A composite drill pipe rubber plug resistant to high and low temperatures

Abstract

The present invention relates to the technical field of oilfield machinery, and particularly relates to a composite drill pipe rubber plug resistant to high and low temperatures. The composite drill pipe rubber plug resistant to high and low temperatures is used for cooperative operation with a liner rubber plug, and includes a guiding head, a core shaft, a supporting skeleton, rubber discs and an adjusting mechanism. One end of the core shaft is fixedly inserted into the guiding head, and the other end is suspended. The supporting skeleton is sleeved on the core shaft and can slide axially. The supporting skeleton has a plurality of bowl-shaped parts arranged at intervals along the axial direction, and the bowl openings of the bowl-shaped parts face away from the guiding head. Each bowl-shaped part is sleeved with a rubber disc, and all the rubber discs are integrally formed. The part of the rubber disc in contact with the inner wall of the drill pipe is recessed inward to form a U-shaped part. The outer wall of the U-shaped part is composed of a sealing surface and two cleaning surfaces, and the sealing surface is located between the two cleaning surfaces. The rubber disc is configured to have a cleaning state and a sealing state, and the adjusting mechanism is configured to be able to switch the state of the rubber disc, so that the cleaning surface can be used to scrape the residual cement on the inner wall of the drill pipe, and the sealing surface can be used to form a seal with the drill pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield machinery, and particularly relates to a composite drill pipe plug resistant to high and low temperatures. Background Art

[0002] A drill pipe plug is a key tool used in the cementing operation of oil and gas drilling. Its main function is to ensure that the cement slurry can be evenly filled in the annular space between the casing and the formation by controlling the flow and displacement of the cement slurry, so as to achieve the goal of the cementing operation.

[0003] In the related art, for example, Chinese Patent CN207437004U discloses a drill pipe plug. In the process of the drill pipe plug moving downward in the pipe string, the edge of the rubber disc fits with the inner wall of the pipe string to separate the displacement fluid and the cement slurry; by setting at least one end of the core shaft to be closed, it can prevent the displacement fluid and the cement slurry from mixing through the inner cavity of the core shaft.

[0004] However, there are also some problems with the existing drill pipe plugs in actual use: in the cementing operation, the cement slurry and the displacement fluid will carry a large amount of abrasive particles during the flow process, such as tiny rock particles, sand grains, etc. When the drill pipe plug moves in the pipe string, these abrasive particles will cause abrasive wear on both the cleaning surface and the sealing surface of the plug. And the cleaning surface and the sealing surface of the existing drill pipe plug are of the same structure. With the increase of the operation time and the aggravation of the abrasive wear degree, scratches, depressions and other damages will gradually appear on the sealing surface of the drill pipe plug, resulting in the destruction of the flatness and tight fit of the sealing surface, and then greatly reducing the sealing effect of the drill pipe plug. Once the sealing effect decreases, the displacement fluid and the cement slurry are likely to leak, which will not only affect the filling quality of the cement slurry in the annular space, reduce the stability and reliability of the cementing, but also may lead to serious problems such as subsequent wellbore instability and formation fluid leakage, bringing huge potential safety hazards and economic losses to the oil and gas drilling operation. Summary of the Invention

[0005] Based on this, in view of the problem of poor sealing performance of the current drill pipe plugs during use, it is necessary to provide a composite drill pipe plug resistant to high and low temperatures.

[0006] The above object is achieved by the following technical solutions:

[0007] A composite drill pipe plug resistant to high and low temperatures, the composite drill pipe plug resistant to high and low temperatures is configured to be able to cooperate with the liner plug; the composite drill pipe plug resistant to high and low temperatures includes:

[0008] A guide head;

[0009] A core shaft, one end of which is fixedly inserted into the guide head, and the other end is suspended.

[0010] A support skeleton, sleeved on the mandrel and capable of sliding along the axial direction of the mandrel. The support skeleton has a plurality of bowl-shaped parts, the openings of the bowl-shaped parts face away from the guiding head, and the plurality of bowl-shaped parts are arranged at intervals along the axial direction of the mandrel;

[0011] A glue disk is sleeved on each bowl-shaped part, and all the glue disks are integrally formed. The part of the glue disk in contact with the inner wall of the drill pipe is recessed inward to form a U-shaped part. The outer side wall of the U-shaped part is composed of a sealing surface and two cleaning surfaces, and the sealing surface is located between the two cleaning surfaces. The glue disk is configured to have a cleaning state and a sealing state. When in the cleaning state, the cleaning surface is in contact with the inner wall of the drill pipe; when in the sealing state, the sealing surface is in contact with the inner wall of the drill pipe;

[0012] An adjusting mechanism configured to be able to switch the state of the glue disk.

[0013] Further, the adjusting mechanism includes a plurality of guiding ring grooves and a plurality of ejector rod groups. The guiding ring grooves are arranged on the circumferential side wall of the mandrel, and the plurality of guiding ring grooves are arranged at intervals along the axial direction of the mandrel; the plurality of ejector rod groups are arranged at intervals along the axial direction of the mandrel. Each ejector rod group includes a plurality of ejector rods. The plurality of ejector rods of the same ejector rod group are simultaneously inserted into the same bowl-shaped part and the same guiding ring groove. The plurality of ejector rods of the same ejector rod group are arranged circumferentially and all extend along the generatrix direction of the bowl-shaped part. The ejector rod is configured to form a stop fit with the U-shaped part under the action of the guiding ring groove when the support skeleton moves in the direction close to the guiding head.

[0014] Further, the high and low temperature resistant composite drill pipe rubber plug further includes a one-way mechanism. A push ring is sleeved on each ejector rod. The push ring can slide along its own axial direction and can form a one-way fit with the ejector rod under the action of the one-way mechanism to be able to synchronously drive the ejector rod to extend outwards; a push piece is arranged on each push ring. The push piece can be deformed. The push piece is simultaneously arranged on the support skeleton. The push piece can form a stop fit with the glue disk to drive the push ring to move.

[0015] Further, the one-way mechanism includes a card slot and a pin. A card slot is arranged on each ejector rod; a pin is arranged on the inner circumferential wall of each push ring. The pin has elasticity and can form a clamping fit with the card slot.

[0016] Further, the push piece has elasticity.

[0017] Further, the high and low temperature resistant composite drill pipe rubber plug further comprises a buffer sleeve, the buffer sleeve is fixed on the support skeleton, and simultaneously sleeved on the mandrel and the guide head. The buffer sleeve, the mandrel and the guide head jointly enclose a damping cavity, and the damping cavity is filled with damping liquid; a damping plug is fixedly sleeved on the mandrel, the damping plug is inserted into the damping cavity, and divides the damping cavity into two sub-cavities. The damping plug is provided with damping holes, and the damping holes communicate the two sub-cavities.

[0018] Further, the rubber disc comprises a rubber matrix and an internal network structure.

[0019] Further, the rubber matrix is composed of hydrogenated nitrile rubber and fluororubber compounded according to a preset mass ratio, and forms an interpenetrating network structure through a dynamic vulcanization process.

[0020] Further, a low temperature plasticizer and / or nano-silica are added into the rubber disc.

[0021] Further, the internal network structure comprises multiple layers of aramid fiber braided nets, there is a preset distance between adjacent layers of aramid fiber braided nets, and the aramid fiber braided nets are surface-treated with a silane coupling agent and chemically bonded to the rubber matrix to form a three-dimensional reinforcement skeleton.

[0022] The beneficial effects of the present invention are:

[0023] During the use of the high and low temperature resistant composite drill pipe rubber plug provided by the present invention, when scraping the residual cement on the inner wall of the drill pipe, the rubber disc is adjusted to the cleaning state through the adjusting mechanism, so that the cleaning surface contacts the inner wall of the drill pipe to ensure the cleaning effect; when forming a seal with the drill pipe, the rubber disc is adjusted to the sealing state through the adjusting mechanism, so that the sealing surface contacts the inner wall of the drill pipe to ensure the sealing effect.

[0024] Further, by setting the push ring, the push piece and the one-way mechanism, during the process of injecting the displacement fluid into the drill pipe, under the high pressure of the displacement fluid, the rubber disc is compressed, and then the rubber disc forms a stop fit with the push piece, and then the push piece is deformed. When the push piece is deformed, it drives the push ring to move outwards. Subsequently, the push ring forms a one-way fit with the push rod under the action of the one-way mechanism and drives the push rod to extend outwards, thereby increasing the contact force between the sealing surface and the inner wall of the drill pipe, and further improving the sealing effect between the sealing surface and the inner wall of the drill pipe.

[0025] Further, by providing a buffer sleeve and a damping plug, during the cooperation of the composite drill pipe rubber plug and the liner rubber plug, since the buffer sleeve is fixed to the support skeleton, relative movement occurs between the support skeleton and the guide head, and further, the damping liquid exchanges between the two sub-cavities through the damping holes, thereby reducing the influence on the sealing performance between the rubber disk structure and the sealing surface and the inner wall of the drill pipe caused by the collision pressure of the composite drill pipe rubber plug and the liner rubber plug.

[0026] Further, by providing that the rubber disk includes a rubber matrix and an internal network structure, the high and low temperature resistance of the composite drill pipe rubber plug is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic three-dimensional structure diagram of the high and low temperature resistant composite drill pipe rubber plug provided by an embodiment of the present invention;

[0028] Figure 2 FIG. is a schematic cross-sectional structure diagram of the high and low temperature resistant composite drill pipe rubber plug provided by an embodiment of the present invention;

[0029] Figure 3 is Figure 2 a partially enlarged structural diagram at A in;

[0030] Figure 4 FIG. is a partially enlarged structural diagram when the rubber disk of the high and low temperature resistant composite drill pipe rubber plug provided by an embodiment of the present invention is in a sealed state;

[0031] Figure 5 FIG. is a schematic three-dimensional structure diagram of the high and low temperature resistant composite drill pipe rubber plug without the rubber disk provided by an embodiment of the present invention.

[0032] Wherein:

[0033] 1. Guide head; 101. Sealing ring; 102. One-way ratchet ring; 1021. Vertical ring; 10211. One-way tooth; 10212. Notch; 1022. Horizontal ring; 10221. First pin hole; 103. Fixed ring; 104. Second pin hole;

[0034] 2. Mandrel;

[0035] 3. Support skeleton; 301. Bowl-shaped part; 3011. Chute; 302. Base pipe; 303. Threaded sleeve; 304. Nut;

[0036] 4. Rubber disk; 401. U-shaped part; 4011. Sealing surface; 4012. Cleaning surface; 402. Bulge part;

[0037] 5. Adjusting mechanism; 501. Guide ring groove; 502. Ejector rod group; 5021. Ejector rod;

[0038] 6. Thrust ring; 601. Convex block;

[0039] 7. Thrust piece

[0040] 8. One-way mechanism; 801. Card slot; 802. Cotter pin

[0041] 9. Buffer sleeve; 901. Damping chamber

[0042] 10. Damping plug; 1001. Damping hole

[0043] 11. Reinforcing sleeve Detailed implementation manners

[0044] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meanings. The terms "connection" and "coupling" as used herein, unless otherwise clearly specified and defined, both include direct and indirect connections (couplings). In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0046] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0047] Such as Figures 1 to 5As shown in the figure, a composite drill pipe rubber plug with high and low temperature resistance provided by an embodiment of the present invention is configured to cooperate with a liner rubber plug, and is provided with a guide head 1, a mandrel 2, a support skeleton 3, a rubber disc 4 and an adjusting mechanism 5. One end of the mandrel 2 is fixedly inserted into the guide head 1, and the other end is suspended; the support skeleton 3 is sleeved on the mandrel 2 and can slide along the axis of the mandrel 2. The support skeleton 3 has a plurality of bowl-shaped parts 301, and the bowl mouths of the bowl-shaped parts 301 face away from the guide head 1. The plurality of bowl-shaped parts 301 are arranged at intervals along the axis of the mandrel 2; a rubber disc 4 is sleeved on each bowl-shaped part 301, and all the rubber discs 4 are integrally formed. The part of the rubber disc 4 in contact with the inner wall of the drill pipe is recessed inward to form a U-shaped part 401. The outer wall of the U-shaped part 401 is composed of a sealing surface 4011 and two cleaning surfaces 4012. The sealing surface 4011 is located between the two cleaning surfaces 4012. The rubber disc 4 is configured to have a cleaning state and a sealing state. When in the cleaning state, the cleaning surface 4012 is in contact with the inner wall of the drill pipe. When in the sealing state, the sealing surface 4011 is in contact with the inner wall of the drill pipe; the adjusting mechanism 5 is configured to be able to switch the state of the rubber disc 4.

[0048] Specifically in this embodiment, when installed, the bottom end of the mandrel 2 is fixedly inserted into the top of the guide head 1, and the top end is suspended. To facilitate sleeving on the mandrel 2, the support skeleton 3 is provided with a base pipe 302. When installed, the base pipe 302 is slidably sleeved on the mandrel 2; the bowl-shaped part 301 is fixedly sleeved on the base pipe 302, and the opening of the bowl-shaped part 301 faces upward. The sealing surface 4011 is formed at the outer U-shaped surface of the U-shaped part 401, and the cleaning surface 4012 is formed at the tops of the two cantilevers of the U-shaped part 401. To facilitate fixing the rubber disc 4, on the one hand, a threaded sleeve 303 is coaxially arranged at the top of the base pipe 302, and a nut 304 is threadedly sleeved on the threaded sleeve 303. The nut 304 presses the uppermost rubber disc 4 against the top of the support skeleton 3. On the other hand, a reinforcing sleeve 11 is tightly sleeved outside each rubber disc 4. The reinforcing sleeve 11 prevents the rubber disc 4 from protruding outward and is used to strengthen the connection rigidity between the rubber disc 4 and the base pipe 302.

[0049] During the use process, when the composite drill pipe rubber plug is put into use and faces the task of scraping the residual cement on the inner wall of the drill pipe, the adjusting mechanism 5 adjusts the rubber disc 4 to enter the cleaning state. At this time, the cleaning surface 4012 is in close contact with the inner wall of the drill pipe, and it can efficiently and powerfully scrape off the cement residue attached to the inner wall of the drill pipe, ensuring the cleanliness of the internal channel of the drill pipe, laying a solid foundation for the smooth transportation of subsequent cement slurry and displacement fluid, and thus guaranteeing the smooth progress of the pre-preparation stage of the entire cementing operation and ensuring that the cleaning effect meets the expected standard.

[0050] When the process of the cementing operation advances to the link of jointly constructing a seal with the liner plug, the adjusting mechanism 5 switches the rubber disc 4 to the sealed state. In this state, the sealing surface 4011 fits against the inner wall of the drill pipe, forming a reliable sealing barrier. This sealing barrier effectively prevents the mixing of the cement slurry and the displacement fluid, ensuring that the cement slurry can be evenly and stably filled in the annular space between the casing and the formation according to the design requirements, greatly guaranteeing the sealing effect, improving the stability and reliability of the cementing operation, and effectively avoiding a series of serious problems such as wellbore instability and formation fluid leakage that may be caused by seal failure, providing a solid guarantee for the safe and efficient development of oil and gas drilling operations.

[0051] Furthermore, the adjusting mechanism 5 is provided to include a plurality of guiding ring grooves 501 and a plurality of ejector rod groups 502. The guiding ring grooves 501 are arranged on the circumferential side wall of the mandrel 2, and the plurality of guiding ring grooves 501 are arranged at intervals along the axial direction of the mandrel 2; the plurality of ejector rod groups 502 are arranged at intervals along the axial direction of the mandrel 2, and each ejector rod group 502 includes a plurality of ejector rods 5021. The plurality of ejector rods 5021 of the same ejector rod group 502 are simultaneously inserted into the same bowl-shaped part 301 and the same guiding ring groove 501. The plurality of ejector rods 5021 of the same ejector rod group 502 are arranged circumferentially and all extend along the generatrix direction of the bowl-shaped part 301. The ejector rod 5021 is configured to form a stop fit with the U-shaped part 401 under the action of the guiding ring groove 501 when the support skeleton 3 moves in the direction close to the guiding head 1.

[0052] Specifically in this embodiment, the guiding ring groove 501 is provided with a first tapered ring sub-groove and a second tapered ring sub-groove. The first tapered ring sub-groove is located above the second tapered ring sub-groove. The small end of the first tapered ring sub-groove faces downward and is oppositely arranged with the small end of the second tapered ring sub-groove. The taper of the first tapered ring sub-groove is approximately equal to the taper of the bowl-shaped part 301, ensuring that the ejector rod 5021 can be simultaneously inserted into the bowl-shaped part 301 and the guiding ring groove 501. The end of the ejector rod 5021 pointing to the inner U-shaped surface of the U-shaped part 401 ensures that when moving outward, it can simultaneously push two sealing surfaces 4011 outward, so as to facilitate switching the position of the sealing surface 4011. To facilitate the installation of the ejector rod 5021, mounting holes are provided on the support skeleton 3. The mounting holes are arranged on the circumferential side wall of the bowl-shaped part 301 and penetrate through the base pipe 302 at the same time. The mounting holes are strip-shaped structures and extend along the generatrix direction of the bowl-shaped part 301. The number of mounting holes on each bowl-shaped part 301 is equal to the number of ejector rods 5021 and is arranged circumferentially. The ejector rod 5021 is slidably inserted into the mounting hole during installation.

[0053] During the process of injecting the displacement fluid into the drill pipe, under the pushing of the displacement fluid, the composite drill pipe plug moves towards the liner plug. When the composite drill pipe plug moves to the liner plug, the guiding head 1 is clamped with the liner plug. Subsequently, under the high pressure of the displacement fluid, the support frame 3 and the rubber disc 4 move downward relative to the mandrel 2 together. During the movement of the support frame 3, the support frame 3 synchronously drives the ejector rod 5021 to move downward. At this time, under the conical surface guidance of the second conical ring split groove, the ejector rod 5021 moves outward synchronously, and then forms a stop fit with the U-shaped part 401, and then pushes the U-shaped part 401 outward, making the U-shaped part 401 become a straight shape. At this time, the sealing surface 4011 fits with the inner wall of the drill pipe, so that the rubber disc 4 switches from the cleaning state to the sealing state.

[0054] In a further embodiment, in order to further improve the sealing effect between the sealing surface 4011 and the inner wall of the drill pipe, the composite drill pipe plug made of heat-resistant and cold-resistant materials further includes a one-way mechanism 8. A push ring 6 is sleeved on each ejector rod 5021. The push ring 6 can slide along its own axis direction, and under the action of the one-way mechanism 8, it can form a one-way fit with the ejector rod 5021 to synchronously drive the ejector rod 5021 to extend outward; a push piece 7 is arranged on each push ring 6. The push piece 7 can be deformed. The push piece 7 is also arranged on the support frame 3. The push piece 7 can form a stop fit with the rubber disc 4 to drive the push ring 6 to move.

[0055] Specifically in this embodiment, the push ring 6 is sleeved on the outer end of the ejector rod 5021. The push piece 7 is of an arc-shaped structure and extends along the generatrix direction of the bowl-shaped part 301 as a whole. The push piece 7 has its opening facing downward when installed. To facilitate the installation of the push piece 7, the rubber disc 4 is also provided with a raised part 402. The raised part 402 is of an annular structure and is formed at the upper conical part of the rubber disc 4. The raised part 402 is of a C-shaped structure and has its opening facing downward. To facilitate the connection of the push piece 7, a sliding groove 3011 is arranged on the upper conical surface of the bowl-shaped part 301. The sliding groove 3011 extends along the generatrix direction of the bowl-shaped part 301 and communicates with the installation hole. The number of sliding grooves 3011 on each bowl-shaped part 301 is equal to the number of ejector rods 5021 and is arranged circumferentially. A convex block 601 is arranged on the outer peripheral wall of the push ring 6. The convex block 601 is arranged inward and is slidably inserted into the sliding groove 3011. The outer end of the push piece 7 is fixed on the convex block 601 when installed, and the inner end is fixed at the connection between the bowl-shaped part 301 and the base pipe 302.

[0056] During the process of injecting the displacement fluid into the drill pipe, the rubber disc 4, as the core component for realizing the sealing function, begins to undergo elastic deformation and be compressed under the continuous action of the high pressure of the displacement fluid. With the compression deformation of the rubber disc 4, the raised portion 402 is pressed down, thereby being able to reduce the overall deformation of the rubber disc 4 until it forms a stop fit with the preset push piece 7. Subsequently, under the extrusion of the rubber disc 4, the push piece 7 gradually changes from an arc shape to a straight shape. During this dynamic process of the push piece 7 becoming straight, the displacement generated by it will be converted into a driving force for the push ring 6, prompting the push ring 6 to move outward along its own axis direction.

[0057] Subsequently, the push ring 6 forms a one-way fit with the push rod 5021 under the action of the one-way mechanism 8 and drives the push rod 5021 to extend outward. As the push rod 5021 extends, an additional thrust is applied to the sealing surface 4011, causing the contact force between the sealing surface 4011 and the inner wall of the drill pipe to increase significantly. This increase in the contact force, from a microscopic perspective, can make the fit between the sealing surface 4011 and the inner wall of the drill pipe closer, effectively reducing or even eliminating the possible tiny gaps between the two, thereby greatly improving the sealing effect. From a macroscopic perspective, it can effectively prevent the mutual leakage between the displacement fluid and the cement slurry, ensure that the cement slurry is uniformly and stably filled in the annular space between the casing and the formation according to the design requirements, lay a solid foundation for the high-quality completion of the cementing operation, and effectively guarantee the stability of the wellbore and the smooth progress of the subsequent drilling operation.

[0058] Furthermore, the one-way mechanism 8 can be set to include a card slot 801 and a pin 802. Each push rod 5021 is provided with a card slot 801; a pin 802 is provided on the inner peripheral wall of each push ring 6. The pin 802 has elasticity and can form a snap fit with the card slot 801.

[0059] Specifically in this embodiment, the card slot 801 is a conical structure with the small end facing outward. To facilitate the installation of the pin 802, an installation groove is provided on the inner peripheral wall of each push ring 6. The pin 802 is a strip-shaped structure, with the inner end fixedly installed at the installation groove and the outer end suspended.

[0060] Initially, the pin 802 retracts into the installation groove and is located outside the card slot 801. The pin 802 has a tendency to swing towards the axis direction of the push ring 6 under the elastic action.

[0061] After the ejector rod 5021 moves outward, the retaining pin 802 disengages from the mounting groove under its own elastic force and inserts into the card slot 801. During the process of injecting displacement fluid into the drill pipe, under the high pressure of the displacement fluid, the rubber disc 4 is compressed. Subsequently, the rubber disc 4 and the push piece 7 form a stop fit, and then the push piece 7 is straightened. When the push piece 7 is straightened, it drives the push ring 6 to move outward. Subsequently, the push ring 6 forms a one-way fit with the ejector rod 5021 through the engagement between the retaining pin 802 and the card slot 801, and drives the ejector rod 5021 to extend outward, thereby increasing the contact force between the sealing surface 4011 and the inner wall of the drill pipe, and further improving the sealing effect between the sealing surface 4011 and the inner wall of the drill pipe.

[0062] In other embodiments, the card slot 801 is of an annular structure, thus avoiding the influence on the engagement between the retaining pin 802 and the card slot 801 caused by the relative rotation between the ejector rod 5021 and the push ring 6.

[0063] In some other embodiments, the push piece 7 is provided with elasticity, so that after the high pressure of the displacement fluid disappears, the push piece 7 can drive the push ring 6 to reset under its own elastic force.

[0064] In some other embodiments, in the actual working conditions of oil and gas drilling and cementing operations, when the composite drill pipe rubber plug and the liner rubber plug cooperate, they will inevitably collide at a specific stage. The impact force generated during this collision process is relatively large, which is extremely likely to cause stress concentration in the structure of the composite drill pipe rubber plug and the key component rubber disc 4. If the stress is too large and exceeds the bearing limit of the materials of the composite drill pipe rubber plug structure and the rubber disc 4, it will lead to deformation and rupture of the composite drill pipe rubber plug structure, as well as damage such as tearing and degumming of the rubber disc 4, and further cause the composite drill pipe rubber plug to completely lose its sealing function, seriously threatening the smooth progress and final quality of the cementing operation.

[0065] To improve this situation, the composite drill pipe rubber plug resistant to high and low temperatures is further provided with a buffer sleeve 9. The buffer sleeve 9 is fixed on the support skeleton 3 and simultaneously sleeved on the mandrel 2 and the guide head 1. The buffer sleeve 9, the mandrel 2 and the guide head 1 jointly enclose a damping cavity 901, and the damping cavity 901 is filled with damping fluid; a damping plug 10 is fixedly sleeved on the mandrel 2, the damping plug 10 is inserted into the damping cavity 901 and divides the damping cavity 901 into two sub-cavities, and a damping hole 1001 is provided on the damping plug 10, and the damping hole 1001 communicates with the two sub-cavities.

[0066] Specifically in this embodiment, when the support skeleton 3 is installed, the bottom end of the base pipe 302 is threadedly sleeved on the top of the buffer sleeve 9 to ensure that the support skeleton 3 can move axially together with the buffer sleeve 9. At the same time, the bottom end of the base pipe 302 presses the lowermost rubber disc 4 against the top of the buffer sleeve 9 to ensure that the rubber disc 4 can be fixed. The bottom end of the buffer sleeve 9 is hermetically sleeved on the top of the guide head 1 to ensure that a damping cavity 901 can be formed.

[0067] During use, when the composite drill pipe rubber plug and the liner rubber plug enter the mating process, especially at the moment of bump pressure, a strong impact force will be first transmitted to the buffer sleeve 9. At this time, since the buffer sleeve 9 and the support skeleton 3 are tightly fixed, under the action of the impact force, the support skeleton 3 will immediately displace relative to the guide head 1. This relative movement causes the damping liquid in the damping cavity 901 to start flowing. The damping liquid is blocked by the damping plug 10 and can only be exchanged between the two sub-cavities through the damping holes 1001. The damping holes 1001 have a certain current-limiting effect, and the damping liquid will encounter a large resistance when passing through the damping holes 1001. This resistance causes the damping liquid to continuously convert the kinetic energy generated by the collision into heat energy and internal energy during the flowing process, thereby efficiently buffering and consuming most of the impact force.

[0068] In some other embodiments, to improve the sealing performance when the composite drill pipe rubber plug and the liner rubber plug are mated, a sealing ring 101 is sleeved on the guide head 1.

[0069] In some other embodiments, to facilitate the formation of a clamping fit between the composite drill pipe rubber plug and the liner rubber plug, a one-way tooth ring 102 and a fixing ring 103 are sleeved on the guide head 1. The one-way tooth ring 102 has a vertical ring 1021 and a horizontal ring 1022, where the vertical ring 1021 is located at the top of the horizontal ring 1022, and the horizontal ring 1022 presses on the top of the guide head 1. A plurality of circles of one-way teeth 10211 are provided on the outer peripheral wall of the vertical ring 1021, and the fixing ring 103 presses on the top of the horizontal ring 1022. To facilitate fixing the fixing ring 103 on the guide head 1, a plurality of notches 10212 are formed on the circumferential side wall of the vertical ring 1021, and a plurality of first pin holes 10221 are formed on the circumferential side wall of the fixing ring 103. The number of the first pin holes 10221 is equal to the number of the notches 10212 and they are correspondingly arranged. A plurality of second pin holes 104 are provided on the circumferential side wall of the guide head 1. The number of the second pin holes 104 is equal to the number of the first pin holes 10221 and they are correspondingly arranged. The composite drill pipe rubber plug with high and low temperature resistance is further provided with a plurality of pin rods. The number of the pin rods is equal to the number of the notches 10212, and during installation, they are correspondingly press-fitted into the notches 10212, the first pin holes 10221 and the second pin holes 104.

[0070] In some other embodiments, to improve the high and low temperature resistance performance of the composite drill pipe rubber plug, it is provided that the rubber disc 4 includes a rubber matrix and an internal network structure.

[0071] Further, the rubber matrix can be set to be composed of hydrogenated nitrile rubber (HNBR) and fluororubber (FKM) compounded according to a preset mass ratio, and an interpenetrating network structure is formed through a dynamic vulcanization process, so as to take into account low-temperature elasticity and high-temperature oil resistance.

[0072] Further, the preset mass ratio can be set to hydrogenated nitrile rubber (HNBR): fluororubber (FKM) = 6:4.

[0073] Further, the built-in network structure can be set to include multiple layers of aramid fiber woven meshes, with a preset spacing between adjacent layers of aramid fiber woven meshes. After the aramid fiber woven meshes are surface-treated with a silane coupling agent, they are chemically bonded to the rubber matrix to form a three-dimensional reinforcement skeleton. The fiber network can disperse local stress, inhibit crack propagation caused by low-temperature embrittlement, and at the same time improve the compressive strength of the rubber disk 4 (≥15 MPa).

[0074] Further, the preset spacing can be set to 1 to 2 mm.

[0075] Further, the preset spacing can be set to 1.5 mm. At this time, the stress dispersion effect is the best, and the crack propagation resistance is increased by 30%.

[0076] In a further embodiment, to further improve the high and low temperature resistance of the composite drill pipe rubber plug, it is set to add a low-temperature plasticizer (such as dioctyl sebacate) and / or nano-silica in the rubber disk 4. Among them, dioctyl sebacate as a low-temperature plasticizer can reduce the glass transition temperature (T≤-50 °C); nano-silica (particle size 20-50 nm) can be used as an anti-freezing filler to inhibit the freezing of rubber molecular chains at low temperatures.

[0077] In some other embodiments, the guide head 1, the mandrel 2, and the support skeleton 3 can all be set to be made of lightweight and high-strength aluminum alloy (such as 7075-T6).

[0078] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should be considered as the scope described in this specification.

[0079] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A composite drill pipe rubber plug resistant to high and low temperatures, characterized in that, The high and low temperature resistant composite drill pipe rubber plug is configured to cooperate with the liner rubber plug; The high and low temperature resistant composite drill pipe rubber plug includes: A guide head; A mandrel, one end of which is fixedly inserted into the guide head, and the other end is suspended; A support skeleton, sleeved on the mandrel and capable of sliding along the axial direction of the mandrel. The support skeleton has a plurality of bowl-shaped parts, the mouths of the bowl-shaped parts face away from the guide head, and the plurality of bowl-shaped parts are arranged at intervals along the axial direction of the mandrel; A rubber disc is sleeved on each bowl-shaped part, and all the rubber discs are integrally formed. The part of the rubber disc in contact with the inner wall of the drill pipe is recessed inward to form a U-shaped part. The outer wall of the U-shaped part is composed of a sealing surface and two cleaning surfaces. The sealing surface is located between the two cleaning surfaces. The rubber disc is configured to have a cleaning state and a sealing state. When in the cleaning state, the cleaning surface is in contact with the inner wall of the drill pipe; when in the sealing state, the sealing surface is in contact with the inner wall of the drill pipe; An adjusting mechanism, configured to be able to switch the state of the rubber disc; The adjusting mechanism includes a plurality of guide ring grooves and a plurality of ejector rod groups. The guide ring grooves are arranged on the circumferential side wall of the mandrel, and the plurality of guide ring grooves are arranged at intervals along the axial direction of the mandrel; the plurality of ejector rod groups are arranged at intervals along the axial direction of the mandrel. Each ejector rod group includes a plurality of ejector rods. The plurality of ejector rods in the same ejector rod group are simultaneously inserted into the same bowl-shaped part and the same guide ring groove. The plurality of ejector rods in the same ejector rod group are arranged circumferentially and all extend along the generatrix direction of the bowl-shaped part. The ejector rod is configured to form a stop fit with the U-shaped part under the action of the guide ring groove when the support skeleton moves towards the direction close to the guide head.

2. The high and low temperature resistant composite drill pipe rubber plug according to claim 1, characterized in that, The high and low temperature resistant composite drill pipe rubber plug further includes a one-way mechanism. A thrust ring is sleeved on each ejector rod. The thrust ring can slide along its own axial direction, and under the action of the one-way mechanism, it can form a one-way fit with the ejector rod to be able to synchronously drive the ejector rod to extend outwards; a thrust piece is arranged on each thrust ring. The thrust piece can be deformed. The thrust piece is simultaneously arranged on the support skeleton. The thrust piece can form a stop fit with the rubber disc to drive the thrust ring to move.

3. The high and low temperature resistant composite drill pipe rubber plug according to claim 2, characterized in that, The one-way mechanism includes a card slot and a pin. A card slot is arranged on each ejector rod; a pin is arranged on the inner peripheral wall of each thrust ring. The pin has elasticity and can form a clamping fit with the card slot.

4. The high and low temperature resistant composite drill pipe rubber plug according to claim 2, characterized in that, The thrust piece has elasticity.

5. The high and low temperature resistant composite drill pipe rubber plug according to claim 1, characterized in that, The high and low temperature resistant composite drill pipe rubber plug further includes a buffer sleeve. The buffer sleeve is fixed on the support skeleton and simultaneously sleeved on the mandrel and the guide head. A damping cavity is jointly formed by the buffer sleeve, the mandrel and the guide head. The damping cavity is filled with damping liquid; a damping plug is fixedly sleeved on the mandrel. The damping plug is inserted into the damping cavity and divides the damping cavity into two sub-cavities. A damping hole is arranged on the damping plug, and the damping hole communicates the two sub-cavities.

6. The high and low temperature resistant composite drill pipe rubber plug according to claim 1, characterized in that, The rubber disc includes a rubber matrix and an internal network structure.

7. The high and low temperature resistant composite drill pipe rubber plug according to claim 6, characterized in that, The rubber matrix is composed of hydrogenated nitrile rubber and fluororubber compounded according to a preset mass ratio, and an interpenetrating network structure is formed through a dynamic vulcanization process.

8. The high and low temperature resistant composite drill pipe rubber plug according to claim 6, characterized in that, A low-temperature plasticizer and / or nano-silica is added into the rubber disc.

9. The high and low temperature resistant composite drill pipe rubber plug according to claim 6, characterized in that, The built-in network structure includes multiple layers of aramid fiber braided nets, and there is a preset spacing between adjacent layers of the aramid fiber braided nets. After the aramid fiber braided nets are surface-treated with a silane coupling agent, they are chemically bonded to the rubber matrix to form a three-dimensional reinforcing framework.

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