Fracturing sliding sleeve, cementing casing and perforation-free staged fracturing method

Abstract

The present invention relates to the technical field of unconventional oil and gas horizontal well drilling and completion, and particularly relates to a fracturing sleeve, a cementing casing, and a perforation-free staged fracturing method. The fracturing sleeve is used in cooperation with a soluble bridge plug, and includes an upper joint, an inner bushing, and a lower joint. The upper joint is circumferentially provided with a plurality of fracturing channel holes; the lower joint is sealingly connected to the upper joint, and the lower joint is inserted into the upper joint to form an annulus between the lower joint and the upper joint; the inner bushing is fixed inside the upper joint through shear pins and is sealingly connected to the upper joint for plugging the fracturing channel holes, and the inner bushing is inserted into the annulus to plug the annulus; the lower joint is also provided with a pressure transmission hole, and the pressure transmission hole communicates the lower joint and the annulus; and the cementing casing including a plurality of the above fracturing sleeves uses the part of the lower joint inserted into the upper joint to receive the soluble bridge plug, a pressure difference is formed at both ends of the inner bushing, the fracturing sleeve is opened, and fracturing operations can be carried out, achieving a zero differential pressure of the fixed sleeve, high fracturing operation efficiency, and low operation cost.

Description

Technical Field

[0001] The present invention relates to the technical field of unconventional oil and gas horizontal well drilling and completion, and particularly to a fracturing sleeve, a cementing casing, and a perforation-free staged fracturing method. Background Art

[0002] China is rich in unconventional oil and gas resources and they are widely distributed. The combined fracturing of long horizontal section horizontal wells and bridge plug perforation is an important means and development measure for increasing production and improving efficiency in unconventional oil and gas development. Usually, the number of fracturing stages in the combined fracturing of long horizontal well bridge plug perforation exceeds 20 stages, and the number of perforations per stage exceeds 6 clusters. In this way, an unconventional oil and gas horizontal well generally needs to be perforated more than a hundred clusters, and the perforating gun needs to be tripped in and out more than 20 times to install ammunition, which makes the completion operation efficiency low. In addition, the perforating charges used for perforation belong to civilian explosives, and the large amount of use of perforating charges will have a certain impact on social security and environmental protection and increase uncontrollable factors, and also increase the oil and gas development cost.

[0003] Therefore, people open the sliding sleeve by connecting mechanical tools to the cementing casing, or by throwing balls (throwing darts and building pressure). However, opening the sliding sleeve with mechanical tools requires lowering special switching tools, and each time the sliding sleeve is switched, a round trip of drilling is also required, increasing the completion operation time; while throwing balls (throwing darts and building pressure) requires pre-setting a setting ball seat (dart seat), which is difficult to meet the fracturing requirements of too many stages. Moreover, after the fracturing operation is completed, the setting ball seat needs to be drilled out, increasing the completion operation difficulty and raising the operation cost. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a fracturing sleeve that can achieve no differential pressure in the cementing casing, and has high fracturing operation efficiency and low operation cost.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] The fracturing sleeve is used in cooperation with a soluble bridge plug. The fracturing sleeve includes an upper joint, a sliding sleeve, and a lower joint. The upper joint is circumferentially provided with a plurality of fracturing channel holes; the lower joint is hermetically connected to the upper joint, the lower joint is inserted into the upper joint and an annular space is formed between the lower joint and the upper joint; the sliding sleeve is fixed inside the upper joint by shear pins and is hermetically connected to the upper joint for blocking the fracturing channel holes, the sliding sleeve is inserted into the annular space and is hermetically connected to the lower joint; the lower joint is also provided with a pressure transmission hole, and the pressure transmission hole communicates the lower joint and the annular space.

[0007] Optionally, the annular space is filled with a hot-melt type solid.

[0008] Optionally, a plugging prevention hole is further formed in the lower joint. The plugging prevention hole communicates with the pressure transmission hole and the interior of the lower joint. A temporary plug is sealed in the plugging prevention hole. One end of the temporary plug is closed and protrudes from the plugging prevention hole, and the other end is inserted into the plugging prevention hole to communicate with the pressure transmission hole.

[0009] Optionally, a first shoulder is provided on the inner wall of the upper joint, and one end of the sliding sleeve away from the lower joint faces the first shoulder.

[0010] Optionally, the upper joint includes an axially connected upper connecting portion, an upper transition portion, and an upper main body portion. The inner diameter of the upper main body portion is larger than that of the upper transition portion to form the first shoulder. The lower joint includes an axially connected lower main body portion, a lower transition portion, and a lower connecting portion. The lower transition portion and the lower main body portion are inserted into the upper main body portion to be connected to the upper main body portion. The outer diameter of the lower transition portion is larger than the outer diameters of the lower connecting portion and the lower main body portion, and a second shoulder is formed between the lower transition portion and the lower main body portion. The inner diameter of the upper transition portion is the same as the inner diameter of the lower joint. The length of the soluble bridge plug for the sealing layer is greater than the distance between the shoulder surface of the first shoulder and the lower main body portion.

[0011] Optionally, the two orifices of the pressure transmission hole are respectively formed on the inner wall of the lower transition portion and the shoulder surface of the second shoulder.

[0012] Optionally, a plurality of annular grooves are provided at both axial ends of the sliding sleeve, and first sealing rings are placed in the grooves to form a seal between the sliding sleeve and the upper joint.

[0013] Optionally, an annular groove is formed on the outer wall of one end of the lower joint in contact with the sliding sleeve, and a second sealing ring is placed in the groove to form a seal between the lower joint and the sliding sleeve.

[0014] Another object of the present invention is to provide a cementing casing, which includes a casing, a toe-end sliding sleeve, a float collar, and the fracturing sliding sleeve as described above. Multiple sections of the fracturing sliding sleeves are connected to multiple sections of the casing at intervals to form a casing string. The lower end of the casing string is connected to the toe-end sliding sleeve, and the lower end of the toe-end sliding sleeve is connected to the float collar.

[0015] Another object of the present invention is to provide a method for perforation-free staged fracturing, which is realized by using the above-mentioned cementing casing. The cementing casing includes a fracturing sliding sleeve with a temporary plug. The method specifically includes the following steps:

[0016] S1. Lower the cementing casing to a predetermined position in the well and perform normal cementing operations;

[0017] S2. In the later stage of the cementing operation, the cementing plug displaces the cement slurry into the annulus between the cementing casing and the wellbore. When passing through the sliding sleeve, the temporary plugging head is sheared off, enabling the pressure inside the pipe to communicate with the pressure transmission hole through the temporary plugging head.

[0018] S3. By applying pressure at the wellhead, the toe-end sliding sleeve is opened to establish the first-stage communication channel between the inside and outside of the pipe and complete the first-stage fracturing operation.

[0019] S4. Pump a soluble bridge plug into the lower joint of the fracturing sliding sleeve to be opened and located above the temporary plugging head inside the cementing casing. Then, apply pressure at the wellhead to make the pressure above the soluble bridge plug higher than the pressure below it. When the pressure difference reaches a certain value, the thrust generated by the pressure difference shears the shear pin, and the sliding sleeve moves downward to expose the fracturing channel hole, establishing a pressure channel and conducting a fracturing operation.

[0020] S5. Repeat step S4 to sequentially open the fracturing sliding sleeves from the bottom of the well to the wellhead and conduct fracturing operations for each stage until the fracturing operation is completed.

[0021] The beneficial effects of the present invention are as follows: In the present invention, the fracturing sliding sleeve forms an annulus by inserting the lower joint into the upper joint. The soluble bridge plug can be seated in the part where the lower joint is inserted into the upper joint to achieve layer sealing. The part where the lower joint is inserted into the upper joint functions as the seating ball seat in the existing fracturing sliding sleeve, and the subsequent soluble bridge plug can automatically melt without the need for drilling and removal. The fixed sleeve in the present invention adopts the above-mentioned fracturing sliding sleeve, achieving no pressure difference. Moreover, the toe-end sliding sleeve is used to open the first-stage communication channel between the inside and outside of the pipe. The entire fracturing operation process is perforation-free, eliminating the need to use explosives, reducing the social safety risk. The perforation-free staged fracturing method in the present invention has high operation efficiency and low operation cost. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the fracturing sliding sleeve in an embodiment of the present invention;

[0023] Figure 2 is Figure 1 an enlarged structural diagram of part A in

[0024] Figure 3 is Figure 1 an enlarged structural diagram of part B in

[0025] Figure 4 is a schematic structural diagram of the fracturing sliding sleeve with the temporary plugging head sheared off in an embodiment of the present invention;

[0026] Figure 5 is a schematic structural diagram of the soluble bridge plug seated in the fracturing sliding sleeve in an embodiment of the present invention;

[0027] Figure 6It is a schematic diagram of the fracturing sleeve structure when the fracturing channel hole is opened in the embodiment of the present invention;

[0028] Figure 7 It is a schematic diagram of the fracturing sleeve structure after the soluble bridge plug melts in the embodiment of the present invention;

[0029] Figure 8 It is a schematic diagram of the structure of the cementing casing in the embodiment of the present invention.

[0030] In the figure, 10 is the fracturing sleeve; 11 is the upper joint, 111 is the upper connecting part, 112 is the upper transition part, 113 is the upper main body part, 114 is the first shoulder, 115 is the fracturing channel hole, 12 is the internal bushing, 13 is the lower joint, 131 is the lower main body part, 132 is the lower transition part, 133 is the lower connecting part, 134 is the second shoulder, 135 is the pressure transmission hole, 136 is the anti-blocking hole, 14 is the shear pin, 15 is the temporary plug, 16 is the first sealing ring, 17 is the second sealing ring, 18 is the third sealing ring;

[0031] 20 is the casing;

[0032] 30 is the toe-end sleeve;

[0033] 40 is the float collar;

[0034] 50 is the soluble bridge plug. Specific embodiments

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0036] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may also include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.

[0038] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "left", "right", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0039] The ball-throwing sliding sleeve generally includes an outer cylinder, an inner bushing and shear pins. A fracturing channel hole is provided on the outer cylinder. The inner bushing is fixed to the outer cylinder through the shear pins. When the shear pins are cut off, the inner bushing can axially move relative to the outer cylinder, so that the fracturing channel hole is opened to connect the inner and outer spaces of the ball-throwing sliding sleeve. And the cutting off of the shear pins is realized by throwing a plugging ball into the ball-throwing sliding sleeve. After the plugging ball is thrown in, pressure is built up to open the fracturing channel hole. Generally, considering the coaxiality problem of the outer cylinder and the inner bushing during processing, in order to ensure that the inner bushing can axially move relative to the outer cylinder to open the fracturing channel hole, the length of the inner bushing should not be too long. And in order to make the plugging ball accurately stay in the inner bushing, a setting ball seat is arranged on the inner wall of the inner bushing so that the plugging ball can accurately land at the position of the inner bushing. When the plugging ball is limited in the setting ball seat, it can drive the inner bushing to axially move, so as to open the fracturing channel hole. This results in the inability to achieve full-bore of the cementing casing, and it is necessary to drill out the setting ball seat later, with cumbersome operation steps. Moreover, the number of fracturing stages is limited and it is difficult to meet the fracturing requirements with too many stages.

[0040] Therefore, the present invention provides a fracturing sliding sleeve, and this fracturing sliding sleeve 10 is used in cooperation with a soluble bridge plug 50. Figures 1-7In one embodiment of the present invention, the fracturing sleeve 10 is proposed. The fracturing sleeve 10 includes an upper joint 11, a lower joint 13, an inner bushing 12 and shear pins 14. The upper joint 11, the lower joint 13 and the inner bushing 12 are all arranged in a cylindrical structure. The first end of the upper joint 11 is connected to an external pipe joint, and the second end is hermetically connected to the lower joint 13. A plurality of fracturing channel holes 115 are circumferentially formed in the upper joint 11. At least a part of the lower joint 13 extends into the upper joint 11 and forms an annular annulus with the upper joint 11. The inner bushing 12 is fixed inside the upper joint 11 by shear pins 14 and is used to block the fracturing channel holes 115. In order to ensure the blocking of the fracturing channel holes 115 by the inner bushing 12, a seal is provided between the inner bushing 12 and the upper joint 11. Exemplarily, a plurality of annular grooves are provided on the outer walls at both axial ends of the inner bushing 12, and first sealing rings 16 are placed in the grooves. When the shear pins 14 are not cut, the first sealing rings 16 are distributed on both sides of the fracturing channel holes 115 to form a seal between the inner bushing 12 and the upper joint 11. One end of the inner bushing 12 away from the first end of the upper joint 11 is inserted into the annulus. The inner bushing 12 can cut the shear pins 14 under the pressure difference at both ends of the inner bushing 12 and slide axially towards the lower joint 13.

[0041] The opening of the fracturing channel holes 115 on the above-mentioned fracturing sleeve 10 is realized by a soluble bridge plug 50. The soluble bridge plug 50 can be pumped to the part of the lower joint 13 inserted into the upper joint 11 and set in place. By pressurization, the pressure inside the fracturing sleeve 10 above the soluble bridge plug 50 is higher than the pressure inside the fracturing sleeve 10 below the soluble bridge plug 50. When the pressure difference reaches a certain value, the inner bushing 12 moves downward under the push of the pressure. The thrust pushes the inner bushing 12 to cut the shear pins 14. The inner bushing 12 moves downward, exposing the fracturing channel holes 115, establishing a pressure channel and performing a fracturing operation. After the fracturing operation is completed, the soluble bridge plug 50 can automatically dissolve inside the fracturing sleeve 10 without being drilled out, improving the fracturing efficiency and reducing the operation cost. The soluble bridge plug 50 belongs to the prior art, and its setting means will not be described in detail in this embodiment. It can be understood that the length of the lower joint 13 inserted into the upper joint 11 must be longer than the length of the inner bushing 12, so as to ensure that the soluble bridge plug 50 falls into the lower joint 13 and is set in the lower joint 13. Moreover, the lower joint 13 is fixed relative to the upper joint 11, and the coaxiality problem between the upper joint 11 and the lower joint 13 does not need to be considered. As for the specific length, it can be determined according to the overall length of the cementing casing. Exemplarily, the length of the lower joint 13 inserted into the upper joint 11 is not less than 2m.

[0042] After the cementing casing is lowered into the unconventional oil well according to the requirements of the cementing design, cementing operation needs to be carried out first and then fracturing operation. During the cementing process, drilling fluid and cement slurry need to be injected into the fixed sleeve successively. In order to prevent the cement slurry from entering the annulus and solidifying, which may affect the subsequent movement of the inner bushing 12, the inner bushing 12 is hermetically connected to the lower joint 13. Refer to Figure 1 As shown, an annular groove is formed on the outer wall of one end of the lower joint 13 in contact with the inner bushing 12, and a second sealing ring 17 is placed in the groove. Of course, an annular groove can also be provided on the inner wall of one end of the inner bushing 12 in contact with the lower joint 13, and the second sealing ring 17 is placed in the groove to achieve the sealing between the inner bushing 12 and the lower joint 13.

[0043] On this basis, in order to prevent the inner bushing 12 from moving unexpectedly, a pressure transmission hole 135 communicating the annulus with the lower joint 13 is formed on the lower joint 13. The pressure transmission hole 135 can balance the pressures on the upper and lower end faces of the inner bushing 12 and prevent the generation of sliding shear force. The size of the pressure transmission hole 135 only allows the entry and exit of liquids or gases with little or no viscosity, such as cement slurry is not allowed to enter, while drilling fluid and gases are allowed to enter.

[0044] Refer to Figure 1 and Figures 4-7 As shown, a first shoulder 114 is provided on the inner wall of the upper joint 11, and one end of the inner bushing 12 away from the lower joint 13 faces the shoulder surface of the first shoulder 114. When the drilling fluid or cement slurry enters the fracturing sleeve 10 from the first end of the upper joint 11, the impact on the inner bushing 12 can be reduced, and the pressure difference between the two ends of the inner bushing 12 can be further decreased.

[0045] In this embodiment, the upper joint 11 includes an axially connected upper connecting portion 111, an upper transition portion 112 and an upper main body portion 113. The upper connecting portion 111 is used to connect the external pipe section, and the upper transition portion 112 serves to connect the upper connecting portion 111 and the upper main body portion 113. The lower joint 13 includes a lower main body portion 131, a lower transition portion 132 and a lower connecting portion 133. The lower connecting portion 133 is used to connect the external pipe section, and the lower transition portion 132 serves to connect the lower connecting portion 133 and the lower main body portion 131. The lower transition portion 132 and the lower main body portion 131 are inserted into the upper main body portion 113, and an external thread is provided on the outer wall of the lower transition portion 132, and an internal threaded hole is provided on the inner wall of the upper main body portion 113. The lower transition portion 132 is screwed to the upper main body portion 113. To ensure sealing, a third sealing ring 18 is also provided between the lower transition portion 132 and the upper main body portion 113.

[0046] The inner diameter of the upper main body portion 113 is greater than that of the upper transition portion 112 to form a first shoulder 114. The outer diameter of the lower transition portion 132 is greater than the outer diameters of the lower connecting portion 133 and the lower main body portion 131 to cooperate with the upper joint 11 to form an annulus. A second shoulder 134 is formed between the lower transition portion 132 and the lower main body portion 131. The inner diameter of the upper transition portion 112 is the same as the inner diameter of the entire lower joint 13. And the length of the soluble bridge plug 50 is greater than the distance between the shoulder surface of the first shoulder 114 and the lower main body portion 131, so that the soluble bridge plug 50 can smoothly pass through the inner sleeve 12 and partially enter the lower joint 13.

[0047] When the soluble bridge plug 50 enters the fracturing sleeve 10 to open the fracturing channel hole 115, it needs to be set at the upper position of the lower joint 13 where the pressure transmission hole 135 is located to avoid the continuous communication between the annulus and the inside of the lower joint 13. In order to provide a greater displacement difference for the soluble bridge plug 50 to move in the fracturing sleeve 10, the two orifices of the pressure transmission hole 135 are respectively opened on the inner wall of the lower transition portion 132 and the shoulder surface of the second shoulder 134.

[0048] During the cementing process, the cement slurry may block the pressure transmission hole 135 when passing through the fracturing sleeve 10, resulting in different pressures on the axial two ends of the inner sleeve 12 and generating a pressure difference. Therefore, a hot-melt type solid, such as paraffin wax, can be pre-filled in the annulus. During the process of lowering the cementing casing, the temperature gradually rises, and the paraffin wax melts into a liquid and fills the annulus to prevent the generation of a pressure difference at the axial two ends of the inner sleeve 12. It can be understood that the hot-melt type solid should have a certain viscosity after melting and is difficult to flow out of the annulus through the pressure transmission hole 135. Only when the pressure difference at the two ends of the inner sleeve 12 reaches the value that can shear the shear pin 14, can the melted hot-melt type solid flow out, and the melted hot-melt type solid blocks the entry of the cement slurry.

[0049] Or, as shown in Figure 3 An anti-blocking hole 136 communicating with the pressure transmission hole 135 is further opened on the inner wall of the lower joint 13. A temporary plug 15 is plugged in the anti-blocking hole 136. One end of the temporary plug 15 is closed and protrudes from the anti-blocking hole 136, and the other end is inserted into the anti-blocking hole 136 to communicate with the pressure transmission hole 135. The closed end of the temporary plug 15 will be sheared off by the cementing plug passing through the fracturing sleeve 10 in the later stage of the cementing operation, so that the inside of the lower joint 13 is re-connected to the annulus. The cementing plug is used to isolate the cement slurry from the drilling fluid or the spacer fluid, which belongs to the prior art and will not be described in detail in this embodiment.

[0050] As shown in Figure 8As shown in the figure, in another embodiment of the present invention, a cementing casing is proposed. The cementing casing includes a casing 20, a toe-end sliding sleeve 30, a float collar 40, and the above-mentioned fracturing sliding sleeve 10. Among them, multiple sections of the fracturing sliding sleeve 10 are connected to multiple sections of the casing 20 at intervals to form a casing string. The lower end of the casing string is connected to the toe-end sliding sleeve 30, and the lower end of the toe-end sliding sleeve 30 is connected to the float collar 40. The toe-end sliding sleeve 30 and the float collar 40 both belong to the prior art. The toe-end sliding sleeve 30 is opened by pressurization to connect the internal and external channels of the cementing casing to complete the first-stage fracturing operation. Then, the entire fracturing process realizes perforation-free operation, with high completion efficiency and low development cost. The number of the fracturing sliding sleeves 10 can be determined according to the number of fracturing intervals and is not limited herein.

[0051] In still another embodiment of the present invention, a perforation-free staged fracturing method is also proposed, which is realized by using the above-mentioned cementing casing. The fracturing sliding sleeve 10 in the cementing casing includes a temporary plug 15. The method specifically includes the following steps:

[0052] S1. Lower the cementing casing to a predetermined position in the well, and perform normal cementing operations (connect the circulation pipeline and the cement injection pipeline, circulate and inject cement). The pressures on the upper and lower end faces of the internal bushing 12 reach pressure balance through the pressure transmission holes 135. The internal bushing 12 has no sliding shear force and is in a stationary state relative to the upper joint 11.

[0053] S2. In the later stage of the cementing operation, the cementing plug displaces the cement slurry into the annulus between the cementing casing and the wellbore. When passing through the internal bushing 12, the temporary plug 15 is sheared off, so that the pressure in the pipe is communicated with the pressure transmission holes 135 through the temporary plug 15.

[0054] S3. Pressurize through the wellhead to open the toe-end sliding sleeve 30, establish the first-stage internal and external communication channel of the pipe, and complete the first-stage fracturing operation.

[0055] S4. Pump the soluble bridge plug 50 into the lower joint 13 of the fracturing sliding sleeve 10 to be opened and above the temporary plug 15 in the cementing casing, and then perform wellhead pressurization, so that the pressure on the upper part of the soluble bridge plug 50 is higher than the pressure on the lower part of the soluble bridge plug 50, thereby generating a pressure difference at both ends of the internal bushing 12 in the fracturing sliding sleeve 10 to generate a downward sliding thrust. When the pressure difference reaches a certain value, the thrust generated by the pressure difference shears the shear pin 14, and the internal bushing 12 moves downward to expose the fracturing channel hole 115, establish a pressure channel, and perform a fracturing operation.

[0056] S5. Repeat step S4, open the fracturing sliding sleeves 10 in sequence from the bottom of the well to the wellhead and perform the fracturing operations for each section until the fracturing operation is completed. The soluble bridge plugs 50 at each stage automatically dissolve in the wellbore over time and do not need to be drilled out, thereby realizing perforation-free fracturing operation of the entire cementing casing, improving the completion operation effect, and achieving the purpose of reducing the development cost.

[0057] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A fracturing sliding sleeve, which is used in cooperation with a soluble bridge plug (50), and is characterized in that Comprising: An upper joint (11), wherein a plurality of fracturing channel holes (115) are circumferentially formed in the upper joint (11); A lower joint (13) sealingly connected to the upper joint (11), the lower joint (13) being inserted into the upper joint (11) and an annulus being formed between the lower joint (13) and the upper joint (11); An inner bushing (12) fixed inside the upper joint (11) by shear pins (14) and sealingly connected to the upper joint (11) for plugging the fracturing channel holes (115), the inner bushing (12) being inserted into the annulus to close the annulus; A pressure transmission hole (135) provided on the lower joint (13) to communicate the lower joint (13) and the annulus; An anti-blocking hole (136) is further formed on the lower joint (13), the anti-blocking hole (136) communicating the pressure transmission hole (135) and the inside of the lower joint (13), a temporary plug (15) being plugged in the anti-blocking hole (136), one end of the temporary plug (15) being closed and protruding from the anti-blocking hole (136), and the other end being inserted into the anti-blocking hole (136) to communicate with the pressure transmission hole (135).

2. The frac sleeve according to claim 1, wherein, The annulus is filled with a hot-melt solid.

3. The frac sleeve according to claim 1, wherein A first shoulder (114) is provided on the inner wall of the upper joint (11), and one end of the inner bushing (12) away from the lower joint (13) faces the first shoulder (114).

4. The frac sleeve according to claim 3, wherein The upper joint (11) includes an axially connected upper connecting portion (111), an upper transition portion (112) and an upper main body portion (113), the inner diameter of the upper main body portion (113) being larger than that of the upper transition portion (112) to form the first shoulder (114), the lower joint (13) includes an axially connected lower main body portion (131), a lower transition portion (132) and a lower connecting portion (133), the lower transition portion (132) and the lower main body portion (131) being inserted into the upper main body portion (113) to be connected to the upper main body portion (113), the outer diameter of the lower transition portion (132) being larger than the outer diameters of the lower connecting portion (133) and the lower main body portion (131) and forming a second shoulder (134) with the lower main body portion (131), the inner diameter of the upper transition portion (112) being the same as the inner diameter of the lower joint (13), and the length of the soluble bridge plug (50) being greater than the distance between the shoulder surface of the first shoulder (114) and the lower main body portion (131).

5. The frac sleeve according to claim 4, wherein The two orifices of the pressure transmission hole (135) are respectively formed on the inner wall of the lower transition portion (132) and the shoulder surface of the second shoulder (134).

6. The frac sleeve according to any one of claims 1-5, characterized in that, A plurality of annular grooves are provided at both axial ends of the inner bushing (12), and first sealing rings (16) are placed in the grooves to form the seal between the inner bushing (12) and the upper joint (11).

7. The fracturing sliding sleeve according to any one of claims 1-5, characterized in that, An annular groove is formed on the outer wall of one end of the lower joint (13) in contact with the inner bushing (12), and a second sealing ring (17) is placed in the groove to form the seal between the lower joint (13) and the inner bushing (12).

8. The cementing casing is characterized in that, It includes a casing (20), a toe sleeve (30), a float collar (40), and a fracturing sleeve (10) as described in any one of claims 1-7. Multiple sections of the fracturing sleeves (10) are connected to multiple sections of the casing (20) at intervals to form a casing string. The lower end of the casing string is connected to the toe sleeve (30), and the lower end of the toe sleeve (30) is connected to the float collar (40).

9. A perforation-free staged fracturing method, characterized in that, It is implemented by using the cementing casing as described in claim 8. The cementing casing includes a fracturing sleeve (10) with a temporary plug (15). The method specifically includes the following steps: S1. Lower the cementing casing to a predetermined position in the well and perform normal cementing operations; S2. In the later stage of the cementing operation, the cementing plug displaces the cement slurry into the annulus between the cementing casing and the wellbore. When passing through the internal bushing (12), the temporary plug (15) is sheared off, so that the pressure inside the pipe is communicated with the pressure transmission hole (135) through the temporary plug (15); S3. Apply pressure through the wellhead to open the toe sleeve (30), establish a communication channel between the inside and outside of the first section of the pipe, and complete the fracturing operation of the first section; S4. Pump a soluble bridge plug (50) into the lower joint (13) of the fracturing sleeve (10) to be opened in the cementing casing and above the temporary plug (15). Then apply pressure through the wellhead to make the pressure above the soluble bridge plug (50) higher than the pressure below the soluble bridge plug (50). When the pressure difference reaches a certain value, the thrust generated by the pressure difference shears the shear pin (14), and the internal bushing (12) moves downward to expose the fracturing channel hole (115), establish a pressure channel, and perform a fracturing operation; S5. Repeat step S4 to sequentially open the fracturing sleeves (10) from the bottom of the well to the wellhead and perform the fracturing operations for each section until the fracturing operation is completed.

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