Unidirectional sealing soluble bridge plug

Abstract

The utility model provides a one-way sealing soluble bridge plug, and belongs to the field of bridge plugs. The one-way sealing soluble bridge plug comprises a center pipe and a guiding shoe connected to the lower end of the center pipe, the guiding shoe is provided with an extending section protruding out of the lower end wall of the center pipe in the axial direction, the extending section is provided with a center hole coaxially communicated with the center pipe, and the inner wall of the center hole of the guiding shoe and / or the inner wall of the center pipe are / is provided with a flow guide groove allowing flow-back liquid to bypass the fracturing ball. The flow guide grooves are formed in the inner wall of the center pipe and / or the inner wall of the center hole of the guide shoe, so that the surface area of the center pipe and / or the guide shoe is increased, the dissolving speed of the center pipe and / or the guide shoe is increased, flowback liquid can still flow smoothly when the fracturing ball is clamped into the center hole of the center pipe or the guide shoe, and the fracturing effect is improved. And the fast dissolving speed of the one-way sealed soluble bridge plug is ensured.

Description

Technical Field

[0001] The utility model belongs to the field of bridge plugs, in particular to a one-way sealed soluble bridge plug. Background Art

[0002] The post-completion fracturing and transformation of horizontal wells generally adopts the staged fracturing process of pumping bridge plugs and perforating. The bridge plugs are mainly used to seal the lower transformed reservoir and force the fracturing fluid into the target layer. In the early stage of this process, drillable materials are used to process the bridge plugs. After the fracturing and transformation operation is completed, the bridge plugs are destroyed by drilling, grinding and milling to open the production channel. In recent years, soluble bridge plugs have appeared, which can dissolve in the chloride ion solution in the well, reducing construction costs and construction risks.

[0003] The existing Chinese utility model patent with authorization announcement number CN210530797U and authorization announcement date May 15, 2020 discloses a synchronous ball-delivering soluble bridge plug, which includes an axially hollow center tube, and the outer circumference of the center tube is sequentially provided with a cone, a slip and a guide shoe from top to bottom, and the lower end of the center tube is connected to the guide shoe by a thread, and the guide shoe has an extension section protruding from the lower end wall of the center tube in the axial direction, and the extension section has a center hole coaxially connected to the center tube, and the inner cavity of the center tube and the center hole of the guide shoe can be used as a return channel for post-fracturing blowback. The lower end wall of the guide shoe is provided with a "cross"-shaped flow groove, which can prevent the fracturing balls of the previous layer from returning to block the lower end of the guide shoe during the blowback after fracturing, and can ensure the smooth flow back channel.

[0004] However, the flow capacity of the flow groove is limited, and the fracturing ball will still hinder the flow of the return liquid after it is stuck in the guide shoe; and the fracturing ball will shrink in size during the dissolution process and just get stuck in the center hole or center tube of the guide shoe, which will block the return channel and prevent the return liquid from flowing, seriously affecting the dissolution rate of the bridge plug. Utility Model Content

[0005] The utility model aims to provide a one-way sealed soluble bridge plug to solve the technical problem in the prior art that the fracturing ball of the previous layer section is easily stuck in the center hole of the guide shoe or the center pipe, thereby affecting the flow of the return liquid and causing the dissolution rate of the bridge plug to be reduced.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the one-way sealed soluble bridge plug provided by the utility model is:

[0007] A one-way sealed soluble bridge plug comprises a center pipe and a guide shoe connected to the lower end of the center pipe, the guide shoe having an extended section protruding axially from the lower end wall of the center pipe, the extended section having a center hole coaxially connected to the center pipe, and a guide groove for allowing return liquid to bypass a fracturing ball is provided on the inner wall of the center hole of the guide shoe and / or the inner wall of the center pipe.

[0008] As a further improvement, the guide groove is a long groove extending along the axial direction of the central tube.

[0009] As a further improvement, the guide grooves are arranged in groups, each group has at least two guide grooves and the guide grooves are arranged at intervals along the circumference of the central pipe or the guide shoe.

[0010] As a further improvement, a slip is provided on the outer sleeve of the center tube, and the inner wall of the slip is a conical wall. An annular flow channel is formed between the inner wall of the slip and the outer wall of the center tube. The guide groove includes a through guide groove which is arranged on the inner wall of the center tube and radially penetrates the center tube. The through guide groove corresponds to the position of the annular flow channel and is connected with the annular flow channel. After the slip is radially expanded, it has a flow channel for the return liquid to flow from the outside of the slip into the annular flow channel.

[0011] As a further improvement, the slip is provided with an open groove which penetrates the slip in radial direction and is connected with the annular flow channel, and the open groove constitutes a flow passage.

[0012] As a further improvement, a guide groove extending axially along the cava is provided on the outer wall of the cava, and the two ends of the guide groove respectively penetrate the two axial end walls of the cava surface, the open groove corresponds to the position of the guide groove and is connected, and the guide groove constitutes a drainage groove for the return liquid to flow.

[0013] As a further improvement, a guide groove extending axially along the cava is provided on the outer wall of the cava, and the two ends of the guide groove respectively penetrate the two axial end walls of the cava surface. The guide groove is used to weaken the strength of the cava so that the cava can be cracked from the guide groove after being stretched open, and the cracked opening constitutes a flow channel.

[0014] As a further improvement, the guide groove includes an end guide groove opened on the inner wall of the central sleeve, and one end of the end guide groove passes through the lower end wall of the central sleeve.

[0015] As a further improvement, a flow groove is provided on the lower end wall of the guide shoe, and the flow groove is connected with the end guide groove.

[0016] As a further improvement, the depth of the flow groove is not less than the axial length of the extended section, and the end guide groove corresponds to the position of the flow groove, so that the flow groove is connected with the end guide groove.

[0017] The beneficial effect is that the one-way sealed soluble bridge plug provided by the utility model is an improvement on the prior art. The one-way sealed soluble bridge plug is provided with a guide groove on the inner wall of the center hole of the central tube and / or the guide shoe, so that when the fracturing ball is stuck in the center hole of the guide shoe or in the central tube, the return liquid can bypass the fracturing ball from the guide groove to ensure smooth flow of the return liquid and the dissolution speed of the one-way sealed soluble bridge plug. In addition, the guide groove also increases the surface area of ​​the central tube and / or the guide shoe, which can increase the faster dissolution speed of the central tube and the guide shoe. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an embodiment of a one-way sealed soluble bridge plug in the utility model;

[0019] Figure 2 It is a partial structural schematic diagram of an embodiment of a one-way sealed soluble bridge plug in the utility model;

[0020] Figure 3 The present invention is a schematic structural diagram of an embodiment of a one-way sealed soluble bridge plug in the present invention after a connecting rod and a push cylinder are installed.

[0021] Description of reference numerals:

[0022] 1. Center pipe; 2. Fracturing ball; 3. Accommodating chamber; 4. Baffle; 5. Baffle ring; 6. Locking ring; 7. Locking sleeve; 8. Soluble rubber tube; 9. Cone; 10. Slip; 11. Guide shoe; 111. Connecting section; 112. Extending section; 12. Inner sealing ring groove; 13. Soluble sealing ring; 14. Support ring; 15. Upper opening ring; 16. Lower opening ring; 17. Opening groove; 18. Guide groove; 19. Flow groove; 20. End guide groove; 21. Through guide groove; 22. Connecting rod; 23. Push cylinder. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the embodiments.

[0024] In order to solve the problems in the prior art, the basic concept of the utility model is to open a guide groove on the inner wall of the center hole of the center pipe and / or the guide shoe, thereby increasing the surface area of ​​the center pipe and / or the guide shoe, improving the dissolution rate of the center pipe and / or the guide shoe, and also enabling the return liquid to continue to flow smoothly when the fracturing ball is stuck in the center hole of the center pipe or the guide shoe, thereby ensuring a faster dissolution rate of the one-way sealed soluble bridge plug.

[0025] Specific embodiments of the one-way sealed soluble bridge plug provided by the utility model:

[0026] See attached Figure 1 A one-way sealed soluble bridge plug includes a central tube 1, a receiving chamber 3 for receiving a fracturing ball 2 is provided inside the upper end of the central tube 1, a baffle 4 is threadedly connected inside the central tube 1 to seal the upper end of the receiving chamber 3 to prevent the fracturing ball 2 from escaping, and a hole for liquid to flow through is opened on the baffle 4. The outer part of the central tube 1 is sleeved with a baffle ring 5, a locking ring 6, a locking sleeve 7, a soluble rubber tube 8, a cone 9, a slip 10 and a guide shoe 11 from top to bottom.

[0027] The retaining ring 5 and the central tube 1, as well as the cone 9 and the central tube 1, are connected by shear nails, which can prevent the retaining ring 5 and the cone 9 from moving relative to the central tube 1 before the one-way sealing soluble bridge plug is lowered into place, thereby completing the sealing in advance.

[0028] The inner wall of the locking ring 6 and the corresponding outer wall of the central tube 1 are both provided with ratchet teeth that mesh with each other, so as to prevent the locking ring 6 from retreating after the locking ring 6 moves downward relative to the central tube 1 .

[0029] An inner sealing ring groove 12 is provided on the inner wall of the soluble gel tube 8, and the inner sealing ring groove 12 is located in the middle of the axial direction of the soluble gel tube 8. A soluble sealing ring 13 is provided in the inner sealing ring groove 12 and is sleeved on the outside of the central tube 1. A support ring 14, an upper opening ring 15, and a lower opening ring 16 are provided between the soluble gel tube 8 and the cone 9. The support ring 14 and the cone 9 are both provided with outer cone surfaces. The upper opening ring 15 and the lower opening ring 16 are respectively provided with inner cone surfaces that match the outer cone surfaces on the support ring 14 and the cone 9. When the support ring 14 moves toward the cone 9, the upper opening ring 15 and the lower opening ring 16 will be radially expanded and fit with the inner wall of the casing. After the two ends of the soluble gel tube 8 are squeezed, radial expansion will occur, so as to fit with the inner wall of the casing to achieve sealing. The upper opening ring 15 and the lower opening ring 16 can prevent the soluble gel tube 8 from flowing along the gap between the one-way sealed soluble bridge plug and the inner wall of the casing. The structures of the upper opening ring 15 and the lower opening ring 16 are the same as those of the lower male expansion ring and the lower female expansion ring in the Chinese invention patent application with application publication number CN112796701A, and are not described in detail here.

[0030] The inner wall of the slip 10 is a conical wall, and cooperates with the other outer conical surface of the cone 9. After the slip 10 is propped up by the cone 9, a gap is formed between the inner wall of the slip 10 and the outer wall of the center pipe 1, and the gap constitutes an annular flow channel for the return liquid to flow. The slip 10 is provided with an open groove 17 that penetrates the slip 10 in the radial direction so that the slip 10 can be radially stretched. The open groove 17 connects the outside of the slip 10 with the annular flow channel, and one end of the open groove 17 is located at the end of the slip 10 away from the guide shoe 11. A plurality of guide grooves 18 extending along the axial direction of the slip 10 are provided on the outer wall of the slip 10, and the two ends of the guide groove 18 respectively penetrate the axial end walls of the slip 10 surface, and the positions of the open groove 17 and the guide groove 18 correspond and are connected.

[0031] The guide shoe 11 has a connecting section 111 sleeved on the central tube 1 and an extending section 112 protruding from the lower end wall of the central tube 1 in the axial direction, and the connecting section 111 of the guide shoe 1 is connected to the central tube 1 by threads. The extending section 112 has a central hole coaxial with and connected to the central tube 1, and the diameter of the central hole is equal to the inner diameter of the central tube 1.

[0032] See attached Figure 1 and attached Figure 2A flow groove 19 is formed on one end wall of the extension section 112 away from the connection end. The flow groove 19 is a "cross" structure. The opening depth of the flow groove 19 is greater than the axial length of the extension section 112, so that the return liquid has a sufficiently long flow path.

[0033] A guide groove is provided on the inner wall of the central pipe 1 for the return fluid to bypass the fracturing ball 2 , and the guide groove is divided into an end guide groove 20 and a through guide groove 21 .

[0034] The end guide groove 20 is located at the lower end of the central pipe 1. The end guide groove 20 is a long groove extending along the axial direction of the central pipe 1, and a plurality of end guide grooves 20 are arranged at intervals along the circumferential direction of the central pipe 1. One end of the end guide groove 20 penetrates the lower end wall of the central pipe 1, so that the end guide groove 20 is connected with the flow groove 19, so as to provide a longer flow path for the return liquid.

[0035] The through guide groove 21 penetrates the central tube 1 in the radial direction, and the through guide groove 21 is arranged at a position corresponding to the position of the annular flow channel and is connected to the annular flow channel. The extending direction of the through guide groove 21 is the same as the extending direction of the axis of the central tube 1, and a plurality of through guide grooves 21 are also arranged at intervals along the circumference of the central tube 1.

[0036] When using, see the attached Figure 3 , the upper end of the center pipe 1 is connected with the connecting rod 22 through the shear nail, and then the connecting rod 22 is connected to the inner part of the setting tool, and the push tube 23 is sleeved on the upper end of the center pipe 1, and the push tube 23 abuts against the axial end wall of the retaining ring 5, and the push tube 23 is connected to the outer tube of the setting tool. After the one-way sealed soluble bridge plug is lowered to a predetermined position in the well, the setting tool is used to make the connecting rod 22 and the push tube 23 move relative to each other. In this process, the push tube 23 pushes the retaining ring 5 to cut the shear nail and moves downward relative to the center pipe, and the cone 9 also moves downward relative to the center pipe 1 to cut the shear nail between it and the center pipe 1.

[0037] The retaining ring 5 continues to move downward relative to the center tube, and the locking ring 6 and the locking sleeve 7 will also move together, thereby squeezing the soluble gel tube 8, causing the soluble gel tube 8 to expand radially, so that a good seal is formed between the center tube 1 and the casing. Since the end of the slip 10 away from the cone 9 is restricted by the guide shoe 11 and cannot move, the cone 9 will move toward the slip 10, so that the slip 10 is radially expanded, and the outer wall of the slip 10 contacts the inner wall of the casing so that the one-way sealed soluble bridge plug is anchored and stabilized. The guide groove 18 weakens the strength of the slip 10. When the slip 10 is expanded, it will crack along the guide groove 18, and finally form multiple petals. The cracked opening can serve as a flow channel for the liquid outside the slip 10 to flow into the annular flow channel. If the slip 10 has good ductility and does not crack along the guide groove 18, the open groove 17 opened on the slip 10 can be used as a flow channel. At this time, the guide groove 18 can constitute a drainage groove that guides the return liquid to flow to the open groove 17 to ensure smooth flow of the return liquid.

[0038] After the fracturing is completed, the blowdown begins, causing the liquid in the well to flow upward, accelerating the dissolution of the one-way sealed soluble bridge plug and discharging the dissolved residue. If the fracturing ball 2 of the previous layer is stuck on the lower end of the guide shoe 11, part of the return liquid will flow into the central pipe 1 through the flow groove 19, and the other part will reach the slip 10 from the gap between the guide shoe 11 and the casing, and then enter the annular flow channel from the open groove 17 on the slip 10, and then enter the central pipe 1 from the through guide groove 21, and continue to flow upward along the central pipe 1. Both parts of the return liquid can bypass the fracturing ball 2 to ensure the dissolution efficiency.

[0039] As the fracturing ball 2 dissolves, the size of the fracturing ball 2 decreases, but the shape of the fracturing ball 2 becomes irregular during the dissolution process. At a certain moment, the fracturing ball 2 can just enter the center hole of the guide shoe 11 or the center pipe 1 at a certain angle, but under the push of the return fluid, the fracturing ball 2 may get stuck in the center hole of the guide shoe 11 or the lower end of the center pipe 1 if it deflects slightly.

[0040] Since the depth of the flow groove 19 is greater than the axial length of the extension section 112, when the fracturing ball 2 is stuck in the center hole of the guide shoe 11, the return liquid can still bypass the fracturing ball 2 from the flow groove 19. When the fracturing ball 2 is stuck at the lower end of the central pipe 1, the return liquid can bypass the fracturing ball 2 through the end guide groove 20 and then enter the central pipe 1.

[0041] The middle and upper parts of the central pipe 1 are far away from the lower end thereof, and the fracturing ball 2 generally does not get stuck there. In other embodiments, in order to prevent the fracturing ball 2 from getting stuck in the middle and upper parts of the central pipe 1 and affecting the flow of the return liquid, a guide groove may also be provided there. The guide groove here is a middle guide groove, which is divided into sections and arranged in groups, each group having at least two guide grooves and each guide groove is arranged at intervals along the circumference of the central pipe 1.

[0042] In addition to enabling the flowback fluid to bypass the fracturing ball 2 , the guide groove can also increase the surface area of ​​the central pipe 1 or the guide shoe 11 , thereby effectively improving the dissolution efficiency of the central pipe 1 or the guide shoe 11 .

[0043] In other embodiments, the depth of the flow groove may be equal to the axial length of the extension section. The depth of the flow groove may be less than the axial length of the extension section. In this case, in order to ensure the flow of the return liquid, a guide groove may be opened on the inner wall of the central hole of the guide shoe, and the guide groove is the guide shoe guide groove, and the guide shoe guide groove connects the flow groove with the end guide groove.

[0044] In other embodiments, the flow channel may not be connected to the end guide channel, or the end guide channel may not be provided.

[0045] In the above embodiments, the guide groove can make the slip easier to split, and can also guide the flow of the return liquid. In other embodiments where the slip has good ductility and does not split, the guide groove may not be provided. In this embodiment, ceramic particles are embedded on the outer wall of the slip, which can ensure the stability of the slip after anchoring with the casing, and on the other hand, the ceramic particles can also form a gap between the outer wall of the slip and the casing, so that the return liquid can smoothly reach the opening groove. In other embodiments where the slip has poor ductility and is prone to splitting, the opening groove may not be provided, and only the guide groove is provided in this embodiment.

[0046] In the above embodiments, the guide grooves are arranged in groups in order to improve the flow capacity of the guide grooves. In other embodiments, the flow capacity of the guide grooves can be improved by widening the width of the guide grooves, while reducing the number of the guide grooves.

[0047] In the above embodiments, the guide grooves are long grooves extending along the axial direction of the central tube, so as to ensure that the return liquid can bypass the fracturing ball more smoothly. In other embodiments, the guide grooves can also be square grooves or inclined grooves.

[0048] The guide groove can be set only on the inner wall of the central tube, or only on the inner wall of the central hole of the guide shoe, or on both the inner wall of the central tube and the inner wall of the central hole of the guide shoe, which can be selected according to actual needs.

[0049] The guide groove on the central tube can be one, two or all of the through guide groove, the end guide groove and the middle guide groove. Other forms of guide grooves can also be set at other positions according to actual conditions, which will not be elaborated here.

[0050] Finally, it should be noted that the above is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments without creative work, or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A one-way sealed soluble bridge plug, comprising a central tube and a guide shoe connected to the lower end of the central tube, the guide shoe having an extended section protruding from the lower end wall of the central tube in the axial direction, the extended section having a central hole coaxially connected to the central tube, characterized in that: A guide groove is provided on the inner wall of the center hole of the guide shoe and / or the inner wall of the center pipe for the return fluid to bypass the fracturing ball.

2. The one-way sealed soluble bridge plug according to claim 1 is characterized in that: The guide groove is a long groove extending along the axial direction of the central tube.

3. The one-way sealing soluble bridge plug according to claim 2 is characterized in that: The guide grooves are arranged in groups, each group has at least two guide grooves, and the guide grooves are arranged at intervals along the circumference of the central tube or the guide shoe.

4. The one-way sealed soluble bridge plug according to any one of claims 1 to 3, characterized in that: A slip is arranged on the outer sleeve of the center tube, and the inner wall of the slip is a conical wall. An annular flow channel is formed between the inner wall of the slip and the outer wall of the center tube. The guide groove includes a through guide groove which is arranged on the inner wall of the center tube and radially penetrates the center tube. The through guide groove corresponds to the position of the annular flow channel and is connected with the annular flow channel. After the slip is radially expanded, a flow channel is provided for the return liquid to flow from the outside of the slip into the annular flow channel.

5. The one-way sealing soluble bridge plug according to claim 4 is characterized in that: The slip is provided with an open groove which penetrates the slip in radial direction and is communicated with the annular flow channel, and the open groove constitutes a flow passage.

6. The one-way sealing soluble bridge plug according to claim 5 is characterized in that: A guide groove extending axially along the slip is provided on the outer wall of the slip, and the two ends of the guide groove respectively penetrate the two axial end walls of the slip surface, the open groove corresponds to the position of the guide groove and is connected, and the guide groove constitutes a drainage groove for the return liquid to flow.

7. The one-way sealing soluble bridge plug according to claim 4 is characterized in that: A guide groove extending axially along the slip is provided on the outer wall of the slip, and the two ends of the guide groove respectively penetrate the two axial end walls of the slip surface. The guide groove is used to weaken the strength of the slip so that the slip is cracked from the guide groove after being stretched open, and the cracked opening constitutes a flow channel.

8. The one-way sealed soluble bridge plug according to any one of claims 1 to 3, characterized in that: The guide groove comprises an end guide groove which is arranged on the inner wall of the central sleeve, and one end of the end guide groove passes through the lower end wall of the central sleeve.

9. The one-way sealing soluble bridge plug according to claim 8, characterized in that: A flow groove is arranged on the lower end wall of the guide shoe, and the flow groove is communicated with the end guide groove.

10. The one-way sealing soluble bridge plug according to claim 9, characterized in that: The depth of the flow groove is not less than the axial length of the extended section, and the end guide groove corresponds to the position of the flow groove, so that the flow groove is connected with the end guide groove.

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