Full-bore fracturing sliding sleeve for directional well

Abstract

The invention relates to the technical field of oil and gas exploitation equipment, and provides a full-bore fracturing sliding sleeve for a directional well, comprising: a fracturing assembly having an outer pipe, an inner pipe and a pipe joint, the inner pipe being connected to the inside of the outer pipe through a pair of pins to block a plurality of kidney-shaped holes formed in the outer pipe, the upper end of the pipe joint being hermetically embedded in the lower end of the outer pipe; the expansion assembly is provided with a bottom support, an expansion piece and an expansion cone, the bottom support is arranged in the inner pipe in a sliding friction mode, the expansion piece is hinged to the upper end of the bottom support, the conical surface of the expansion cone is tightly attached to the expansion piece, and the lower end of the expansion cone is in sliding sealing fit with the inner side wall of the bottom support; the expansion cone can slide downwards relative to the bottom support under the pressure effect of fracturing fluid so that the expansion piece can be expanded outwards, and therefore the inner pipe is driven to shear the pin and then move downwards so that the kidney-shaped hole can be exposed, and the fed fracturing fluid can be fed into a stratum to achieve fracturing operation. Through sliding friction between the bottom support and the inner pipe and sliding sealing between the expansion cone and the bottom support, a gap is reduced, and seepage loss of fracturing fluid is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas production equipment, and in particular to a full-bore fracturing sleeve for a directional well. Background Art

[0002] Conventional oil and gas resources can no longer meet the world economy's rapidly growing demand for energy, so unconventional oil and gas resources with large reserves and concentrated distribution have become the focus of global exploitation. However, unconventional oil and gas resource reservoirs are deeply buried, have low porosity, low permeability, low production capacity, and complex reservoir types, making their exploration and development more difficult. The application of full-bore fracturing sleeves can effectively overcome the above defects and is currently being widely used in the exploitation of unconventional oil and gas resources, and is gradually becoming the dominant exploitation method in this field.

[0003] In directional well fracturing operations, due to the variability of wellbore sizes, traditional ball sleeves can only complete fracturing tasks in a single well section. This limitation requires the replacement of fracturing balls of different sizes in different well sections, which not only reduces operational efficiency but also increases operational costs. Based on this, the improved full-bore fracturing ball sleeve is not affected by changes in wellbore size, and can ensure the reuse of the ball sleeve to achieve continuous staged fracturing operations. However, there is a problem of high fracturing fluid loss in the gaps within the ball sleeve.

[0004] Therefore, a new full-bore fracturing sleeve for directional well production is needed to adapt to wellbores of different sizes and realize continuous staged fracturing operations, while effectively reducing the loss of fracturing fluid, thereby improving operation efficiency and reducing costs. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a full-bore fracturing sleeve for directional wells to solve the problem of high fracturing fluid loss in the gaps within the full-bore fracturing ball sleeve in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A full-bore fracturing sleeve for a directional well, comprising: A fracturing assembly comprises an outer tube, an inner tube and a pipe joint, wherein the upper end of the outer tube is sealedly connected to the upper casing in the directional well, the inner tube is connected to the inner part of the outer tube through a pair of pins to block a plurality of waist holes opened on the outer tube, the upper end of the pipe joint is sealedly embedded in the lower end of the outer tube, and the lower end is sealedly connected to the lower casing in the directional well; and An expansion assembly comprises a base, an expansion sheet and an expansion cone, wherein the base is arranged in the inner tube in a sliding friction manner, the expansion sheet is hinged to the upper end of the base, the conical surface of the expansion cone is closely fitted with the expansion sheet and the lower end thereof is slidingly and sealingly matched with the inner side wall of the base; Wherein, the expansion cone can slide downward relative to the bottom support under the action of the fracturing fluid pressure to make the expansion piece open outward, thereby driving the inner tube to cut off the pin and move downward to expose the waist hole to send the introduced fracturing fluid into the formation to realize the fracturing operation.

[0007] In one embodiment disclosed in the present application, an annular oblique step is provided on the inner side wall of the inner tube to divide the inner tube into a large inner diameter portion and a small inner diameter portion from top to bottom; The bottom bracket has a U-shaped longitudinal section, and its outer side wall is slidably frictionally matched with the inner side wall of the small inner diameter portion, and the outer side wall of the upper part of the bottom bracket is connected to the lower half of a cylindrical hinge in an embedded manner through a first screw; There are multiple expansion pieces evenly distributed around the circumference of the expansion piece, each of which has an overall arc-shaped appearance and a right-angled trapezoidal structure in longitudinal section, and the surface where the right-angled trapezoid is located is connected to the upper half of the cylindrical hinge in an embedded manner through a second screw; The expansion cone is divided into a first cylindrical portion, an inverted truncated cone portion and a second cylindrical portion from bottom to top. The outer wall of the first cylindrical portion is slidably sealed with the inner wall of the base through an expansion cone sealing ring, and the outer wall of the inverted truncated cone portion is tightly fitted with the inclined surface where the hypotenuse of the right-angled trapezoid is located.

[0008] In one embodiment disclosed in the present application, a limit screw is threadedly connected to the middle of the bottom surface of the first cylindrical portion, and the limit screw slides upward from the middle of the outer bottom surface of the base and seals through the base; A return spring is sleeved on the limit screw, and two ends of the return spring are respectively in contact with the middle part of the inner bottom surface of the base and the middle part of the bottom surface of the first cylindrical part.

[0009] In one embodiment disclosed in the present application, the internal area of ​​the base corresponding to the return spring forms a closed cavity due to the presence of the expansion cone sealing ring; A pressure relief hole is provided on the inner side wall of the base, which is used for relieving pressure in the closed cavity when the expansion cone moves downward relative to the base.

[0010] In one embodiment disclosed in the present application, a torsion spring is connected between the upper and lower halves of the cylindrical hinge; The torsion spring is sleeved on the central axis of the cylindrical hinge and is used to reset the expansion piece so that it is in a tightly fitted state with the outer side wall of the inverted truncated table portion when no fracturing operation is performed.

[0011] In one embodiment disclosed in the present application, the upper half of the inverted truncated cone portion and the interior of the second cylindrical portion are hollow, so as to reduce the weight of the expansion cone and reduce the influence of the weight of the expansion cone itself on the movement of the expansion piece; The second cylindrical portion is threadedly connected with an end cover, and the end cover is sealed with the outer side wall of the second cylindrical portion through an end cover sealing ring.

[0012] In one embodiment disclosed in the present application, an annular boss with an inner diameter equal to the inner diameter of the large inner diameter portion of the inner tube is provided at an upper position inside the outer tube, which is used to position the inner tube and ensure that a pin radially passing through the outer tube can be aligned with a radial pin hole reserved on the inner tube.

[0013] In one embodiment disclosed in the present application, two inner tube sealing rings are embedded between the outer side wall of the inner tube and the inner side wall of the outer tube; The two inner tube sealing rings are respectively located at the upper and lower sides of the radial pin hole.

[0014] In one embodiment disclosed in the present application, the upper end of the pipe joint is sealed and matched with the lower end of the outer tube in an embedded manner through a pipe joint sealing ring, and the inner diameter of the pipe joint is equal to the inner diameter of the small inner diameter portion of the inner tube to facilitate the passage of the expansion assembly.

[0015] In one embodiment disclosed in the present application, the fracturing assembly is lowered into the well together with the upper and lower casings, and a fracturing assembly is installed between every two adjacent upper and lower casings to be recorded as one level; Under the action of the fracturing fluid pressure, the expansion assembly passes through the upper casing, the fracturing assemblies of different levels and the lower casing in sequence to achieve full-bore fracturing.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Through the sliding friction between the bottom bracket and the inner tube and the sliding seal between the expansion cone and the bottom bracket, the gap when using the traditional ball-casting sliding sleeve is reduced, the seepage loss of the fracturing fluid is reduced, and the utilization rate of the fracturing fluid is improved.

[0017] 2. The expansion cone and expansion sheet can be reset by the reset spring mounted on the limit screw, so that the expansion assembly can pass through the casing to adapt to the variable diameter wellbore and realize continuous staged fracturing operation.

[0018] 3. The end cover sealing ring can prevent the fracturing fluid from entering the expansion cone; the end cover can ensure the effective pressure action area of ​​the fracturing fluid, so that the expansion piece can open outward.

[0019] 4. The two inner tube sealing rings can effectively prevent the fracturing fluid from entering between the outer wall of the inner tube and the inner wall of the outer tube, thereby reducing the seepage loss of the fracturing fluid.

[0020] 5. The full-diameter expansion assembly can adapt to variable-diameter wellbores and realize continuous staged fracturing operations, which reduces the number of times different-sized fracturing balls need to be replaced due to changes in wellbore size, thereby improving the efficiency of fracturing operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application 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 only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a structural schematic diagram of the expansion cone and the end cover; Figure 3 for Figure 1 A schematic diagram of the enlarged structure of the middle part A; Figure 4 It is a schematic diagram of the structure of the present invention during fracturing operation.

[0023] The following are the descriptions of the reference numerals: 100, fracturing assembly, 110, outer tube, 111, waist hole, 112, annular boss, 120, inner tube, 121, annular oblique step, 122, radial pin hole, 123, inner tube sealing ring, 130, pipe joint, 131, pipe joint sealing ring, 140, pin; 200. Expansion assembly; 210. Bottom support; 211. Limit screw; 212. Return spring; 213. Pressure relief hole; 220. Expansion sheet; 230. Expansion cone; 231. First cylindrical portion; 232. Frustum cone portion; 233. Second cylindrical portion; 234. Expansion cone sealing ring; 240. Cylindrical hinge; 241. First screw; 242. Second screw; 250. End cover; 251. End cover sealing ring. DETAILED DESCRIPTION

[0024] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0025] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0026] In addition, 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention.

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] See also Figure 1 to Figure 4As shown, the present invention provides a full-bore fracturing sleeve for a directional well, comprising: The fracturing assembly 100 comprises an outer tube 110, an inner tube 120 and a pipe joint 130. The upper end of the outer tube 110 is sealedly connected to an upper casing (not shown in the figure) in a directional well. The inner tube 120 is connected to the inner part of the outer tube 110 through a pair of pins 140 to block a plurality of waist holes 111 opened on the outer tube 110. The upper end of the pipe joint 130 is sealedly embedded in the lower end of the outer tube 110, and the lower end is sealedly connected to a lower casing (not shown in the figure) in the directional well. The expansion assembly 200 comprises a base 210, an expansion sheet 220 and an expansion cone 230. The base 210 is arranged in the inner tube 120 in a sliding friction manner. The expansion sheet 220 is hinged to the upper end of the base 210. The conical surface of the expansion cone 230 is closely fitted with the expansion sheet 220 and the lower end thereof is in sliding and sealing cooperation with the inner wall of the base 210. Among them, the expansion cone 230 can slide downward relative to the base 210 under the action of the fracturing fluid pressure to make the expansion sheet 220 open outward, thereby driving the inner tube 120 to cut off the pin 140 and move downward to expose the waist hole 111 to send the introduced fracturing fluid into the formation to achieve fracturing operation.

[0032] See also Figure 2 and Figure 3As shown in the figure, an annular inclined step 121 is provided on the inner side wall of the inner tube 120 to divide the inner tube 120 into a large inner diameter part and a small inner diameter part up and down; the longitudinal section of the bottom support 210 is in a U-shaped structure, and its outer side wall is in sliding friction fit with the inner side wall of the small inner diameter part. The upper outer side wall of the bottom support 210 is connected to the lower half of a cylindrical hinge 240 in an embedded manner through a first screw 241; a plurality of expansion pieces 220 are evenly distributed in the circumferential direction. The overall appearance of each expansion piece 220 is arc-shaped and its longitudinal section is in a right trapezoidal structure. The surface where the height of the right trapezoid is located (i.e., the outer side of the expansion piece 220) is connected to the upper half of the cylindrical hinge 240 in an embedded manner through a second screw 242; the expansion cone 230 is divided into a first cylindrical part 231, a frustum part 232 and a second cylindrical part 233 from bottom to top. The outer side wall of the first cylindrical part 231 is in sliding and sealing fit with the inner side wall of the bottom support 210 through an expansion cone sealing ring 234. The outer side wall of the frustum part 232 (i.e., the conical surface of the expansion cone 230) is closely attached to the inclined surface where the hypotenuse of the right trapezoid is located (i.e., the inner side of the expansion piece 220). Due to the sliding friction between the outer side wall of the bottom support 210 and the inner side wall of the small inner diameter part of the inner tube 120, the first cylindrical part 231 of the expansion cone 230 will slide up and down in the bottom support 210 before the whole expansion assembly 200 moves down, which can make the expansion piece 220 rotate around the cylindrical hinge 240, so as to realize the inward closing or outward opening of the expansion piece 220; during the fracturing operation, the expansion assembly 200 moves down as a whole under the action of the continuously increasing fracturing fluid pressure. The outer side of the outward-opening expansion piece 220 is placed on the annular inclined step 121 to press down the inner tube 120, so as to apply a gradually increasing shearing force to the pin 140 until the pin 140 is cut off. The inner tube 120 moves down following the expansion assembly 200 to expose the waist hole 111 that it blocked before. At this time, the injected fracturing fluid enters the formation through the waist hole 111 to realize the fracturing operation.

[0033] Due to the sliding friction fit, the gap between the outer side wall of the bottom support 210 and the inner side wall of the small inner diameter part of the inner tube 120 is small, and the seepage loss of the fracturing fluid is small; due to the existence of the expansion cone sealing ring 234 between the expansion cone 230 and the bottom support 210, it is very difficult for the fracturing fluid to penetrate into the bottom support 210; before the fracturing operation, the expansion piece 220 is closely attached to the conical surface of the expansion cone 230, which can reduce the seepage loss of the fracturing fluid; during the fracturing operation, the expansion piece 220 opens, the expansion cone 230 moves down relative to the bottom support 210, and the expansion cone sealing ring 234 can make up for the gap caused by the sliding between the two, further reducing the seepage loss of the fracturing fluid. That is to say, through the sliding friction between the bottom support 210 and the inner tube 120 and the sliding seal between the expansion cone 230 and the bottom support 210, the gap when using the traditional ball-drop sliding sleeve is reduced, the seepage loss of the fracturing fluid is reduced, and the utilization rate of the fracturing fluid is improved.

[0034] See Figure 1 and Figure 4As shown, the middle part of the bottom surface of the first cylindrical part 231 is threadedly connected with a limit screw 211, and the limit screw 211 slides upward from the middle part of the outer bottom surface of the bottom bracket 210 to seal and penetrate the bottom bracket 210; a reset spring 212 is mounted on the limit screw 211, and the two ends of the reset spring 212 are respectively in contact with the middle part of the inner bottom surface of the bottom bracket 210 and the middle part of the bottom surface of the first cylindrical part 231. The rigidity of the reset spring 212 is sufficient to hold up the expansion cone 230, and the first cylindrical part 231 with a suitable height is selected, and the contact between the inverted truncated cone part 232 and the upper edge of the bottom bracket 210 can limit the downward sliding distance of the expansion cone 230 relative to the bottom bracket 210, so as to prevent the reset spring 212 from being crushed and ineffective by the expansion cone 230 subjected to excessive fracturing fluid pressure during the fracturing operation. During the fracturing operation, the first cylindrical portion 231 slides downward in the bottom bracket 210, the reset spring 212 is compressed, and at the same time, the inverted truncated terrace portion 232 is driven to make the expansion piece 220 open outward; when the fracturing operation stops, the reset spring 212 is reset, and the first cylindrical portion 231 is lifted upward, so that the expansion cone 230 returns to the initial position, and the expansion piece 220 is pushed inward by the reverse push of the inner wall of the small inner diameter portion of the inner tube 120 when the bottom bracket 210 moves downward, so as to be tightly fitted with the outer wall of the inverted truncated terrace portion 232 again. That is to say, the expansion cone 230 and the expansion piece 220 can be reset by the reset spring 212 mounted on the limit screw 211, so that the expansion assembly 200 can be adapted to the variable diameter wellbore by lowering the casing, and realize the continuous staged fracturing operation.

[0035] The inner area of ​​the base 210 corresponding to the reset spring 212 forms a closed cavity due to the presence of the expansion cone sealing ring 234; the inner wall of the base 210 is provided with a pressure relief hole 213, which is used to relieve the pressure of the closed cavity when the expansion cone 230 moves downward relative to the base 210. When the expansion cone 230 moves downward relative to the base 210, the closed cavity is compressed and pressure accumulates. The accumulated pressure can be released in time through the pressure relief hole 213, which can avoid the closed cavity from being damaged due to the pressure when the space is reduced.

[0036] In order to achieve automatic resetting of the expansion piece 220, a torsion spring (not shown in the figure) is connected between the upper and lower parts of the cylindrical hinge 240. The torsion spring is mounted on the central axis of the cylindrical hinge 240 and is used to reset the expansion piece 220 so that it is in close contact with the outer wall of the inverted frustum 232 when no fracturing operation is performed.

[0037] See also Figure 2As shown, the upper half of the inverted truncated cone 232 and the interior of the second cylindrical portion 233 are hollow, which is used to reduce the weight of the expansion cone 230 to reduce the influence of the weight of the expansion cone 230 itself on the movement of the expansion sheet 220 (i.e., opening outward or closing inward); the second cylindrical portion 233 is threadedly connected with an end cap 250, and the end cap 250 and the outer side wall of the second cylindrical portion 233 are sealed by an end cap sealing ring 251. The end cap sealing ring 251 can prevent the fracturing fluid from entering the expansion cone 230; the end cap 250 can ensure the effective pressure action area of ​​the fracturing fluid, so that the expansion sheet 220 can open outward.

[0038] An annular boss 112 having an inner diameter equal to that of the inner diameter of the inner tube 120 is provided at the upper position inside the outer tube 110, and is used to position the inner tube 120 to ensure that the pin 140 passing through the outer tube 110 in the radial direction can be aligned with the radial pin hole 122 reserved on the inner tube 120. During assembly, the lower end of the outer tube 110 is facing upward, and then the inner tube 120 is placed and pressed against the annular boss 112, and finally the pin 140 is inserted so that its tip is inserted into the radial pin hole 122 to complete the installation of the inner tube 120. The annular boss 112 can realize the rapid positioning and precise installation of the outer tube 110.

[0039] In order to further reduce the seepage loss of the fracturing fluid and reduce the degree of wear of the inner tube 120 when it moves downward relative to the outer tube 110, two inner tube sealing rings 123 are embedded between the outer wall of the inner tube 120 and the inner wall of the outer tube 110, and the two inner tube sealing rings 123 are respectively located at the upper and lower sides of the radial pin hole 122. The two inner tube sealing rings 123 can effectively prevent the fracturing fluid from entering between the outer wall of the inner tube 120 and the inner wall of the outer tube 110, thereby reducing the seepage loss of the fracturing fluid.

[0040] The upper end of the pipe joint 130 is sealed and matched with the lower end of the outer tube 110 in an embedded manner through a pipe joint sealing ring 131, and the inner diameter of the pipe joint 130 is equal to the inner diameter of the small inner diameter part of the inner tube 120 to facilitate the passage of the expansion assembly 200.

[0041] The fracturing assembly 100 is lowered into the well together with the upper and lower casings, and a fracturing assembly 100 is installed between every two adjacent upper and lower casings to be recorded as one level; under the pressure of the fracturing fluid, the expansion assembly 200 passes through the upper casing, the fracturing assemblies 100 of different levels and the lower casing in turn to achieve full-bore fracturing (that is, after the expansion piece 220 is automatically reset, the expansion assembly 200 can enter the next level for reuse, effectively reducing the mining cost). The upper casing and the lower casing are only relative to the current level, that is, the upper casing of the current level can be the lower casing of the previous level, and the lower casing of the current level can be the upper casing of the next level.

[0042] In combination with the above, the working principle of the present invention is as follows: 1. During the fracturing operation, after the expansion assembly 200 moves into the interior of the fracturing assembly 100, the fracturing fluid pressure increases, and the fracturing fluid pressure acts on the end cover 250, driving the expansion cone 230 to slide downward relative to the bottom support 210, the return spring 212 is compressed, and the inverted truncated table portion 232 forces the expansion piece 220 to rotate around the cylindrical hinge 240 and open outward after overcoming the torsion force of the torsion spring. At the same time, the expansion assembly 200 after the expansion piece 220 is opened moves downward relative to the fracturing assembly 100, and the annular inclined step 121 presses against the outer side of the opened expansion piece 220 to press the expansion assembly 200. After limiting, the expansion assembly 200 remains stationary relative to the inner tube 120; the fracturing fluid pressure continues to increase, and the downward movement of the expansion assembly 200 relative to the fracturing assembly 100 drives the inner tube 120 to shear the pin 140, and the expansion assembly 200 and the inner tube 120 move downward relative to the outer tube 110 to expose the multiple waist holes 111 previously blocked by the inner tube 120, until the inner tube 120 collides with the pipe joint 130, thereby stopping movement under the limiting effect of the latter; at this time, the fracturing fluid is released, and the fracturing fluid flows out from the multiple waist holes 111 of the outer tube 110 to realize fracturing operations on the formation.

[0043] 2. When performing continuous fracturing operations, it is necessary to continuously increase the fracturing fluid pressure so that the expansion assembly 200 can overcome the friction force and enter the next stage through the lower casing and cut off the pins 140 of the next stage.

[0044] 3. When the fracturing operation is stopped, the pressure of the fracturing fluid is reduced, and the expansion cone 230 slides upward relative to the base 210 under the restoring force of the reset spring 212, and the expansion sheet 220 closes inwardly under the restoring force of the torsion spring and fits tightly together with the outer wall of the frustum 232 again. After the expansion sheet 220 is closed, the expansion assembly 200 continues to move downward relative to the fracturing assembly 100 under the pressure of the fracturing fluid, and enters the next stage through the pipe joint 130 and the lower casing, and finally gradually stops moving under the action of friction resistance.

[0045] To summarize, firstly, the full-bore expansion assembly 200 can adapt to variable-diameter wellbores and realize continuous staged fracturing operations, which reduces the number of times that fracturing balls of different sizes need to be replaced due to changes in wellbore size, thereby improving the efficiency of fracturing operations; secondly, the number of fracturing stages can be increased infinitely to achieve refined transformation of oil and gas reservoirs; thirdly, the full-bore structure provides an unobstructed channel for subsequent well repair operations, simplifies the construction process, and reduces construction complexity and danger.

[0046] The above embodiments are only preferred embodiments of the present invention and are not limitations of the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. A full-bore fracturing sleeve for directional wells, characterized in that: include: A fracturing assembly comprises an outer tube, an inner tube and a pipe joint, wherein the upper end of the outer tube is sealedly connected to the upper casing in the directional well, the inner tube is connected to the inner part of the outer tube through a pair of pins to block a plurality of waist holes opened on the outer tube, the upper end of the pipe joint is sealedly embedded in the lower end of the outer tube, and the lower end is sealedly connected to the lower casing in the directional well; and An expansion assembly comprises a base, an expansion sheet and an expansion cone, wherein the base is arranged in the inner tube in a sliding friction manner, the expansion sheet is hinged to the upper end of the base, the conical surface of the expansion cone is closely fitted with the expansion sheet and the lower end thereof is slidingly and sealingly matched with the inner side wall of the base; Wherein, the expansion cone can slide downward relative to the bottom support under the action of the fracturing fluid pressure to make the expansion piece open outward, thereby driving the inner tube to cut off the pin and move downward to expose the waist hole to send the introduced fracturing fluid into the formation to realize the fracturing operation.

2. The full-bore fracturing sleeve for directional wells according to claim 1, characterized in that: An annular inclined step is provided on the inner side wall of the inner tube to divide the inner tube into a large inner diameter portion and a small inner diameter portion from top to bottom; The bottom bracket has a U-shaped longitudinal section, and its outer side wall is slidably frictionally matched with the inner side wall of the small inner diameter portion, and the outer side wall of the upper part of the bottom bracket is connected to the lower half of a cylindrical hinge in an embedded manner through a first screw; There are multiple expansion pieces evenly distributed around the circumference of the expansion piece, each of which has an overall arc-shaped appearance and a right-angled trapezoidal structure in longitudinal section, and the surface where the right-angled trapezoid is located is connected to the upper half of the cylindrical hinge in an embedded manner through a second screw; The expansion cone is divided into a first cylindrical portion, an inverted truncated cone portion and a second cylindrical portion from bottom to top. The outer wall of the first cylindrical portion is slidably sealed with the inner wall of the base through an expansion cone sealing ring, and the outer wall of the inverted truncated cone portion is tightly fitted with the inclined surface where the hypotenuse of the right-angled trapezoid is located.

3. The full-bore fracturing sleeve for directional well according to claim 2, characterized in that: A limit screw is threadedly connected to the middle of the bottom surface of the first cylindrical portion, and the limit screw slides upward from the middle of the outer bottom surface of the base and seals through the base; A return spring is sleeved on the limit screw, and two ends of the return spring are respectively in contact with the middle part of the inner bottom surface of the base and the middle part of the bottom surface of the first cylindrical part.

4. The full-bore fracturing sleeve for directional wells according to claim 3, characterized in that: The inner area of ​​the base corresponding to the return spring forms a closed cavity due to the presence of the expansion cone sealing ring; A pressure relief hole is provided on the inner side wall of the base, which is used for relieving pressure in the closed cavity when the expansion cone moves downward relative to the base.

5. The full-bore fracturing sleeve for directional wells according to any one of claims 2 to 4, characterized in that: A torsion spring is connected between the upper and lower parts of the cylindrical hinge; The torsion spring is sleeved on the central axis of the cylindrical hinge and is used to reset the expansion piece so that it is in a tightly fitted state with the outer side wall of the inverted truncated table portion when no fracturing operation is performed.

6. The full-bore fracturing sleeve for directional well according to claim 5, characterized in that: The upper half of the inverted truncated cone portion and the interior of the second cylindrical portion are hollow, so as to reduce the weight of the expansion cone and reduce the influence of the weight of the expansion cone itself on the movement of the expansion piece; The second cylindrical portion is threadedly connected with an end cover, and the end cover is sealed with the outer side wall of the second cylindrical portion through an end cover sealing ring.

7. The full-bore fracturing sleeve for directional well according to claim 2, characterized in that: An annular boss having an inner diameter equal to that of the inner tube's large inner diameter portion is provided at the upper position inside the outer tube for positioning the inner tube to ensure that a pin passing radially through the outer tube can be aligned with a radial pin hole reserved on the inner tube.

8. The full-bore fracturing sleeve for directional wells according to claim 7, characterized in that: Two inner tube sealing rings are embedded between the outer side wall of the inner tube and the inner side wall of the outer tube; The two inner tube sealing rings are respectively located at the upper and lower sides of the radial pin hole.

9. The full-bore fracturing sleeve for directional well according to claim 2, characterized in that: The upper end of the pipe joint is sealed and matched with the lower end of the outer tube in an embedded manner through a pipe joint sealing ring, and the inner diameter of the pipe joint is equal to the inner diameter of the small inner diameter portion of the inner tube, so as to facilitate the passage of the expansion component.

10. The full-bore fracturing sleeve for directional well according to claim 1, characterized in that: The fracturing assembly is lowered into the well together with the upper casing and the lower casing, and a fracturing assembly is installed between every two adjacent upper and lower casings to be recorded as one level; Under the action of the fracturing fluid pressure, the expansion assembly passes through the upper casing, the fracturing assemblies of different levels and the lower casing in sequence to achieve full-bore fracturing.

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