A differential pressure sliding sleeve and a manufacturing method of a damaged element thereof

Abstract

The application provides a differential pressure sliding sleeve, comprising: an outer cylinder, a side wall of the outer cylinder being provided with a flow guide hole; an upper joint and a lower joint being fixedly connected to two ends of the outer cylinder respectively; a first inner cylinder and a second inner cylinder being concentrically arranged in the inner part of the outer cylinder, the second inner cylinder being located at the lower end of the first inner cylinder; a damage element being configured in a cylindrical shape, the damage element being arranged axially between the first inner cylinder and the second inner cylinder; wherein the damage element supports the first inner cylinder in an initial state, so that the first inner cylinder closes the flow guide hole, the damage element can be damaged by pressure accumulation when the critical breaking pressure is reached, so that the first inner cylinder can descend to open the flow guide hole. The application also provides a manufacturing method of the damage element for the differential pressure sliding sleeve.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas well completion and reservoir stimulation technology, specifically relating to a differential pressure sliding sleeve, particularly for use in horizontal wells of unconventional oil and gas reservoirs. This invention also relates to a method for manufacturing a failure element for the differential pressure sliding sleeve. Background Technology

[0002] With the large-scale development of unconventional oil and gas resources such as shale gas and tight sandstone oil and gas reservoirs, horizontal well staged fracturing technology has become one of the most effective means of developing unconventional oil and gas reservoirs. Domestically and internationally, unconventional oil and gas reservoir development employs sliding sleeve staged fracturing and pumped bridge plug staged fracturing. The initial fracturing stimulation methods generally include two types: coiled tubing perforation and differential pressure sliding sleeve fracturing. Coiled tubing perforation has low construction efficiency and high construction costs. Using differential pressure sliding sleeves allows for direct opening through pressure buildup, eliminating the need for coiled tubing perforation, thereby improving construction efficiency and saving costs.

[0003] However, existing differential pressure sleeves suffer from several drawbacks in application, including low success rates due to the influence of cementing slurry; limited operating pressure range for opening the differential pressure sleeve due to the constraints of the full-bore test pressure and wellhead equipment pressure levels; and difficulty in opening ordinary differential pressure sleeves. These issues hinder their application in unconventional gas reservoirs. Furthermore, delayed differential pressure sleeves employ a delayed structure with a small inlet hole, making them prone to blockage and difficult to open. Additionally, delayed differential pressure sleeves suffer from short delay times, preventing repeated pressure tests. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a differential pressure sliding sleeve and a method for manufacturing its failure element. The differential pressure sliding sleeve is equipped with a failure element, which can prevent cement slurry residue at the sliding sleeve from affecting its opening during cementing. Furthermore, after cementing is completed, the failure element can be destroyed by pressure buildup, allowing the sliding sleeve to open directly, thus ensuring the smooth progress of cementing and fracturing operations.

[0005] Therefore, according to a first aspect of the present invention, a differential pressure sleeve is provided, comprising: an outer cylinder having a flow guide hole on its side wall; an upper connector and a lower connector respectively fixedly connected to both ends of the outer cylinder; a first inner cylinder and a second inner cylinder concentrically arranged inside the outer cylinder, the second inner cylinder being located at the lower end of the first inner cylinder; and a cylindrical breaking element disposed axially between the first inner cylinder and the second inner cylinder; wherein, in its initial state, the breaking element supports the first inner cylinder, causing the first inner cylinder to close the flow guide hole, and by pressurizing, the breaking element can be destroyed when a critical rupture pressure is reached, thereby allowing the first inner cylinder to descend and open the flow guide hole.

[0006] In one embodiment, the wall thickness of the damaged element is set to be in the range of 3-5 mm, preferably 3 mm.

[0007] In one embodiment, the broken element is made of a brittle resin material.

[0008] In one embodiment, a plurality of annular grooves are provided on the outer surface of the damaged element, the plurality of annular grooves being evenly spaced apart along the axial direction, and the number of annular grooves being 6-8.

[0009] In one embodiment, a plurality of annular retaining edges are provided on the outer surface of the damaged element, which are evenly spaced apart in the circumferential direction. The annular retaining edges extend radially outward, and the plurality of annular grooves are respectively located between adjacent annular retaining edges in the axial direction.

[0010] In one embodiment, the axial width of the annular flange is set to be in the range of 6-10 mm.

[0011] In one embodiment, the connection between the annular retaining edge and the outer wall of the damaged element is chamfered, and the chamfer is not less than 0.2 mm.

[0012] In one embodiment, the axial extension length of the broken element is set to be in the range of 102-150 mm.

[0013] In one embodiment, a first sealing element is provided between the first inner cylinder and the outer cylinder and near both ends of the first inner cylinder, and a second sealing element is provided between the second inner cylinder and the outer cylinder and near both ends of the second inner cylinder.

[0014] According to a second aspect of the present invention, a method for manufacturing a failure element for the aforementioned differential pressure sleeve is provided. The failure critical pressure of the failure element is set according to the wall thickness of the failure element, the material used for the failure element, the number of annular grooves provided on the surface of the failure element, the axial width of the annular retaining edge provided on the surface of the failure element, the chamfer of the annular retaining edge, and the axial extension length of the failure element. The optimal failure critical pressure is determined by different combinations of parameters.

[0015] Compared with the prior art, the advantages of this application are:

[0016] The differential pressure sleeve according to the present invention is equipped with a breaking element. This breaking element prevents cement slurry residue from remaining at the sleeve during cementing, thus preventing it from affecting the sleeve's opening. Furthermore, after cementing, the breaking element is detonated by pressure buildup, allowing the sleeve to open directly, ensuring the smooth progress of cementing and fracturing operations. This differential pressure sleeve exhibits stable and reliable opening performance, significantly reducing the difficulty of opening and lowering operational risks. The use of the breaking element reduces the need for pressure-building components, simplifying the structure of the differential pressure sleeve. In addition, the differential pressure sleeve effectively ensures the sealing performance between the first inner cylinder, the second inner cylinder, and the outer cylinder, thereby guaranteeing the opening performance of the differential pressure sleeve. The operation of the differential pressure sleeve is simple and convenient, greatly simplifying the construction process and significantly contributing to reduced construction costs and improved efficiency. Attached Figure Description

[0017] The present invention will now be described with reference to the accompanying drawings.

[0018] Figure 1 The structure of the differential pressure sleeve according to the present invention is shown schematically.

[0019] Figure 2 schematically shown Figure 1 The structure of the damaged element in the differential pressure sleeve is shown.

[0020] Figures 3 to 5 The diagram schematically illustrates the process of fracturing and failure of a damaged component.

[0021] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0022] The invention will now be described with reference to the accompanying drawings.

[0023] In this application, it should be noted that the end of the differential pressure sleeve according to the present invention that is lowered into the wellbore and closer to the wellhead is defined as the upper end, and the end that is farther away from the wellhead is defined as the lower end.

[0024] Figure 1 The structure of the differential pressure sleeve 100 according to the present invention is shown. For example... Figure 1 As shown, the differential pressure sleeve 100 includes an outer cylinder 1. In one embodiment, both ends of the outer cylinder 1 are configured with negative stepped connecting buckles. The two ends of the outer cylinder 1 are respectively connected to an upper connector 12 and a lower connector 13 for connecting to a downhole tubing string. In another embodiment, both ends of the outer cylinder 1 are configured with positive stepped connecting buckles, and the two ends of the outer cylinder 1 are respectively fitted and connected to the negative stepped connecting buckles of the upper connector 12 and the lower connector 13 via positive stepped connecting buckles, thereby forming a fixed connection. This connection structure of the outer cylinder 1 is simple and convenient, has high installation efficiency, and can ensure stable and reliable installation connections with other components.

[0025] In this embodiment, to ensure the sealing of the connection between the outer cylinder 1 and the upper connector 12 and the lower connector 13, a third sealing element 121 is provided between the connecting surfaces of the outer cylinder 1 and the upper connector 12 and the lower connector 12, respectively. In one embodiment, a radially inwardly extending sealing groove 122 is provided on the stepped connecting buckle of the upper connector 12 and the lower connector 13 on the axially inner side of the end face, and the third sealing element 121 is installed in the corresponding sealing groove 122. Preferably, the third sealing element 121 is an O-ring.

[0026] like Figure 1 As shown, a plurality of flow guide holes 11 are provided on the side wall of the outer cylinder 1. The flow guide holes 11 are located at the same axial position on the outer cylinder 1 and are evenly spaced apart in the circumferential direction. The flow guide holes 11 are located in the side wall region near the upper end of the outer cylinder 1. In one embodiment, the flow guide holes 11 are configured as axially extending strip-shaped through holes. This structure of the flow guide holes 11 can improve the flow guiding effect.

[0027] According to the present invention, a first inner cylinder 2, a second inner cylinder 3, and a breaking element 4 are sleeved inside the outer cylinder 1. The second inner cylinder 3 is located at the lower end of the first inner cylinder 2, and the breaking element is located axially between the first inner cylinder 2 and the second inner cylinder 3. The lower end face of the second inner cylinder 3 abuts against the upper end face of the lower connector 13. The two axial end faces of the breaking element 4 abut against the lower end face of the first inner cylinder 2 and the upper end face of the second inner cylinder 3, respectively. In the initial state, the breaking element 4 provides support to the first inner cylinder 2, causing the first inner cylinder 2 to close the guide hole 11. By applying pressure, the breaking element 4 can be broken when the critical rupture pressure is reached, thereby allowing the first inner cylinder 2 to descend and open the guide hole 11. A gap is left between the upper end face of the first inner cylinder 2 and the lower end face of the upper connector 12.

[0028] To ensure a tight seal between the inner cylinder 2 and the outer cylinder 1, a first sealing element 21 is provided between the mounting surfaces of the inner cylinder 2 and the outer cylinder 1, near both ends of the inner cylinder 2. Preferably, the first sealing element 21 is an O-ring. Figure 1 As shown, a plurality of first sealing grooves 22 are provided on the outer surface of the first inner cylinder 2. For example, a plurality of first sealing grooves 22 are provided on the outer surface of the first inner cylinder 2 and on the axial inner side at both ends, and first sealing elements 21 are respectively installed in the first sealing grooves 22. The first sealing elements 21 can effectively ensure the sealing performance between the inner cylinder 2 and the outer cylinder 1, thereby improving the working performance of the differential pressure sleeve 100.

[0029] With the guide hole 11 closed, the first sealing member 21, located near the upper end of the first inner cylinder 2, is positioned above the guide hole 11, thereby ensuring the sealing performance of the guide hole 11.

[0030] Similarly, second sealing elements 31 are also provided between the second inner cylinder 3 and the outer cylinder 1, and near both ends of the second inner cylinder. Figure 1 The image only schematically shows a second sealing element 31 between the second inner cylinder 3 and the outer cylinder 1. For example, a second sealing groove 32 is provided on the outer surface of the second inner cylinder 3, and the second sealing element 31 is installed in the corresponding second sealing groove 32.

[0031] According to the present invention, such as Figure 2 As shown, the failure element 4 is constructed in a cylindrical shape. The wall thickness of the failure element 4 is set in the range of 3-5 mm. In a preferred embodiment, the wall thickness of the failure element 4 is set to 3 mm. Since the wall thickness of the failure element 4 has an almost linear relationship with the critical rupture pressure, that is, the larger the wall thickness of the failure element 4, the larger the critical rupture pressure. Therefore, under the premise of satisfying the overcurrent condition, the smaller the wall thickness of the failure element 4, the better.

[0032] According to the present invention, the failure element 4 is made of a brittle resin material. For example, the failure element 4 can be made of PS (polystyrene) or PMMA (polymethyl methacrylate). Preferably, PS material is used, which can achieve the minimum critical fracture pressure, and PS material has a temperature resistance of up to about 85°C, which can meet the requirements of use in downhole environments.

[0033] According to one embodiment of the present invention, the outer cylinder 1, the first inner cylinder 2, and the second inner cylinder 3 can be made of 42CrMo. 42CrMo steel is an ultra-high strength steel with high strength and toughness, good hardenability, no obvious temper brittleness, and after tempering, it has a high fatigue limit and resistance to repeated impacts, as well as good low-temperature impact toughness, enabling the outer cylinder 1, the first inner cylinder 2, and the second inner cylinder 3 to have good rigidity and strength. As for the fracture element 4 made of brittle resin material, it has good corrosion resistance, making it very suitable for downhole tools. Furthermore, the fracture element 4 has low surface hardness and is brittle and easily cracked, meeting the process requirements for downhole tool fracturing. The fracture element 4 can effectively fracture when the critical fracture pressure is reached.

[0034] like Figure 2 As shown, multiple annular grooves 41 are provided on the outer surface of the damaged component 4, and the multiple annular grooves 41 are evenly spaced along the axial direction. The number of annular grooves 41 is 6-8.

[0035] During simulation tests on the damaged component 4, the critical pressure of rupture was lowest when there were 8 annular grooves 41. The critical pressure was highest when there were no annular grooves 41. When there were 0 to 2 annular grooves 41, the critical pressure decreased significantly, proving that the annular grooves 41 can effectively reduce the critical pressure of rupture. When there were 2 to 6 annular grooves 41, the critical pressure did not change much. However, when there were 6 to 8 annular grooves 41, the critical pressure decreased significantly. Therefore, in a preferred embodiment, the damaged component 4 has 8 annular grooves. Figure 2 The image only schematically shows that an annular groove 42 is provided on the outer surface of the damaged element 4.

[0036] The fracturing of the damaged element 4 depends not only on the value and location of the maximum stress, but also on the stress values ​​on the inner and outer surfaces of the thin-walled portion of the damaged element. Different structures of the damaged element 4 result in different failure locations, but they are generally located in the thin-walled front end. When an annular groove 41 is provided, the failure occurs near the annular groove 41. By setting an appropriate number of annular grooves 41, the critical fracture pressure of the damaged element 4 can be effectively reduced.

[0037] According to the present invention, such as Figure 2 As shown, multiple annular retaining edges 42, evenly spaced circumferentially, are provided on the outer surface of the damaged component 4, extending radially outward. Multiple annular grooves 41 are respectively located between adjacent annular retaining edges 42 along their axial directions. Figure 2 In the embodiment shown, the outer surface of the damaged element 4 is provided with three annular retaining edges 42 that are evenly spaced apart in the axial direction, and the outer axial end faces of the annular retaining edges 42 at both ends are flush with the axial end faces of the damaged element 4.

[0038] Because a wider axial width of the annular flange 42 means that during fracturing, the thin wall of the fracture element 4 may fracture while the annular flange 42 may not break, leading to accumulation in the axial direction, the axial width of the annular flange 42 is set within the range of 6-10 mm. Furthermore, as the flange width varies within the range of 6 mm to 10 mm, the critical fracture pressure of the fracture element 4 first increases and then decreases.

[0039] Preferably, the axial width of the annular flange 42 is set to 10 mm, at which point the critical pressure for the failure of the broken element 4 is minimized.

[0040] More preferably, the axial width of the annular flange 42 can be set to 6 mm. In this case, the critical fracture pressure is relatively small and the axial accumulation after fracture is small.

[0041] According to the present invention, the connection between the annular retaining edge 42 and the outer wall surface of the damaged element 4 is provided with a chamfer 43, and the size of the chamfer 43 is not less than 0.2mm.

[0042] In a preferred embodiment, the chamfer 43 is set to R0.5mm, at which point the critical pressure for breakage of the broken element 4 is minimized.

[0043] According to the present invention, the axial extension length of the fracturing element 4 is set within the range of 102-150 mm. Since the critical fracture pressure is highest when the axial extension length of the fracturing element 4 is set to 102-114 mm or 150 mm, and the variation in the axial extension length of the fracturing element 4 has little effect on the fracturing force, it can be appropriately varied according to actual needs. Therefore, in a preferred embodiment, the axial extension length of the fracturing element 4 can be set to 126 mm or 138 mm.

[0044] According to the present invention, the critical rupture pressure of the broken element 4 is affected by multiple factors. According to the present invention, a method for manufacturing a broken element is provided, wherein the critical rupture pressure of the broken element is set based on the wall thickness of the broken element, the material used in the broken element, the number of annular grooves provided on the surface of the broken element, the axial width of the annular retaining edge provided on the surface of the broken element, the chamfer of the annular retaining edge, and the axial extension length of the broken element. The optimal critical rupture pressure is determined by different combinations of parameters.

[0045] During the manufacturing process of the broken element 4, the wall thickness of the broken element 4 has the greatest impact on the critical fracture pressure, followed by the material used in the broken element 4, then the number of annular grooves 41 on the surface of the broken element 4, then the axial width of the annular retaining edge 42, then the chamfer 43 of the annular retaining edge, and finally the axial extension length of the broken element 4 has the least impact on the critical fracture pressure. Therefore, to obtain the minimum or appropriate critical fracture pressure when the broken element 4 fails, it is necessary to combine the different factors according to their order of influence and select a suitable combination of broken element parameters.

[0046] After the differential pressure sleeve 100 is inserted into the well, it can withstand the pressure of the first inner cylinder 2 before the fracturing element 4 fails. Therefore, before the fracturing element 4 fails, it can effectively occupy the area axially between the lower end face of the first inner cylinder 2 and the upper end face of the second inner cylinder 3. Thus, the fracturing element 4 can effectively prevent mud or other solid impurities in the working fluid from solidifying or adhering to the inner wall of the outer cylinder 1, preventing obstruction of the downward movement of the first inner cylinder 2 and effectively reducing the difficulty of opening the differential pressure sleeve 100.

[0047] According to the present invention, the critical rupture pressure of the broken element 4 can be adjusted according to the wall thickness of the broken element 4, the material used, the number of annular grooves 41, the axial width of the annular flange 42, the chamfer 43 of the annular flange, and the axial extension length of the broken element 4. This ensures that the broken element 4 can break within a set time.

[0048] According to the present invention, the critical rupture pressure of the optimized failure element 4 is 8.01 MPa, which significantly reduces the critical rupture pressure compared with ordinary failure elements.

[0049] The working process of the differential pressure sleeve 100 according to the present invention is briefly described below. First, the differential pressure sleeve 100 is lowered into the wellbore along with the tubing string for operation. During the lowering process, the failure element 4 remains intact, providing effective support for the first inner cylinder 2, thereby keeping the guide hole 11 closed. Then, high-pressure working fluid is pumped in from the wellhead. The high-pressure working fluid generates high pressure within the tubing string, creating a pressure difference between the upper and lower end faces of the first inner cylinder 2, which have different areas. Because the upper end face area of ​​the first inner cylinder 2 is larger than the lower end face area, and a gap exists between the upper end face of the first inner cylinder 2 and the lower end face of the upper connector 12, the pressure on the upper end face of the first inner cylinder 2 is greater than the pressure on the lower end face. Therefore, the working fluid exerts downward pressure on the first inner cylinder 2. After the pressure on the first inner cylinder 2 reaches a predetermined pressure value (the critical rupture pressure of the failure element 4), the failure element 4 is destroyed by the pressure, and the first inner cylinder 2 loses its support and moves downward, thereby exposing the guide hole 11 on the outer cylinder 1. The first inner cylinder 2 descends to its lower end face and abuts against the upper end face of the second inner cylinder 3 to form an axial limit on the first inner cylinder 2, thereby fully opening the guide hole 11, thereby opening the differential pressure sleeve 200 and connecting the inside and outside of the downhole tubing.

[0050] During the pressure failure process, the location where the damaged element 4 fails is near the annular groove 41. Figures 3 to 5 The process of fracturing failure of the damaged element 4 is illustrated schematically.

[0051] The differential pressure sleeve 100 according to the present invention is provided with a breaking element 4. This breaking element 4 prevents cement slurry residue from remaining at the sleeve during cementing, thus preventing it from affecting the sleeve's opening. Furthermore, after cementing, the breaking element 4 can be depressurized to allow the sleeve to open directly, ensuring the smooth progress of cementing and fracturing operations. The differential pressure sleeve 100 has stable and reliable opening performance, significantly reducing the difficulty of opening and lowering operational risks. The use of the breaking element 4 reduces the need for pressure-blocking components, simplifying the structure of the differential pressure sleeve 100. In addition, the differential pressure sleeve 100 effectively ensures the sealing performance between the first inner cylinder 2, the second inner cylinder 3, and the outer cylinder 1, thereby guaranteeing the opening performance of the differential pressure sleeve 100. The differential pressure sleeve 100 is simple and convenient to operate, greatly simplifying the construction process and significantly reducing construction costs and improving efficiency.

[0052] In this invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0053] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A differential pressure sliding sleeve, characterized in that, include: Outer cylinder (1), with a flow guide hole (11) on the side wall of the outer cylinder; The upper connector (12) and lower connector (13) are fixedly connected to both ends of the outer cylinder respectively. A first inner cylinder (2) and a second inner cylinder (3) are concentrically arranged inside the outer cylinder, with the second inner cylinder located at the lower end of the first inner cylinder; A cylindrical breakable element (4) is disposed axially between the first inner cylinder and the second inner cylinder; In its initial state, the broken element supports the first inner cylinder, causing the first inner cylinder to close the flow guide hole. By pressurizing, the broken element can be destroyed when the critical rupture pressure is reached, thereby allowing the first inner cylinder to descend and open the flow guide hole. The wall thickness of the damaged component is 3-5 mm; The damaged component is made of brittle resin material; Multiple annular grooves (41) are provided on the outer surface of the damaged component. The multiple annular grooves are evenly spaced along the axial direction, and the number of annular grooves is 6-8. On the outer surface of the damaged element, there are a plurality of annular retaining edges (42) evenly spaced apart in the circumferential direction. The annular retaining edges extend outward in the radial direction, and the plurality of annular grooves are respectively located between the axial directions of adjacent annular retaining edges.

2. The differential pressure sliding sleeve according to claim 1, characterized in that, The axial width of the annular retaining edge is set to be in the range of 6-10mm.

3. The differential pressure sliding sleeve according to claim 2, characterized in that, The connection between the annular retaining edge and the outer wall of the damaged component is chamfered (43), and the chamfer is not less than 0.2 mm.

4. The differential pressure sliding sleeve according to claim 3, characterized in that, The axial extension length of the damaged element is set to 102-150 mm.

5. The differential pressure sliding sleeve according to claim 1, characterized in that, A first sealing element (21) is provided between the first inner cylinder and the outer cylinder and near both ends of the first inner cylinder, and a second sealing element (31) is provided between the second inner cylinder and the outer cylinder and near both ends of the second inner cylinder.

6. A method for manufacturing a failure element for a differential pressure sleeve according to any one of claims 1 to 5, characterized in that, The critical rupture pressure of a broken component is set based on the wall thickness of the broken component, the material used in the broken component, the number of annular grooves on the surface of the broken component, the axial width of the annular retaining edge on the surface of the broken component, the chamfer of the annular retaining edge, and the axial extension length of the broken component. The optimal critical rupture pressure is determined by different combinations of parameters.

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