A toe-end sliding sleeve and a wellbore pressure testing method

Abstract

The present invention discloses a toe-end sliding sleeve and a wellbore pressure testing method. The toe-end sliding sleeve includes: a tool body, a rupture disk, a pushing mechanism, a moving control sleeve, a sealing sleeve and a sliding sleeve; a rupture disk is arranged between the pressure transmission channel and the inner cavity of the tool body; the pushing mechanism is installed in the first installation groove of the tool body, the sealing sleeve is installed in the inner cavity, the sliding sleeve is installed in the second installation groove of the tool body, and the moving control sleeve is nested between the sealing sleeve and the sliding sleeve; in the initial state, the rupture disk seals the pressure transmission channel, and the pushing mechanism, the moving control sleeve, the sealing sleeve and the sliding sleeve cooperate with the tool body to make the inside and outside of the tool body not communicate; in the use state, when the inner cavity is pressurized, the rupture disk breaks, and the pushing mechanism pushes the moving control sleeve to move in the first direction; when the inner cavity is depressurized, the pushing mechanism resets; after at least one pressurization, the moving control sleeve is separated from the sliding sleeve, and the sliding sleeve moves in the second direction to make the inside and outside of the tool body communicate. It can meet the requirements of multiple pressure tests on the entire wellbore after cementing and before fracturing, and facilitate the construction operation.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling and completion engineering, and particularly relates to a toe-end sliding sleeve and a wellbore pressure testing method. Background Art

[0002] The toe-end sliding sleeve can effectively replace the perforation operation of the first stage of the volume fracturing of the horizontal well in the long horizontal section of oil and gas, solve the problem that it is difficult for the perforating gun in the long horizontal section of the horizontal well to reach the bottom of the well, improve the completion operation efficiency, and reduce the construction risk and development cost of the completion operation.

[0003] At present, there are already some toe-end sliding sleeves that can be used for horizontal well operations. For example, the toe-end sliding sleeves disclosed in the Chinese utility model patent with the publication number CN205189848U and the name "Fracture Disk Toe-end Cementing Fracturing Sliding Sleeve", the Chinese utility model patent with the publication number CN210660028U and the name "A Controllable Delay Opening Toe-end Sliding Sleeve", and the Chinese utility model patent with the publication number CN212428776U and the name "Toe-end Sliding Sleeve and Its Oil Well String". Summary of the Invention

[0004] The inventors of the present application found that most of the existing toe-end sliding sleeves have unstable opening pressures, and there is a risk of opening the sliding sleeve before or during the cementing construction, which brings certain risks and uncertainties to the cementing operation; or they cannot meet the requirements of full wellbore pressure testing before fracturing of oil and gas wells. For example, when the wellbore is pressure tested to a certain pressure value according to the fracturing construction design (the subsequent fracturing construction does not exceed this pressure value), the sliding sleeve cannot be opened, and the sliding sleeve opens after a certain stable time (30 minutes) of pressure testing or opens in other ways lower than the pressure testing value; or a full wellbore pressure test cannot be carried out again after a sudden failure occurs during the pressure testing process. Moreover, the existing toe-end sliding sleeves also cannot meet the requirements of full wellbore multiple pressure tests after cementing and before fracturing, which brings inconvenience and other uncertainties to judging the integrity of the wellbore after cementing and the construction operation.

[0005] In view of the above problems, the present invention is proposed to provide a toe-end sliding sleeve and a wellbore pressure testing method that overcome the above problems or at least partially solve the above problems.

[0006] An embodiment of the present invention provides a toe-end sliding sleeve, including: a tool body, a rupture disk, a pushing mechanism, a moving control sleeve, a sealing sleeve, and a sliding sleeve;

[0007] The tool body has an inner cavity, and a pressure transmission channel is provided on the side wall of the tool body. A rupture disk for sealing is arranged between the pressure transmission channel and the inner cavity; the pushing mechanism is installed in a first installation groove on the tool body, the sealing sleeve is installed in the inner cavity of the tool body, the sliding sleeve is installed in a second installation groove of the tool body, and the moving control sleeve is nested between the sealing sleeve and the sliding sleeve;

[0008] In the initial state, the rupture disc seals the pressure transmission channel, and the pushing mechanism, the moving control sleeve, the sealing sleeve and the sliding sleeve cooperate with the tool body to make the inside and outside of the tool body not communicate with each other;

[0009] In the working state, after the pressure in the inner cavity is increased to be greater than the first pressure, the rupture disc breaks, and the pressure in the inner cavity acts on the pushing mechanism through the pressure transmission channel to make it move in the first direction and push the moving control sleeve to move in the first direction; after the pressure in the inner cavity is reduced to be less than the second pressure, the pushing mechanism resets; after at least one pressurization, the moving control sleeve is separated from the sliding sleeve, and the pressure in the inner cavity acts on the sliding sleeve to make it move in the second direction, so that the tool body realizes the internal and external communication through the fracturing holes on the side wall.

[0010] In some alternative embodiments, the pressure transmission channel includes: a pressure transmission hole and a rupture disc mounting hole;

[0011] The rupture disc mounting hole communicates with the inner cavity, and the rupture disc is mounted in the rupture disc mounting hole to isolate the pressure transmission hole from the inner cavity.

[0012] In some alternative embodiments, when the rupture disc mounting hole is a through hole provided on the side wall, it further includes: a plugging screw mounted in the rupture disc mounting hole to isolate the pressure transmission channel from the external space of the tool body.

[0013] In some alternative embodiments, the pushing mechanism includes a pushing sleeve and a return spring;

[0014] The pushing sleeve is hermetically connected to the first mounting groove and the sealing sleeve to isolate the pressure transmission hole from the inner cavity;

[0015] The return spring is located in the mounting groove cavity formed by the pushing sleeve and the first mounting groove, and is compressed when the pushing sleeve moves in the first direction. After the pressure in the inner cavity is relieved, a restoring force is generated to push the pushing sleeve to reset.

[0016] In some alternative embodiments, a spring piece is provided on the pushing mechanism, and the moving control sleeve has a serrated groove; the serrated groove includes a plurality of slots, and the spring piece cooperates with one slot to push the moving control sleeve to move; after the pushing mechanism resets, the spring piece contracts and falls into the next slot of the serrated groove, so as to push the moving control sleeve to move during the next pressurization.

[0017] In some alternative embodiments, the tool body includes: an upper joint, a lower joint, and a body connecting sleeve connecting the upper joint and the lower joint;

[0018] The pressure transmission channel and the first installation groove are arranged on the upper joint;

[0019] The sliding sleeve is installed in the second installation groove formed by the body connecting sleeve and the lower joint, and is fixedly connected to the body connecting sleeve through shear pins. After the sliding sleeve moves in the second direction, it can fall into the second installation groove.

[0020] In some alternative embodiments, the body connecting sleeve is provided with fracturing holes. In the initial state, the sliding sleeve seals the fracturing holes and the inner cavity. After the sliding sleeve moves in the second direction, the inner cavity communicates with the outside of the tool body through the fracturing holes.

[0021] In some alternative embodiments, multiple groups of fracturing holes are arranged along the circumference of the body connecting sleeve, and each group includes at least one fracturing hole;

[0022] The sum of the cross-sectional areas of all the fracturing holes is greater than the cross-sectional area of the inner cavity of the tool body.

[0023] In some alternative embodiments, the upper joint is threadedly connected to the body connecting sleeve, and the lower joint is threadedly connected to the body connecting sleeve. A sealing member is provided at the threaded connection to achieve a sealed connection.

[0024] In some alternative embodiments, sealing members are provided between the pushing mechanism and the first installation groove, between the pushing mechanism and the sealing sleeve, between the sealing sleeve and the tool body, between the sealing sleeve and the movement control sleeve, between the sliding sleeve and the second installation groove, between the sliding sleeve and the tool body, and between the sliding sleeve and the movement control sleeve to achieve a sealed connection.

[0025] An embodiment of the present invention provides a wellbore pressure test method, which uses the above-mentioned toe-end sliding sleeve to perform a wellbore pressure test after cementing and before fracturing, including:

[0026] After cementing, increase the pressure to break the rupture disk, and perform multiple pressure tests on the wellbore through multiple pressurizations and pressure releases until the movement control sleeve is separated from the sliding sleeve, and the toe-end sliding sleeve is internally and externally connected, opening the fracturing channels inside and outside the casing.

[0027] In some alternative embodiments, after cementing, increase the pressure to break the rupture disk, and perform multiple pressure tests on the wellbore through multiple pressurizations and pressure releases until the movement control sleeve is separated from the sliding sleeve, and the toe-end sliding sleeve is internally and externally connected, including:

[0028] After the first pressurization in the inner cavity to a pressure greater than the first pressure, the rupture disk breaks, and the pressure in the inner cavity acts on the pushing mechanism through the pressure transmission channel to move it in the first direction. The elastic piece on the pushing mechanism cooperates with a slot position of the serrated groove on the moving control sleeve to push the moving control sleeve in the first direction;

[0029] After the pressure in the inner cavity is relieved to a pressure less than the second pressure, the pushing mechanism resets, and the elastic piece on the pushing mechanism falls into the next slot position of the moving control sleeve;

[0030] After the pressure is increased again to a pressure greater than the first pressure, the elastic piece on the pushing mechanism cooperates with the next slot position to push the moving control sleeve in the first direction;

[0031] The above processes of pressurization and pressure relief are repeated multiple times until the moving control sleeve is separated from the sliding sleeve. The pressure in the inner cavity acts on the sliding sleeve to move it in the second direction, so that the tool body realizes internal and external communication through the fracturing holes on the side wall.

[0032] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0033] The toe-end sliding sleeve provided by the embodiment of the present invention. In the initial state, the rupture disk seals the pressure transmission channel, and the pushing mechanism, the moving control sleeve, the sealing sleeve and the sliding sleeve cooperate with the tool body to make the inside and outside of the tool body not communicate; in the use state, after the pressure in the inner cavity is increased to a pressure greater than the first pressure, the rupture disk breaks, and the pressure in the inner cavity acts on the pushing mechanism through the pressure transmission channel to move it in the first direction and push the moving control sleeve in the first direction; after the pressure in the inner cavity is relieved to a pressure less than the second pressure, the pushing mechanism resets; when the pressure is increased and relieved again after the pushing mechanism resets, the above process can be repeated until the moving control sleeve is separated from the sliding sleeve, and the pressure in the inner cavity acts on the sliding sleeve to move it in the second direction, so that the tool body realizes internal and external communication through the fracturing holes on the side wall; this toe-end sliding sleeve can meet the requirements of multiple pressure tests after cementing and before fracturing. After the pressure test is completed, the inside and outside of the tool body are communicated so that fracturing construction operations can be carried out; this toe-end sliding sleeve can improve the completion operation efficiency and reduce the construction risk of the completion operation.

[0034] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written description, claims and drawings.

[0035] The technical solutions of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0036] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the accompanying drawings:

[0037] Figure 1 It is a schematic diagram of the toe-end sliding sleeve structure in the embodiment of the present invention;

[0038] Figure 2 It is a schematic diagram of the structure after the inside and outside of the toe-end sliding sleeve in the embodiment of the present invention are connected;

[0039] Figure 3 is Figure 1 an enlarged view of part A in

[0040] Figure 4 It is a flow chart of the wellbore pressure test method in the embodiment of the present invention.

[0041] Explanation of reference numerals:

[0042] 1 - tool body, 2 - rupture disk, 3 - pushing mechanism, 4 - moving control sleeve, 5 - sealing sleeve, 6 - sliding sleeve, 7 - pressure transmission channel, 8 - plugging nut, 9 - shear pin;

[0043] 11 - upper joint of tool body, 12 - connecting sleeve of tool body, 13 - lower joint of tool body, 14 - first installation groove, 15 - second installation groove, 16 - fracturing hole;

[0044] 31 - pushing sleeve, 32 - return spring, 33 - elastic piece;

[0045] 41 - serrated groove;

[0046] 71 - pressure transmission hole, 72 - rupture disk installation hole. Detailed implementation manners

[0047] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0048] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0049] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. 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.

[0050] In order to solve the problem that the toe-end sliding sleeve in the prior art cannot meet the requirement of multiple full-wellbore pressure tests before fracturing after cementing, an embodiment of the present invention provides a full-wellbore pressure-testable toe-end sliding sleeve that can adapt to casing cementing and meet the requirements of multiple full-wellbore pressure tests.

[0051] An embodiment of the present invention provides a toe-end sliding sleeve, the structure of which is as Figure 1 and Figure 2 shown, where Figure 1 is a schematic diagram of the initial state of the toe-end sliding sleeve, Figure 2 is a schematic diagram of the structure after internal and external communication in the toe-end sliding sleeve, Figure 1 and Figure 2 are both half-sectional views. The toe-end sliding sleeve includes: a tool body 1, a rupture disk 2, a pushing mechanism 3, a moving control sleeve 4, a sealing sleeve 5, and a sliding sleeve 6.

[0052] The tool body 1 has an inner cavity, and a pressure transmission channel 7 is provided on the side wall of the tool body 1. A rupture disk 2 for sealing is arranged between the pressure transmission channel 7 and the inner cavity; the pushing mechanism 3 is installed in the first installation groove 14 on the tool body 1, the sealing sleeve 5 is installed in the inner cavity of the tool body 1, the sliding sleeve 6 is installed in the second installation groove 15 of the tool body 1, and the moving control sleeve 4 is nested inside the sealing sleeve 5 and the sliding sleeve 6;

[0053] In the initial state, the rupture disk 2 seals the pressure transmission channel 7, and the pushing mechanism 3, the moving control sleeve 4, the sealing sleeve 5, and the sliding sleeve 6 cooperate with the tool body 1 to make the inside and outside of the tool body 1 not communicate;

[0054] In the state of use, after the pressure in the inner cavity is increased to be greater than the first pressure, the rupture disc 2 breaks, and the pressure in the inner cavity acts on the pushing mechanism 3 through the pressure transmission channel 7 to make it move in the first direction and push the moving control sleeve 4 to move in the first direction; after the pressure in the inner cavity is relieved to be less than the second pressure, the pushing mechanism 3 resets; after at least one pressurization, the moving control sleeve 4 is separated from the sliding sleeve 6, and the pressure in the inner cavity acts on the sliding sleeve 6 to make it move in the second direction, so that the tool body 1 is communicated inside and outside through the fracturing holes 16 on the side wall.

[0055] In the above-mentioned toe-end sliding sleeve, during the cementing operation, the rupture disc does not break, and the pressure in the wellbore does not act on the pushing mechanism. After the cementing operation, the pressure is increased to break the rupture disc. The pressure in the inner cavity of the tool body acts on the pushing mechanism and pushes the moving control sleeve to move a certain distance. After the pressure is relieved, the pushing mechanism resets. After the pressure is increased again, the pushing mechanism pushes the moving control sleeve to move a certain distance again. After multiple pressurization and pressure relief experiments, the moving control sleeve is separated from the sliding sleeve, and the pressure in the inner cavity acts on the sliding sleeve to make it move in the second direction, so that the inside and outside of the tool body are communicated to establish a fracturing channel for fracturing operations; this toe-end sliding sleeve can meet the requirement of performing multiple full-wellbore pressure tests after cementing and before fracturing in horizontal wells with long horizontal sections of oil and gas, and can automatically open the sliding sleeve to establish a fracturing channel inside and outside the casing after the wellbore pressure test is qualified, without the need for casing perforation operations, and then the first-stage fracturing can be carried out, improving the completion operation efficiency and reducing the completion construction risk.

[0056] In some alternative embodiments, the above-mentioned pressure transmission channel 7 includes: a pressure transmission hole 71 and a rupture disc installation hole 72; the rupture disc installation hole 72 is communicated with the inner cavity, and the rupture disc 2 is installed in the rupture disc installation hole 72 to isolate the pressure transmission hole 71 from the inner cavity. When the rupture disc installation hole 72 is a through hole provided on the side wall, it further includes: a plugging screw 8 installed in the rupture disc installation hole 72 to isolate the pressure transmission channel 7 from the external space of the tool body.

[0057] As Figure 1 and Figure 2 shown, the pressure transmission hole 71 is a long hole arranged parallel to the axis of the tool body 1, and the rupture disc installation hole 72 is a hole perpendicular to the axis of the tool body. The diameter of its distal end communicated with the inner cavity is smaller, and the diameter of the end far from the inner cavity is larger. The rupture disc 2 is installed in the middle part of the rupture disc installation hole 72 to block the pressure transmission hole 71, so that the pressure transmission hole 71 and the inner cavity are not communicated and are communicated again after the rupture disc 2 breaks; in order to prevent the inner cavity pressure from leaking out after communication, a plugging nut 8 is used for plugging. Optionally, the rupture disc installation hole 72 may not be designed as the structure shown in the figure. The rupture disc installation hole 72 may not be a through hole but a blind hole, and in this case, no plugging nut is required. Optionally, multiple pressure transmission channels may be provided along the circumferential direction.

[0058] In some alternative embodiments, the pushing mechanism 3 includes a pushing sleeve 31 and a return spring 32; the pushing sleeve 31 is sealingly connected to the first mounting groove 14 and the sealing sleeve 5 to isolate the pressure transmission hole 71 from the inner cavity; the return spring 32 is located in the mounting cavity formed by the pushing sleeve 31 and the first mounting groove 14 and is compressed when the pushing sleeve 31 moves in the first direction. After the inner cavity is depressurized, a restoring force is generated to push the pushing sleeve 31 back to its original position.

[0059] Optionally, a spring piece is provided on the pushing mechanism 3, and the moving control sleeve 4 has a serrated groove 41; the serrated groove 41 includes a plurality of slots, and the spring piece cooperates with one slot to push the moving control sleeve 4 to move; after the pushing mechanism 3 is reset, the spring piece 33 contracts and falls into the next slot of the serrated groove 41 so as to push the moving control sleeve 4 to move during the next pressurization.

[0060] During each pressurization, the pushing mechanism 3 pushes the moving control sleeve 4 to move a certain distance. During each depressurization, the pushing mechanism 3 resets, and the moving control sleeve 4 remains in the position after being pushed. During the next pressurization, the pushing mechanism 3 pushes the moving control sleeve 4 to move a certain distance again. The moving distance of the moving control sleeve 4 each time and the total movable distance can be designed according to the number of times of pressurization and depressurization tests required. The pushing mechanism 3 can adopt the structure of the pushing sleeve 31 and the return spring 32 as shown in the figure to achieve pushing and resetting, or other structures can also be adopted. For example, it can be achieved by the cooperation of a pushing sleeve and a return spring piece. In short, as long as pushing and resetting can be achieved. The serrated groove 41 on the moving control sleeve 4 is not limited to the form shown in the figure, as long as the cooperation between the pushing mechanism 3 and the moving control sleeve 4 can be achieved and pushing can be performed multiple times.

[0061] In some alternative embodiments, the tool body 1 includes: an upper sub 11, a lower sub 13, and a body connecting sleeve 12 connecting the upper sub 11 and the lower sub 13; a pressure transmission channel 7 and a first mounting groove 14 are provided on the upper sub 1; a sliding sleeve 6 is installed in a second mounting groove 15 formed by the body connecting sleeve 12 and the lower sub 13 and is fixedly connected to the body connecting sleeve 12 through a shear pin 9. After the sliding sleeve 6 moves in the second direction, it can fall into the second mounting groove 15.

[0062] The upper sub 11, the body connecting sleeve 12 and the lower sub 13 can be connected to form the tool body in a sealing connection manner, so that the tool body forms a sealable inner cavity. The sealing connection manner is not limited. For example: the upper sub 11 and the body connecting sleeve 12 are threadedly connected, and the lower sub 13 and the body connecting sleeve 12 are threadedly connected, and a sealing member is provided at the threaded connection to achieve a sealing connection. Of course, other connection methods can also be adopted, as long as a sealed inner cavity can be formed after the tool body is connected to the casing.

[0063] Optionally, the body connecting sleeve 12 is provided with fracturing holes 16. In the initial state, the sliding sleeve 6 seals off the fracturing holes 16 from the inner cavity. After the sliding sleeve 6 moves in the second direction, the inner cavity communicates with the outside of the tool body 1 through the fracturing holes 16. Multiple groups of fracturing holes 16 are arranged along the circumference of the body connecting sleeve 12, and each group includes at least one fracturing hole; the sum of the cross-sectional areas of all the fracturing holes is greater than the cross-sectional area of the inner cavity of the tool body 1. As Figure 1 and Figure 2 shown, each group includes 3 fracturing holes, and multiple groups are distributed along the circumference of the body connecting sleeve 12; the cross-sectional area of the fracturing hole represents the flow-through area of the fracturing hole, and the cross-sectional area of the inner cavity of the tool body 1 represents the flow-through area of the tool body. The sum of the cross-sectional areas of all the fracturing holes is greater than the cross-sectional area of the inner cavity of the tool body 1 so that the fluid flowing through the inner cavity can flow out of the fracturing holes without any blockage, avoiding stagnation. Preferably, the cross-sectional area of the inner cavity can be the cross-sectional area at the maximum diameter of the inner cavity.

[0064] For the above-mentioned toe-end sliding sleeve, seals are provided between the pushing mechanism 3 and the first installation groove 14, between the pushing mechanism 3 and the sealing sleeve 5, between the sealing sleeve 5 and the tool body 1, between the sealing sleeve 5 and the movement control sleeve 4, between the sliding sleeve 6 and the second installation groove 15, between the sliding sleeve 6 and the tool body 1, and between the sliding sleeve 6 and the movement control sleeve 4 to achieve sealed connection. The seals can be arranged in seal installation grooves, and one or more seal installation grooves can be provided between two components to be sealed for installing the seals. The seals can be O-rings. One or more O-rings can be arranged in one O-ring installation groove. In the seal installation groove, only O-rings can be installed to achieve sealing, or a sealing washer + O-ring + sealing washer can be installed to achieve sealing.

[0065] See Figure 1 、 Figure 2 and Figure 3A specific toe-end sliding sleeve structure is shown. This full-wellbore testable toe-end sliding sleeve includes an upper joint 11, a plugging nut 8, a rupture disc 2, a return spring 32, a push sleeve 31, a connecting sleeve 12, a sealing sleeve 5, a moving control sleeve 4, a sliding sleeve 6, a lower joint 13, etc. The upper joint 11 is designed with a rupture disc installation hole 72, and a pressure transmission hole 71 is designed inside the pipe wall to be docked with the rupture disc installation hole 72. There are the rupture disc installation hole 72, the return spring 32, and a first installation groove for installing the push sleeve, etc.; The connecting sleeve 12 is circumferentially and evenly designed with fracturing holes 16, and the connecting sleeve 12 is connected to the upper joint 11 and the lower joint 13 through threads at both ends; The push sleeve 31 is designed with radially deformable elastic pieces 33, and the push sleeve 31 and the return spring 32 are installed in the first installation groove of the upper joint 11; A matching moving control sleeve 4 is installed inside the push sleeve 31. The upper half of the moving control sleeve 4 is designed with serrated grooves 41 matching the elastic pieces 33, which is convenient for the push sleeve 31 to drive the moving control sleeve 4 to move when the push sleeve 31 moves. A sealing sleeve 5 is installed between the moving control sleeve 4 and the connecting sleeve 12 to seal the moving control sleeve 4 and form a hydraulic cavity with the push sleeve 31, so that the push sleeve 31 is pushed under hydraulic action to generate power; The sliding sleeve 6 is installed between the moving control sleeve 4 and the connecting sleeve 12 and at the lower end face of the sealing sleeve 5. When the lower end face of the moving control sleeve 4 moves to the upper end face of the sliding sleeve 6 through the push sleeve 31, the sliding sleeve 6 is opened, and the sliding sleeve 6, the lower joint 13, and the connecting sleeve 12 form a closed air cavity.

[0066] The toe-end sliding sleeve provided by the embodiment of the present invention is mainly used for the first-stage perforation-free operation of the volume fracturing of the horizontal well in the long horizontal section of oil and gas, providing full-wellbore pressure testing for the first-stage fracturing of the horizontal well in the long horizontal section of oil and gas and establishing a fracturing channel between the inside of the casing and the formation for the first-stage perforation-free fracturing operation, improving the completion operation efficiency and reducing the construction risk of the completion operation.

[0067] The embodiment of the present invention provides a wellbore pressure testing method, which uses the above-mentioned toe-end sliding sleeve to realize the wellbore pressure testing after cementing and before fracturing. The process is as Figure 3 shown, including the following steps:

[0068] Step S101: After cementing, increase the pressure to break the rupture disc.

[0069] Step S102: Perform multiple pressure tests on the wellbore by increasing and releasing the pressure multiple times.

[0070] Step S103: Until the moving control sleeve is separated from the sliding sleeve, the inside and outside of the toe-end sliding sleeve are connected, and the fracturing channel inside and outside the casing is opened.

[0071] In the above method, after the pressure in the inner cavity is increased for the first time to be greater than the first pressure, the rupture disk breaks, and the pressure in the inner cavity acts on the pushing mechanism through the pressure transmission channel to make it move in the first direction. The elastic piece on the pushing mechanism cooperates with a slot position of the serrated groove on the moving control sleeve to push the moving control sleeve to move in the first direction; after the pressure in the inner cavity is relieved to be less than the second pressure, the pushing mechanism resets, and the elastic piece on the pushing mechanism falls into the next slot of the moving control sleeve; after the pressure is increased again to be greater than the first pressure, the elastic piece on the pushing mechanism cooperates with the next slot to push the moving control sleeve to move in the first direction; the above processes of pressure increase and pressure relief are repeated multiple times until the moving control sleeve is separated from the sliding sleeve, and the pressure in the inner cavity acts on the sliding sleeve to make it move in the second direction, so that the tool body realizes internal and external communication through the fracturing holes on the side wall.

[0072] During actual use, connect the toe-end sliding sleeve to the cementing casing string according to the design requirements and lower it to the predetermined position to provide temporary plugging for the string and perform normal cementing operations. During the cementing operation, the sum of the wellhead pump pressure and the hydrostatic pressure at the position of the toe-end sliding sleeve that can be pressure-tested in the whole wellbore should be less than the rupture pressure value of the rupture disk, that is, the pressure in the inner cavity of the toe-end sliding sleeve is less than the rupture pressure value of the rupture disk, and the rupture disk will not break; after the cementing operation, wait for the cement to completely solidify and reach the design strength. When waiting for the fracturing construction, normally connect the fracturing wellhead and the fracturing truck, and pressure-test the surface pipeline to the design value; after the wellhead is depressurized, open the wellhead valve to connect the fracturing truck to the wellbore through the surface pipeline, and pressure-test to the design pressure value of the whole wellbore through the fracturing truck. The sum of the pressure-test value and the hydrostatic pressure at the position of the toe-end sliding sleeve that can be pressure-tested in the whole wellbore is greater than the rupture pressure value of the rupture disk, that is, the pressure in the inner cavity of the toe-end sliding sleeve is greater than the rupture pressure value of the rupture disk, and the rupture disk breaks. At this time, the rupture disk 2 in the toe-end sliding sleeve that can be pressure-tested in the whole wellbore breaks, and the hydraulic pressure in the wellbore is transmitted through the rupture disk 2 and the pressure transmission hole 71 to the lower end surface ( Figure 1 the right end surface in the middle) of the pushing sleeve 31, causing a hydraulic pressure difference between the upper and lower end surfaces of the pushing sleeve 31 to move upward and compress the return spring 32, and pushing the moving control sleeve 4 to move up a stroke distance through the elastic piece 33. After the whole wellbore pressure test meets the pressure test time of 30 minutes, the wellhead is depressurized, the pressure in the casing string decreases, the pressure in the pressure transmission hole 71 decreases with the pressure in the casing string, and the return spring 32 pushes the pushing sleeve 31 to move downward. When moving downward, the elastic piece 33 contracts into the second tooth groove of the serrated groove on the moving control sleeve 4; pressurize the wellhead again, and the pressure is transmitted through the pressure transmission hole 71 to the lower end surface of the pushing sleeve 31, so that the pushing sleeve 31 pushes the moving control sleeve 4 to move up a stroke distance again through the elastic piece 33. Repeat the wellhead pressurization and depressurization in this way until the lower end surface of the moving control sleeve 4 moves to the upper end surface position of the sliding sleeve 6, the seal between the original moving control sleeve 4 and the sliding sleeve 6 fails, the hydraulic pressure in the pipe is transmitted to the upper end surface of the sliding sleeve 6, causing a hydraulic pressure difference between the upper and lower end surfaces of the sliding sleeve 6, and moving downward, so that the tool opens, the fracturing holes are leaked, and a communication channel between the inside and outside of the pipe is established, as Figure 2 shown in the state, and normal first-stage fracturing construction operations are carried out.

[0073] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy recited.

[0074] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention lies in less than the full scope of the features of the single disclosed embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0075] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but one of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Accordingly, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, this word is intended to be inclusive in a manner similar to the term "including" as interpreted when used as a transitional word in a claim. Further, any use of the term "or" in the claims or specification is intended to mean "non-exclusive or".

Claims

1. A toe-end sliding sleeve, characterized in that, Comprising: A tool body, a rupture disc, a pushing mechanism, a moving control sleeve, a sealing sleeve, and a sliding sleeve; The tool body has an inner cavity, and a pressure transmission channel is provided on the side wall of the tool body. A rupture disc for sealing is arranged between the pressure transmission channel and the inner cavity; the pushing mechanism is installed in a first installation groove on the tool body, the sealing sleeve is installed in the inner cavity of the tool body, the sliding sleeve is installed in a second installation groove of the tool body, and the moving control sleeve is nested within the sealing sleeve and the sliding sleeve; In the initial state, the rupture disc seals the pressure transmission channel, and the pushing mechanism, the moving control sleeve, the sealing sleeve, and the sliding sleeve cooperate with the tool body to make the inside and outside of the tool body not communicate; In the working state, after the pressure in the inner cavity increases to be greater than a first pressure, the rupture disc breaks, and the pressure in the inner cavity acts on the pushing mechanism through the pressure transmission channel to make it move in a first direction and push the moving control sleeve to move in the first direction; after the pressure in the inner cavity decreases to be less than a second pressure, the pushing mechanism resets; after multiple pressurizations, the moving control sleeve is separated from the sliding sleeve, and the pressure in the inner cavity acts on the sliding sleeve to make it move in a second direction, so that the tool body realizes internal and external communication through the fracturing holes on the side wall; the first direction is the direction of the upper joint of the tool body, and the second direction is the direction of the lower joint of the tool body; The pushing mechanism is provided with a spring piece, and the moving control sleeve has a serrated groove; the serrated groove includes a number of slots, and the spring piece cooperates with one slot to push the moving control sleeve to move; after the pushing mechanism resets, the spring piece contracts and falls into the next slot of the serrated groove, so as to push the moving control sleeve to move during the next pressurization.

2. The toe-end sliding sleeve according to claim 1, characterized in that, The pressure transmission channel includes: a pressure transmission hole and a rupture disc installation hole; The rupture disc installation hole communicates with the inner cavity, and the rupture disc is installed in the rupture disc installation hole to isolate the pressure transmission hole from the inner cavity.

3. The toe-end sliding sleeve according to claim 2, characterized in that, When the rupture disc installation hole is a through hole provided on the side wall, it further includes: a plugging screw installed in the rupture disc installation hole to isolate the pressure transmission channel from the external space of the tool body.

4. The toe-end sliding sleeve according to claim 1, wherein, The pushing mechanism includes a pushing sleeve and a return spring; The pushing sleeve is hermetically connected to the first installation groove and the sealing sleeve to isolate the pressure transmission hole from the inner cavity; The return spring is located in the installation cavity formed by the pushing sleeve and the first installation groove, and is compressed when the pushing sleeve moves in the first direction. After the pressure in the inner cavity is relieved, a restoring force is generated to push the pushing sleeve to reset.

5. The toe-end sliding sleeve according to claim 1, characterized in that, The tool body includes: an upper joint, a lower joint, and a body connecting sleeve connecting the upper joint and the lower joint; The pressure transmission channel and the first installation groove are provided on the upper joint; The sliding sleeve is installed in a second installation groove formed by the body connecting sleeve and the lower joint, and is fixedly connected to the body connecting sleeve through a shear pin. After the sliding sleeve moves in the second direction, it can fall into the second installation groove.

6. The toe-end sliding sleeve according to claim 1, wherein The body connecting sleeve is provided with fracturing holes. In the initial state, the sliding sleeve seals off the fracturing holes from the inner cavity. After the sliding sleeve moves in the second direction, the inner cavity communicates with the outside of the tool body through the fracturing holes.

7. The toe-end sliding sleeve according to claim 5, characterized in that, Multiple groups of the fracturing holes are arranged along the circumference of the body connecting sleeve, and each group includes at least one fracturing hole; The sum of the cross-sectional areas of all the fracturing holes is greater than the cross-sectional area of the inner cavity of the tool body.

8. The toe-end sliding sleeve according to claim 5, characterized in that, The upper joint is threadedly connected to the body connecting sleeve, and the lower joint is threadedly connected to the body connecting sleeve. A seal is provided at the threaded connection to achieve a sealed connection.

9. The toe-end sliding sleeve according to any one of claims 1-8, characterized in that, Seals are provided between the pushing mechanism and the first installation groove, between the pushing mechanism and the sealing sleeve, between the sealing sleeve and the tool body, between the sealing sleeve and the movement control sleeve, between the sliding sleeve and the second installation groove, between the sliding sleeve and the tool body, and between the sliding sleeve and the movement control sleeve to achieve a sealed connection.

10. A wellbore pressure test method, characterized in that, Using the toe-end sliding sleeve as described in any one of claims 1-6 to perform a wellbore pressure test after cementing and before fracturing, includes: After cementing, increasing the pressure to break the rupture disc, and performing multiple pressure tests on the wellbore by repeatedly increasing and releasing the pressure until the movement control sleeve is separated from the sliding sleeve, and the inside and outside of the toe-end sliding sleeve are communicated, opening the fracturing channels inside and outside the casing.

11. The method according to claim 10, wherein After the cementing, increasing the pressure to break the rupture disc, and performing multiple pressure tests on the wellbore by repeatedly increasing and releasing the pressure until the movement control sleeve is separated from the sliding sleeve, and the inside and outside of the toe-end sliding sleeve are communicated, includes: After the pressure in the inner cavity is first increased to be greater than the first pressure, the rupture disc breaks, and the pressure in the inner cavity acts on the pushing mechanism through the pressure transmission channel to make it move in the first direction. The elastic piece on the pushing mechanism cooperates with a slot position of the serrated groove on the movement control sleeve to push the movement control sleeve in the first direction; After the pressure in the inner cavity is released to be less than the second pressure, the pushing mechanism resets, and the elastic piece on the pushing mechanism falls into the next slot position of the movement control sleeve; After the pressure is increased again to be greater than the first pressure, the elastic piece on the pushing mechanism cooperates with the next slot position to push the movement control sleeve in the first direction; The above processes of increasing and releasing the pressure are repeated multiple times until the movement control sleeve is separated from the sliding sleeve, and the pressure in the inner cavity acts on the sliding sleeve to make it move in the second direction, so that the tool body is communicated inside and outside through the fracturing holes on the side wall.

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