Temporary sealing tool and temporary sealing method for casing pipe

Abstract

The invention belongs to the technical field of underground key tools for petroleum and natural gas drilling and fracturing, and particularly relates to a temporary sealing tool and a temporary sealing method for a casing pipe. The temporary sealing tool for the casing is used for plugging the interior of a casing string, and comprises a tool mandrel, a central shaft, a sealing structure, a push block, a locking rod, a connecting shaft, a clamping arm structure, a release sub and a gapless ring, when the center shaft is pushed, the sawtooth-shaped protrusions on the outer surface of the push block and the casing string form first-stage positioning, and the sealing structure and the casing string form sealing. The clamping arm structure is arranged on the outer surface of the connecting shaft, and the clamping arm structure is matched with a groove formed in a casing string to achieve second-stage positioning. Through cooperation of the sealing structure, the push block, the clamping arm structure and other structures, sealing of the casing pipe can be achieved; and two-time positioning setting is achieved through the push block and the clamping arm structure, sliding and shifting of the temporary sealing tool are avoided, and the better setting effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of downhole key tools for oil and natural gas drilling and fracturing, and specifically relates to a casing temporary sealing tool and a temporary sealing method. Background Art

[0002] With the in-depth development of unconventional oil and gas resources, especially shale oil and gas, tight oil and gas, low permeability oil and gas, etc., in order to increase the initial production and final recovery rate, stratified injection and production and multi-stage fracturing have become one of the effective means for the efficient development of unconventional oil and gas resources. During the staged fracturing construction process, the casing temporary sealing tool is lowered and sealed at a pre-set position in the wellbore to achieve segmented isolation of the bottom casing and ensure the effective construction of segmented fracturing of oil and gas wells. Therefore, the casing temporary sealing tool is a necessary tool for realizing multi-stage segmented fracturing. After the fracturing construction is completed, the temporary sealing tool body can be completely dissolved by relying on the wellbore temperature and mineralization liquid environment, ensuring that the wellbore quickly resumes full-bore production. It has been widely used at home and abroad.

[0003] For example, Chinese patent: CN112576231B discloses an all-metal soluble fracturing segmenter, the anchoring system of which is to set a continuous concave and convex wave shape on the outer wall of the integral slip and make the slip by spraying, surfacing, particle bonding, etc. Other common slip components are structures in which cemented carbide and polymer ceramic-supported anchor teeth are embedded in the outer circle of the slip. When the downhole sealing tool applies axial force, the high-strength anchor teeth bite into the inner wall of the casing during the outward expansion of the slip, realizing the anchoring of the temporary plugging tool, and the sealing component is squeezed and expanded to deform and close to the casing wall and locked, thereby realizing the sealing of the downhole casing and interlayer isolation.

[0004] However, due to the complex working conditions in the downhole casing or casing deformation, it is easy to cause inconsistent expansion of the various petals of the slips, uneven anchoring, or inconsistent or insufficient depth of the slips' anchor teeth biting into the casing. During the construction process, the temporary sealing tool is prone to slippage and movement after setting, causing failure of setting and thus affecting the fracturing construction. At the same time, the anchor teeth cannot dissolve underground, and a large number of anchor teeth are embedded in the casing arms or accumulated in the casing, which increases the complexity and risks of subsequent construction and return flow; and when the anchor teeth bite into the inner wall of the casing to a certain depth, it will cause local damage to the inner wall of the casing, reduce the strength, and increase the risk of casing deformation.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a casing temporary sealing tool and a temporary sealing method. The structure of the present invention can achieve sealing of the casing through the cooperation of a sealing structure, a push block, a clamping arm structure and other structures; two-time positioning and sealing are achieved through the push block and the clamping arm structure, thereby avoiding slippage and movement of the temporary sealing tool and having a better sealing effect.

[0007] The present invention includes the following technical solutions:

[0008] A first aspect of the present invention provides a casing temporary sealing tool for plugging inside a casing string, the temporary sealing tool comprising: a tool mandrel, a center shaft, a sealing structure, a push block, a locking rod, a connecting shaft, a clamping arm structure, a hand-release joint and a gap-free ring;

[0009] A release joint is provided at the end of the tool spindle; extending from the release joint end to the end away from the release joint end, the connecting shaft, the locking rod and the central shaft are sequentially provided outside the tool spindle; the release joint limits one end of the connecting shaft, the other end of the connecting shaft cooperates with one end of the locking rod, and a boss that cooperates with the push block is provided on the connecting shaft, and the other end of the locking rod cooperates with the central shaft;

[0010] A sealing structure, a gapless ring and a push block are arranged outside the central shaft and / or the locking rod and matched in sequence;

[0011] The inner surfaces of the sealing structure, the gapless ring and the push block are set to be inner cones, and the outer surface of the central shaft is set to be outer cones; and the tapers of the inner cone and the outer cone are consistent;

[0012] The central shaft is pushed, the outer cone and the inner cone move relative to each other, the central shaft squeezes the sealing structure, the gapless ring and the push block to expand, the sawtooth protrusion on the outer surface of the push block forms a first-level positioning with the casing string, and the sealing structure forms a seal with the casing string;

[0013] The clamping arm structure is arranged on the outer surface of the connecting shaft, and the clamping arm structure and the casing column are further arranged, and the clamping arm structure includes a first clamping arm, a second clamping arm, a sliding ring, a tail ring, a compression spring, a first anti-loosening ring and a second anti-loosening ring, the tail ring is connected to the connecting shaft through the first anti-loosening ring, and the sliding ring is connected to the connecting shaft through the second anti-loosening ring; one end of the tail ring is clamped with the release joint, and there is a movable space between the connecting shaft and the release joint, the other end of the tail ring cooperates with one end of the sliding ring, the other end of the sliding ring is rotatably connected to one end of the first clamping arm, the other end of the first clamping arm is connected to one end of the second clamping arm, and the other end of the second clamping arm is rotatably connected to the boss; the compression spring is arranged between the tail ring and the sliding ring.

[0014] Further, the external serrated thread of the first anti-loosening ring cooperates with the internal serrated thread of the tail ring, and the internal serrated thread of the first anti-loosening ring cooperates with the serrated thread of the connecting shaft; and / or the external serrated thread of the second anti-loosening ring cooperates with the internal serrated thread of the sliding ring, and the internal serrated thread of the second anti-loosening ring cooperates with the serrated thread of the connecting shaft.

[0015] Furthermore, the sealing structure comprises a protective ring and a rubber ring which are arranged in sequence, the push block cooperates with the gapless ring, the gapless ring cooperates with the rubber ring, and the rubber ring cooperates with the protective ring.

[0016] Furthermore, the gapless annulus includes a plurality of Z-shaped arc segments, and the plurality of Z-shaped arc segments are overlapped and connected with each other.

[0017] Furthermore, the protective ring and the rubber ring are matched by means of an inclined surface, and the inclination direction of the inclined surface is the same as the inclination direction of the outer surface of the central axis; the rubber ring is matched by means of chamfering.

[0018] Furthermore, the rubber ring is made of soluble rubber pressed together, and the central shaft, sealing structure, push block, locking rod, connecting shaft, clamp arm structure, release joint and gapless ring are all made of soluble metal.

[0019] Furthermore, the push block includes a fastening ring and a plurality of fastening blocks, the plurality of fastening blocks are arranged around the outside of the locking rod, and the plurality of fastening blocks are fixed into a circular ring shape by the fastening ring.

[0020] A second aspect of the present invention provides a casing temporary sealing method, comprising the temporary sealing tool described above, the temporary sealing method comprising:

[0021] The temporary sealing tool is lowered into the casing string and located in the upper casing above the groove through the movable sleeve and the tool mandrel;

[0022] Keep the tool mandrel stationary, push the movable sleeve downward, the central shaft slides downward under the action of the movable sleeve, the sealing structure and the gapless ring gradually deform under the joint action of the push block and the central shaft to abut against the inner wall of the sleeve for sealing, and the sawtooth protrusion on the outer surface of the push block under the action of the central shaft forms the first-level positioning with the sleeve;

[0023] Continue to push the movable sleeve until the arm structure sticks to the inner wall of the casing string; continue to push the movable sleeve, the release thread is sheared, the movable sleeve and the tool mandrel are separated from the temporary sealing tool under the drive of the downhole tool, and the release joint is separated from the temporary sealing tool at the same time;

[0024] A pressure ball is dropped and cooperates with the central axis. When the upper pressure of the temporary sealing tool is greater than the lower pressure, the temporary sealing tool will gradually slide downward due to not being fully positioned until it slides to the groove of the casing string. The clamping arm structure abuts against the groove of the casing string to form a second-level positioning.

[0025] Furthermore, the method further comprises the step of releasing the seal and positioning of the temporary sealing tool: after the fracturing operation is completed, the temporary sealing tool dissolves itself under specific temperature and mineralization conditions underground to release the seal and positioning, and restore the diameter of the casing string.

[0026] By adopting the above technical solution, the present invention has the following advantages:

[0027] 1. The structure of the present invention can achieve sealing of the casing through the cooperation of the sealing structure, the push block, the clamp arm structure and other structures; the push block and the clamp arm structure are used to achieve double positioning and sealing, thereby avoiding the slippage and movement of the temporary sealing tool and having a better sealing effect.

[0028] 2. The present invention has the effect of separating the sealing and positioning. The connecting shaft on the sealing side pushes the push block, which further pushes the gapless ring, the rubber ring and the protective ring to move forward along the conical surface of the central axis and expand outward. When the protective ring stops moving forward, the rubber ring further expands outward under the support of the protective ring, fully filling the gap between the central axis and the inner wall of the casing, and bearing a certain pressure. Since the locking rod connects the connecting shaft and the central axis together, the position of the push block relative to the rubber ring is locked, so that a seal is formed. A serrated protrusion is provided on the outer circle of the push block, which forms a certain friction force with the inner wall of the casing after sealing, achieving the effect of preliminary sealing positioning (first positioning). Pins are installed between the hanging arm on the positioning side and the connecting shaft and the sliding ring to ensure that the temporary sealing tool implements the sealing and fracturing process as planned; a second anti-loosening ring is installed between the sliding ring and the connecting shaft to prevent the sliding ring from driving the right hanging arm to move in the opposite direction, thereby ensuring secure positioning; when the temporary sealing tool is subjected to upper pressure and moves downward to the position of the casing coupling, it can always maintain a sealed state, and can quickly achieve hanging positioning (second positioning) after reaching the concave space.

[0029] 3. The present invention adopts the functions of compression rebound of the compression spring and reverse locking of the serrated thread of the anti-loosening ring, etc., and adds the positioning of the clamping arm on the basis of the initial sealing positioning, so as to achieve the effects of stable sealing, reliable pressure bearing, convenient hanging and positioning during the fracturing process of the temporary sealing tool, and ensure the smooth progress of the construction process.

[0030] 4. The present invention adopts the coordination of the clamp arm structure and the concave space on the casing column to realize the hanging and positioning of the temporary sealing tool, effectively avoiding the problem of slippage and anchoring failure of the temporary sealing tool caused by the unreliable anchoring of the conventional temporary sealing tool slip anchoring teeth.

[0031] 5. The temporary sealing tool of the present invention leaves no residue after dissolution, and no continuous tubing drilling and plugging are required after fracturing construction, which can effectively solve the problem of staged fracturing transformation of ultra-long horizontal wells and complex well conditions. Differentiated designs with matching specifications, sizes and performance indicators can be made for different casing and wellbore conditions, and the sealing pressure and dissolution time can be controlled to ensure the implementation of operations under different conditions, thereby forming a set of dedicated design methods and operation processes.

[0032] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a structural schematic diagram of a casing temporary sealing tool in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the initial state structure of the gapless ring in an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the structure after the gapless ring is expanded in an embodiment of the present invention;

[0037] Figure 4 It is a schematic diagram of the structure of a casing temporary sealing tool after sealing and first positioning in an embodiment of the present invention;

[0038] Figure 5 It is a schematic diagram of the structure of a casing temporary sealing tool after sealing and setting in an embodiment of the present invention;

[0039] In the figure: 10-tool mandrel, 20-center axis, 30-sealing structure, 31-protection ring, 32-rubber ring, 321-deformation space, 40-gapless ring, 50-push block, 51-fastening ring, 52-fastening block, 60-locking rod, 70-connecting shaft, 71-boss, 80-clamp arm structure, 81-first clamp arm, 82-second clamp arm, 83-slip ring, 84-tail ring, 85-compression spring, 86-first anti-loosening ring, 87-second anti-loosening ring, 90-hand-release joint, 100-casing column, 101-groove, 110-movable sleeve, 120-pressure ball. DETAILED DESCRIPTION

[0040] The following description provides many different embodiments or examples for implementing different features of the present invention. The components and arrangements described in the following specific examples are only used to simplify the present invention and are only used as examples, not to limit the present invention.

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] This embodiment provides a casing temporary sealing tool for sealing the inside of a casing string 100. Figure 1 As shown, the temporary sealing tool comprises: a tool mandrel 10, a central shaft 20, a sealing structure 30, a push block 50, a locking rod 60, a connecting shaft 70, a clamping arm structure 80, a hand release joint 90 and a gap-free ring 40;

[0043] A release joint 90 is provided at the end of the tool spindle 10; extending from the end of the release joint 90 to the end away from the release joint 90, the connecting shaft 70, the locking rod 60 and the central shaft 20 are sequentially provided outside the tool spindle 10; the release joint 90 limits one end of the connecting shaft 70, the other end of the connecting shaft 70 cooperates with one end of the locking rod 60, and the connecting shaft 70 is provided with a boss 71 that cooperates with the push block 50, the other end of the locking rod 60 cooperates with one end of the central shaft 20, one end of the central shaft 20 cooperates with one end of the locking rod 60, and the other end of the locking rod 60 cooperates with the connecting shaft 70;

[0044] A sealing structure 30, a gapless ring 40 and a push block 50 are arranged outside the central shaft 20 and / or the locking rod 60, and they cooperate in sequence. In the initial state of the temporary sealing tool, the positions of the sealing structure 30, the gapless ring 40 and the push block 50 are not limited. It is only necessary to ensure that after the central shaft 20 is pushed, the sealing structure 30, the sealing ring and the push block 50 can cooperate with the central shaft 20 to achieve sealing and positioning.

[0045] The inner surfaces of the sealing structure 30, the gapless ring 40 and the push block 50 are set to an inner cone, and the outer surface of the central shaft 20 is set to an outer cone; and the tapers of the inner cone and the outer cone are consistent; this can make the sealing structure 30, the gapless ring 40 and the push block 50 fit more closely with the central shaft 20, thereby improving the sealing and positioning effects;

[0046] The central shaft 20 is pushed, the outer cone and the inner cone move relative to each other, the central shaft 20 squeezes the sealing structure 30, the gapless ring 40 and the push block 50 to expand, the sawtooth protrusion on the outer surface of the push block 50 forms a first-level positioning with the casing string 100, and the sealing structure 30 forms a seal with the casing string 100;

[0047] The clamping arm structure 80 is disposed on the outer surface of the connecting shaft 70 , and the clamping arm structure 80 cooperates with the groove 101 disposed in the casing string 100 to achieve the second level positioning.

[0048] Among them, Figure 1 As shown, one end of the central shaft 20 is provided with a step for cooperating with the movable sleeve 110 . When the temporary sealing tool of the present invention is used for temporary sealing of the casing string 100 , the movable sleeve 110 is used to drive the central shaft 20 to move.

[0049] The tool mandrel 10 is a solid shaft structure. Figure 1 As shown, the end of the tool mandrel 10 is provided with a connecting thread, and the release joint 90 is provided with a release thread, and the tool mandrel 10 is connected to the release joint 90 by a connecting bolt. The size of the release pressure is determined by the diameter of the connecting thread and the number of turns of the matching buckle.

[0050] The release joint 90 is also an annular structure, with a release thread in the center and a step hole on the right side. Two pin holes are arranged on the circumference of the step hole on the right side. The outer surface of the release joint 90 is a conical structure, which can play a guiding role during the downhole process.

[0051] Preferably, Figure 1 The central shaft 20 is provided with an inner conical surface, and the inner conical surface is used to cooperate with the outer conical surface provided on the working core shaft; the inner conical surface of the central shaft 20 can also cooperate with the pressure ball 120 when the pressure ball 120 is placed; and can better bear the pressure of the pressure ball 120.

[0052] In some embodiments, the clamping arm structure 80 includes a first clamping arm 81, a second clamping arm 82, a sliding ring 83, a tail ring 84, a compression spring 85, a first anti-loosening ring 86 and a second anti-loosening ring 87. The tail ring 84 is connected to the connecting shaft 70 through the first anti-loosening ring 86, and the sliding ring 83 is connected to the connecting shaft 70 through the second anti-loosening ring 87; one end of the tail ring 84 is clamped with the release joint 90, such as the lower end of the tail ring 84 is processed with several first bosses, and the upper end of the release joint 90 is provided with several first grooves connected and matched with the first bosses; and there is a movable space between the connecting shaft 70 and the release joint 90, the other end of the tail ring 84 is matched with one end of the sliding ring 83, the other end of the sliding ring 83 is rotatably connected to one end of the first clamping arm 81, the other end of the first clamping arm 81 is connected to one end of the second clamping arm 82, and the other end of the second clamping arm 82 is rotatably connected to the boss 71; the compression spring 85 is arranged between the tail ring 84 and the sliding ring 83.

[0053] like Figure 1 As shown, the mating surface between the boss 71 on the connecting shaft 70 and the push block 50 is inclined, so that the force of the push block 50 can act more evenly and effectively on the boss 71; Figure 1 The inclination direction of the matching surface is toward the boss 71, which further improves the uniformity and effectiveness of the force.

[0054] The first clamping arm 81 is connected to the sliding ring 83 through a pin shaft and a pin. In the initial state, the first clamping arm 81 and the sliding ring 83 are fixed by the pin. The pin is sheared after being subjected to force, so that the first clamping arm 81 can rotate relative to the sliding ring 83; similarly, the first clamping arm 81 and the second clamping arm 82 are also connected through a pin shaft and a pin, and the second clamping arm 82 and the boss 71 are also connected through a pin shaft and a pin.

[0055] The boss 71 is provided with a second connecting groove for connecting with the second clamping arm 82, and the second connecting groove is provided in plurality, and the plurality of second connecting grooves are evenly arranged on the boss 71 around, and the corresponding second clamping arm 82 and the second clamping arm 82 are also provided in plurality. The sliding ring 83 is also provided with a first connecting groove for connecting with the first clamping arm 81, and the second connecting groove is provided in plurality, and the plurality of second connecting grooves are evenly arranged on the boss 71 around; such a structure enables the first clamping arm 81 and the second clamping arm 82 to evenly act in the groove 101 of the casing column 100 around, and has a better positioning effect.

[0056] The sliding ring 83 is also provided with spring connecting grooves for connecting the compression springs 85. The number of the connecting grooves is determined according to the number of the compression springs 85. The number of the compression springs 85 is set to 4-12 according to their elastic force. The number in this embodiment is 8.

[0057] like Figure 1 As shown, the outer circle right side of the tail ring 84 is a conical surface structure, which plays a guiding role in the process of the temporary sealing tool going down the well; at the same time, the conical surface structure and the conical surface structure of the outer surface of the release joint 90 are smoothly transitioned, which plays a better guiding role; the tail ring 84 is provided with an inner step hole on the left side of the tail ring 84, and the sliding ring 83 is provided with an outer step on the right side of the sliding ring 83. The inner step hole cooperates with the outer step, and the inner step hole cooperates with the outer step, which can play a guiding role when the sliding ring 83 moves. The spring connection groove is provided on the outer step.

[0058] like Figure 5 As shown, when the compression spring 85 rebounds, it pushes the sliding ring 83 and the clamping arm (the first clamping arm 81 and the second clamping arm 82) to move until they are hooked in the groove 101, and the sliding ring 83 itself must slide axially in the stepped hole of the tail ring 84 without being separated. Such a structure makes the positioning of the first clamping arm 81 and the second clamping arm 82 more stable and has a better positioning effect.

[0059] Specifically, in the initial state, the first clamping arm 81 and the second clamping arm 82 are in contact with the inner wall of the casing after being expanded. When the temporary sealing tool moves downward, the first clamping arm 81 and the second clamping arm 82 are instantly clamped into the groove 101 of the casing column 100 by the force generated by the rebound of the compression spring 85. This process requires the sliding ring 83 to have an axial stroke.

[0060] 1. The compression amount of the compression spring 85 must be greater than the axial stroke of the sliding ring 83 to ensure that the first clamping arm 81 and the second clamping arm 82 can be pushed into place. There is a rebound length of the compression spring 85.

[0061] 2. The depth of the left step hole of the tail ring 84 should be greater than the rebound length of the compression spring 85, that is, when the compression spring 85 rebounds, the sliding ring 83 cannot be separated from the step hole of the tail ring 84, so as to avoid the tail ring 84 from losing its limiting and guiding function on the sliding ring 83; at the same time, the positioning effect of the first clamping arm 81 and the second clamping arm 82 is improved.

[0062] In some embodiments, the external serrated thread of the first anti-loosening ring 86 cooperates with the internal serrated thread of the tail ring 84, and the internal serrated thread of the first anti-loosening ring 86 cooperates with the serrated thread of the connecting shaft 70; and / or the external serrated thread of the second anti-loosening ring 87 cooperates with the internal serrated thread of the sliding ring 83, and the internal serrated thread of the second anti-loosening ring 87 cooperates with the serrated thread of the connecting shaft 70.

[0063] Preferably, the outer serrated thread pitch of the first anti-loosening ring 86 is greater than the inner serrated thread pitch; the outer serrated thread pitch of the second anti-loosening ring 87 is greater than the inner serrated thread pitch; this is more conducive to the shearing of the pin connecting the first clamping arm 81 and the second clamping arm 82, the pin connecting the first clamping arm 81 and the sliding ring 83, and the pin connecting the second clamping arm 82 and the boss 71, which has the advantage of improving the positioning efficiency.

[0064] Preferably, the first anti-loosening ring 86 and the second anti-loosening ring 87 are annular structures with notches, and have a certain elastic deformation of contraction / expansion, and have a certain elastic deformation capacity of contraction / expansion, ensuring that they can self-lock after sliding on the outer circle of the connecting shaft 70; thereby locking the sliding ring 83 and the tail ring 84 in the position of the connecting shaft 70 to prevent rebound.

[0065] In some embodiments, the sealing structure 30 includes a protective ring 31, a rubber ring 32 and a gapless ring 40 which are arranged in sequence, the push block 50 cooperates with the gapless ring 40, the gapless ring 40 cooperates with the rubber ring 32, and the rubber ring 32 cooperates with the protective ring 31.

[0066] like Figure 1 As shown, the cross section of the protection ring 31 is a triangular structure, which can ensure that the rubber ring 32 is always supported by the protection ring 31 when it is pushed upward and extended; the height of the protection ring 31 is higher than the distance between the central axis 20 and the sleeve when the rubber ring 32 reaches the maximum position (that is, when the protection ring 31 is deformed to the limit position), as shown in FIG. Figure 4 , Figure 5 As shown, it can be supported at the front end of the rubber ring 32, and in addition to ensuring the effective deformation of the rubber ring 32, it can also withstand the pressure from the upper end.

[0067] like Figure 1 As shown, the front end of the gapless ring 40 cooperates with the chamfer of the rubber ring 32 to support the rubber ring 32. The rear end of the gapless ring 40 is a step hole, which cooperates with the step at the front end of the push block 50 to tighten the push block 50 so that the push block 50 forms a whole.

[0068] In some embodiments, Figure 2 As shown, it is a schematic diagram of the structure of the gapless ring 40 in the initial state, wherein the gapless ring 40 comprises a plurality of Z-shaped arc segments, and the plurality of Z-shaped arc segments overlap and connect with each other; Figure 3 As shown, it is a schematic diagram of the structure of the setting after the gapless ring 40 is expanded. The overlapping length between the two gapless blocks needs to be greater than the gap between the push blocks 50 after setting, so as to achieve sufficient pressure support during the expansion of the rubber ring 32.

[0069] In some embodiments, the protective ring 31 and the rubber ring 32 are matched by an inclined surface, and the inclined direction of the inclined surface is the same as the inclined direction of the outer surface of the central shaft 20; the rubber ring 32 is matched by chamfering.

[0070] In some embodiments, the rubber ring 32 is made of soluble rubber pressed into a rubber, which can be extended outwards and finally filled between the central shaft 20 and the casing string 100 to form a seal during the setting process. The soluble rubber can be completely dissolved in a solution at a certain temperature. The central shaft 20, the sealing structure 30, the push block 50, the locking rod 60, the connecting shaft 70, the clamping arm structure 80, the release joint 90 and the gapless ring 40 are all made of soluble metal; the soluble metal can be completely dissolved in a solution at a certain temperature; the soluble metal can be a soluble magnesium alloy, a soluble aluminum alloy, etc.

[0071] The tool spindle 10 and the movable sleeve 110 are made of alloy steel, and the compression spring 85 is an existing product and can be directly purchased and used.

[0072] like Figure 1 As shown, the front and rear ends of the rubber ring 32 are both provided with chamfers, and a deformation space 321 is provided in the middle; the chamfer can not only be used to cooperate with the gapless ring 40, but also provide a margin for deformation; the chamfer and the deformation space 321 cooperate to enable the rubber ring 32 to better deform and fit the inner wall of the casing column 100.

[0073] In some embodiments, the push block 50 includes a fastening ring 51 and a plurality of fastening blocks 52 . The plurality of fastening blocks 52 are disposed around the locking rod 60 . The plurality of fastening blocks 52 are fixed into a circular ring shape by the fastening ring 51 .

[0074] like Figure 1 As shown, the front end of the push block 50 has a step for cooperating with the gapless ring 40; a serrated structure is provided on the outer circle, the serration size of the serrated structure is slightly higher than the maximum outer circle, an annular groove is provided at the middle rear end of the outer circle, and a fastening ring 51 is arranged in the annular groove; the front end of the inner hole is a conical structure, and the rear end of the cone is serrated.

[0075] In some embodiments, the outer sawtooth thread of the locking rod 60 cooperates with the inner sawtooth thread of the inner hole of the central shaft 20. Preferably, the locking rod 60 is an annular structure with a notch, and the notch width (arc length) should be no less than 5% of the circumference of the outer sawtooth segment.

[0076] This embodiment further provides a casing temporary sealing method, including the temporary sealing tool described above, and the temporary sealing method includes:

[0077] The temporary sealing tool is lowered into the casing string 100 and into the upper casing above the groove 101 through the movable sleeve 110 and the tool mandrel 10;

[0078] Keep the tool mandrel 10 stationary, push the movable sleeve 110 downward, the central shaft 20 slides downward under the action of the movable sleeve 110, the sealing structure 30 and the gapless ring 40 gradually deform to abut against the inner wall of the sleeve under the joint action of the push block 50 and the central shaft 20, and the sawtooth protrusion on the outer surface of the push block 50 forms the first-level positioning with the sleeve under the action of the central shaft 20;

[0079] Continue to push the movable sleeve 110 until the arm structure 80 is attached to the inner wall of the casing string 100; continue to push the movable sleeve 110, the release thread is sheared, and the movable sleeve 110 and the tool mandrel 10 are separated from the temporary sealing tool under the drive of the downhole tool, and the release joint 90 is separated from the temporary sealing tool;

[0080] The pressure ball 120 is put in and cooperates with the central shaft 20. When the upper pressure of the temporary sealing tool is greater than the lower pressure, the temporary sealing tool will gradually slide downward because it is not fully positioned. Until it slides to the groove 101 of the casing string 100, the clamping arm structure 80 abuts against the groove 101 of the casing string 100 to form a second-level positioning.

[0081] In some embodiments, the temporary sealing method includes:

[0082] The temporary sealing tool is lowered into the casing string 100 and into the upper casing above the groove 101 through the movable sleeve 110 and the tool mandrel 10;

[0083] like Figure 1 As shown, the tool mandrel 10 is kept stationary, and the movable sleeve 110 is pushed downward. The central shaft 20 slides downward under the action of the movable sleeve 110. The sealing structure 30 and the gapless ring 40 are gradually deformed to abut against the inner wall of the sleeve under the joint action of the push block 50 and the central shaft 20 to seal. The sawtooth protrusion on the outer surface of the push block 50 under the action of the central shaft 20 forms the first-level positioning with the sleeve;

[0084] Continue to push the movable sleeve 110, the tail ring 84 moves, the hand-release joint 90 and the tail ring 84 push the second anti-loosening ring 87, and further push the sliding ring 83 to move forward relative to the connecting shaft 70, so that the pin connecting the second clamping arm 82 and the connecting shaft 70 is sheared off, the pin of the first clamping arm 81 and the sliding ring 83 is sheared off, and the first clamping arm 81 and the second clamping arm 82 rotate until the first clamping arm 81 and the second clamping arm 82 are close to the inner wall of the casing string 100 and can no longer rotate. At this time, the compression spring 85 is still in a compressed state; Figure 4As shown, the movable sleeve 110 is continuously pushed. Since the shear force of the release thread of the release joint 90 is less than the thrust of the movable sleeve 110, the release thread is sheared, and the movable sleeve 110 and the tool mandrel 10 are separated from the temporary sealing tool under the drive of the downhole tool; at the same time, the release joint 90 is separated from the temporary sealing tool;

[0085] like Figure 5 As shown, a pressure ball 120 is dropped, and the pressure ball 120 cooperates with the central shaft 20. When the pressure at the upper end of the temporary sealing tool is greater than the pressure at the lower end, the temporary sealing tool will gradually slide downward due to not being fully positioned, until it slides into the groove 101 of the casing string 100; the compression spring 85 pushes the sliding ring 83 under the action of the rebound force and drives the second anti-loosening ring 87 to move forward, while driving the first clamping arm 81 and then the second clamping arm 82 to rotate relative to each other, until the first clamping arm 81 and the second clamping arm 82 abut against the groove 101 of the casing string 100 to form a second-level positioning.

[0086] When the temporary sealing tool continues to move downward, the first clamping arm 81 and the second clamping arm 82 contact the casing, and the downward thrust causes the sliding ring 83 to have a backward movement tendency, and the inner serrated thread of the sliding ring 83 abuts against the outer serrated thread of the second anti-loosening ring 87, and the inner serrated thread of the second anti-loosening ring 87 abuts against the outer serrated thread of the connecting shaft 70. Therefore, the position of the sliding ring 83 is locked and cannot slide backward. Therefore, the hanging clamping arms will not rotate in the opposite direction, and the temporary sealing tool will no longer move downward, thereby achieving the effect of hanging clamping and sealing positioning.

[0087] In some embodiments, the temporary sealing tool further comprises the step of releasing the seal and positioning: after the fracturing operation is completed, the temporary sealing tool dissolves itself under specific temperature and mineralization conditions downhole to release the seal and positioning, and restore the diameter of the casing string 100.

[0088] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0089] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of multiple components or the interaction relationship of multiple components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0090] In the description of the present invention, it should be understood that all terms used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the 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 should not be understood as a limitation on the present invention.

[0091] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A casing temporary sealing tool, used for sealing the inside of a casing string (100), characterized in that: The temporary sealing tool comprises: a tool mandrel (10), a central shaft (20), a sealing structure (30), a push block (50), a locking rod (60), a connecting shaft (70), a clamping arm structure (80), a release joint (90) and a gap-free ring (40); A release joint (90) is provided at the end of the tool spindle (10); extending from the release joint (90) end to the end away from the release joint (90), the connecting shaft (70), the locking rod (60) and the central shaft (20) are sequentially arranged outside the tool spindle (10); the release joint (90) limits one end of the connecting shaft (70), the other end of the connecting shaft (70) cooperates with one end of the locking rod (60), and a boss (71) cooperating with the push block (50) is provided on the connecting shaft (70), and the other end of the locking rod (60) cooperates with the central shaft (20); A sealing structure (30), a gapless ring (40) and a push block (50) are arranged outside the central shaft (20) and / or the locking rod (60) and are matched in sequence; The inner surfaces of the sealing structure (30), the gapless ring (40) and the push block (50) are arranged to be inner cones, and the outer surface of the central shaft (20) is arranged to be outer cones; and the tapers of the inner cone and the outer cone are consistent; The central shaft (20) is pushed, the outer cone and the inner cone move relative to each other, the central shaft (20) squeezes the sealing structure (30), the gapless ring (40) and the push block (50) to expand, the sawtooth protrusion on the outer surface of the push block (50) forms a first-level positioning with the casing string (100), and the sealing structure (30) forms a seal with the casing string (100); The clamping arm structure (80) is disposed on the outer surface of the connecting shaft (70), and the clamping arm structure (80) cooperates with a groove (101) disposed in the casing column (100) to achieve second-level positioning.

2. A casing temporary sealing tool according to claim 1, characterized in that: The clamping arm structure (80) comprises a first clamping arm (81), a second clamping arm (82), a sliding ring (83), a tail ring (84), a compression spring (85), a first anti-loosening ring (86) and a second anti-loosening ring (87); the tail ring (84) is connected to the connecting shaft (70) via the first anti-loosening ring (86), and the sliding ring (83) is connected to the connecting shaft (70) via the second anti-loosening ring (87); one end of the tail ring (84) is clamped with the hand-release joint (90), so that the connecting shaft (70) There is a movable space between the tail ring (84) and the release joint (90), the other end of the tail ring (84) cooperates with one end of the sliding ring (83), the other end of the sliding ring (83) is rotatably connected to one end of the first clamping arm (81), the other end of the first clamping arm (81) is connected to one end of the second clamping arm (82), and the other end of the second clamping arm (82) is rotatably connected to the boss (71); the compression spring (85) is arranged between the tail ring (84) and the sliding ring (83).

3. A casing temporary sealing tool according to claim 2, characterized in that: The external serrated thread of the first anti-loosening ring (86) cooperates with the internal serrated thread of the tail ring (84), and the internal serrated thread of the first anti-loosening ring (86) cooperates with the serrated thread of the connecting shaft (70); and / or the external serrated thread of the second anti-loosening ring (87) cooperates with the internal serrated thread of the sliding ring (83), and the internal serrated thread of the second anti-loosening ring (87) cooperates with the serrated thread of the connecting shaft (70).

4. A casing temporary sealing tool according to claim 1, characterized in that: The sealing structure (30) comprises a protective ring (31) and a rubber ring (32) which are arranged in sequence, the push block (50) cooperates with the gapless ring (40), the gapless ring (40) cooperates with the rubber ring (32), and the rubber ring (32) cooperates with the protective ring (31).

5. A casing temporary sealing tool according to claim 4, characterized in that: The gapless ring (40) sleeve comprises a plurality of Z-shaped arc segments, and the plurality of Z-shaped arc segments are overlapped and connected with each other.

6. A casing temporary sealing tool according to claim 4, characterized in that: The protective ring (31) and the rubber ring (32) are matched via an inclined surface, and the inclination direction of the inclined surface is the same as the inclination direction of the outer surface of the central axis (20); the rubber ring (32) is matched via a chamfer.

7. A casing temporary sealing tool according to claim 6, characterized in that: The rubber ring (32) is made of soluble rubber by pressing, and the central shaft (20), the sealing structure (30), the push block (50), the locking rod (60), the connecting shaft (70), the clamping arm structure (80), the release joint (90) and the gapless ring (40) are all made of soluble metal.

8. A casing temporary sealing tool according to claim 4, characterized in that: The push block (50) comprises a fastening ring (51) and a plurality of fastening blocks (52). The plurality of fastening blocks (52) are arranged around the outside of the locking rod (60). The plurality of fastening blocks (52) are fixed into a circular ring shape by the fastening ring (51).

9. A casing temporary sealing tool according to claim 1, characterized in that: The external sawtooth thread of the locking rod (60) matches the internal sawtooth thread of the inner hole of the central shaft (20).

10. A casing temporary sealing method, characterized in that: The temporary sealing tool according to any one of claims 1 to 9, wherein the temporary sealing method comprises: The temporary sealing tool is lowered into the casing string (100) and into the upper casing above the groove (101) through a movable sleeve (110) and the tool mandrel (10); The tool core shaft (10) is kept stationary, and the movable sleeve (110) is pushed downward, and the central shaft (20) slides downward under the action of the movable sleeve (110), and the sealing structure (30) and the gapless ring (40) are gradually deformed to abut against the inner wall of the sleeve under the joint action of the push block (50) and the central shaft (20) to seal, and the sawtooth protrusion on the outer surface of the push block (50) forms a first-level positioning with the sleeve under the action of the central shaft (20); The movable sleeve (110) is continuously pushed until the clamping arm structure (80) is attached to the inner wall of the casing string (100); the movable sleeve (110) is continuously pushed, the release thread is sheared, and the movable sleeve (110) and the tool mandrel (10) are separated from the temporary sealing tool under the drive of the downhole tool, and the release joint (90) is separated from the temporary sealing tool at the same time; A pressure ball (120) is dropped and matched with the central shaft (20). When the pressure at the upper end of the temporary sealing tool is greater than the pressure at the lower end, the temporary sealing tool will gradually slide downwards due to not being completely positioned until it slides to the groove (101) of the casing string (100). Then, the clamping arm structure (80) abuts against the groove (101) of the casing string (100) to form a second-level positioning.

11. A casing temporary sealing method according to claim 10, characterized in that: The method also includes the step of releasing the seal and positioning of the temporary sealing tool: after the fracturing operation is completed, the temporary sealing tool dissolves itself under specific temperature and mineralization conditions underground to release the seal and positioning, and restore the diameter of the casing string (100).

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