Safety connector

Abstract

The present invention provides a safety joint, including a lower joint, a lower joint and an annular piston, wherein the upper end face of the lower joint has an annular protrusion, and the annular protrusion has a first flow hole; the upper joint and the lower joint are connected by a first pin, the lower end face of the upper joint has an annular groove, the groove wall of the annular groove cooperates with the outer wall of the lower joint to form an annular cavity, the annular protrusion is located in the annular cavity, the groove wall of the annular groove has an opening hole and two second flow holes, and the two second flow holes are opposite to the first flow hole; the annular piston is located between the annular protrusion and the groove wall of the annular groove, and the annular piston can move from a closed position to an open position under the pressure of the fluid injected from the opening hole, the closed position is a position to separate the first flow hole and the second flow hole, and the open position is a position to conduct the first flow hole and the second flow hole. The present invention can flush impurities such as mud sediment in the annulus out of the well when the drill is stuck or buried, so as to facilitate the rapid release of the safety joint.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development engineering, and in particular to a safety joint. Background Art

[0002] As natural gas exploration continues to break through in the ultra-deep well field, the operating depth and reservoir temperature have increased, and the difficulty of oil and gas development has become increasingly greater. During the development of oil and gas fields, when the acidizing pipe string is tripped and lowered, mud precipitation and well-killing solid particles often block the annulus, and the acidizing pipe string often causes the drill bit to get stuck or buried. Usually, a safety joint is installed at the bottom of the drill pipe. The safety joint is a tool used to disconnect the drill pipe from the safety joint when the drill bit is stuck or buried, so as to remove part of the drill pipe from the well.

[0003] The safety joint in the related art includes an upper joint and a lower joint, the lower joint is inserted into the inner hole of the upper joint, and the upper joint and the lower joint are connected by a pin. When the safety joint needs to be activated, the drill pipe needs to be lifted up and down at the wellhead and the drill pipe needs to be rotated so that the pin between the upper joint and the lower joint is cut, so that the drill pipe can be taken out of the well.

[0004] However, after the drill is stuck or buried, if the drill is left idle for a long time, the mud in the annulus between the drill pipe and casing, the safety joint and the casing will not circulate for a long time, resulting in mud sedimentation and cementation, which will cause the torque and lifting force to be unable to be transmitted to the safety joint, resulting in failure of the safety joint. Summary of the invention

[0005] The disclosed embodiment provides a safety joint, which can flush mud sediment and other impurities in the annulus out of the well when the drill is stuck or buried, so as to facilitate the rapid release of the safety joint to raise and lower the drill pipe. The technical solution is as follows:

[0006] The disclosed embodiment provides a safety joint, which comprises: a lower joint, wherein the upper end surface of the lower joint has an axially extending annular protrusion, and the annular protrusion has a first flow hole radially penetrating the annular protrusion; an upper joint, wherein the upper joint and the lower joint are connected by a radially arranged first pin, and the lower end surface of the upper joint has an axially extending annular groove, and the groove wall of the annular groove cooperates with the outer wall of the lower joint to form a sealed annular cavity, wherein the annular protrusion is located in the annular cavity, and the groove wall of the annular groove has a radially extending opening hole and two second flow holes, and the two second flow holes and the first flow hole are radially opposite; an annular piston, which is located in the annular cavity and radially between the annular protrusion and the groove wall of the annular groove, and the annular piston is configured to move from a closed position to an open position under the pressure of the fluid injected from the open hole, wherein the closed position is a position for isolating the first flow hole and the second flow hole, and the open position is a position for connecting the first flow hole and the second flow hole.

[0007] In one implementation of the embodiment of the present disclosure, the inner wall of the annular protrusion is sealed with a groove wall of the annular groove; the annular piston is located between the outer wall of the annular protrusion and the other groove wall of the annular groove, and the inner wall and the outer wall are two radially opposite walls of the annular protrusion; the annular piston located in the closed position divides the annular cavity into a first cavity and a second cavity, and the opening hole is connected to the second cavity.

[0008] In another implementation of the embodiment of the present disclosure, the annular piston is threadedly connected to the groove wall of the annular groove or the outer wall of the annular protrusion; the safety joint also includes an impeller, which is located in the second cavity, and the impeller is coaxially arranged with the annular piston and spaced apart, and the impeller is circumferentially fixedly connected to the annular piston, and the impeller is located between the opening hole and the annular piston in the axial direction of the upper joint.

[0009] In another implementation of the embodiment of the present disclosure, the annular piston and the impeller are connected by a connecting frame, the impeller includes a rotating ring and rotating blades circumferentially arranged on the outer wall of the rotating ring, and the connecting frame includes a plurality of connecting rods arranged circumferentially at intervals, one end of the connecting rod is connected to one end of the rotating ring, and the other end of the connecting rod is connected to one end of the annular piston.

[0010] In another implementation of the embodiment of the present disclosure, the safety joint also includes a torsion spring, which is located in the first cavity and is mounted outside the annular protrusion. The torsion spring is located between the annular piston and the upper end surface of the lower joint, one end of the torsion spring is circumferentially fixed to one end of the annular piston, and the other end of the torsion spring is circumferentially fixed to the annular protrusion.

[0011] In another implementation of the embodiment of the present disclosure, the annular piston is slidably and sealingly connected to the groove wall of the annular groove and the outer side wall of the annular protrusion; the safety joint also includes a compression spring, which is located in the first cavity and is sleeved outside the annular protrusion, and the compression spring is located between the annular piston and the upper end surface of the lower joint, one end of the compression spring is abutted against one end of the annular piston, and the other end of the compression spring is axially fixed to the annular protrusion.

[0012] In another implementation of the embodiment of the present disclosure, two axially spaced annular grooves are provided on the inner wall and the outer wall of the annular piston, and a sealing ring is provided in the annular groove. When the annular piston is in the closed position, the two annular grooves are located on both sides of the first flow hole.

[0013] In another implementation of the embodiment of the present disclosure, the annular protrusion is connected to the groove wall of the annular groove through the first pin.

[0014] In another implementation of the embodiment of the present disclosure, the annular piston is connected to the annular groove via a second pin.

[0015] In another implementation of the embodiment of the present disclosure, a rupture disk is provided in the opening.

[0016] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:

[0017] In the safety joint provided by the embodiment of the present disclosure, an annular piston is arranged in the sealed annular cavity formed by the plug-in cooperation of the upper joint and the lower joint, and the annular piston and the annular protrusion and the annular piston and the annular groove are sealed and cooperated, so that in the initial state, the annular piston can block the first flow hole and the second flow hole, thereby preventing the liquid outside the safety joint or the liquid flow hole inside the safety joint from leaking. If the drill rod is stuck or buried during the construction process, and mud precipitation occurs in the annulus between the safety joint and the casing, at this time, the annulus between the drill rod and the casing can be pressurized by injecting liquid from the wellhead. When the liquid reaches the safety joint, it enters the annular cavity through the opening hole and pushes the annular piston located in the annular cavity to move, so that the annular piston reveals the first flow hole and the second flow hole, so as to conduct the two flow holes, that is, the liquid in the annulus can enter the safety joint through the two flow holes. In this way, after the mud in the annulus is cleaned, the liquid in the annulus can enter the safety joint with the mud, and return to the wellhead through the drill rod to complete the well washing operation. At this point, there is no more mud sediment in the annulus of the drill pipe, safety joint and casing. Therefore, when the technicians manipulate the drill pipe to lift and rotate it up and down at the wellhead, the lifting force and torque can be easily transmitted to the safety joint to ensure that the safety joint can be quickly unfastened and the drill pipe can be removed to avoid economic losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a schematic diagram of a blocking state of a safety joint provided by an embodiment of the present disclosure;

[0020] Figure 2 is a schematic diagram of an open state of a safety joint provided by an embodiment of the present disclosure;

[0021] Figure 3 is a schematic structural diagram of a safety joint provided by an embodiment of the present disclosure;

[0022] Figure 4 It is a structural schematic diagram of a safety joint provided in an embodiment of the present disclosure.

[0023] The descriptions of the symbols in the figure are as follows:

[0024] 1-upper joint, 10-annular groove, 11-second flow hole, 12-opening hole;

[0025] 2-lower joint, 21-annular protrusion, 22-first flow hole;

[0026] 30-annular piston, 31-impeller, 311-rotating ring, 312-rotating blade, 32-connecting frame, 33-torsion spring, 34-sealing ring, 35-compression spring;

[0027] 41-first pin, 42-second pin, 43-rupture disk;

[0028] 5- annular cavity, 51- first cavity, 52- second cavity. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0030] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", "top", "bottom" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0031] Figure 1 Schematic diagram of a blocking state of a safety joint provided by an embodiment of the present disclosure. Figure 1 As shown, the safety joint comprises: an upper joint 1 , a lower joint 2 and an annular piston 30 .

[0032] like Figure 1 As shown, the upper end surface of the lower joint 2 has an axially extending annular protrusion 21 , and the annular protrusion 21 has a first flow hole 22 radially penetrating the annular protrusion 21 .

[0033] like Figure 1As shown, the upper joint 1 and the lower joint 2 are connected by a radially arranged first pin 41, the lower end face of the upper joint 1 has an axially extending annular groove 10, the groove wall of the annular groove 10 cooperates with the outer wall of the lower joint 2 to form a sealed annular cavity 5, the annular protrusion 21 is located in the annular cavity 5, the groove wall of the annular groove 10 has a radially extending opening hole 12 and two second flow holes 11, and the two second flow holes 11 and the first flow hole 22 are radially opposite.

[0034] like Figure 1 As shown, the annular piston 30 is located in the annular chamber 5 and radially between the annular projection 21 and the groove wall of the annular groove 10 .

[0035] Figure 2 Schematic diagram of the opening state of a safety joint provided by an embodiment of the present disclosure. Figure 1 , 2 As shown, the annular piston 30 is configured to move from a closed position to an open position under the fluid pressure injected from the opening hole 12, the closed position is a position that separates the first flow hole 22 and the second flow hole 11, and the open position is a position that connects the first flow hole 22 and the second flow hole 11.

[0036] The safety joint provided by the embodiment of the present disclosure includes an upper joint 1, a lower joint 2 and an annular piston 30, wherein the annular protrusion 21 on the upper end face of the lower joint 2 is coaxially inserted into the annular groove 10 on the lower end face of the upper joint 1, and the upper joint 1 and the lower joint 2 are connected by a first pin 41. In addition, the upper joint 1 has two second flow holes 11 on the groove wall of the annular groove 10 that passes through the upper joint 1, and at the same time, the lower joint 2 also has a first flow hole 22 that passes through the annular protrusion 21 of the lower joint 2. The first flow hole 22 and the second flow hole 11 are opposite in the radial direction, so the liquid outside the safety joint can enter the interior of the safety joint through the second flow hole 11, the annular groove 10, the second flow hole 11, and the first flow hole 22 in sequence. An axially movable annular piston 30 is also provided between the annular protrusion 21 and the groove wall of the annular groove 10. The annular piston 30 separates the first flow hole 22 and the second flow hole 11 when in the open position, and the annular piston 30 is sealed with the annular protrusion 21 and the annular groove 10, that is, the annular piston 30 will not move easily in the annular groove 10 without the action of external force, thereby preventing the liquid outside the safety joint or the liquid inside the safety joint from leaking out of the flow hole.

[0037] If the drill pipe is stuck or buried during the construction process, and mud is deposited in the annulus of the safety joint and the casing. At this time, the annulus between the drill pipe and the casing is pressurized by injecting liquid from the wellhead. When the liquid reaches the safety joint, it enters the annular groove 10 through the opening hole 12, and pushes the annular piston 30 located in the annular groove 10 to move downward, so that the annular piston 30 reveals the second flow hole 11 and the first flow hole 22 to connect the two flow holes, that is, the liquid in the annulus can enter the safety joint through the two flow holes. In this way, after the liquid in the annulus has cleaned the mud in the annulus, it can carry the mud into the safety joint together, and return to the wellhead through the drill pipe to complete the well washing operation. At this time, there is no more mud deposited in the annulus of the drill pipe, safety joint and casing. Therefore, when the technicians manipulate the drill pipe to lift and rotate it up and down at the wellhead, the lifting force and torque can be easily transmitted to the safety joint to ensure that the safety joint can be quickly unfastened and the drill pipe can be removed to avoid economic losses.

[0038] Alternatively, if Figure 1 As shown, a rupture disk 43 is provided in the opening hole 12. The rupture disk 43 is a tool that ruptures automatically when the pressure exceeds the limit pressure to achieve pressure relief. By providing the rupture disk 43 in the opening hole 12, it is prevented that the liquid in the annular space easily enters the annular groove 10, causing the annular piston 30 to slide accidentally, thereby causing the two flow holes of the safety structure to be connected, thereby preventing the safety joint from releasing pressure.

[0039] The rupture disk 43 is a disk-shaped structure with a spherical inner and outer surface. The peripheral edge of the rupture disk 43 is connected to the inner wall of the opening hole 12 to fix the rupture disk 43 in the opening hole 12. The convex surface of the rupture disk 43 faces the annulus between the casing and the safety joint, so that the rupture disk 43 can withstand greater pressure. When in use, the annulus between the safety joint and the casing is pressurized by injecting liquid from the wellhead. When the pressure in the annulus exceeds the pressure limit of the rupture disk 43, the rupture disk 43 is broken, so that the liquid in the annulus can enter the annular groove 10 through the opening hole 12.

[0040] Alternatively, if Figure 1 As shown, the annular protrusion 21 is connected to the groove wall of the annular groove 10 through the first pin 41. That is, the first pin 41 is also arranged in the annular groove 10 to avoid the first pin 41 being arranged on the inner wall or outer wall of the upper joint and the lower joint, and being directly contacted with the air in the external environment or the liquid in the column and corroded.

[0041] Exemplarily, there are multiple first pins 41 for connecting the upper joint 1 and the lower joint 2, and the multiple first pins 41 are arranged at intervals in the circumferential direction so that the upper joint 1 and the lower joint 2 are subjected to force at various positions in the circumferential direction to avoid accidental detachment of the upper joint 1 and the lower joint 2 and improve the connection reliability.

[0042] Alternatively, if Figure 1 , 2 As shown, the inner wall of the annular protrusion 21 is sealed with one groove wall of the annular groove 10; the annular piston 30 is located between the outer wall of the annular protrusion 21 and the other groove wall of the annular groove 10, and the inner wall and the outer wall are two side walls of the annular protrusion 21 that are opposite to each other in the radial direction; the annular piston 30 in the closed position divides the annular cavity 5 into a first cavity 51 and a second cavity 52, and the opening 12 is connected to the second cavity 52.

[0043] In the disclosed embodiment, the annular piston 30 is mounted outside the annular protrusion 21, and the inner wall of the annular piston 30 is in contact with the outer wall of the annular protrusion 21, and the outer wall of the annular piston 30 is in contact with the groove wall of the annular groove 10, so that when the annular piston 30 moves between the first flow hole 22 and the second flow hole 11, that is, when the annular piston 30 moves to the closed position, the annular piston 30 can perform a preliminary sealing on the two flow holes.

[0044] Furthermore, when the annular piston 30 is in the closed position, the annular cavity 5 is divided into a first cavity 51 and a second cavity 52. ​​Thus, when the liquid enters the second cavity 52 through the opening hole 12, it can be pressurized in the second cavity 52 and push the annular piston 30 toward the first cavity 51 to reduce the space of the first cavity 51, thereby connecting the first flow hole 22 and the second flow hole 11, and moving the annular piston 30 to the open position.

[0045] In some other implementations of the present disclosure, the inner wall and the outer wall of the annular protrusion 21 may not be sealed against the groove wall of the annular groove 10, that is, the annular protrusion 21 is inserted into the annular groove 10 with a gap between them.

[0046] At this time, the lower end face of the upper joint 1 can be sealed with the upper end face of the lower joint 2, or the groove wall of the annular groove 10 can also be sealed with the outer wall of the lower joint 2, so that the groove wall of the annular groove 10 and the outer wall of the lower joint 2 cooperate with each other to form a sealed annular cavity 5.

[0047] Figure 3 Schematic diagram of a safety joint provided by an embodiment of the present disclosure. Figure 3 As shown, the annular piston 30 may be a metal cylindrical structure, and the annular piston 30 is slidably inserted between the groove wall of the annular groove 10 and the annular protrusion 21. Among them, two annular grooves arranged axially spaced apart are provided on the inner wall and the outer wall of the annular piston 30, and a sealing ring 34 is provided in the annular groove, and the axial arrangement spacing of the annular grooves is not less than the largest diameter of the second flow hole 11 and the first flow hole 22, so that when the annular piston 30 is in the closed position, the two annular grooves are located on both sides of the first flow hole 22.

[0048] Among them, the inner wall and the outer wall of the annular piston 30 are both smooth, so that after the annular piston 30 is inserted into the annular space between the annular groove 10 and the annular protrusion 21, there is a small friction between the annular piston 30 and the annular groove 10 and the annular protrusion 21, which facilitates the axial sliding of the annular piston 30.

[0049] In order to ensure the sealing between the annular piston 30 and the annular groove 10 and the annular protrusion 21, annular grooves are provided on the inner wall and the outer wall of the annular piston 30, and a sealing ring 34 is installed in the annular groove, and the axial spacing between the two annular grooves is greater than or equal to the diameter of the larger flow hole of the first flow hole 22 and the second flow hole 11, so that it can be ensured that the first flow hole 22 and the second flow hole 11 are both located between the two sealing rings 34, so as to avoid liquid leakage from the gap between the annular piston 30 and the groove wall of the annular groove 10, and the gap between the annular piston 30 and the side wall of the annular protrusion 21, so as to improve the sealing.

[0050] Optionally, the safety joint may further include a reset member, which is used to provide a force to the annular piston 30 to reset the annular piston 30 to the closed position when the annular piston 30 moves from the closed position to the open position.

[0051] For example, Figure 3 As shown, the reset member is a compression spring 35, which is located in the first cavity 51 and is sleeved on the outside of the annular protrusion 21. The compression spring 35 is located between the annular piston 30 and the upper end surface of the lower joint 2. One end of the compression spring 35 is against one end of the annular piston 30, and the other end of the compression spring 35 is axially fixed to the annular protrusion 21.

[0052] Among them, an outer flange is provided on the outer side wall of the annular protrusion 21, the lower end of the compression spring 35 is against the end face of the outer flange, and the upper end of the compression spring 35 is against the lower end of the annular piston 30. In this way, when the liquid breaks the rupture disk 43 and enters the annular cavity 5 from the opening hole 12, if the pressure of the liquid is sufficient to overcome the elastic force of the compression spring 35, the liquid will push the annular piston 30 to move downward, so that the annular piston 30 slides to the bottom of the second flow hole 11 and the first flow hole 22 (that is, the annular piston 30 moves to the open position), thereby connecting the second flow hole 11 and the first flow hole 22, so that the liquid can enter the safety joint from the annulus to realize the well washing operation.

[0053] Moreover, in the above process, the compression spring 35 is compressed and accumulates elastic force, so that after the well washing operation is completed, no liquid is injected into the annulus, and the pressure exerted by the liquid on the annular piston 30 and the compression spring 35 disappears. Under the elastic force of the compression spring 35, the annular piston 30 slides upward, so that the annular piston 30 moves to the closed position, thereby blocking the first flow hole 22 and the second flow hole 11 again to prevent liquid leakage in the drill pipe.

[0054] Alternatively, if Figure 1 As shown, the annular piston 30 is connected to the annular groove 10 via a second pin 42. This prevents the liquid in the annular space from entering the annular cavity 5 through the opening hole 12, pushing the annular piston 30 and causing the first flow hole 22 and the second flow hole 11 to be accidentally connected, thereby improving the reliability of the safety joint.

[0055] like Figure 1 As shown, there are multiple second pins 42 for connecting the annular piston 30 and the annular groove 10, and the multiple second pins 42 are arranged at intervals in the circumferential direction, so that the annular piston 30 and the annular groove 10 are subjected to force at various positions in the circumferential direction, so as to avoid the annular piston 30 and the annular groove 10 from accidentally falling off, thereby improving the connection reliability.

[0056] Figure 4 It is a structural schematic diagram of a safety joint provided in an embodiment of the present disclosure. Figure 4 The safety connector shown in Figure 3 In the safety joint shown in FIG, the upper joint 1 and the lower joint 2 have the same shape and structure, and the connection relationship and arrangement position of the annular protrusion 21 and the annular groove 10 are the same. The annular piston 30 is arranged between the groove wall of the annular groove 10 and the side wall of the annular protrusion 21. The difference lies in the matching mode of the annular piston 30 with the annular groove 10 and the annular protrusion 21 in the annular cavity 5.

[0057] like Figure 4 As shown, the annular piston 30 is threadedly connected to the annular groove 10 or the annular protrusion 21, and the safety joint may include an impeller 31, which is located in the second cavity 52, and the impeller 31 and the annular piston 30 are coaxially arranged and spaced apart, and the impeller 31 and the annular piston 30 are circumferentially fixed, and the impeller 31 is located between the opening hole 12 and the annular piston 30 in the axial direction of the upper joint 1.

[0058] The impeller 31 may include a rotating ring 311 and rotating blades 312 circumferentially arranged on the outer wall of the rotating ring 311. When the liquid flows from one side of the impeller 31 to the impeller 31, after passing through the impeller 31, the impeller 31 and the annular piston 30 are arranged at intervals, that is, there is a gap between the impeller 31 and the annular piston 30, so that the fluid can continue to flow, that is, the liquid will drive the rotating blades 312 of the impeller 31 to rotate, thereby driving the rotating ring 311 to rotate together. That is, the impeller 31 can rotate under the impact of the liquid.

[0059] like Figure 4As shown, since the impeller 31 is located in the annular groove 10 and below the opening, when the liquid in the annulus passes through the opening 12, the liquid will flow downward toward the impeller 31. Under the impact of the liquid, the impeller 31 starts to rotate to drive the annular piston 30 to rotate. Since the annular piston 30 and the annular groove 10 or the annular protrusion 21 are threadedly connected, the annular piston 30 will slide axially in the annular groove 10, so that the annular piston 30 can move to a position that connects the first flow hole 22 and the second flow hole 11 to facilitate well washing.

[0060] In the disclosed embodiment, the inner wall of the annular piston 30 and the outer peripheral wall of the annular protrusion 21 are provided with mutually matching threads, and the thread profile of the thread can be a trapezoidal thread, which ensures the sealing between the annular piston 30 and the annular protrusion 21 while facilitating the rotation between the annular piston 30 and the annular protrusion 21.

[0061] Optionally, the safety joint may further include a reset member, which is used to provide a force to the annular piston 30 to reset the annular piston 30 to the closed position when the annular piston 30 moves from the closed position to the open position.

[0062] Alternatively, if Figure 4 As shown, the reset member is a torsion spring 33, which is located in the first cavity 51 and is mounted outside the annular protrusion 21. The torsion spring 33 is located between the annular piston 30 and the upper end surface of the lower joint 2. One end of the torsion spring 33 is circumferentially fixed to one end of the annular piston 30, and the other end of the torsion spring 33 is circumferentially fixed to the annular protrusion 21.

[0063] The lower end surface of the annular piston 30 and the outer side wall of the annular protrusion 21 may be provided with openings to facilitate inserting the ends of the torsion spring 33 into the openings, so that both ends of the torsion spring 33 are circumferentially fixed.

[0064] In this way, when the liquid breaks the rupture disk 43 and enters the annular cavity 5 from the opening 12, if the liquid drives the impeller 31 to rotate, so as to drive the annular piston 30 to rotate, the annular piston 30 moves downward under the action of the thread pair, so that the annular piston 30 slides to the bottom of the second flow hole 11 and the first flow hole 22 (that is, the annular piston 30 moves to the open position), thereby connecting the second flow hole 11 and the first flow hole 22, so that the liquid can enter the safety joint from the annulus to achieve the well washing operation. In addition, the torsion spring 33 is twisted and accumulates torque, so that after the well washing operation is completed, the liquid is no longer injected into the annulus, and the pressure exerted by the liquid on the annular piston 30 and the torsion spring 33 is reduced. Under the action of the torque exerted by the torsion spring 33, the annular piston 30 rotates, and the annular piston 30 moves upward under the action of the thread pair, thereby blocking the first flow hole 22 and the second flow hole 11 again to prevent the leakage of liquid in the drill pipe.

[0065] Alternatively, if Figure 4 As shown, the annular piston 30 and the impeller 31 are connected by a connecting frame 32, the connecting frame 32 includes a plurality of connecting rods arranged at intervals in the circumferential direction, the impeller 31 includes a rotating ring 311 and rotating blades 312 arranged circumferentially on the outer wall of the rotating ring 311, one end of the connecting rod is connected to one end of the rotating ring 311, and the other end of the connecting rod is connected to one end of the annular piston 30. In addition to improving the connection reliability, the provision of a plurality of connecting rods can also prevent the liquid flowing into the annular cavity 5 from being separated by the connecting frame 32, so that after the two flow holes are connected, the liquid in the annular groove 10 can also be discharged smoothly.

[0066] The safety joint provided by the disclosed embodiment can set the starting pressure according to the well depth and temperature. When it is necessary to unfasten, the annulus is pressurized to the set starting pressure, the rupture disk 43 is broken, and the annular piston 30 moves downward, so that the two flow holes can be connected to achieve positive and negative circulation, flush the bottom mud, and then pull up and down and rotate the drill pipe to cut off the first pin 41 to complete the unfastening; in the normal acid fracturing test, the starting pressure can be set much higher than the normal construction pressure to ensure that the safety joint will not be easily started, ensuring the normal operation of the acid fracturing pipe string, acid fracturing, unsealing, etc. Compared with conventional mechanical safety structures, it is easy to reverse, and compared with other hydraulically controlled safety joints, it does not require a ball, reducing downhole risks. The first pin 41 effectively ensures that the forward and reverse operation of the pipe string during construction will not misoperate the safety joint, which is convenient for on-site construction. Flush and circulate the bottom mud before reverse, ensure that the torque and lifting force can be transmitted to the safety joint, greatly improving the success rate of reverse.

[0067] The above does not limit the present disclosure in any form. Although the present disclosure has been disclosed as above through the embodiments, it is not used to limit the present disclosure. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present disclosure. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present disclosure without departing from the content of the technical solution of the present disclosure still falls within the scope of the technical solution of the present disclosure.

Claims

1. A safety joint, characterized in that: The safety joint comprises: A lower joint (2), wherein the upper end surface of the lower joint (2) has an axially extending annular protrusion (21), and the annular protrusion (21) has a first flow hole (22) radially penetrating the annular protrusion (21); An upper joint (1), wherein the upper joint (1) and the lower joint (2) are connected via a radially arranged first pin (41), the lower end surface of the upper joint (1) has an axially extending annular groove (10), the groove wall of the annular groove (10) cooperates with the outer wall of the lower joint (2) to form a sealed annular cavity (5), the annular protrusion (21) is located in the annular cavity (5), the groove wall of the annular groove (10) has a radially extending opening hole (12) and two second flow holes (11), and the two second flow holes (11) and the first flow hole (22) are radially opposite; An annular piston (30) is located in the annular cavity (5) and radially between the annular protrusion (21) and the groove wall of the annular groove (10). The annular piston (30) is configured to move from a closed position to an open position under the pressure of the fluid injected from the opening hole (12), wherein the closed position is a position that separates the first flow hole (22) and the second flow hole (11), and the open position is a position that connects the first flow hole (22) and the second flow hole (11).

2. The safety joint according to claim 1, characterized in that: The inner side wall of the annular protrusion (21) is in sealing contact with a groove wall of the annular groove (10); The annular piston (30) is located between the outer side wall of the annular protrusion (21) and the other groove wall of the annular groove (10), and the inner side wall and the outer side wall are two side walls of the annular protrusion (21) opposite to each other in the radial direction; The annular piston (30) located in the closed position divides the annular cavity (5) into a first cavity (51) and a second cavity (52), and the opening hole (12) is in communication with the second cavity (52).

3. The safety joint according to claim 2, characterized in that: The annular piston (30) is threadedly connected to the groove wall of the annular groove (10) or the outer side wall of the annular protrusion (21); The safety joint further comprises an impeller (31), wherein the impeller (31) is located in the second cavity (52), the impeller (31) and the annular piston (30) are coaxially arranged and spaced apart, and the impeller (31) and the annular piston (30) are circumferentially fixedly connected, and the impeller (31) is located between the opening hole (12) and the annular piston (30) in the axial direction of the upper joint (1).

4. The safety joint according to claim 3, characterized in that: The annular piston (30) and the impeller (31) are connected via a connecting frame (32); the impeller (31) comprises a rotating ring (311) and rotating blades (312) circumferentially arranged on the outer wall of the rotating ring (311); the connecting frame (32) comprises a plurality of connecting rods arranged at intervals in the circumferential direction; one end of the connecting rod is connected to one end of the rotating ring (311), and the other end of the connecting rod is connected to one end of the annular piston (30).

5. The safety joint according to claim 3, characterized in that: The safety joint further comprises a torsion spring (33), wherein the torsion spring (33) is located in the first cavity (51) and is sleeved outside the annular protrusion (21), wherein the torsion spring (33) is located between the annular piston (30) and the upper end surface of the lower joint (2), wherein one end of the torsion spring (33) is circumferentially fixed to one end of the annular piston (30), and the other end of the torsion spring (33) is circumferentially fixed to the annular protrusion (21).

6. The safety joint according to claim 2, characterized in that: The annular piston (30) is connected to the groove wall of the annular groove (10) and the outer side wall of the annular protrusion (21) in a sliding and sealing manner; The safety joint further comprises a compression spring (35), wherein the compression spring (35) is located in the first cavity (51) and is sleeved outside the annular protrusion (21), wherein the compression spring (35) is located between the annular piston (30) and the upper end surface of the lower joint (2), wherein one end of the compression spring (35) abuts against one end of the annular piston (30), and the other end of the compression spring (35) is axially fixed to the annular protrusion (21).

7. The safety joint according to claim 6, characterized in that: The inner wall and the outer wall of the annular piston (30) are both provided with two annular grooves spaced apart in the axial direction, and a sealing ring (34) is provided in the annular groove. When the annular piston (30) is located in the closed position, the two annular grooves are located on both sides of the first flow hole (22).

8. The safety joint according to any one of claims 1 to 7, characterized in that: The annular protrusion (21) is connected to the groove wall of the annular groove (10) via the first pin (41).

9. The safety joint according to any one of claims 1 to 7, characterized in that: The annular piston (30) is connected to the annular groove (10) via a second pin (42).

10. The safety joint according to any one of claims 1 to 7, characterized in that: A rupture disk (43) is arranged in the opening hole (12).

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