Switchable full-gauge well cementing sliding sleeve and well cementing and completion method

Abstract

The application provides a switchable full-bore well cementing sliding sleeve, which comprises an outer shell, a first inner sleeve, a second inner sleeve and a first soluble support ring, wherein the outer shell is provided with a fracturing hole and connected with an upper joint and a lower joint at two ends respectively, the first inner sleeve is arranged in the outer shell and provided with a first snap ring groove, the second inner sleeve is provided with a first anti-back-off snap ring, a guide pin is fixed on an inner wall of the first inner sleeve, and a guide rail groove is arranged on an outer surface of the second inner sleeve and is composed of one long groove and a plurality of short grooves; in a first state, the first inner sleeve is fixedly connected with the outer shell through the shearing pin to block the fracturing hole; in a second state, the first soluble support ring is dissolved, the guide pin can be switched to the long groove after passing through a ball, the first anti-back-off snap ring is matched with the first snap ring groove, so that the first inner sleeve and the second inner sleeve are locked, and the first inner sleeve is cut off from the shearing pin to descend, so that the fracturing hole is opened. The application also provides a well cementing and completion method.

Description

Technical Field

[0001] This invention belongs to the field of well completion tool technology in the oil and gas exploration and development process, specifically relating to an openable full-bore cementing sleeve and a cementing completion method. Background Technology

[0002] With the continued deepening of oil and gas reservoir exploration and development, the implementation of horizontal well segmented fracturing has become a necessary means for the effective development of unconventional oil and gas reservoirs such as shale gas.

[0003] Currently, the main horizontal well fracturing technologies for shale gas wells are the bridge plug perforation continuous operation process and the dragged tubing string sandblasting perforation fracturing process. This process divides the target formation into multiple segments, first performing perforation treatment before fracturing operations. However, perforation operations often cause casing damage due to uncontrollable downhole factors, reducing casing strength and increasing the difficulty of running bridge plugs and fracturing tubing strings, resulting in a long overall fracturing operation cycle and low efficiency. The cementing sliding sleeve segmented fracturing process has been widely adopted due to its short cycle and high efficiency, and can replace the conventional bridge plug perforation continuous operation process and the dragged tubing string sandblasting perforation fracturing process. Conventional cementing sliding sleeves use differential pressure cementing sliding sleeves for the first stage of fracturing, followed by ball-dropped cementing sliding sleeves or key-switch sliding sleeves for subsequent fracturing operations.

[0004] However, the conventional cementing sleeves currently in use still have some problems. For example, after cementing, the cement sheath can easily prevent the sleeve from opening properly. The sleeve uses a ball-dropping structure, opening it by using pressure-pressurizing balls of different sizes. However, this method cannot achieve a large diameter, requiring subsequent drilling removal. The key in the keyed sleeve can easily pass through a fixed point, causing the sleeve to fail to open. Once opened, the sleeve cannot be closed, making it impossible to handle severe water seepage in that formation. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention aims to propose a switchable full-bore cementing sleeve and a cementing completion method. This switchable full-bore cementing sleeve can be opened at a fixed point using a pressure-blocking ball of the same size. It features unlimited stages and a large diameter, and can effectively prevent premature opening of the sleeve during cementing. In the later stages of fracturing operations, the sleeve can be opened or closed as needed, which is very beneficial for saving operation time and costs and reducing construction risks.

[0006] Therefore, according to a first aspect of the present invention, a switchable full-bore cementing sleeve is provided, comprising: an outer shell, the outer shell having a fracturing hole, and an upper connector and a lower connector respectively connected to both ends of the outer shell; a first inner sleeve concentrically arranged inside the outer shell, the inner wall of the first inner sleeve having a first retaining ring groove; a second inner sleeve sleeved inside the first inner sleeve, the outer wall surface of the second inner sleeve having a first anti-reverse retaining ring; a first soluble support ring, the upper end face of which abuts against the lower end face of the first inner sleeve and the second inner sleeve, the lower end face abutting against the upper end face of the lower connector; wherein a guide is fixed on the inner wall of the first inner sleeve. The first inner sleeve has a guide pin and a guide groove on the outer surface of the second inner sleeve. The guide groove is constructed to include a long groove and multiple short grooves. In the first state, the first inner sleeve is fixedly connected to the outer shell by the shear pin, thereby sealing the fracturing hole. In the second state, the first soluble support ring dissolves, and the guide pin can switch to the long groove after a pressure ball is inserted, so that the first anti-retraction retaining ring is adapted to the first retaining ring groove, thereby locking the first inner sleeve and the second inner sleeve. By inserting the pressure ball again, the first inner sleeve can cut the shear pin and move downward, thereby opening the fracturing hole.

[0007] In one embodiment, the guide rail groove is configured as two rows of grooves that are opposite in direction and staggered in the circumferential direction. The first row of grooves at the upper axial end is formed as a plurality of the short grooves, and the second row of grooves at the lower axial end is formed as a long groove and a plurality of the short grooves.

[0008] In one embodiment, the first sidewall of the groove is a first plane, and the second sidewall is configured to include a second plane and an inclined surface connected to the second plane, the inclined surface being directly opposite the corresponding first plane in a row of axially opposite grooves.

[0009] In one embodiment, a first step with its end face facing downward is provided on the outer wall of the second inner sleeve, and a support spring is provided between the first step and the first soluble support ring.

[0010] In one embodiment, a blocking ring is provided between the first inner sleeve and the second inner sleeve. The blocking ring is locked by a locking ring. The blocking ring is located at one end near the first soluble support ring, and the lower end of the support spring abuts against the upper end surface of the blocking ring.

[0011] In one embodiment, a ball seat groove is provided on the outer wall of the first inner sleeve, and a plurality of circumferentially distributed through grooves are provided on the second inner sleeve. A split ball seat is embedded in the through groove. The split ball seat can be offset from the ball seat groove and extend out of the through groove to be adapted to the pressure ball for pressure, and can be adapted to the ball seat groove to open, so that the pressure ball can pass through the split ball seat.

[0012] In one embodiment, a second anti-reverse retaining ring is provided on the outer wall surface of the first inner sleeve, and a second anti-reverse retaining ring groove is provided on the inner wall of the outer shell. In the second state, the second anti-reverse retaining ring can be adapted to the second anti-reverse retaining ring groove, thereby locking the first inner sleeve and the outer shell.

[0013] In one embodiment, the side wall of the second anti-retraction circlip groove is constructed as an outwardly inclined slope. In the third state, the first inner sleeve can be disengaged from the second anti-retraction circlip groove by a switching tool under the action of the inclined slope.

[0014] In one embodiment, a second step with its end face facing downward is provided on the inner wall of the first inner sleeve, and a second soluble support ring is provided between the second step and the upper end face of the second inner sleeve, the second soluble support ring being dissolved in the second state.

[0015] In one embodiment, a soluble plug is provided in the fracturing hole, and the soluble plug dissolves in the second state.

[0016] According to a second aspect of the present invention, a cementing completion method is provided, comprising the following steps:

[0017] Step 1: Connect multiple switchable full-bore cementing sleeves as described above to the tubing string in sequence at intervals, and lower the tubing string into the wellbore to the predetermined position;

[0018] Step 2: Perform cementing operations, using completion fluid for displacement, and allow it to set.

[0019] Step 3: Perform an in-pipe pressure test as required. The first soluble support ring, the second soluble support ring, and the soluble rubber plug will gradually dissolve upon contact with the completion fluid.

[0020] Step 4: Deploy the pressure-pressurizing ball. After passing through each of the upstream switchable full-bore cementing sleeves in sequence, the pressure-pressurizing ball is adapted to the split ball seat of the second-stage switchable full-bore cementing sleeve to drive the corresponding first inner sleeve to shear the shear pin and move downward, thereby opening the corresponding fracturing hole and carrying out fracturing operations.

[0021] Step 5: Repeat Step 4 above to carry out fracturing construction in subsequent layers;

[0022] Step Six: After all fracturing operations in all sections have been completed, proceed with production assessment.

[0023] In step one, the guide pin of the second-stage switchable full-bore cementing sleeve is set in the long groove, thereby locking the corresponding first inner sleeve and the second inner sleeve. In step four, when the pressure ball passes through the first-stage switchable full-bore cementing sleeve above the second stage, the corresponding guide pin changes track and enters the long groove, thereby locking the corresponding first inner sleeve and the second inner sleeve.

[0024] In one embodiment, the first-stage sliding sleeve at the bottom of the tubing is a toe-end differential pressure sliding sleeve.

[0025] In one embodiment, the dissolution time of the first soluble support ring, the second soluble support ring, and the soluble rubber stopper can be controlled within 1-3 days.

[0026] In one embodiment, in step six, when water emerges from the formation, the lowering of the switching tool can drive the first inner sleeve of the corresponding level switchable full-bore cementing sleeve upward, thereby closing the corresponding fracturing hole.

[0027] Compared with the prior art, the advantages of this application are:

[0028] The switchable full-bore cementing sleeve and cementing completion method of the present invention adopts an inner guide rail structure design, which allows for point opening of the sleeve using a pressure-blocking ball of the same size. It features unlimited stages and a large diameter, and has a switching function, resulting in high implementation efficiency and high safety and reliability. Furthermore, it effectively avoids premature opening of the sleeve during cementing, and allows for mechanical opening and closing as needed in the later stages of fracturing operations, greatly saving operation time and costs, reducing construction risks, and improving production efficiency. By setting a first soluble support ring, a second soluble support ring, and a soluble rubber plug, it effectively prevents the sleeve from failing to open properly after cementing. Attached Figure Description

[0029] The present invention will now be described with reference to the accompanying drawings.

[0030] Figure 1 The structure of the switchable full-bore cementing sleeve according to the present invention is shown.

[0031] Figure 2 yes Figure 1 A magnified view of region A in the middle.

[0032] Figure 3 The structure of the guide groove on the second inner sleeve is adaptively displayed.

[0033] Figure 4 The planar development of the guide rail groove is adaptively displayed.

[0034] 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

[0035] The invention will now be described with reference to the accompanying drawings.

[0036] In this application, it should be noted that the end of the switchable full-bore cementing sleeve according to the present invention that is lowered into the wellbore and is closer to 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.

[0037] Figure 1 The structure of the switchable full-bore cementing sleeve 100 according to the present invention is shown. For example... Figure 1 As shown, the switchable full-bore cementing sleeve 100 includes a cylindrical outer shell 1, a first inner sleeve 2 concentrically arranged inside the outer shell 1, a second inner sleeve 3 concentrically fitted inside the first inner sleeve 2, and a first soluble support ring 4. The outer shell 1 has fracturing holes 11 on its sidewalls, and an upper connector 12 and a lower connector 13 are respectively connected to both ends of the outer shell 1. A first retaining ring groove 21 is provided on the inner wall of the first inner sleeve 2, and a first anti-retraction retaining ring 31 is provided on the outer wall of the second inner sleeve 3. The upper end face of the first soluble support ring 4 abuts against the lower end faces of the first inner sleeve 2 and the second inner sleeve 3, and the lower end face of the first soluble support ring 4 abuts against the upper end face of the lower connector 13. A guide pin 5 is fixed on the inner wall of the first inner sleeve 2, and a guide rail groove 6 (see...) is provided on the outer surface of the second inner sleeve 3. Figure 3 The guide rail groove 6 is configured to include a long groove 61 and a plurality of short grooves 62.

[0038] In the initial state, the first inner sleeve 2 is fixedly connected to the outer shell 1 by the shear pin 7, thereby sealing the fracturing hole 11. At this time, the switchable full-bore cementing sleeve 100 is in the first state, and the switchable full-bore cementing sleeve 100 remains in the first state during the wellbore lowering process.

[0039] When fracturing operations are required, the first soluble support ring 4 dissolves, and the guide pin 5, after being charged with a pressure ball, can switch to the long groove 61 of the guide rail groove 6, so that the first anti-reverse retaining ring 31 fits into the first retaining ring groove 21, thereby locking the first inner sleeve 2 and the second inner sleeve 3. After the first inner sleeve 2 and the second inner sleeve 3 are locked, by charging the pressure ball again, the first inner sleeve 2 can shear the shearing pin 7 and move downward, thereby opening the fracturing hole. Thus, fracturing operations can be carried out. At this time, the switchable full-bore cementing sleeve 100 is in the second state.

[0040] In this embodiment, it should be understood that when the guide pin 5 is initially positioned within the long slot 61 of the guide rail groove 6, the first inner sleeve 2 and the second inner sleeve 3 are locked in the initial state. Then, after one pressurization ball insertion, the first inner sleeve 2 shears the shear pin 7 and moves downwards, thereby opening the fracturing hole. When the guide pin 5 is initially positioned within the short slot 62 of the guide rail groove 6, the guide pin 5 needs to be switched to the long slot 61 of the guide rail groove 6 after at least one pressurization ball insertion, locking the first inner sleeve 2 and the second inner sleeve 3. Then, after another pressurization ball insertion, the first inner sleeve 2 shears the shear pin 7 and moves downwards, thereby opening the fracturing hole.

[0041] During production operations, if water seepage occurs in the formation and the switchable full-bore cementing sleeve 100 needs to be closed, a switching tool (not shown) can be lowered in. The switching tool can drive the first inner sleeve 2 upward to close the fracturing hole 11 again. At this time, the switchable full-bore cementing sleeve 100 is in the third state.

[0042] According to one embodiment of the present invention, such as Figure 1 As shown, both the upper connector 12 and the lower connector 13 are fixedly connected to the outer casing 1 via threads. The upper connector 12 and the lower connector 13 are used to fix the upper and lower tubular sections, respectively. To ensure a tight seal between the upper connector 12 and the lower connector 13 and the outer casing 1, sealing grooves are respectively installed on the outer wall surfaces of the upper connector 12 and the lower connector 13, and sealing elements are installed within these grooves. Preferably, sealing rings can be used as the sealing elements. The sealing elements effectively ensure the sealing performance between the connection surfaces of the upper connector 12 and the lower connector 13 and the outer casing 1.

[0043] In one embodiment, the upper connector 12 and the lower connector 13 are anti-rotationally secured to the housing 1 using set screws (not shown).

[0044] like Figure 1 As shown, fracturing holes 11 penetrate the sidewall of the outer shell 1, and multiple fracturing holes 11 are provided on the sidewall of the outer shell 1. The fracturing holes 11 are evenly spaced in at least three layers along the axial direction, and the multiple fracturing holes 11 in each layer are evenly spaced in the circumferential direction. Furthermore, the fracturing holes 11 in adjacent layers are staggered in the circumferential direction, thus forming a staggered distribution. This distribution structure of the fracturing holes 11 can significantly improve the fracturing operation effect and efficiency, and also helps to improve subsequent production efficiency.

[0045] In one embodiment, dynamic seals are provided between the first inner sleeve 2 and the outer sleeve 1, spaced apart axially. When the switchable full-bore cementing sleeve 100 is closed, the fracturing holes 11 are positioned axially between the dynamic seals. This ensures the sealing between the first inner sleeve 2 and the outer sleeve 1, thereby guaranteeing the reliability of the switchable full-bore cementing sleeve 100 when closed. Preferably, axially spaced sealing grooves are provided on the outer surface of the first inner sleeve 2, and the dynamic seals are correspondingly installed within the respective sealing grooves.

[0046] According to the present invention, such as Figure 2 As shown, the guide rail groove 6 is disposed on the outer surface of the second inner sleeve 3 and is continuously distributed along the circumference. The guide rail groove 6 is constructed as two rows of grooves with opposite directions and staggered distribution in the circumferential direction. Located at the upper axial end ( Figure 2 The first row of grooves at the left end of the middle section is formed into multiple short grooves 62, and the multiple short grooves 62 are evenly spaced apart in the circumferential direction. Meanwhile, at the lower axial end ( Figure 2 The second row of grooves (at the right end of the first row) forms a long groove 61 and multiple short grooves 62, and the long groove 61 and multiple short grooves 62 are evenly distributed circumferentially around the outer surface of the second inner sleeve 3. The number of short grooves 62 in the first row of grooves is the same as the total number of long grooves 61 and short grooves 62 in the second row of grooves.

[0047] like Figure 2 and Figure 3 As shown, the first sidewall of the groove is a first plane 601, and the second sidewall is constructed to include a second plane 602 and an inclined surface 603 connected to the second plane 602, with the inclined surface facing the corresponding first plane 601 in a row of axially opposite grooves. Thus, the front end of the groove is formed as a conical groove, while the rear end is formed as a straight groove. The conical groove allows the second inner sleeve 3 to rotate under the action of the guide pin 5, thereby enabling the guide pin 5 to switch between the short groove 6 and the long groove 61. The straight groove is used to control the degree of axial relative movement between the first inner sleeve 2 and the second inner sleeve 3 under the action of the guide pin 5. The specific switching process of the guide pin 5 between the short groove 6 and the long groove 61 will be described in detail below.

[0048] In this embodiment, in order to ensure the smooth switching of the guide pin 5 between the short groove 6 and the long groove 61, the inclination angle of the inclined surface 603 of the second sidewall in the groove is set to be less than 60 degrees.

[0049] More preferably, the connection between the second plane 602 and the inclined plane 603 of the second sidewall can be made into a transition treatment.

[0050] According to the present invention, such as Figure 1As shown, a first step 32 with its end face facing downwards is provided on the outer wall of the second inner sleeve 3. A support spring 8 is provided between the first step 32 and the first soluble support ring 4. The support spring 8 is preferably a high-load support spring.

[0051] The outer wall surface of the second inner sleeve 3 contacts the inner wall surface of the first inner sleeve 2, thereby forming an annular space between the second inner sleeve 3 and the first inner sleeve 2, in the area below the first step 32. A plugging ring 9 is provided between the first inner sleeve 2 and the second inner sleeve 3, and the plugging ring 9 is locked to the first inner sleeve 2 by a locking ring 91. The plugging ring 9 is located at one end near the first soluble support ring 4. The upper end of the support spring 8 abuts against the first step 32, and the lower end of the support spring 8 abuts against the upper end surface of the plugging ring 9. The plugging ring 9 can prevent drilling fluid from entering the annular space during well completion, thereby preventing the support spring 8 from being corroded by drilling fluid and extending the service life of the support spring 8. The function of the support spring 8 will be described in detail below.

[0052] According to the present invention, such as Figure 1 and Figure 4 As shown, the outer wall of the first inner sleeve 2 is provided with a ball seat groove 23, and the second inner sleeve 3 is provided with multiple circumferentially distributed through grooves 33. A split ball seat 10 is embedded in the through groove 33. The split ball seat 10 is constructed to include multiple ball seat blocks, which are respectively installed in the corresponding through grooves 33. The ball seat blocks can move telescopically along the through grooves 33, thereby realizing the opening and retraction of the split ball seat 10.

[0053] When the split ball seat 10 and the ball seat groove 23 are axially misaligned, the ball seat block extends inward into the through groove 33 under the limiting action of the inner wall surface of the first inner sleeve 2. At this time, the split ball seat 10 retracts, functioning as a ball seat, and the pressure ball can be fitted with the split ball seat 10 for pressure. When the split ball seat 10 and the ball seat groove 23 are axially aligned, the ball seat block can move outward along the through groove 33 under the action of the pressure ball and fit into the ball seat groove 23, thereby opening the split ball seat 10. At this time, the inner diameter of the split ball seat 10 expands, and the pressure ball can pass through the split ball seat 10.

[0054] like Figure 4 As shown, a second anti-retraction ring 22 is provided on the outer wall of the first inner sleeve 2, and a second anti-retraction ring groove 14 is provided on the inner wall of the outer shell 1. In the second state, the second anti-retraction ring 22 can enter into the second anti-retraction ring groove 14 and fit with the second anti-retraction ring groove 14, thereby locking the first inner sleeve 2 and the outer shell 1.

[0055] In one embodiment, the sidewall of the second anti-retraction ring groove 14 is configured as an outwardly inclined slope. In the third state, a switching tool can be used to disengage the first inner sleeve 2 from the second anti-retraction ring groove 14 under the action of the inclined slope. This achieves the re-closure of the fracturing hole 11.

[0056] According to the present invention, such as Figure 1 As shown, a second step 15 with its end face facing downwards is provided on the inner wall of the first inner sleeve 2, and a second soluble support ring 41 is provided between the second step 15 and the upper end face of the second inner sleeve 3. The second soluble support ring 41 dissolves in the second state.

[0057] A soluble plug (not shown) is provided in the fracturing hole 11, and the soluble plug dissolves in the second state.

[0058] The first soluble support ring 4, the second soluble support ring 41, and the soluble rubber plug are all made of soluble materials that gradually dissolve in liquid environments such as mud. During cementing operations, the first soluble support ring 4, the second soluble support ring 41, and the soluble rubber plug can prevent cement slurry from clogging the grooves and causing the sliding sleeve to become unable to open or close later.

[0059] The working process of the switchable full-bore cementing sleeve 100 according to the present invention is briefly described below. In practical applications, the initial state of the switchable full-bore cementing sleeve 100 can be set as needed. The guide pin 5 can be set in the long groove 61 of the guide rail groove 6 or in the short groove 62 of the guide rail groove 6.

[0060] In the initial state, when the guide pin 5 of the switchable full-bore cementing sleeve 100 is positioned within the long groove 61 of the guide rail groove 6, the first inner sleeve 2 and the second inner sleeve 3 are locked together by the first anti-reverse retaining ring 31. Furthermore, the split ball seat 10 is in a retracted state. Only one pressurization ball is needed; the pressurization ball moves to the split ball seat 10 and engages with it. Under the pressure, the first inner sleeve 2 shears the shear pin 7 and descends until the fracturing hole 11 is opened. Simultaneously, the first inner sleeve 2 is locked to the outer shell 1 by the second anti-reverse retaining ring 22, thereby keeping the fracturing hole 11 in the open state.

[0061] In the initial state, when the guide pin 5 of the switchable full-bore cementing sleeve 100 is set in the short groove 62 of the guide rail groove 6, it is necessary to inject pressure balls multiple times to first switch the guide pin 5 to the long groove 61 of the guide rail groove 6, so that the first inner sleeve 2 and the second inner sleeve 3 are locked together. Then, by injecting pressure balls, the first inner sleeve 2 is sheared off the shear pin 7 and moves downward, thereby opening the fracturing hole.

[0062] In this embodiment, the specific process of switching the guide pin 5 to the long slot 61 of the guide rail groove 6 is as follows: the pressure ball cooperates with the split ball seat 10 and drives the second inner sleeve 3 downward, compressing the support spring 8. During the downward movement, when the guide pin 5 is aligned with the inclined surface 603 of the corresponding short slot 62 in the first row of grooves of the guide rail groove 6, the second inner sleeve 3 rotates at a certain angle under the action of the inclined surface. When the second inner sleeve 3 moves downward to the point where the split ball seat 10 corresponds to the ball seat groove 23 on the first inner sleeve 2, the split ball seat 10 enters the ball seat groove 23 and opens, and the pressure ball passes through the split ball seat 10. Afterward, the second inner sleeve 3 moves upward to reset under the action of the support spring 8. During the upward movement, the guide pin 5 enters the short slot 62 in the adjacent second row of grooves, thus completing one switching of the guide pin 5. Afterward, the pressure ball is thrown again, and the above process is repeated until the guide pin 5 is switched into the long slot 61, so that the first inner sleeve 2 and the second inner sleeve 3 are locked together. When the pressure ball is thrown again, the first inner sleeve 2 will cut the shear pin 7 and move downward, thereby opening the fracturing hole.

[0063] According to the present invention, a cementing completion method is also proposed. This cementing completion method uses the switchable full-bore cementing sleeve 100 according to the present invention. The cementing completion method is described in detail below.

[0064] In actual construction, firstly, multiple switchable full-bore cementing sleeves 100 are sequentially and spaced apart and connected to the tubing string, which is then lowered into the wellbore to the predetermined position. The number of switchable full-bore cementing sleeves 100 can be set according to requirements. The first-stage sleeve at the bottom of the tubing string is a toe-end differential pressure sleeve. It should be noted that the sleeve at the end of the tubing string is the first-stage sleeve, and the switchable full-bore cementing sleeves 100 distributed sequentially from the bottom of the well to the wellhead are the second-stage, third-stage... nth-stage, where n is set as needed.

[0065] Before entering the well, the guide pin 8 of the second-stage switchable full-bore cementing sleeve 100 is set in the long groove 61 of the guide groove 6, thereby locking the corresponding first inner sleeve 2 and second inner sleeve 3.

[0066] Afterwards, cementing operations were carried out, using completion fluid for displacement, followed by curing.

[0067] Afterwards, an in-pipe pressure test was conducted as required. The first soluble support ring 4, the second soluble support ring 41, and the soluble rubber plug gradually dissolved upon contact with the completion fluid. The dissolution time of the first soluble support ring 4, the second soluble support ring 41, and the soluble rubber plug was controllable within the range of 1-3 days.

[0068] Afterwards, fracturing operations are initiated using pressure-collecting balls of uniform size. The pressure-collecting balls are sequentially dropped through each upstream switchable full-bore cementing sleeve until they reach the second-stage switchable full-bore cementing sleeve and engage with the corresponding split ball seat 10. This causes the corresponding first inner sleeve 2 to shear off the shear pin 7 and descend, thereby opening the corresponding fracturing hole 11 for fracturing operations. When the pressure-collecting ball passes through the next stage (i.e., the third stage) of switchable full-bore cementing sleeve, the corresponding guide pin 5 changes track and enters the long groove 61, thus locking the corresponding first and second inner sleeves. After this section is completed, fracturing operations for subsequent sections are carried out following the aforementioned steps.

[0069] When the pressure-holding ball passes through each of the upstream switchable full-bore cementing sleeves, the pressure-holding ball drives the corresponding second inner sleeve 3 downward, causing the split ball seat 10 to open into the ball seat groove 23 of the first inner sleeve 2. The pressure-holding ball passes through the split ball seat 10, and the second inner sleeve 3 changes its track under the thrust of the lower support spring 8.

[0070] In this embodiment, in the initial state, the guide pins 8 in each switchable full-bore cementing sleeve 100 in the tubing string are sequentially positioned in the guide groove 6, with the number of ball drops required to lock the first inner sleeve 2 and the second inner sleeve 3 increasing sequentially from bottom to top. That is, the guide pin 8 in the second-stage switchable full-bore cementing sleeve 100 is located in a short groove 62 adjacent to the long groove 61 in the guide groove 6, and one ball drop can switch the guide pin 8 into the long groove 61. The guide pin 8 corresponding to the third stage is set one short groove 62 away from the long groove 61, and it takes two ball drops to switch the guide pin 8 into the long groove 61. The guide pin 8 corresponding to the fourth stage is set two short grooves 62 away from the long groove 61, and it takes three ball drops to switch the guide pin 8 into the long groove 61. The initial positions of the guide pins 8 of the openable full-bore cementing sleeve 100 at each level are set accordingly.

[0071] In one embodiment, the pressure briquette is made of a soluble material that gradually dissolves after pressure, thereby achieving a large diameter tubing.

[0072] After all fracturing operations in all sections are completed, production recovery operations are carried out. During the later stages of production recovery operations, if formation water production or other situations necessitate closure, a switching tool (not shown) is lowered to the position of the corresponding openable full-bore cementing sleeve 100 in the formation. After pressure buildup in the tubing, the switching tool extends through an elastic block on its surface and engages with the opening groove (not shown) on the upper part of the switching sleeve. The tubing string is then lifted 3-5 tons. The second anti-reverse retaining ring 22 retracts under the action of the inclined sidewall of the second anti-reverse retaining ring groove 14, and then moves upward with the switching sleeve until the first inner sleeve 2 re-closes the fracturing hole 11, thereby closing the corresponding openable full-bore cementing sleeve 100. After closure, the first inner sleeve 2 is not subjected to axial force, and the friction between the first inner sleeve 2 and the outer casing 1 allows them to remain relatively stationary under the action of the sealing friction, thus keeping the fracturing hole 11 closed. Afterwards, pressure is released, the elastic block on the surface of the switching tool is retracted, and the tubing string is retrieved.

[0073] The switchable full-bore cementing sleeve and cementing completion method of the present invention adopts an inner guide rail structure design, which allows for point opening of the sleeve using a pressure-blocking ball of the same size. It features unlimited stages and a large diameter, and has a switching function, resulting in high implementation efficiency and reliable safety. Furthermore, it effectively prevents premature opening of the sleeve during cementing, and allows for mechanical opening and closing as needed in the later stages of fracturing operations, significantly saving operating time and costs, reducing construction risks, and improving production efficiency. By setting a first soluble support ring 4, a second soluble support ring 41, and a soluble rubber plug, it effectively prevents the sleeve from failing to open properly after cementing.

[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 switchable full-bore cementing sleeve, comprising: The outer shell (1) is provided with a fracturing hole (11), and the two ends of the outer shell are respectively connected to an upper connector (12) and a lower connector (13). A first inner sleeve (2) is concentrically arranged inside the outer shell, and the inner wall of the first inner sleeve is provided with a first retaining ring groove (21). A second inner sleeve (3) is fitted inside the first inner sleeve, and a first anti-retraction ring (31) is provided on the outer wall surface of the second inner sleeve. The first soluble support ring (4) has its upper end face abutting against the lower end face of the first inner sleeve and the second inner sleeve, and its lower end face abutting against the upper end face of the lower connector. Among them, a guide pin (5) is fixed on the inner wall of the first inner sleeve, and a guide groove (6) is provided on the outer surface of the second inner sleeve. The guide groove is constructed to include a long groove (61) and a plurality of short grooves (62). In the first state, the first inner sleeve is fixedly connected to the outer shell by a shear pin (7), thereby sealing the rupture hole. In the second state, the first soluble support ring dissolves, and the guide pin, after being pressurized by a ball, can switch to the long groove so that the first anti-retraction retaining ring matches the first retaining ring groove, thereby locking the first inner sleeve and the second inner sleeve. By pressing the ball again, the first inner sleeve can shear the shearing pin and move downward, thereby opening the fracturing hole. A second anti-retraction retaining ring (22) is provided on the outer wall surface of the first inner sleeve, and a second anti-retraction retaining ring groove (14) is provided on the inner wall of the outer shell. In the second state, the second anti-recoil ring can be adapted to the second anti-recoil ring groove, thereby locking the first inner sleeve and the outer shell. A second step (15) with its end face facing downward is provided on the inner wall of the first inner sleeve, and a second soluble support ring (41) is provided between the second step and the upper end face of the second inner sleeve. The second soluble support ring dissolves in the second state.

2. The switchable full-bore cementing sleeve according to claim 1, characterized in that, The guide rail groove is constructed as two rows of grooves with opposite directions and staggered in the circumferential direction. The first row of grooves at the upper axial end forms a plurality of short grooves, and the second row of grooves at the lower axial end forms a long groove and a plurality of short grooves.

3. The switchable full-bore cementing sleeve according to claim 2, characterized in that, The first sidewall of the groove is a first plane (601), and the second sidewall is constructed to include a second plane (602) and an inclined surface (603) connected to the second plane. The inclined surface is directly opposite the corresponding first plane in a row of axially opposite grooves.

4. The switchable full-bore cementing sleeve according to any one of claims 1 to 3, characterized in that, The outer wall of the second inner sleeve is provided with a first step (32) with the end face facing downward, and a support spring (8) is provided between the first step and the first soluble support ring.

5. The switchable full-bore cementing sleeve according to claim 4, characterized in that, A blocking ring (9) is provided between the first inner sleeve and the second inner sleeve, and the blocking ring is locked by a locking ring (91). The blocking ring is disposed at one end near the first soluble support ring, and the lower end of the support spring abuts against the upper end surface of the blocking ring.

6. The switchable full-bore cementing sleeve according to claims 4 to 1, characterized in that, The outer wall of the first inner sleeve is provided with a ball seat groove (23), and the second inner sleeve is provided with a plurality of circumferentially distributed through grooves (33), and a split ball seat (10) is embedded in the through groove. The split ball seat can extend out of the through groove, offset from the ball seat groove, to fit with the pressure ball for pressure compression, and can also fit with the ball seat groove to open, so that the pressure ball can pass through the split ball seat.

7. The switchable full-bore cementing sleeve according to claim 1, characterized in that, The sidewall of the second anti-retraction retaining ring groove is constructed as an outwardly inclined slope. In the third state, the first inner sleeve can be dislodged from the second anti-retraction retaining ring groove by the switching tool under the action of the inclined surface.

8. The switchable full-bore cementing sleeve according to claim 1, characterized in that, A soluble plug is provided in the fracturing hole, and the soluble plug dissolves in the second state.

9. A cementing completion method, comprising the following steps: Step 1: Connect multiple switchable full-bore cementing sleeves according to any one of claims 1 to 8 sequentially and spaced apart into the tubing string, and lower the tubing string into the wellbore to the predetermined position; Step 2: Perform cementing operations, using completion fluid for displacement, and allow it to set. Step 3: Perform an in-pipe pressure test as required. The first soluble support ring, the second soluble support ring, and the soluble rubber plug will gradually dissolve upon contact with the completion fluid. Step 4: Deploy the pressure-pressurizing ball. After passing through each of the upstream switchable full-bore cementing sleeves in sequence, the pressure-pressurizing ball is adapted to the split ball seat of the second-stage switchable full-bore cementing sleeve to drive the corresponding first inner sleeve to shear the shear pin and move downward, thereby opening the corresponding fracturing hole and carrying out fracturing operations. Step 5: Repeat Step 4 above to carry out fracturing construction in subsequent layers; Step Six: After all fracturing operations in all sections are completed, proceed with production assessment operations; In step one, the guide pin of the second-stage switchable full-bore cementing sleeve is set in the long groove, thereby locking the corresponding first inner sleeve and the second inner sleeve. In step four, when the pressure ball passes through the first-stage switchable full-bore cementing sleeve above the second stage, the corresponding guide pin changes track and enters the long groove, thereby locking the corresponding first inner sleeve and the second inner sleeve.

10. The cementing completion method according to claim 9, characterized in that, The first-stage sliding sleeve at the bottom of the tubing uses a toe-end differential pressure sliding sleeve.

11. The cementing completion method according to claim 9 or 10, characterized in that, The dissolution time of the first soluble support ring, the second soluble support ring, and the soluble rubber stopper can be controlled within 1-3 days.

12. The cementing completion method according to claim 9 or 10, characterized in that, In step six, when water emerges from the formation, the lowered switching tool can drive the first inner sleeve of the corresponding level of switchable full-bore cementing sleeve upward, thereby closing the corresponding fracturing hole.

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