the lower end of the valve fitting are connected by a shear pin or threaded connection to achieve a detachable connection between the lower mandrel and the valve fitting. In some embodiments, the sealing rubber sleeve assembly is made of heat-resistant rubber material, the upper and lower slips are integrally cast structures, the upper mandrel, upper cone, lower cone, and support ring are made of cast iron material, and the sleeve valve connector, lower mandrel, and elastic scraper cage are made of alloy steel material.

[0015] In some embodiments, the top of the upper mandrel is configured to be directly connected to a mechanical setting tool, or connected to a hydraulic setting tool via an adapter, and the entire retainer is configured to sequentially perform scraping, setting, pressure testing, bottom squeezing, and bidirectional isolation actions during a single insertion process.

[0016] The present invention has at least the following beneficial effects: The device integrates the scraper structure and the cement retainer, enabling the scraper and sealing operations to be completed in one trip of the tubing string, reducing the number of well entry procedures. The scraper straightening component ensures that the tool is centered and straightened throughout the process, reducing wear on the anchoring and sealing components and improving the reliability of the sealing. The flow channel control component enables the internal flow channel to be controlled and bidirectionally sealed and isolated, meeting the requirements of automatic grouting, bottom circulation and bottom squeezing operations. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the positions of the mandrel assembly and the flow channel control assembly of the present invention; Figure 2 This is a schematic diagram of the anchoring and sealing assembly of the present invention; Figure 3 This is a schematic diagram showing the distribution of the sealing rubber sleeve assembly of the present invention; Figure 4 This is a schematic cross-sectional view of the mandrel of the present invention; Figure 5 This is a schematic diagram of the scraper straightening assembly of the present invention; Figure 6 This is a schematic diagram showing the distribution of the guide cone and the elastic scraper cage in this invention; Figure 7 This is a schematic diagram of the elastic claw structure of the present invention; Figure 8 This is a schematic diagram showing the position of the groove in this invention; Figure 9 This is a schematic diagram showing the distribution of the radial guide groove and the axial guide hole of the present invention.

[0018] In the diagram: 1. Mandrel assembly; 101. Upper mandrel; 102. Lower mandrel; 2. Anchoring and sealing assembly; 201. Upper slip; 202. Upper cone; 203. Sealing sleeve assembly; 204. Support ring; 205. Lower slip; 206. Lower cone; 3. Flow channel control assembly; 301. Elastic sliding sleeve valve; 301a. Elastic claw structure; 302. Sleeve valve connector; 303. Radial guide groove; 304. Axial guide hole; 305. Sealing ring; 4. Scraper tube straightening assembly; 401. Elastic scraper cage; 402. Rotary bearing; 403. Scraper rib; 404. Hollowed-out guide groove; 5. Guide cone; 6. Groove; 7. Anti-rotation locking key fit structure. Detailed Implementation

[0019] 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.

[0020] Please see Figure 1-9 The present invention provides a technical solution: a composite scraper cement retainer, including a mandrel assembly 1, an anchoring and sealing assembly 2, a flow channel control assembly 3, a scraper straightening assembly 4 and a guide cone 5. The anchoring and sealing assembly 2 is sleeved on the outside of the mandrel assembly 1 and is used to form axial anchoring and annular sealing with the inner wall of the sleeve. The flow channel control component 3 is located inside the mandrel assembly 1 and is used to control the opening and closing of the flow channels inside the upper mandrel 101 and the lower mandrel 102 and to seal and isolate the wellbore in both directions. The casing scraper and straightening component 4 is connected to the lower end of the mandrel assembly 1 and is used to perform casing inner wall scraping and tool radial straightening during the casing string running. The guide cone 5 is connected to the bottom end of the casing scraper and straightening component 4 and is used to guide the tool running.

[0021] The mandrel assembly 1 includes an upper mandrel 101 and a lower mandrel 102. The lower mandrel 102 is a stepped tubular structure. Its upper end is connected to the flow channel control assembly 3, and its lower end is connected to the scraper and straightening assembly 4. The upper mandrel 101 and the lower mandrel 102 cooperate with each other to form the overall bearing and fluid channel body of the retainer, providing installation support for external components and internal flow channel guidance.

[0022] The anchoring sealing assembly 2 is specifically composed of an upper slip 201, an upper cone 202, a sealing sleeve assembly 203, a support ring 204, a lower slip 205, and a lower cone 206. The upper slip 201 is located at the top and is stacked and fitted with the upper cone 202 below it along the axial direction from top to bottom. Similarly, the lower slip 205 and the lower cone 206 are stacked and fitted together along the axial direction from top to bottom and are located below the sealing sleeve assembly 203. Both the upper cone 202 and the lower cone 206 are provided with a matching conical surface structure, which can withstand axial tension or axial pressure. The upper and lower slips 201 and 205 move radially outward, causing their outer interlocking structures to make close contact with the inner wall of the sleeve, forming a reliable anchor. The outer wall of the upper mandrel 101 is circumferentially fixed to the upper cone 202 and lower cone 206 in the anchoring sealing assembly 2 by shear pins. When the set axial force is not reached, the relative positions of the components remain stable. When the set axial force is reached, the shear pins are sheared, allowing the cone and slip assembly to perform the anchoring action.

[0023] When subjected to axial compressive load, the sealing rubber sleeve assembly 203 will expand and deform radially. After expansion, the sealing rubber sleeve assembly 203 will tightly fit the inner wall of the sleeve and the outer wall of the mandrel to achieve sealing of the annular space. The support ring 204 is arranged at the adjacent position of the sealing rubber sleeve assembly 203 to constrain the radial and axial deformation directions of the sealing rubber sleeve assembly 203, avoid excessive deformation, folding or damage of the sealing rubber sleeve, and improve sealing stability and pressure bearing capacity. The flow control component 3 specifically includes an elastic sliding valve 301 and a sleeve valve connector 302. The sleeve valve connector 302 has interconnected radial guide grooves 303 and axial guide holes 304. The radial guide grooves 303 and axial guide holes 304 together form a continuous and through fluid channel. The elastic sliding valve 301 is slidably mounted on the inner wall of the upper mandrel 101 and can move axially linearly along the inner wall of the upper mandrel 101. By switching the axial position, the opening and closing of the guide holes inside the sleeve valve connector 302 can be realized, thereby completing the control of the conduction and isolation of the overall flow channel inside the mandrel.

[0024] The top of the elastic sliding valve 301 is integrally formed with an elastic claw structure 301a. The elastic claw structure 301a can form an axial driving engagement with the insertion tube at the lower end of the setting tool. When the insertion tube of the setting tool moves up and down, it drives the elastic sliding valve 301 to move synchronously. Multiple sealing rings 305 are fixedly provided on the outer wall of the elastic sliding valve 301. When the elastic sliding valve 301 moves to the closed position, the multiple sealing rings 305 respectively block the upper and lower ends of the guide hole of the valve joint 302, completely sealing the guide hole and forming a bidirectional sealing isolation structure between the upper and lower wellbore of the retainer.

[0025] The top of the upper mandrel 101 is machined with a reverse internal thread, which is specifically designed to form a detachable connection with a mechanical or hydraulic sealing tool. The lower inner wall of the upper mandrel 101 is also machined with a groove 6 structure, which is adapted to and engages with the elastic sliding valve 301. This groove is used for positioning and limiting the elastic sliding valve 301 when it moves to the closed position, ensuring a stable sealing position.

[0026] The scraper straightening assembly 4 specifically includes an elastic scraper cage 401 and a rotary bearing 402. The elastic scraper cage 401 is formed by a spiral scraping rib 403 structure with 360° full circumference coverage. The scraping rib 403 has a hollow guide groove 404 reserved between it. The hollow guide groove 404 can keep the annular fluid flowing smoothly during the scraping operation. During the tool insertion process, the elastic scraper cage 401 continuously adheres to the inner wall of the sleeve to perform scraping action, removing the attached objects and debris from the inner wall of the sleeve. The rotary bearing 402 is fixedly installed at the upper and lower ends of the elastic scraper cage 401 respectively. The upper end of the elastic scraper cage 401 can be fixedly connected to the lower mandrel 102 through a pin, so that the elastic scraper cage 401 is assembled on the outside of the lower mandrel 102 in a free rotation manner. It can rotate independently of the lower mandrel 102 in the circumferential direction, release the torsional force generated during the scraping process in real time, and avoid the torque being transmitted to the upper mandrel 101 and the sealing anchoring component, which may cause malfunction.

[0027] The upper end of the lower mandrel 102 and the lower end of the sleeve valve connector 302 are connected by shear pins or threads. When there are no abnormalities downhole, the threaded connection is used, which has high strength. If the downhole conditions are unclear, a shear pin connection is used. If the casing is deformed or jammed, the retainer and the elastic scraper cage 401 can be disconnected to facilitate subsequent handling of complex downhole conditions. The shear pin is set with a fixed shearing force. When the pulling force on the tubing reaches the preset value, the shear pin is sheared, so that the lower mandrel 102 and the sleeve valve joint 302 are separated, which meets the requirements of segmented release operation under complex downhole conditions.

[0028] The sealing sleeve assembly 203 is made of heat-resistant rubber material, which can adapt to the sealing requirements of different temperature conditions in the well. The upper slip 201 and the lower slip 205 are both integrally cast structures with high overall strength and stable interlocking and anchoring effect. The upper mandrel 101, upper cone 202, lower cone 206 and support ring 204 are all made of cast iron material, which can ensure structural strength and have good drillability. The sleeve valve joint 302, lower mandrel 102 and elastic scraper cage 401 are all made of alloy steel material, which has high structural strength and wear resistance, and meets the requirements of long-term operation and scraping conditions in the well.

[0029] The connection structure at the top of the upper mandrel 101 can be directly connected and cooperated with conventional mechanical setting tools, or it can form a stable connection with hydraulic setting tools through a special adapter, adapting to different field operation equipment and process requirements. The entire retainer is configured to complete the entire set of operation actions, including casing scraping, tool setting, annular pressure testing, bottom injection, and bidirectional wellbore isolation, in sequence during a single tubing string run, achieving integrated and efficient operation.

[0030] Working principle: During the process of the composite scraper cement retainer of this device being lowered into the wellbore along with the working tubing, the scraper straightening component 4 relies on the elastic scraper cage 401 to continuously adhere to the inner wall of the casing to complete 360° full-circumference scraping, and releases torque through the free rotation of the rotary bearing 402. At the same time, it radially centers and straightens the entire tool, protecting the upper anchoring sealing component 2 from friction damage with the casing wall. During the lowering process, the elastic sliding sleeve valve 301 in the flow channel control component 3 is in the open position, and the radial guide groove 303 inside the sleeve valve joint 302 is kept in communication with the axial guide hole 304 to realize automatic grouting inside the drill bit. The fluid can be guided to the bottom of the tool by starting the pump to complete the bottom hole circulation flushing.

[0031] After the tool reaches the designed sealing depth, it applies an axial force to the mandrel assembly 1, and the shearing pin is sheared off. The upper cone 202 and the lower cone 206 drive the upper slip 201 and the lower slip 205 to expand radially and bite into the inner wall of the sleeve, achieving bidirectional axial anchoring. The sealing rubber sleeve assembly 203 expands radially under axial compression, and cooperates with the support ring 204 to constrain deformation, thus completing the annular seal.

[0032] After the sealing is completed, the sealing tool is lifted to disengage it from the upper mandrel 101. At the same time, the elastic sliding sleeve valve 301 is moved axially to the closed position. The sealing ring 305 on the outer wall of the elastic sliding sleeve valve 301 seals the upper and lower ends of the guide hole of the sleeve valve joint 302, so that the upper and lower wellbore of the retainer form a bidirectional sealing barrier, effectively preventing the backflow of fluid at the bottom.

[0033] When injection operations are required in the section of the well below the retainer, the setting tool is reinserted into the upper mandrel 101 and the elastic sliding valve 301 is pushed down to reopen the flow channel and complete the injection. When the tubing is pulled up again, the elastic sliding valve 301 moves up and closes, restoring the bidirectional sealing state. If a jamming situation occurs downhole, the tubing is pulled up to the preset tension to shear the shearing pin between the lower mandrel 102 and the sleeve valve joint 302, allowing the lower component to be released and ensuring the smooth retrieval of the upper tool.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0035] 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.

Claims

1. A composite scraper cement retainer, characterized in that: It includes a mandrel assembly (1), an anchoring seal assembly (2), a flow channel control assembly (3), a scraper straightening assembly (4), and a guide cone (5); The anchoring sealing assembly (2) is axially sleeved on the outside of the mandrel assembly (1) to form axial anchoring with the inner wall of the sleeve and achieve annular sealing; The flow channel control component (3) is axially disposed inside the mandrel assembly (1) and is used to control the opening and closing of the flow channel inside the mandrel and to achieve bidirectional sealing and isolation between the upper and lower parts of the wellbore. The scraper straightening assembly (4) is axially connected to the lower end of the mandrel assembly (1) and is used to scrape the inner wall of the casing and straighten the tool radially during the process of lowering the casing string. The guide cone (5) is axially connected to the bottom end of the scraper straightening assembly (4) and is used to guide the tool downward.

2. The composite scraper cement retainer according to claim 1, characterized in that: The mandrel assembly (1) includes an upper mandrel (101) and a lower mandrel (102). The lower mandrel (102) is a stepped tubular structure, with its upper end connected to the flow channel control component (3) and its lower end connected to the scraper and straightening component (4).

3. The composite scraper cement retainer according to claim 2, characterized in that: The anchoring sealing assembly (2) includes an upper slip (201), an upper cone (202), a sealing rubber sleeve assembly (203), a support ring (204), a lower slip (205), and a lower cone (206). The upper slip (201) and the upper cone (202), and the lower slip (205) and the lower cone (206) are stacked and fitted together in sequence along the axial direction. The upper cone (202) and lower cone (206) drive the corresponding slip to expand radially outward under axial force to achieve anchoring fit with the inner wall of the sleeve. The outer wall of the upper mandrel (101) is connected to the upper cone (202) and lower cone (206) of the anchoring sealing assembly (2) respectively through shear pins. The sealing rubber sleeve assembly (203) expands radially under axial compression to achieve annular sealing. The support ring (204) is used to limit the deformation direction of the sealing rubber sleeve assembly (203).

4. The composite scraper cement retainer according to claim 3, characterized in that: An anti-rotation locking key fit structure (7) is provided between the upper mandrel (101) and the upper cone (202). The anti-rotation locking key fit structure (7) is used to restrict the relative circumferential rotation between the upper mandrel (101) and the upper cone (202) during the setting process, and to restrict the upper cone (202) from rotating circumferentially with the milling tool during the drilling and grinding process.

5. The composite scraper cement retainer according to claim 3, characterized in that: The flow channel control component (3) includes an elastic sliding valve (301) and a sleeve valve connector (302); the sleeve valve connector (302) is provided with a radial flow guide groove (303) and an axial flow guide hole (304) that are interconnected, which are used to form a through flow channel; the elastic sliding valve (301) can move axially along the inner wall of the upper mandrel (101) to open or close the flow guide hole of the sleeve valve connector (302) so as to realize the conduction and isolation of the mandrel flow channel.

6. The composite scraper cement retainer according to claim 5, characterized in that: The elastic sliding valve (301) is provided with an elastic claw structure (301a) on the top. The elastic claw structure (301a) is used to form an axial driving engagement with the seat sealing tool insertion tube. The outer wall of the elastic sliding valve (301) is provided with multiple sealing rings (305). The sealing rings (305) are used to block the upper and lower ends of the guide hole respectively when the elastic sliding valve (301) is in the closed position, so as to form a bidirectional sealing barrier. The top of the upper mandrel (101) is provided with a reverse internal thread for connecting with the seat sealing tool. The inner wall of the lower end of the upper mandrel (101) is also provided with a groove (6) that engages with the elastic sliding valve (301).

7. The composite scraper cement retainer according to claim 1, characterized in that: The scraper straightening assembly (4) includes an elastic scraper cage (401) and a rotary bearing (402). The elastic scraper cage (401) is composed of multiple spiral scraping ribs (403). Hollowed-out guide grooves (404) are provided between the scraping ribs (403) for scraping the inner wall of the sleeve and guiding the annular fluid. The rotary bearings (402) are respectively located at the upper and lower ends of the elastic scraper cage (401) for allowing the elastic scraper cage (401) to rotate freely in the circumferential direction relative to the lower spindle (102).

8. The composite scraper cement retainer according to claim 5, characterized in that: The upper end of the lower mandrel (102) and the lower end of the sleeve valve connector (302) are connected by shear pins or threads to achieve a detachable connection between the lower mandrel (102) and the sleeve valve connector (302).

9. The composite scraper cement retainer according to claim 5, characterized in that: The sealing rubber sleeve assembly (203) is made of heat-resistant rubber material. The upper slip (201) and lower slip (205) are integrally cast structures. The upper mandrel (101), upper cone (202), lower cone (206), and support ring (204) are made of cast iron material. The sleeve valve connector (302), lower mandrel (102), and elastic scraper cage (401) are made of alloy steel material.

10. The composite scraper cement retainer according to claim 2, characterized in that: The top of the upper mandrel (101) is configured to be directly connected to a mechanical setting tool, or connected to a hydraulic setting tool via an adapter.

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