Open tool for coiled tubing and full-gauge stepless multi-cluster sliding sleeve

Abstract

The application provides an opening tool for coiled tubing, which comprises a spring plate, a slotted inner cylinder and a swivel joint connected to the upper end of the slotted inner cylinder for connecting the coiled tubing, wherein the spring plate comprises a cylindrical part and a plurality of circumferentially distributed spring plate claws, the slotted inner cylinder is provided with a plurality of axially extending cutting grooves, the spring plate claws are provided with first compression tapered surfaces, the cutting grooves are provided with second compression tapered surfaces, the spring plate claws can freely contract and freely rebound in the cutting grooves under the cooperation of the first compression tapered surfaces and the second compression tapered surfaces, and the first compression tapered surfaces correspond to and are engaged with the second compression tapered surfaces, so that the opening tool can be lowered into the pipe column through the coiled tubing and sequentially open a plurality of stepless multi-cluster sliding sleeves. The application further provides a full-bore stepless multi-cluster sliding sleeve, which comprises a plurality of cluster sliding sleeves sequentially connected in the pipe column, and the opening tool can sequentially open the cluster sliding sleeves.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas well completion and fracturing operations, specifically relating to a tool for opening coiled tubing and a full-bore stepless multi-cluster sliding sleeve. Background Technology

[0002] Multi-stage fracturing, especially horizontal well fracturing, is a key technology for improving oil and gas recovery during the development of unconventional oil and gas reservoirs such as shale gas and tight gas. Increasing the number of fracturing channel clusters during multi-stage fracturing increases the complexity of the formation fracture network, enabling effective communication between these networks. Current technologies for multi-stage, multi-cluster fracturing primarily employ a combination of bridge plug and perforation techniques, which suffers from drawbacks such as numerous operational steps, long construction time, high operating costs, and discontinuous operation. In contrast, conventional multi-stage sliding sleeve packer segmented fracturing technology divides the formation into multiple segments using packers based on the production conditions, then uses ball dropping or specialized opening tools to open the sliding sleeves, enabling layer-by-layer fracturing operations, continuous construction, and simplified procedures.

[0003] Chinese invention patent ZL201210587000.7 discloses a ball-throwing method for opening multiple clusters of sliding sleeves, which can open multiple clusters of sliding sleeves with a single ball throw. However, due to the use of conventional ball-throwing methods, there are grade differences, with the size of the ball increasing from bottom to top. Since the inner diameter of the wellbore is fixed, the number of stages in this method is limited, and it cannot achieve unlimited stages. Moreover, since the inner diameter of the sliding sleeves in different levels gradually decreases, it cannot achieve full-bore operation, thus limiting the maximum pumping efficiency of the surface pumping equipment.

[0004] Chinese invention patent ZL201610037797.1 discloses a new type of sliding sleeve, a sliding sleeve opening tool, and a fracturing tubing string. The sliding sleeve has a full-bore stepless function, but it can only open one sliding sleeve with one opening tool, and cannot open multiple sliding sleeves with one opening tool, which cannot meet the needs of on-site construction for multi-segment and multi-cluster technology.

[0005] Therefore, there is an urgent need for a tool for opening coiled tubing, as well as a multi-cluster fracturing sleeve with full bore and unlimited size. Summary of the Invention

[0006] To address the technical problems described above, this invention aims to provide an opening tool for coiled tubing and a full-bore stepless multi-cluster sliding sleeve. This opening tool for coiled tubing can open multiple stepless multi-cluster sliding sleeves with a single tool. The opening tool is not affected by the diversion effect of already opened sliding sleeves, and there is no need to adjust construction parameters such as pumping flow rate in a timely manner. It is convenient and quick to operate, and the sequential opening of multiple cluster sliding sleeves ensures high construction reliability and avoids the phenomenon of missing clusters.

[0007] Therefore, according to a first aspect of the present invention, a tool for opening coiled tubing is provided, comprising: a spring, the spring including a cylindrical portion and a plurality of circumferentially distributed spring claws; a slotted inner cylinder having a plurality of axially extending slots; and a conversion joint connected to the upper end of the slotted inner cylinder for connecting coiled tubing; wherein the spring claws have a first compression cone surface, the slots have a second compression cone surface, the spring claws are capable of freely retracting and freely rebounding within the slots under the cooperative action of the first compression cone surface and the second compression cone surface, and the first compression cone surface corresponds to and engages with the second compression cone surface, thereby enabling the opening tool to be lowered into the tubing string through the coiled tubing and sequentially open a plurality of stepless multi-cluster sliding sleeves.

[0008] In one embodiment, at least one bearing tooth is provided on the outer wall surface of each of the spring claws, and the bearing tooth is configured as a right-angle tooth or a barbed tooth.

[0009] In one embodiment, the tail end face of the spring claw is configured as a conical surface to form the first compression conical surface, and the tail bottom surface of the groove is configured as a conical surface to form the second compression conical surface. The slotted inner cylinder can move axially relative to the spring, so that the second compression conical surface can act on the first compression conical surface, thereby enabling the spring claw to retract or spring back within the groove.

[0010] In one embodiment, the radial wings of the bearing protrusion are respectively provided with conical bosses to form the first compression conical surface, and the radial wings of each groove are respectively provided with conical surfaces to form the second compression conical surface. The slotted inner cylinder can move axially relative to the spring piece so that the second compression conical surface can act on the first compression conical surface, thereby enabling the spring piece claw to retract or spring back within the groove.

[0011] In one embodiment, at least one guide tooth is provided on the outer wall surface of each of the spring claws, the guide teeth being axially spaced apart at the axial lower end of the bearing protrusion, and the lower end surface of the guide tooth being constructed as an inclined surface.

[0012] In one embodiment, a ball seat is fixedly installed on the inner wall of the cylindrical portion, and a soluble ball is adapted to be installed on the ball seat.

[0013] In one embodiment, an annular mounting groove is provided on the outer wall surface of the slotted inner cylinder, a retaining spring is installed in the mounting groove, and a retaining spring groove is provided on the inner wall surface of the cylindrical portion. The retaining spring can be fitted into the retaining spring groove to form an axial limit on the slotted inner cylinder.

[0014] In one embodiment, a compression spring is provided between the cylindrical portion and the slotted inner cylinder. The cylindrical portion has an inner step with its end face facing upward, and the slotted inner cylinder has an outer step with its end face facing downward. The two ends of the compression spring abut against the inner step and the outer step, respectively.

[0015] According to a second aspect of the present invention, a full-bore stepless multi-cluster sliding sleeve is provided, comprising a plurality of clustered sliding sleeves sequentially connected in series in a tubing string. Each clustered sliding sleeve includes: an outer sleeve having a flow guide hole; an upper connector and a lower connector respectively connected to both ends of the outer sleeve; and an inner sleeve concentrically arranged within the outer sleeve. In a first state, the inner sleeve is fixedly connected to the outer sleeve by a shear pin and blocks the flow guide hole. In a second state, an opening tool, as described above, is lowered into the wellbore through coiled tubing until it enters the matching clustered sliding sleeve. Lifting the opening tool causes the inner sleeve to shear the shear pin, thereby causing the inner sleeve to move upward and open the flow guide hole. The opening tool can sequentially open multiple clustered sliding sleeves.

[0016] In one embodiment, the flow guide orifice is configured as a throttling orifice.

[0017] Compared with the prior art, the advantages of this application are:

[0018] The opening tool for coiled tubing and the full-bore stepless multi-cluster sliding sleeve of the present invention enable one opening tool to open multiple stepless multi-cluster sliding sleeves. This opening tool is unaffected by the diversion effect of already opened sliding sleeves, eliminating the need for timely adjustments to pumping flow rate and other construction parameters. Operation is convenient and quick, and the sequential opening of multiple cluster sliding sleeves ensures high reliability, avoiding cluster loss. Furthermore, the opening tool for coiled tubing of the present invention is unaffected by the diversion effect of already opened sliding sleeves, eliminating the need for timely adjustments to pumping flow rate and other construction parameters. Operation is convenient and quick, and the sequential opening of multiple cluster sliding sleeves ensures high reliability, avoiding cluster loss. By setting multiple cluster sliding sleeves and conventional stepless sliding sleeves on the fracturing string to form a full-bore, infinitely-level multi-cluster fracturing sliding sleeve, the fracturing string can be formed into a full-bore, infinitely-level multi-cluster fracturing sliding sleeve, which can meet the needs of unconventional oil and gas reservoir stimulation. The opening tool, through its multi-cluster opening module, enables clustered and conventional sliding sleeves to operate without altering their original anti-erosion structure. It eliminates the need to add new sliding surfaces for multi-functional operation, preventing erosion of the sliding sleeve tooth groove by fracturing sand and avoiding the potential for the sliding sleeve to fail to open due to fracturing sand blockage. This ensures the continuity of construction for up to dozens of multi-cluster sliding sleeves and greatly improves work efficiency. Attached Figure Description

[0019] The present invention will now be described with reference to the accompanying drawings.

[0020] Figure 1 The structure of an opening tool for coiled tubing according to the present invention is shown.

[0021] Figure 2 The structure of the spring of the opening tool according to Embodiment 1 of the present invention is shown.

[0022] Figure 3 The structure of the slotted inner cylinder of the opening tool according to Embodiment 1 of the present invention is shown.

[0023] Figure 4 The structure of the spring of the opening tool according to Embodiment 2 of the present invention is shown.

[0024] Figure 5 The structure of the slotted inner cylinder of the opening tool according to Embodiment 2 of the present invention is shown.

[0025] Figure 6 The structure of the clustered sleeve in the full-bore stepless multi-clustered sleeve according to the present invention is shown.

[0026] Figure 7 The diagram schematically illustrates the state of the opening tool for coiled tubing according to the invention during the pumping process within the tubing string.

[0027] Figure 8 The diagram below schematically shows the structure where the opening tool reaches the inner sleeve.

[0028] Figure 8a schematically shown Figure 8 The diagram shows the unfolded planar structure of the track groove in the track groove locking mechanism.

[0029] Figures 9 to 10 The illustration schematically shows the process of opening one of the clustered sleeves in a full-bore continuously variable multi-clustered sleeve according to Embodiment 1 of the present invention.

[0030] Figure 11 The process of opening the tool passing through the clustered sliding sleeve according to Embodiment 2 of the present invention is shown.

[0031] Figure 12 The diagram schematically illustrates the connection method of the full-bore stepless multi-cluster sliding sleeve connection in the tubular column according to the present invention.

[0032] Figure 13 The diagram schematically shows the structure of the opening tool according to the invention, which is located within a conventional sliding sleeve after being released.

[0033] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0034] The invention will now be described with reference to the accompanying drawings.

[0035] In this application, it should be noted that the end of the opening tool for coiled tubing according to the present invention that is lowered into the wellbore near the wellhead is defined as the upper end or a similar term, and the end that is farther from the wellhead is defined as the lower end or a similar term.

[0036] Figure 1 The structure of an opening tool 100 for coiled tubing according to the present invention is shown. For example... Figure 1 As shown, the opening tool 100 includes a spring clip 1, a slotted inner cylinder 2, and a conversion connector 3. The spring clip 1 is fitted onto the outside of the slotted inner cylinder 2, and the conversion connector 3 is connected to the upper end of the slotted inner cylinder 2. The conversion connector 3 is used to connect to a continuous tubing. The spring clip 1 is constructed to include a cylindrical portion 11 and multiple circumferentially distributed spring clip claws 12, which are fixedly connected to the upper end face of the cylindrical portion 11. The slotted inner cylinder 2 has multiple axially extending grooves 21 (see...). Figure 3 Multiple grooves 21 are evenly distributed in the circumferential direction. Multiple spring claws 12 are positioned corresponding to the grooves 21. The spring claws 12 are elastic in the radial direction and can retract or spring back within the grooves 21 in the radial direction.

[0037] According to the present invention, the spring claw 12 is provided with a first compression cone surface, and the groove 21 of the slotted inner cylinder 2 is provided with a second compression cone surface. The spring claw 12 can freely retract and freely rebound in the groove 21 under the cooperation of the first compression cone surface and the second compression cone surface. The first compression cone surface and the second compression cone surface correspond to and engage with each other, so that the opening tool 100 can be lowered into the tubing through the continuous oil pipe and open multiple stepless multi-cluster sliding sleeves in sequence.

[0038] According to the present invention, such as Figure 1 and Figure 2 As shown, a bearing protrusion 121 is provided on the outer wall surface of the spring claw 12. Each spring claw 12 has at least one bearing protrusion 121. In one embodiment, the bearing protrusion 121 can be configured as a right-angle protrusion or a barbed protrusion. Each spring claw 12 has at least one guide tooth 13, which is axially spaced at the lower axial end of the bearing protrusion 121. In one embodiment, the lower end face of the guide tooth 13 is configured as a bevel. The guide tooth 13 can guide the opening tool 100 to descend, which helps to improve the descending efficiency of the opening tool 100.

[0039] like Figure 1As shown, a ball seat 4 is fixedly installed on the inner wall of the cylindrical portion 11 of the spring 1, and the ball seat 4 is equipped with a soluble ball 5. The ball seat 4 is fixedly connected to the cylindrical portion 11, for example, by threads. The front end of the cylindrical portion 11 of the spring 1 has a radially inwardly tapered annular protrusion, and the axial inner end face of the annular protrusion is formed into a conical surface, thereby forming the ball seat bearing surface. During assembly, the soluble ball 5 is first inserted into the cylindrical portion 11 of the spring 1, and then the ball seat 4 is screwed in to form a ball cage, with the soluble ball 5 located inside the ball cage.

[0040] A through hole 112 is provided on the side wall region corresponding to the outer axial direction of the ball seat 4 in the cylindrical section 11. When the oil pump is running while the opening tool 100 is being lowered and the pump is circulating, the presence of the through hole 112 helps to stabilize the circulation pressure and avoids interference from the contraction and rebound of the spring. At the same time, it helps to control the circulation displacement and circulation pressure within the design range of the construction parameters, preventing complex downhole problems such as the key being pulled out of the retaining spring lock after pressure buildup, which could cause the opening tool 100 to be unable to descend or the spring to fail and not be able to reset.

[0041] According to the present invention, such as Figure 1 As shown, the opening tool 100 also includes a retaining ring 6. An annular mounting groove 61 is provided on the outer wall of the slotted inner cylinder 2, and the retaining ring 6 is installed in the mounting groove 61. At the same time, a retaining ring groove 62 is provided on the inner wall of the cylindrical portion 11 of the spring piece 1, and the retaining ring 6 can be fitted into the retaining ring groove 62, thereby axially limiting the spring piece 1.

[0042] like Figure 1 As shown, a compression spring 7 is provided between the cylindrical portion 11 of the spring piece 1 and the slotted inner cylinder 2. An inner step 111 with its end face facing upwards is provided on the inner wall surface of the cylindrical portion 11 (see...). Figure 2 Meanwhile, the outer wall of the slotted inner cylinder 2 is provided with an outer step 23 facing downwards. The two ends of the compression spring 7 abut against the inner step 111 and the outer step 23, respectively. The upper and lower side walls of the retaining spring groove 62 are both constructed as conical surfaces. When the spring piece 1 is engaged with the matching sliding sleeve and is in a limited state, the slotted inner cylinder 2 can be operated by pressing down the continuous oil pipe, causing the retaining spring 6 to retract along the conical surface of the retaining spring groove 62, thereby generating relative movement between the spring piece 1 and the slotted inner cylinder 2, and compressing the compression spring 7. In order to prevent the compression spring 7 from falling off, a spring seat 71 is provided at the lower end of the slotted inner cylinder 2. The outer diameter of the spring seat 71 is larger than the inner and outer diameters of the lower end of the slotted inner cylinder 2, and larger than the inner diameter of the compression spring 7.

[0043] In one embodiment, the spring 1 and the ball seat 4 connected therein can be made of stainless steel or a soluble material. Thus, after fracturing operations, the full-bore sliding sleeve (including the cluster sliding sleeve 200 and the ordinary sliding sleeve 300) can still achieve the full bore of the wellbore after the spring 1 is retrieved, which is conducive to the smooth implementation of subsequent drainage and gas production operations of the gas well.

[0044] Of course, the spring 1 and the ball seat 4 connected therein can also be made of soluble material, so that the wellbore can be fully vented without the need for retrieval after fracturing, thus meeting the needs of subsequent construction.

[0045] During assembly, the opening tool 100 for continuous tubing according to the present invention involves first inserting a soluble ball 5 into the spring piece 1, then screwing in a ball seat 4 to form a ball cage. Components such as a retaining ring 6 and a spring 7 are sequentially installed on the slotted inner cylinder 2. The retaining ring 6 is first spread open and embedded into the mounting groove 61 of the slotted inner cylinder 2. The spring 7 is then fitted onto the small-diameter outer circumference surface at the lower end of the slotted inner cylinder 2, and a spring seat 71 is connected to limit its position. A conversion connector 3 is then connected at the upper end of the slotted inner cylinder 2. Afterward, the spring piece 1 and its components are rotated until each spring piece claw 12 corresponds one-to-one with the groove of the slotted inner cylinder 2. The spring piece 1 and its components are then pressed down until the retaining ring 6 is embedded in the retaining ring groove 62 of the cylindrical portion 11 of the spring piece 1. After assembly, the spring piece claw 12 of the spring piece 1 can freely retract and spring back within the groove 21 of the slotted inner cylinder 2.

[0046] The working principle between the spring piece 1 and the slotted inner cylinder 2 is described in detail below according to different embodiments.

[0047] Example 1:

[0048] In Example 1, as Figure 2 and Figure 3 As shown, the tail end face of the spring clip 12 is constructed into a conical surface, thereby forming a first compression conical surface 122. Simultaneously, the tail bottom surface of the groove 21 of the slotted inner cylinder 2 is constructed into a conical surface, thereby forming a second compression conical surface 211. The slotted inner cylinder 2 can move axially relative to the spring clip 1, allowing the second compression conical surface 211 to act on the first compression conical surface 122, thus enabling the spring clip 12 to retract or spring back radially within the groove 21. Specifically, when the slotted inner cylinder 2 moves downward relative to the spring clip 1, the second compression conical surface 211 exerts pressure on the first compression conical surface 122, thereby creating a radially inward pressure on the tail of the spring clip 12, causing the spring clip 12 to retract radially inward. When the slotted inner cylinder 2 moves upward relative to the spring clip 1, the second compression conical surface 211 disengages from the first compression conical surface 122, its force on the first compression conical surface 122 disappears, releasing the constraint on the tail of the spring clip 12, thus allowing the spring clip 12 to spring back.

[0049] Example 2:

[0050] In Example 2, as Figure 4 and Figure 5As shown, conical bosses are provided on the radial sides of the bearing protrusion 121 of the spring piece 1, thereby forming the first compression conical surface 122. Simultaneously, conical surfaces are provided on the radial sides of each groove 21 of the slotted inner cylinder 2, thereby forming the second compression conical surface 211. The slotted inner cylinder 2 can move axially relative to the spring piece 1, so that the second compression conical surface 211 can act on the first compression conical surface 122, thereby causing the spring piece claw 12 to retract or spring back radially within the groove 21. Specifically, when the slotted inner cylinder 2 moves downward relative to the spring piece 1, the second compression conical surface 211 exerts pressure on the first compression conical surface 122, thereby creating a radially inward pressure on the tail of the spring piece claw 12, causing the spring piece claw 12 to retract radially inward. When the slotted inner cylinder 2 moves upward relative to the spring piece 1, the second compression cone surface 211 disengages from the first compression cone surface 122, and the force exerted on the first compression cone surface 122 disappears, releasing the constraint on the tail of the spring piece claw 12, thereby enabling the spring piece claw 12 to rebound.

[0051] According to the present invention, a full-bore stepless multi-cluster sliding sleeve is also provided, the full-bore stepless multi-cluster sliding sleeve comprising a plurality of sleeves sequentially connected in series in a tubular column 400 (see...). Figure 12 The clustered sliding sleeve 200 in ) . For example Figure 6 As shown, each cluster-type sliding sleeve 200 is constructed including an outer sleeve 210, an upper connector 220 and a lower connector 230 respectively connected to both ends of the outer sleeve 210, and an inner sleeve 240 concentrically arranged inside the outer sleeve 210. A guide hole 201 is provided on the outer sleeve 210. Preferably, the guide hole 201 is located near the lower end of the outer sleeve 210, and multiple guide holes 201 are evenly spaced circumferentially. The inner wall surface of the inner sleeve 240 is provided with a switching groove 241, which includes axially spaced bearing grooves and guiding grooves. The bearing grooves and guiding grooves are respectively adapted to the bearing protrusion 121 and guiding tooth 13 of the opening tool 100, thereby enabling the bearing protrusion 121 to engage within the switching groove 241, thus opening the cluster-type sliding sleeve 200.

[0052] In the initial state, the inner sleeve 240 is fixedly connected to the outer sleeve 210 via the shear pin 250, which also blocks the guide hole 201, thereby closing the cluster-type sliding sleeve 200. At this time, the cluster-type sliding sleeve 200 is in the first state. The shear pin 250 is preferably a copper pin.

[0053] During the opening process, the opening tool 100 for coiled tubing according to the present invention is inserted into the wellbore until it enters the matching cluster sleeve 200. The bearing protrusion 121 on the spring piece 1 of the opening tool 100 is adapted to engage with the switching groove 241 of the inner sleeve 240 to form a latch. Then, by lifting the coiled tubing, the opening tool 100 can drive the inner sleeve 240 to shear the shear pin 250, thereby driving the inner sleeve 240 upward, thus opening the guide hole 201 to open the cluster sleeve 200. Furthermore, the inner sleeve 240 is locked by the track groove locking mechanism. At this time, the cluster sleeve 200 is in the second state.

[0054] In one embodiment, such as Figure 8 and Figure 8a As shown, the track groove locking mechanism comprises a track groove 243 disposed on the outer surface of the inner sleeve 240 and a track pin 242 installed in the side wall of the outer sleeve 210, the inner end of the track pin 242 extending into the track groove 243. The track groove 243 includes a straight groove extending axially and an inclined limiting groove formed at the lower end of the straight groove. After the outer sleeve 210 cuts the shearing pin 250, the continuous tubing continues to move upward under the action of inertial force until the force of the track pin 242 acts on the conical surface of the inclined limiting groove of the track groove 243, forcing the inner sleeve 240 to rotate during the upward movement, so that the track pin 242 enters the inclined limiting groove and is limited within the track groove 243. Preferably, there are two track pins 242 and two track grooves 243, which are symmetrically distributed radially.

[0055] Of course, the track groove locking mechanism can also be other locking structures such as C-rings. When a C-ring is used, the inner sleeve 240 can be axially locked by the C-ring mechanism and the spring-loaded locking mechanism on the upper connector.

[0056] To ensure the seal at the joint, such as Figure 6 As shown, a first sealing ring is provided at the connection between the upper connector 220, the lower connector 230 and the outer sleeve 210. In order to ensure the sealing of the guide hole 201, a second sealing ring is provided between the inner sleeve 240 and the outer sleeve 210 at intervals. In the initial state, the guide hole 201 is located between the axial directions of the second sealing ring.

[0057] The opening tool 100 for coiled tubing according to the present invention can sequentially open multiple cluster sleeves 200. In use, the opening tool 100 is matched with the coding of the multiple serially connected cluster sleeves 200 to form a downhole cluster tool. Furthermore, the cluster sleeves 200 are inverted flow channel sleeves, and the flow channels are opened by pulling the inner sleeve 240 upward to eliminate the influence of coiled tubing downward bending, thus making full use of the high tensile strength of the coiled tubing.

[0058] In a preferred embodiment, the guide hole 201 can be configured as a throttling orifice. Here, the orifice diameter of the guide hole 201 does not need to match the pumping displacement, and it will not be affected by the diversion effect of the already opened sliding sleeve after opening several clusters, but its size, quantity, number of clusters, fracturing displacement and other parameters should still be matched.

[0059] The following describes the working process of the opening tool 100 for coiled tubing according to the present invention, taking the opening process of a clustered sliding sleeve 200 opened by the opening tool 100 as an example.

[0060] like Figure 7 As shown, firstly, a continuous tubing is used to connect the opening tool 100 via a conversion joint 3. During the lowering process, under the downward pressure on the guide teeth 13 of the spring piece 1, the spring piece claw 12 of the spring piece 1 freely retracts within the groove 21 of the slotted inner cylinder 2, so that the bearing protrusion 121 is in a concealed state. This facilitates the lowering of the pump-type opening tool 100.

[0061] During the lowering process, when sand or other dirt adheres to the tubing, the pump can be started to circulate the fluid while the opening tool 100 is being inserted. At a certain discharge rate, the fluid flows out from the annular gap at the guide head of the spring 1 at a high flow rate to flush the tubing, ensuring the smooth lowering of the opening tool 100.

[0062] like Figure 8 As shown, when the coiled tubing, carrying the opening tool 100, enters the matching multi-cluster sleeve 200, the opening tool 100 engages with the switching groove 241 of the inner sleeve 240 of the cluster sleeve 200 via the bearing protrusion 121 on the spring claw 12, thus locking the opening tool 100 within the cluster sleeve 200. First, the coiled tubing string is pressed down with a small tonnage to verify that the opening tool 100 is in place. (The text continues with further details about the process.) Figure 9 As shown, when the continuous tubing is lifted, the bidirectional bearing protrusions 121 of the spring piece 1 act on the corresponding switching grooves 241 of the inner sleeve 240 until the shearing pin 250 is cut off, which drives the inner sleeve 240 to move upward to expose the guide hole 201, thereby opening the cluster-type sliding sleeve 100 and locking the inner sleeve 240 through the track groove locking mechanism.

[0063] like Figure 10As shown, in Embodiment 1, after the clustered sliding sleeve 200 is opened and locked, the coiled tubing string is pressed down with a large tonnage. The initial state of the spring piece 12 of the opening tool 100 is limited by the bearing protrusion 121. Under the action of the downward pressure, the slotted inner cylinder 2 of the opening tool 100 pushes the retaining spring 6 to retract along the conical surface of the retaining spring groove 62 and compress the compression spring 7. At the same time, the slotted inner cylinder 2 acts on the first compression conical surface 122 of the tail of the spring piece 12 through the second compression conical surface 211 of the groove tail to retract the spring piece 12 until the bearing protrusion 121 of the spring piece 12 is in the retracted state. This allows the opening tool 100 to pass through this stage of the clustered sliding sleeve 200 and then be lowered into the next stage of multi-clustered sliding sleeve 200 using the coiled tubing. The above action process is repeated to open the next stage of multi-clustered sliding sleeve 200 with the same code. Thus, the same opening tool 100 can open multiple clustered sliding sleeves 200.

[0064] like Figure 11 As shown, in Embodiment 2, after the clustered sliding sleeve 200 is opened and locked, the coiled tubing string is pressed down with a large tonnage. The initial state of the spring piece 12 of the opening tool 100 is limited by the bearing protrusion 121. Under the action of the downward pressure, the slotted inner cylinder 2 of the opening tool 100 pushes the retaining spring 6 to retract along the conical surface of the retaining spring groove 62 and compress the compression spring 7. At the same time, the slotted inner cylinder 2 acts on the first compression conical surface 122 of the radial wings of the bearing protrusion 121 of the spring piece 12 through the second compression conical surface 211 formed on the radial wings of the groove 21, thereby retracting the spring piece 12 until the bearing protrusion 121 of the spring piece 12 is in a concealed state. This allows the opening tool 100 to pass through this stage of the clustered sliding sleeve 200 and then be lowered into the next stage of the multi-cluster sliding sleeve 200 using the coiled tubing. The above action process is repeated to open the next stage of the multi-cluster sliding sleeve 200 with the same code. Thus, the same opening tool 100 can open multiple clustered sliding sleeves 200.

[0065] In one embodiment, when each spring clip 12 has multiple bearing protrusions 121, the opening tool 100 in Embodiment 2 can more quickly retract the spring clip 12. The conical protrusions of the two wings can be positioned near the first bearing protrusion of the guide tooth 13. When a bearing protrusion on the spring clip 1 is in a depressed state, the deflection from that bearing protrusion to the tail of the spring clip gradually increases to its maximum value. Therefore, as long as the first bearing protrusion is retracted, the remaining bearing protrusions are all in a concealed state. This allows for precise control of the spring clip 1's retraction through radial retraction, greatly reducing the axial travel required for the spring clip 1 to retract.

[0066] After the opening tool 100 passes through the clustered sliding sleeve 200, under the action of the rebound force of the compression spring 7, the slotted inner cylinder 2 moves upward relative to the spring piece 1 until the retaining spring 6 is re-embedded in the retaining spring groove 62 of the spring piece 1, and the opening tool 100 is in the reset state.

[0067] In the abnormal situation where the opening tool 100 is blocked inside the completion tubing and cannot pass through, even after the spring piece 1 bends and retracts and the bearing tooth 121 is in the concealed state, the opening tool 100 still cannot pass through. At this time, the shoulder end face of the slotted inner cylinder 2 abuts against the root of the spring piece 1, and the downward pressure of the coiled tubing is transmitted through the shoulder end face. The spring piece 1 is in a limited state, preventing the spring piece 1 from retracting further.

[0068] In actual operation, at least one multi-cluster sleeve 200 is connected in series with a conventional sleeve 300 on the fracturing tubing string 400. The conventional sleeve 300 is positioned after the multi-cluster sleeve 200. When the opening tool 100 is deployed from the wellhead, it passes through the mismatched sleeve and enters the matched multi-cluster sleeve 200, forming a lock. The multi-cluster sleeve 200 is opened by lifting the coiled tubing. Then, by pressing down the coiled tubing, the spring 1 of the opening tool 100 retracts, allowing the opening tool 100 to pass through that stage of the multi-cluster sleeve 200. The opening tool 100 is then lowered into the next stage of multi-cluster sleeve 200 through the coiled tubing, repeating the above process to open multiple multi-cluster sleeves 200 one by one, finally entering the conventional sleeve 300. Thus, the function of opening multiple sleeves with a single pump-type opening tool 100 is achieved. Figure 12 In the embodiment shown, three multi-cluster sliding sleeves 200 are connected in series in the fracturing tubing 400 and then used in conjunction with a conventional sliding sleeve 300.

[0069] like Figure 13 As shown, a conventional sliding sleeve 300 includes an upper connector, an outer cylinder 304, an inner cylinder 302, a shear pin 303, and a lower connector. The outer cylinder 304 is provided with a guide hole 301, which is located near the upper end of the outer cylinder 304. The inner wall surface of the inner cylinder 302 is provided with a switching groove. The difference between the cluster-type sliding sleeve 200 in the full-bore stepless multi-cluster sliding sleeve of the present invention and the conventional sliding sleeve 300 is that the guide hole 201 of the cluster-type sliding sleeve 200 is an inverted structure. The opening tool 200 is connected to a continuous oil pipe above. In order to eliminate the influence of the continuous oil pipe bending under pressure, the cluster-type sliding sleeve 200 with the inverted guide hole 201 is used. During construction, the continuous oil pipe is pulled upward to open the sliding sleeve instead of the conventional method of pressing down to open the sliding sleeve. This keeps the continuous oil pipe in a tensile state at all times, making full use of its high tensile strength characteristics, and ensuring that the cluster-type sliding sleeve 200 can be opened smoothly in sequence.

[0070] After the opening tool 100 sequentially opens multiple clustered sliding sleeves 200, it finally enters the conventional sliding sleeve 300 and forms a clamp within the conventional sliding sleeve 300. Then, the coiled tubing string is first pressed down with a small tonnage to verify that the opening tool 200 is in place. The coiled tubing is then lifted to perform a release operation. The bidirectional bearing protrusion 121 of the spring piece 1 acts on the corresponding switch groove of the inner cylinder 302 to play a limiting role. After the lifting tonnage of the coiled tubing reaches the release tonnage, the slotted inner cylinder 2 drives the retaining ring 6 to retract along the upper conical surface of the retaining ring groove 62 and exit the groove. The coiled tubing drives the slotted inner cylinder 2 and the retaining ring 6, spring 7, spring seat 71 and other components to be lifted out of the wellhead. After the release, the opening tool 100 leaves only the spring piece 1, the soluble ball 5 and the ball seat 4 inside the conventional sliding sleeve 300. Figure 13 The diagram schematically shows the structure of the opening tool 100 according to the invention, which is located within the conventional sliding sleeve 300 after being released.

[0071] After releasing the opening tool 100, fluid is pumped into the tubing, and the flow rate is gradually increased. Under the throttling effect of the multi-cluster sliding sleeve 200, the spring 1, under the pressure of the pressure accumulator, drives the inner cylinder 302 to shear the pin 303, thereby driving the inner cylinder 302 downward, thus opening the guide hole 301 and opening the flow channel of the conventional sliding sleeve 300. At the same time, after squeezing the inner rubber sleeve (not shown) of the sliding sleeve to seal the guide head of the spring 1, the process directly transitions to the normal single-stage multi-cluster fracturing operation.

[0072] According to the present invention, the spring 1 and the ball seat 4 can be made of stainless steel or soluble material. After the fracturing operation is completed, the full diameter of the wellbore can be achieved by retrieving the stainless steel spring 1 and components or by the gradual dissolution of the soluble spring 1 and components in the flowback formation fluid, which is conducive to the smooth implementation of subsequent drainage and gas production operations of the gas well.

[0073] The opening tool 100 for coiled tubing and the downhole tool formed by the full-bore stepless multi-cluster sliding sleeve according to the present invention can realize the function of opening multiple stepless multi-cluster sliding sleeves with one opening tool. This opening tool is not affected by the diversion effect of already opened sliding sleeves, and there is no need to adjust construction parameters such as pumping flow rate in a timely manner. Operation is convenient and quick, and the sequential opening of multiple cluster sliding sleeves has high reliability, avoiding the phenomenon of cluster loss. Furthermore, the opening tool 100 for coiled tubing according to the present invention is not affected by the diversion effect of already opened sliding sleeves, and there is no need to adjust construction parameters such as pumping flow rate in a timely manner. Operation is convenient and quick, and the sequential opening of multiple cluster sliding sleeves has high reliability, avoiding the phenomenon of cluster loss. By setting multiple cluster sliding sleeves 200 and conventional stepless sliding sleeves 300 on the fracturing string 400 to form a full-bore stepless multi-cluster fracturing sliding sleeve, the fracturing string is formed into a full-bore, infinitely graded multi-cluster fracturing sliding sleeve, which can meet the needs of unconventional oil and gas reservoir stimulation. The opening tool 100, through its multi-cluster opening function module, enables the clustered sliding sleeve 200 and the conventional sliding sleeve 300 to operate without altering their original anti-erosion structure. It eliminates the need to add new sliding surfaces for multi-functional operation, preventing erosion of the sliding sleeve tooth groove by fracturing sand and preventing the hidden danger of the sliding sleeve being unable to open due to the obstruction of fracturing sand. This ensures the continuity of construction for up to dozens of multi-cluster sliding sleeves and greatly improves work efficiency.

[0074] In this invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0075] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0076] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tool for opening coiled tubing, comprising: Spring (1), the spring includes a cylindrical part (11) and a plurality of circumferentially distributed spring claws (12). A slotted inner cylinder (2), wherein the slotted inner cylinder is provided with a plurality of axially extending slots (21); and The adapter (3) connected to the upper end of the slotted inner cylinder is used to connect the continuous tubing; The spring claw is provided with a first compression cone surface, and the slot is provided with a second compression cone surface. The spring claw can freely retract and rebound in the slot under the cooperation of the first compression cone surface and the second compression cone surface. The first compression cone surface and the second compression cone surface correspond to and engage with each other, so that the opening tool can be lowered into the tubing through the continuous oil pipe and open multiple stepless multi-cluster sliding sleeves in sequence. At least one bearing protrusion (121) is provided on the outer wall surface of each spring claw. The bearing protrusion is constructed as a right-angle protrusion or a barbed protrusion. A ball seat (4) is fixedly installed on the inner wall of the cylindrical part. A soluble ball (5) is adapted to be installed on the ball seat. A compression spring (7) is provided between the cylindrical part and the slotted inner cylinder. The cylindrical part is provided with an inner step (111) with the end face facing upward. The slotted inner cylinder is provided with an outer step (23) with the end face facing downward. The two ends of the compression spring abut against the inner step and the outer step, respectively.

2. The tool for opening coiled tubing according to claim 1, characterized in that, The tail end face of the spring claw is constructed into a conical surface to form the first compression conical surface (122), and the tail bottom surface of the groove is constructed into a conical surface to form the second compression conical surface (211). The slotted inner cylinder can move axially relative to the spring piece, so that the second compression cone surface can act on the first compression cone surface, thereby allowing the spring piece claw to retract or spring back within the slot.

3. The tool for opening coiled tubing according to claim 1, characterized in that, The first compression cone surface (122) is formed by conical bosses on both radial wings of the bearing tooth, and the second compression cone surface (211) is formed by conical surfaces on both radial wings of each groove. The slotted inner cylinder can move axially relative to the spring piece, so that the second compression cone surface can act on the first compression cone surface, thereby allowing the spring piece claw to retract or spring back within the slot.

4. The tool for opening coiled tubing according to claim 1, characterized in that, At least one guide tooth (13) is provided on the outer wall surface of each of the spring claws. The guide teeth are axially spaced apart at the lower axial end of the bearing protrusion, and the lower end surface of the guide tooth is constructed as an inclined surface.

5. The tool for opening coiled tubing according to claim 1, characterized in that, An annular mounting groove (61) is provided on the outer wall surface of the slotted inner cylinder, and a retaining spring (6) is installed in the mounting groove. A retaining spring groove (62) is provided on the inner wall surface of the cylindrical part. The retaining spring can be fitted into the retaining spring groove to form an axial limit on the slotted inner cylinder.

6. A full-bore stepless multi-cluster sliding sleeve, comprising a plurality of clustered sliding sleeves (200) sequentially connected in series in a tubing string, and an opening tool according to any one of claims 1 to 5, wherein the clustered sliding sleeve comprises: Outer sleeve (210), the outer sleeve is provided with a flow guide hole (201); The upper connector (220) and the lower connector (230) are respectively connected to the two ends of the outer sleeve; Inner sleeve (240) concentrically arranged inside the outer sleeve shown; In the first state, the inner sleeve is fixedly connected to the outer sleeve by a shear pin (250) and blocks the guide hole. In the second state, the opening tool is lowered into the wellbore through coiled tubing until it enters the matching clustered sliding sleeve. By lifting the opening tool, the inner sleeve can be driven to shear the shear pin, thereby driving the inner sleeve upward and opening the guide hole. The opening tool can sequentially open multiple clustered sliding sleeves.

7. The full-bore stepless multi-cluster sliding sleeve according to claim 6, characterized in that, The flow guide hole is configured as a throttling orifice.

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