Soluble time-delay opening toe-end sliding sleeve

Abstract

The invention provides a soluble time-delay opening toe end sliding sleeve which comprises a central tube and an outer sleeve arranged outside the central tube, a cavity is formed between the outer sleeve and the central tube, and the outer sleeve and the central tube are provided with flow guide holes communicating the interior of the central tube with the exterior of the outer sleeve; the sliding sleeve is arranged in the cavity, and the sliding sleeve is located at a first position in an initial state and blocks the flow guide hole; when the sliding sleeve moves to a second position, the sliding sleeve moves away from the flow guide hole, so that the flow guide hole is opened; and the delayed opening mechanism is arranged in the cavity, and the sliding sleeve is pushed to move from the first position to the second position through fluid pressure after delayed opening is performed for a period of time.

Description

Technical Field

[0001] This invention relates to a soluble delayed-opening toe sleeve, belonging to the field of downhole operation technology for oil and gas wells. Background Technology

[0002] In the field of oil and gas extraction, with the increasing development of unconventional oil and gas resources, drilling is becoming deeper and horizontal well sections are becoming longer, making development increasingly difficult. Due to the low porosity and tightness of unconventional oil and gas reservoirs, industrial production capacity can only be achieved through fracturing. For the initial fracturing stage, since there is no flow channel in the entire wellbore, two methods are currently commonly used to establish the fracturing channel: continuous tubing perforation and toe-end sliding sleeve.

[0003] Coiled tubing perforation is a mature and highly successful method; however, it faces certain technical limitations due to the special control of explosives, on-site installation, commissioning, and dismantling of coiled tubing equipment, long construction time, and the increasing limitation on the working depth of coiled tubing as well depth and horizontal section length increase. Conventional toe-sleeve perforation, which utilizes pressure differential to open fracturing channels, offers advantages such as lower construction costs and higher efficiency compared to coiled tubing perforation. However, in practical applications, it often encounters difficulties in opening the fracturing channel and fails to meet the requirements for full-wellbore pressure testing.

[0004] Therefore, there is an urgent need for a delayed-opening toe sleeve that can meet the requirements of full-bore pressure testing and can be used for the first stage of fracturing and modification construction. Summary of the Invention

[0005] In view of the above-mentioned technical problems existing in the prior art, the present invention proposes a soluble delayed opening toe sleeve, which can meet the requirements of full wellbore pressure testing and can be used for delayed opening in the first stage of fracturing and stimulation construction.

[0006] The invention proposes a soluble delayed-opening toe sleeve, comprising: Central tube, An outer sleeve is disposed outside the central tube, forming a cavity between the outer sleeve and the central tube, and guide holes are provided on the outer sleeve and the central tube to communicate with the interior of the central tube and the exterior of the outer sleeve; A sliding sleeve disposed within the cavity is initially positioned in a first position, blocking the flow guide hole; when the sliding sleeve moves to a second position, it moves away from the flow guide hole, opening it. A time-delay opening mechanism is provided inside the cavity. After a certain time delay, the sliding sleeve is moved from a first position to a second position by fluid pressure.

[0007] A further improvement of the present invention is that a first spring is provided on one side of the sliding sleeve, and the first spring is provided on the side of the sliding sleeve away from the delayed opening mechanism; Initially, the first spring is in an extended state and the sliding sleeve is in a first position; when the pressure of the fluid pushes the sliding sleeve from the first position to a second position, the first spring is in a compressed state.

[0008] A further improvement of the present invention is that the guide hole includes an outer hole disposed on the outer sleeve and an inner hole disposed on the central tube, the outer hole and the inner hole being arranged opposite to each other.

[0009] A further improvement of the present invention is that a step or a groove is provided on the outer sleeve, and an elastic claw is provided on the sliding sleeve; when the sliding sleeve moves to the second position, the claw engages in the step or groove, thereby fixing the sliding sleeve.

[0010] A further improvement of the present invention is that the delayed opening mechanism includes an inlet disposed on the central tube, the inlet being connected to the cavity through a flow channel, a rupture disc disposed on the inlet, and a first one-way valve disposed within the cavity; the rupture disc blocks the inlet, and under a certain pressure, the rupture disc ruptures, thereby opening the inlet.

[0011] A further improvement of the present invention is that a temporary plugging ring and a second check valve are also provided in the cavity, and there is a certain distance between the temporary plugging ring and the second check valve; A dissolving chamber is formed between the first flow valve and the second flow valve, and the dissolving chamber is filled with a dissolving solution.

[0012] A further improvement of the present invention is that the temporary plugging ring is made of a soluble material, and the dissolving liquid can dissolve the temporary plugging ring over a certain period of time, thereby allowing the liquid in the dissolving liquid chamber to flow to the position of the sliding sleeve.

[0013] A further improvement of the present invention is that the dissolving solution is a liquid acid or a highly mineralized solution.

[0014] A further improvement of the present invention is that the dissolving liquid is a solid acid, wherein the fluid in the central tube enters the dissolving liquid chamber through the inlet and dissolves the solid acid.

[0015] A further improvement of the present invention is that the crushing disc includes a threaded sleeve connected to the inlet by a thread, and the threaded sleeve is provided with a rupture disc.

[0016] Compared with the prior art, the advantages of the present invention are as follows: According to the present invention, a soluble delayed-opening toe sleeve can meet the requirements of full-bore pressure testing and can be used for delayed opening in the first stage of fracturing and stimulation construction. Attached Figure Description

[0017] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 The diagram shown is a schematic representation of the soluble delayed-opening toe sleeve according to an embodiment of the present invention, illustrating the initial state. Figure 2 The diagram shown is a schematic diagram of the soluble delayed opening toe sleeve according to an embodiment of the present invention, showing the state of the fractured disc after it is broken. Figure 3 The diagram shown is a schematic diagram of the structure of a soluble delayed-opening toe sleeve according to an embodiment of the present invention, showing the state after the dissolving solution dissolves the temporary plugging ring; Figure 4 The diagram shown is a schematic diagram of the structure of a soluble delayed opening toe sleeve according to an embodiment of the present invention, showing the state of the guide hole being open.

[0018] Figure 5 The diagram shown is a structural schematic of an elastic claw according to an embodiment of the present invention.

[0019] Figure 6 The diagram shown is a structural schematic of a soluble delayed-opening toe sleeve according to an embodiment of the present invention, showing a structure provided with a second spring.

[0020] Figure 7 The figure shows the pressure change over time during the process of opening the soluble delayed-opening toe sleeve from the full wellbore pressure test to the opening, according to an embodiment of the present invention.

[0021] The accompanying drawings are not drawn to scale.

[0022] The meanings of the reference numerals in the attached figures are as follows: 1. Central tube, 2. Outer sleeve, 3. Sliding sleeve, 4. Cavity, 11. Inner hole, 12. Upper connector, 13. Lower connector, 14. Crushing disc, 21. Outer hole, 31. First spring, 32. Elastic claw, 33. Step or groove, 41. Dissolving liquid chamber, 42. Dissolving liquid, 43. Temporary plugging ring, 44. First check valve, 45. Second check valve, 46. Second spring. Detailed Implementation

[0023] To make the technical solutions and advantages of the present invention clearer, exemplary embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. Furthermore, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0024] In the field of oil and gas extraction, with the increasing development of unconventional oil and gas resources, drilling is becoming deeper and horizontal well sections are becoming longer, making development increasingly difficult. Due to the low porosity and tightness of unconventional oil and gas reservoirs, industrial production capacity can only be achieved through fracturing. For the initial fracturing stage, since there is no flow channel in the entire wellbore, two methods are currently commonly used to establish the fracturing channel: continuous tubing perforation and toe-end sliding sleeve.

[0025] Coiled tubing perforation is a mature and highly successful method; however, it faces certain technical limitations due to the special control of explosives, on-site installation, commissioning, and dismantling of coiled tubing equipment, long construction time, and the increasing limitation on the working depth of coiled tubing as well depth and horizontal section length increase. Conventional toe-sleeve perforation, which utilizes pressure differential to open fracturing channels, offers advantages such as lower construction costs and higher efficiency compared to coiled tubing perforation. However, in practical applications, it often encounters difficulties in opening the fracturing channel and fails to meet the requirements for full-wellbore pressure testing.

[0026] To address the aforementioned issues, this invention proposes a soluble delayed-opening toe sleeve that can meet the requirements of full-wellbore pressure testing and can be used for delayed opening during the initial fracturing and stimulation operation.

[0027] In such Figure 1 In the illustrated embodiment, a soluble delayed-opening toe sleeve includes: Central tube 1, wherein the central tube 1 has a circular tube structure; An outer sleeve 2 is disposed outside the central tube 1, forming a cavity 4 between the outer sleeve 2 and the central tube 1, and a guide hole is provided on the outer sleeve 2 and the central tube 1, the guide hole connecting the inside of the central tube 1 and the outside of the outer sleeve 2; A sliding sleeve 3 is disposed inside the cavity 4. Initially, the sliding sleeve 3 is in a first position, blocking the flow guide hole; when the sliding sleeve 3 moves to a second position, it moves away from the flow guide hole, opening it. The delayed opening mechanism installed inside the cavity 4 pushes the sliding sleeve 3 from the first position to the second position by fluid pressure after a delay period of time.

[0028] In one embodiment, a first spring 31 is provided on one side of the sliding sleeve 3, and the first spring 31 is provided on the side of the sliding sleeve 3 away from the delayed opening mechanism.

[0029] Initially, the first spring 31 is in an extended state, the sliding sleeve 3 is in a first position, and blocks the guide hole; When the pressure of the fluid pushes the sliding sleeve 3 from the first position to the second position, it simultaneously compresses the first spring 31, thereby opening the guide hole.

[0030] In one embodiment, the guide hole includes an outer hole 21 disposed on the outer sleeve 2 and an inner hole 11 disposed on the central tube 1, wherein the outer hole 21 and the inner hole 11 are arranged opposite to each other.

[0031] In this embodiment, the thickness of the sliding sleeve 3 matches the thickness of the cavity 4. When the sliding sleeve 3 is in the first position, it can block the inner hole 11 and the outer hole 21 at the same time. When the sliding sleeve 3 is in the second position, the sliding sleeve 3 moves away from the positions of the inner hole 11 and the outer hole 21, thereby connecting the inner hole 11 and the outer hole 21 and opening the guide hole.

[0032] In one embodiment, the delayed opening mechanism includes an inlet disposed on the central tube 1, the inlet being connected to the cavity 4 via a flow channel, a rupture disc disposed on the inlet, and a first one-way valve 44 disposed within the cavity 4. The rupture disc blocks the inlet, and under a certain pressure, the rupture disc ruptures. Figure 2 (as shown), thereby opening the entry point.

[0033] The direction of the first one-way valve is from the inlet to the cavity 4.

[0034] When the inlet is opened, the pressure inside the central tube 1 will enter the cavity 4 through the flow channel and the second one-way valve 45, increasing the pressure inside the cavity 4 (e.g., Figure 3 As shown), thereby using fluid to push the sliding sleeve 3 from the first position to the second position, and opening the guide hole (as shown). Figure 4 (As shown).

[0035] In one embodiment, the cavity 4 is further provided with a temporary clogging ring 43 and a second check valve 45. The temporary clogging ring 43 is located on the side closer to the sliding sleeve 3, and the second check valve 45 is located on the side closer to the inlet. There is a certain distance between the temporary clogging ring 43 and the second check valve 45.

[0036] The temporary blocking ring 43 blocks the cavity 4, preventing pressure from one side from entering the other side.

[0037] A dissolving chamber 41 is formed between the first flow valve 44 and the second flow valve 45, and the dissolving chamber 41 is filled with dissolving liquid 42.

[0038] The flow direction of the second one-way valve 45 is from the direction of the dissolving liquid chamber 41 to one side of the temporary blocking ring 43.

[0039] In this embodiment, the second one-way valve 45 includes a one-way valve seat and a one-way valve core disposed on the one-way valve seat. Sealing rings are provided between the one-way valve seat and both the outer sleeve 2 and the central tube 1.

[0040] Preferably, such as Figure 6 As shown, a second spring 46 is also provided between the one-way valve core and the temporary plugging ring 43. The second spring 46 provides a certain pressure to the one-way valve core, keeping it in a closed state. When pressure is applied from one side of the dissolving chamber 41 to one side of the temporary plugging ring, the pressure will push the second spring 46 to compress, thereby allowing fluid to pass through the one-way valve core and flow into the position of the temporary plugging ring.

[0041] Initially, due to the stable pressure on both sides of the dissolving chamber 41, the dissolving liquid 42 does not flow and therefore does not react with the temporary plugging ring 43, preventing premature dissolution of the temporary plugging ring 43. When the fluid enters the chamber 4, it pushes the dissolving liquid 42 through the second check valve 45 to the position of the temporary plugging ring 43, dissolving the temporary plugging ring 43. The pressure of the fluid after passing through the dissolved temporary plugging ring 43 is applied to the sliding sleeve 3, pushing the sliding sleeve 3 from the first position to the second position, thereby opening the guide hole.

[0042] When using the soluble delayed-opening toe sleeve according to this embodiment, initially, the first spring 31 is in an extended state, the sleeve 3 is in a first position, and it blocks the guide hole; the dissolving liquid chamber 41 is filled with dissolving liquid 42. Since the pressure on both sides of the dissolving liquid chamber 41 is stable, the dissolving liquid 42 will not flow and therefore will not react with the temporary blocking ring 43, avoiding premature dissolution of the temporary blocking ring 43. At the same time, the crushing disc 14 remains intact and blocks the inlet.

[0043] When the pressure inside the pipe is increased by pressurization, the rupture disc 14 ruptures, and the fluid inside the pipe enters the cavity 4 through the inlet, then enters the dissolving liquid cavity 41 through the first one-way valve 44, and pushes the dissolving liquid 42 in the dissolving liquid cavity 41 out through the second one-way valve 45. Afterwards, the dissolving liquid 42 reacts with the temporary plugging ring 43, dissolving the temporary plugging ring 43.

[0044] After the temporary blocking ring 43 dissolves, the liquid will enter the upper end of the cavity 4, apply pressure to the sliding sleeve 3, push the sliding sleeve 3 from the first position to the second position, and at the same time push the first spring 31 to compress, thereby opening the guide hole.

[0045] In one embodiment, the temporary plugging ring 43 is composed of a soluble material, and the dissolving liquid 42 can dissolve the temporary plugging ring 43 over a certain period of time, so that the liquid in the dissolving liquid chamber 41 can flow out through the dissolved temporary plugging ring 43, and thus the liquid in the dissolving liquid chamber 41 can flow to the position of the sliding sleeve 3 to apply pressure to the sliding sleeve 3.

[0046] In the initial state, the temporary plugging ring 43 blocks both sides of the cavity 4, preventing pressure from being applied to the sliding sleeve 3. After being lowered into the well, pressure is applied to allow the dissolving liquid 42 to flow onto the temporary plugging ring 43. The dissolving liquid 42 gradually dissolves the temporary plugging ring 43, and the dissolution rate of the temporary plugging ring 43 can be adjusted by the thickness of the temporary plugging ring 43 and the composition and concentration of the dissolving liquid 42.

[0047] After a period of time, the inlet rupture disc is broken by pressure inside the pipe, and the fluid inside the pipe enters the cavity 4 through the inlet flow channel and the first one-way valve 44. When the dissolving liquid 42 flows to the position of the temporary plugging ring 43 through the second one-way valve 45 and dissolves the temporary plugging ring 43, the front and rear ends of the cavity 4 are connected. The pressure inside the pipe enters the front end of the cavity 4 through the inlet, flow channel, first one-way valve 44 and second one-way valve 45, thereby pushing the dissolving liquid 42 to move and applying pressure to the sliding sleeve 3, pushing the sliding sleeve 3 from the first position to the second position, so that the guide hole is opened.

[0048] In one embodiment, the dissolving medium of the solution 42 can be a solid acid, dilute acid, strong acid, organic acid, high mineralization, etc., for example, it can be dilute hydrochloric acid, acetic acid, KCl solution, etc.

[0049] In the soluble delayed-opening toe sleeve according to this embodiment, the dissolving medium can be a liquid acid or a solid acid.

[0050] In one embodiment, the acid is a liquid acid or a highly mineralized solution that can corrode or dissolve the temporary plugging ring 43. During assembly, after the acid is injected into the dissolving chamber 41, the pressure is stable and the dissolving liquid 42 will not flow because the front and rear ends of the dissolving chamber 41 are sealed.

[0051] When it needs to be opened, the crushing disc 14 is broken by pressurizing inside the pipe, allowing fluid to flow into the cavity 4 through the inlet. Driven by the fluid pressure, the fluid in the dissolving chamber 41 flows into the space between the temporary plugging ring 43 and the second check valve 45, and contacts the temporary plugging ring 43. After the dissolving liquid 42 contacts the temporary plugging ring 43, it gradually dissolves the ring, applying pressure to the sliding sleeve 3, thereby pushing the slide bar from the first position to the second position and opening the guide hole.

[0052] In another embodiment, the acid is a solid acid. When the rupture disc breaks, the fluid in the central tube 1 enters the dissolving chamber 41 through the flow channel and the first one-way valve 44, where it dissolves the solid acid to form an acid solution. The acid solution flows into the space between the temporary plugging ring 43 and the second one-way valve 45 and contacts the temporary plugging ring 43. After the dissolving liquid 42 contacts the temporary plugging ring 43, it gradually dissolves the temporary plugging ring 43, causing the pressure inside the tube to be applied to the sliding sleeve 3, thereby pushing the slide bar from the first position to the second position and opening the guide hole.

[0053] In one embodiment, such as Figure 5 As shown, a step or groove 33 is provided on the outer sleeve 2, and an elastic claw 32 is provided on the sliding sleeve 3; when the sliding sleeve 3 moves to the second position, the claw engages in the step or groove 33, thereby fixing the sliding sleeve 3 and preventing the sliding sleeve 3 from springing back to the first position and blocking the guide hole.

[0054] The inner wall of the outer sleeve 2 is provided with a step or groove 33, and the sliding sleeve 3 is provided with an elastic claw 32. The elastic claw 32 has a certain elasticity and can extend and retract. When the sliding sleeve 3 is in the first position, the elastic claw 32 is in a retracted state. When the sliding sleeve 3 moves to the step position or the groove position, the elastic claw 32 loses its support, thereby popping out and engaging in the step or groove 33.

[0055] In one embodiment, the rupture disc 14 includes a threaded sleeve connected to the inlet by a thread, the threaded sleeve being provided with rupture discs.

[0056] In one embodiment, the upper end of the central tube 1 is provided with an upper connector 12 for connecting an upper tool, and the lower end is provided with a lower connector 13 for connecting a lower tool.

[0057] A sealing ring is provided between the upper connector 12 and the central tube 1, and a sealing ring is also provided between the lower connector 13 and the central tube 1. Sealing rings are provided on both the inner and outer sides of the sliding sleeve 3 to seal the gap between the sliding sleeve 3 and the central tube 1, as well as the gap between the sliding sleeve 3 and the outer sleeve 2, thereby sealing the guide hole in the first position.

[0058] When using the device according to this embodiment, the soluble delay-delay toe sleeve is run into the designed position in the well along with the cementing completion string. After cementing is completed, when a full wellbore pressure test is required, pressure is applied from the wellhead. The pressure is transmitted through the channel inside the string to the fracture disc on the soluble delay-delay toe sleeve. Under the action of the wellhead pressure and the hydrostatic column pressure, the fracture disc ruptures (e.g., Figure 2 (As shown).

[0059] The liquid inside the pipe enters the flow channel between the outer cylinder and the central pipe 1 through the through hole of the ruptured disc, and then flows into the dissolving liquid chamber 41 through the first one-way valve 44. Under the action of hydraulic pressure, it squeezes the second spring 46 and flows into the cavity 4. At this time, under the action of hydraulic pressure, the solvent mixes with the liquid in the wellbore and flows into the soluble temporary plugging ring 43, and the soluble temporary plugging ring 43 begins to enter the dissolution stage. Since the gap through which the fluid flows in the soluble delay toe sleeve is negligible compared to the volume of the entire wellbore, the wellhead pressure will not drop during the pressure test, which can meet the requirements of the full wellbore pressure test. According to the full wellbore pressure test standard, the pressure is gradually increased to the test value and the pressure is maintained for a specified time before the wellhead valve is closed. The wellhead shut-in pressure is maintained at 10~20MPa, and the strength of the soluble temporary plugging ring 43 is dissolved and weakened. The temporary plugging channel is released, and the fluid enters the cavity between the sleeve 3 and the soluble temporary plugging ring 43.

[0060] Under the action of wellhead pressure, the sliding sleeve 3 is pushed and the first spring 31 is squeezed. The sliding sleeve 3 slides a certain distance, and the elastic claw 32 engages with the groove. After engagement, the sliding sleeve 3 cannot slide in the opposite direction. The guide hole is connected to the formation. At this time, the wellhead pressure drops by a certain amount, thereby completing the opening action of the soluble delay toe sliding sleeve. Figure 7 It is the trend curve of pressure change over time during the process of opening the soluble delayed toe sleeve from the full wellbore pressure test. At the beginning, as the surface pump truck pressurizes the wellhead, the pressure rises rapidly over time. When the full wellbore pressure test value is reached, the pressure is maintained for a period of time. The pressure is transmitted to the inner cavity of the sleeve 3 with the fluid. After the soluble temporary plugging ring 43 is destroyed, the piston is pushed and the sleeve 3 is finally opened.

[0061] The following description uses specific examples to illustrate the point.

[0062] Example 1 A soluble delayed-opening toe sleeve includes: Central tube 1, wherein the central tube 1 has a circular tube structure; An outer sleeve 2 is disposed outside the central tube 1, forming a cavity 4 between the outer sleeve 2 and the central tube 1, and a guide hole is provided on the outer sleeve 2 and the central tube 1, the guide hole connecting the inside of the central tube 1 and the outside of the outer sleeve 2; A sliding sleeve 3 is disposed inside the cavity 4. Initially, the sliding sleeve 3 is in a first position, blocking the flow guide hole; when the sliding sleeve 3 moves to a second position, it moves away from the flow guide hole, opening it. The delayed opening mechanism installed inside the cavity 4 pushes the sliding sleeve 3 from the first position to the second position by fluid pressure after a delay period of time.

[0063] A first spring 31 is provided on one side of the sliding sleeve 3, and the first spring 31 is located on the side of the sliding sleeve 3 away from the delayed opening mechanism. Initially, the first spring 31 is in an extended state, the sliding sleeve 3 is in a first position, and it blocks the guide hole; when the pressure of the fluid pushes the sliding sleeve 3 from the first position to a second position, it simultaneously pushes the first spring 31 to compress, thereby opening the guide hole.

[0064] The guide hole includes an outer hole 21 provided on the outer sleeve 2 and an inner hole 11 provided on the central tube 1, with the outer hole 21 and the inner hole 11 arranged opposite to each other.

[0065] The thickness of the sliding sleeve 3 matches the thickness of the cavity 4. When the sliding sleeve 3 is in the first position, it can block the inner hole 11 and the outer hole 21 at the same time. When the sliding sleeve 3 is in the second position, the sliding sleeve 3 moves away from the positions of the inner hole 11 and the outer hole 21, thereby connecting the inner hole 11 and the outer hole 21 and opening the guide hole.

[0066] The delayed opening mechanism includes an inlet on the central tube 1, which is connected to the cavity 4 through a flow channel. A rupture disc is provided on the inlet, and a first one-way valve 44 is provided inside the cavity 4. The rupture disc blocks the inlet, and under a certain pressure, the rupture disc breaks, thereby opening the inlet.

[0067] The direction of the first one-way valve is from the inlet to the cavity 4.

[0068] When the inlet is opened, the pressure in the central tube 1 will enter the cavity 4 through the flow channel and the second one-way valve 45, increasing the pressure in the cavity 4, thereby pushing the sliding sleeve 3 from the first position to the second position through the fluid and opening the guide hole.

[0069] The cavity 4 is also equipped with a temporary clogging ring 43 and a second check valve 45. The temporary clogging ring 43 is located on the side closer to the sliding sleeve 3, and the second check valve 45 is located on the side closer to the inlet. There is a certain distance between the temporary clogging ring 43 and the second check valve 45.

[0070] The temporary blocking ring 43 blocks the cavity 4, preventing pressure from one side from entering the other side.

[0071] A dissolving chamber 41 is formed between the first flow valve 44 and the second flow valve 45, and the dissolving chamber 41 is filled with dissolving liquid 42.

[0072] The flow direction of the second one-way valve 45 is from the direction of the dissolving liquid chamber 41 to one side of the temporary blocking ring 43.

[0073] In this embodiment, the second one-way valve 45 includes a one-way valve seat and a one-way valve core disposed on the one-way valve seat. Sealing rings are provided between the one-way valve seat and both the outer sleeve 2 and the central tube 1.

[0074] Initially, due to the stable pressure on both sides of the dissolving chamber 41, the dissolving liquid 42 does not flow and therefore does not react with the temporary plugging ring 43, preventing premature dissolution of the temporary plugging ring 43. When the fluid enters the chamber 4, it pushes the dissolving liquid 42 through the second check valve 45 to the position of the temporary plugging ring 43, dissolving the temporary plugging ring 43. The pressure of the fluid after passing through the dissolved temporary plugging ring 43 is applied to the sliding sleeve 3, pushing the sliding sleeve 3 from the first position to the second position, thereby opening the guide hole.

[0075] The temporary blocking ring 43 is composed of a soluble material, and the dissolving liquid 42 can dissolve the temporary blocking ring 43 within a certain time, so that the liquid in the dissolving liquid chamber 41 can flow out through the dissolved temporary blocking ring 43, and thus the liquid in the dissolving liquid chamber 41 can flow to the position of the sliding sleeve 3, applying pressure to the sliding sleeve 3.

[0076] The dissolving medium in the dissolving liquid 42 is solid acid. When the rupture disc breaks, the fluid in the central tube 1 enters the dissolving liquid chamber 41 through the flow channel and the first one-way valve 44, where it dissolves the solid acid to form an acid solution. The acid solution flows into the space between the temporary plugging ring 43 and the second one-way valve 45 and contacts the temporary plugging ring 43. After the dissolving liquid 42 contacts the temporary plugging ring 43, it gradually dissolves the temporary plugging ring 43, causing the pressure inside the pipe to be applied to the sliding sleeve 3, thereby pushing the slide bar from the first position to the second position and opening the guide hole.

[0077] The outer sleeve 2 is provided with a step or groove 33, and the sliding sleeve 3 is provided with an elastic claw 32; when the sliding sleeve 3 moves to the second position, the claw engages in the step or groove 33, thereby fixing the sliding sleeve 3 and preventing the sliding sleeve 3 from springing back to the first position and blocking the guide hole.

[0078] The inner wall of the outer sleeve 2 is provided with a step or groove 33, and the sliding sleeve 3 is provided with an elastic claw 32. The elastic claw 32 has a certain elasticity and can extend and retract. When the sliding sleeve 3 is in the first position, the elastic claw 32 is in a retracted state. When the sliding sleeve 3 moves to the step position or the groove position, the elastic claw 32 loses its support, thereby popping out and engaging in the step or groove 33.

[0079] The crushing disc 14 includes a threaded sleeve connected to the inlet by a thread, and the threaded sleeve is provided with a rupture disc.

[0080] The upper end of the central tube 1 is provided with an upper connector 12 for connecting the upper tool, and the lower end is provided with a lower connector 13 for connecting the lower tool.

[0081] A sealing ring is provided between the upper connector 12 and the central tube 1, and a sealing ring is also provided between the lower connector 13 and the central tube 1. Sealing rings are provided on both the inner and outer sides of the sliding sleeve 3 to seal the gap between the sliding sleeve 3 and the central tube 1, as well as the gap between the sliding sleeve 3 and the outer sleeve 2, thereby sealing the guide hole in the first position.

[0082] Example 2 A soluble delayed-opening toe sleeve includes: Central tube 1, wherein the central tube 1 has a circular tube structure; An outer sleeve 2 is disposed outside the central tube 1, forming a cavity 4 between the outer sleeve 2 and the central tube 1, and a guide hole is provided on the outer sleeve 2 and the central tube 1, the guide hole connecting the inside of the central tube 1 and the outside of the outer sleeve 2; A sliding sleeve 3 is disposed inside the cavity 4. Initially, the sliding sleeve 3 is in a first position, blocking the flow guide hole; when the sliding sleeve 3 moves to a second position, it moves away from the flow guide hole, opening it. The delayed opening mechanism installed inside the cavity 4 pushes the sliding sleeve 3 from the first position to the second position by fluid pressure after a delay period of time.

[0083] A first spring 31 is provided on one side of the sliding sleeve 3, and the first spring 31 is located on the side of the sliding sleeve 3 away from the delayed opening mechanism. Initially, the first spring 31 is in an extended state, the sliding sleeve 3 is in a first position, and it blocks the guide hole; when the pressure of the fluid pushes the sliding sleeve 3 from the first position to a second position, it simultaneously pushes the first spring 31 to compress, thereby opening the guide hole.

[0084] The guide hole includes an outer hole 21 provided on the outer sleeve 2 and an inner hole 11 provided on the central tube 1, with the outer hole 21 and the inner hole 11 arranged opposite to each other.

[0085] The thickness of the sliding sleeve 3 matches the thickness of the cavity 4. When the sliding sleeve 3 is in the first position, it can block the inner hole 11 and the outer hole 21 at the same time. When the sliding sleeve 3 is in the second position, the sliding sleeve 3 moves away from the positions of the inner hole 11 and the outer hole 21, thereby connecting the inner hole 11 and the outer hole 21 and opening the guide hole.

[0086] The delayed opening mechanism includes an inlet on the central tube 1, which is connected to the cavity 4 through a flow channel. A rupture disc is provided on the inlet, and a first one-way valve 44 is provided inside the cavity 4. The rupture disc blocks the inlet, and under a certain pressure, the rupture disc breaks, thereby opening the inlet.

[0087] The direction of the first one-way valve is from the inlet to the cavity 4.

[0088] When the inlet is opened, the pressure in the central tube 1 will enter the cavity 4 through the flow channel and the second one-way valve 45, increasing the pressure in the cavity 4, thereby pushing the sliding sleeve 3 from the first position to the second position through the fluid and opening the guide hole.

[0089] The cavity 4 is also equipped with a temporary clogging ring 43 and a second check valve 45. The temporary clogging ring 43 is located on the side closer to the sliding sleeve 3, and the second check valve 45 is located on the side closer to the inlet. There is a certain distance between the temporary clogging ring 43 and the second check valve 45.

[0090] The temporary blocking ring 43 blocks the cavity 4, preventing pressure from one side from entering the other side.

[0091] A dissolving chamber 41 is formed between the first flow valve 44 and the second flow valve 45, and the dissolving chamber 41 is filled with dissolving liquid 42.

[0092] The flow direction of the second one-way valve 45 is from the direction of the dissolving liquid chamber 41 to one side of the temporary blocking ring 43.

[0093] In this embodiment, the second one-way valve 45 includes a one-way valve seat and a one-way valve core disposed on the one-way valve seat. Sealing rings are provided between the one-way valve seat and both the outer sleeve 2 and the central tube 1.

[0094] Initially, due to the stable pressure on both sides of the dissolving chamber 41, the dissolving liquid 42 does not flow and therefore does not react with the temporary plugging ring 43, preventing premature dissolution of the temporary plugging ring 43. When the fluid enters the chamber 4, it pushes the dissolving liquid 42 through the second check valve 45 to the position of the temporary plugging ring 43, dissolving the temporary plugging ring 43. The pressure of the fluid after passing through the dissolved temporary plugging ring 43 is applied to the sliding sleeve 3, pushing the sliding sleeve 3 from the first position to the second position, thereby opening the guide hole.

[0095] The temporary blocking ring 43 is composed of a soluble material, and the dissolving liquid 42 can dissolve the temporary blocking ring 43 within a certain time, so that the liquid in the dissolving liquid chamber 41 can flow out through the dissolved temporary blocking ring 43, and thus the liquid in the dissolving liquid chamber 41 can flow to the position of the sliding sleeve 3, applying pressure to the sliding sleeve 3.

[0096] In one embodiment, the acid is a liquid acid or a highly mineralized solution that can corrode or dissolve the temporary plugging ring 43. During assembly, after the acid is injected into the dissolving chamber 41, the pressure is stable and the dissolving liquid 42 will not flow because the front and rear ends of the dissolving chamber 41 are sealed.

[0097] When it needs to be opened, the crushing disc 14 is broken by pressurizing inside the pipe, allowing fluid to flow into the cavity 4 through the inlet. Driven by the fluid pressure, the fluid in the dissolving chamber 41 flows into the space between the temporary plugging ring 43 and the second check valve 45, and contacts the temporary plugging ring 43. After the dissolving liquid 42 contacts the temporary plugging ring 43, it gradually dissolves the ring, applying pressure to the sliding sleeve 3, thereby pushing the slide bar from the first position to the second position and opening the guide hole.

[0098] The outer sleeve 2 is provided with a step or groove 33, and the sliding sleeve 3 is provided with an elastic claw 32; when the sliding sleeve 3 moves to the second position, the claw engages in the step or groove 33, thereby fixing the sliding sleeve 3 and preventing the sliding sleeve 3 from springing back to the first position and blocking the guide hole.

[0099] The inner wall of the outer sleeve 2 is provided with a step or groove 33, and the sliding sleeve 3 is provided with an elastic claw 32. The elastic claw 32 has a certain elasticity and can extend and retract. When the sliding sleeve 3 is in the first position, the elastic claw 32 is in a retracted state. When the sliding sleeve 3 moves to the step position or the groove position, the elastic claw 32 loses its support, thereby popping out and engaging in the step or groove 33.

[0100] The crushing disc 14 includes a threaded sleeve connected to the inlet by a thread, and the threaded sleeve is provided with a rupture disc.

[0101] The upper end of the central tube 1 is provided with an upper connector 12 for connecting the upper tool, and the lower end is provided with a lower connector 13 for connecting the lower tool.

[0102] A sealing ring is provided between the upper connector 12 and the central tube 1, and a sealing ring is also provided between the lower connector 13 and the central tube 1. Sealing rings are provided on both the inner and outer sides of the sliding sleeve 3 to seal the gap between the sliding sleeve 3 and the central tube 1, as well as the gap between the sliding sleeve 3 and the outer sleeve 2, thereby sealing the guide hole in the first position.

[0103] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0104] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0105] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0106] Certain terms are used throughout this application to refer to specific system components. As those skilled in the art will recognize, the same components may often be referred to by different names, and therefore this application is not intended to distinguish components that differ only in name and not in function. The terms "an embodiment" or "embodiment" used in the specification mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "embodiment" appearing throughout the specification does not necessarily refer to the same embodiment.

[0107] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

[0108] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and / or modifications falling within the scope of the invention, and all changes and / or modifications made according to embodiments of the invention should be covered within the protection scope of the invention.

Claims

1. A soluble delayed-opening toe sleeve, characterized in that, include: Central tube (1) An outer sleeve (2) is disposed outside the central tube (1), and a cavity (4) is formed between the outer sleeve (2) and the central tube (1). A flow guide hole is provided on the outer sleeve (2) and the central tube (1) to communicate with the inside of the central tube (1) and the outside of the outer sleeve (2). The sliding sleeve (3) is disposed in the cavity (4). In the initial state, the sliding sleeve (3) is in the first position, blocking the guide hole; when the sliding sleeve (3) moves to the second position, it moves away from the guide hole, so that the guide hole is opened. as well as The delayed opening mechanism is installed inside the cavity (4). After a delay period, the sliding sleeve (3) is pushed from the first position to the second position by fluid pressure.

2. The soluble delayed-opening toe sleeve according to claim 1, characterized in that, A first spring (31) is provided on one side of the sliding sleeve (3), and the first spring (31) is provided on the side of the sliding sleeve (3) away from the delayed opening mechanism; Initially, the first spring (31) is in an extended state and the sliding sleeve (3) is in a first position; when the pressure of the fluid pushes the sliding sleeve (3) from the first position to the second position, the first spring (31) is in a compressed state.

3. The soluble delayed-opening toe sleeve according to claim 2, characterized in that, The flow guide hole includes an outer hole (21) disposed on the outer sleeve (2) and an inner hole (11) disposed on the central tube (1), the outer hole (21) and the inner hole (11) being arranged opposite to each other.

4. The soluble delayed-opening toe sleeve according to claim 3, characterized in that, A step or groove (33) is provided on the outer sleeve (2), and an elastic claw (32) is provided on the sliding sleeve (3); when the sliding sleeve (3) moves to the second position, the claw engages in the step or groove (33) to fix the sliding sleeve (3).

5. The soluble delayed-opening toe sleeve according to any one of claims 1 to 4, characterized in that, The delayed opening mechanism includes an inlet on the central tube (1), which is connected to the cavity (4) through a flow channel. A rupture disc is provided on the inlet, and a first one-way valve (44) is provided inside the cavity (4). The rupture disc blocks the inlet, and under a certain pressure, the rupture disc breaks, thereby opening the inlet.

6. The soluble delayed-opening toe sleeve according to claim 5, characterized in that, The cavity (4) is also provided with a temporary blocking ring (43) and a second one-way valve (45), and there is a certain distance between the temporary blocking ring (43) and the second one-way valve (45); A dissolving chamber (41) is formed between the first flow valve (44) and the second flow valve (45), and the dissolving chamber (41) is filled with dissolving liquid (42).

7. The soluble delayed-opening toe sleeve according to claim 6, characterized in that, The temporary plugging ring (43) is made of soluble material, and the dissolving liquid (42) can dissolve the temporary plugging ring (43) in a certain period of time, so that the liquid in the dissolving liquid chamber (41) can flow to the position of the sliding sleeve (3).

8. The soluble delayed-opening toe sleeve according to claim 7, characterized in that, The solution (42) is a liquid acid or a highly mineralized solution.

9. The soluble delayed-opening toe sleeve according to claim 7, characterized in that, The dissolving liquid (42) is a solid acid, wherein the fluid in the central tube (1) enters the dissolving liquid chamber (41) through the inlet and dissolves the solid acid.

10. The soluble delayed-opening toe sleeve according to claim 7, characterized in that, The rupture disc (14) includes a threaded sleeve connected to the inlet by a thread, and the threaded sleeve is provided with a rupture disc.

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