Rubber combined casing pipe capable of preventing casing pipe deformation and preparation method of rubber combined casing pipe

Abstract

The invention relates to a rubber combined casing pipe capable of preventing casing pipe deformation and a preparation method thereof.The rubber combined casing pipe capable of preventing casing pipe deformation comprises a casing pipe body and rubber layers, the two rubber layers are fixed to the outer side wall of the casing pipe body through vulcanization, and the two rubber layers are arranged in the axial direction of the casing pipe body at intervals; a gap formed between the two sections of rubber layers is a first blank section, and the first blank section is located in the middle of the sleeve body; the outer side wall of the rubber layer is provided with a plurality of grooves which are arranged at intervals in the circumferential direction of the casing pipe body, the grooves extend in the axial direction of the casing pipe body, a rubber band is formed between every two adjacent grooves, and the peripheral side wall of each rubber band is sequentially provided with a heat insulation layer and a wear-resistant layer. The rubber layer with the grooves is arranged, and the heat insulation layer is sprayed to the protruding part making contact with the well wall, so that rubber is prevented from being softened in the high-temperature well shaft environment. And the wear-resistant layer is sprayed on the outermost layer of the rubber layer so as to protect the rubber layer from being worn due to contact with the well wall in the tripping-in process.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, specifically to a rubber composite casing for preventing casing deformation and its preparation method. Background Technology

[0002] Currently, in the development of shale gas in Sichuan and shale oil in Jimsar and Dagang oilfields in Xinjiang, casing deformation of varying degrees has occurred. In particular, as shale gas moves into deeper areas, casing deformation becomes more prominent, leading to increased fracturing costs and difficulties, a reduction in the number of fracturing stages, and serious consequences such as low single-well production and short well lifecycles.

[0003] Regarding the causes of casing deformation during fracturing, Chen Chaowei, Xiang Degui, and others, through the analysis of extensive field data, proposed a fluid channel-fault activation model, revealing the mechanism of casing deformation in shale oil and gas reservoirs: due to the development of fracture systems in shale oil and gas reservoirs, hydraulic fracturing induces fracture slippage, and the shear displacement generated by this slippage directly acts on the casing, leading to casing deformation. On the other hand, statistical analysis of field data shows that the casing deformation is limited, mainly distributed in the range of 15-25 mm, and does not cause shearing of the oil layer casing. Since fracture slippage is a displacement loading process, the slippage force approaches infinity, and conventional measures such as increasing the casing steel grade and wall thickness cannot fundamentally solve the problem of casing deformation.

[0004] To prevent casing deformation during fracturing, Xiang Degui, Chen Chaowei, and others proposed the concept of "using flexibility to overcome rigidity." CNPC engineering and technical researchers developed a rubber composite casing, mainly composed of the oil layer casing and a water-absorbing, expandable rubber casing located outside the oil layer casing (patents CN212671582U, CN207177747U, CN106761443B). The specific idea is to add an elastic rubber sleeve to the outer layer of the casing, i.e., to run the rubber composite casing. In high-risk well sections with fracture slippage, the rubber composite casing is run. During fracturing, if slippage occurs, the outer rubber layer can absorb the slippage displacement, thus protecting the inner casing from being affected. The addition of a rubber sleeve to the casing increases the resistance during casing installation. To reduce this resistance, a special rubber that does not swell in oil but swells in water is used. This prevents expansion during casing installation in oil-based environments, ensuring safe installation. After installation, the rubber absorbs water and expands during the thickening of the cementing slurry, further increasing its thickness and maximizing its ability to absorb displacement loads. Based on this, to further enhance the rubber's water absorption, patent CN115822509 A designed a rubber composite casing with alternating slots. To prevent damage to the rubber layer on irregular well walls during installation, patent CN118110430A designed a self-expanding rubber composite casing by adding a soluble cover. To prevent excessive expansion of the rubber layer, patent CN118088067A designed an elastic protective cover, creating a rubber composite casing and its usage method to prevent excessive expansion.

[0005] However, as the burial depth of oil and gas reservoirs increases, the reservoir temperature also rises, with deep shale oil and gas temperatures generally exceeding 130℃. Under high-temperature conditions, rubber is prone to softening, leading to the risk that existing rubber-coated casing may not be able to be safely run into high-temperature environments. Furthermore, during the running of ultra-long wellbores, especially in the build-up and horizontal sections, the casing is prone to bending deformation, increasing friction and causing localized contact and friction between the rubber layer and the wellbore, further increasing string resistance and running difficulty. Therefore, there is an urgent need to design a high-temperature resistant, high-strength rubber-coated casing that can withstand high temperatures and maintain high strength during running, reduce contact between the rubber layer and the wellbore, and simultaneously retain the effective water absorption and expansion function of the rubber layer, in order to achieve efficient prevention of casing deformation in unconventional reservoirs such as shale oil and gas. Summary of the Invention

[0006] In order to solve one or more technical problems existing in the prior art, the present invention provides a rubber composite sleeve for preventing sleeve deformation and a method for preparing the same.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A rubber composite sleeve for preventing sleeve deformation includes a sleeve body and rubber layers. Two rubber layers are fixed on the outer wall of the sleeve body by vulcanization. The two rubber layers are arranged at intervals along the axial direction of the sleeve body, and the interval formed between the two rubber layers is a first blank segment. The first blank segment is located in the middle position of the sleeve body. A plurality of grooves are provided on the outer wall of the rubber layer, which are arranged at intervals along the circumference of the sleeve body. The grooves extend along the axial direction of the sleeve body, and a rubber rib is formed between two adjacent grooves. A heat insulation layer and a wear-resistant layer are sequentially provided on the outer peripheral sidewall of the rubber rib.

[0008] The beneficial effects of this invention are as follows: The rubber composite casing of this invention, which prevents casing deformation, features a grooved rubber layer and a heat-insulating layer sprayed on the protruding parts in contact with the well wall to prevent the rubber from softening in the high-temperature wellbore environment. A wear-resistant layer is sprayed on the outermost layer of the rubber layer to protect it from wear caused by contact with the well wall during installation. In other words, the combination of the grooves, heat-insulating layer, and wear-resistant layer enables safe installation of the rubber composite casing in high-temperature environments, effectively preventing deformation of deep and ultra-deep casing and improving the overall efficiency of shale oil and gas development. By setting a first blank section in the middle of the casing body, the rubber is not vulcanized, reducing friction and wear of the rubber layer in these areas.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, the rubber layer is arranged so that both ends of the groove in the length direction are respectively connected through the groove.

[0011] Furthermore, the groove is a straight groove or a spiral groove, and the spiral angle of the spiral groove is 15° to 30°.

[0012] Furthermore, the cross-section of the groove is a fan-shaped structure, the outer end groove width of the fan-shaped structure is 10-20mm, the inner end groove width of the fan-shaped structure is 5-10mm, and the groove opening thickness is 5-10mm.

[0013] Furthermore, the width of the outer peripheral sidewall of the rubber band is 80-90 mm.

[0014] Furthermore, a second blank segment is formed between one section of the rubber layer and one end face of the adjacent casing body, and a third blank segment is formed between another section of the rubber layer and the other end face of the adjacent casing body.

[0015] The beneficial effects of adopting the above-mentioned further solution are: by setting the second blank section and the third blank section, it can be used for hoisting and installation at the wellhead, which can further reduce the friction and wear of the rubber layer at both ends of the casing body.

[0016] Furthermore, the length of the first blank segment is 0.5m to 1m, the length of the second blank segment is 0.5m to 0.8m, and the length of the third blank segment is 0.5m to 0.8m.

[0017] Furthermore, the thickness of the rubber layer is 10-20 mm, the thickness of the heat insulation layer is 0.3-0.8 mm, the thickness of the wear-resistant layer is 0.3-1 mm, and the sum of the thicknesses of the heat insulation layer and the wear-resistant layer is not greater than 1-1.5 mm.

[0018] Furthermore, the pull-out test value of the heat insulation layer is not less than 10 MPa, the pull-out test value of the wear-resistant layer is not less than 10 MPa, the Shore hardness of the wear-resistant layer is not less than 50D, the tear strength of the wear-resistant layer is not less than 120 N / mm, and the tensile strength of the wear-resistant layer is not less than 25 MPa.

[0019] A method for preparing the above-mentioned rubber composite sleeve for preventing sleeve deformation includes the following steps:

[0020] S1, perform surface pretreatment on the surface of the casing body;

[0021] S2, wrap two rubber layers around the surface of the casing body, leaving a first blank section between the two rubber layers, and leaving a second blank section and a third blank section at both ends of the casing body respectively.

[0022] S3, vulcanize the rubber layer to ensure a firm bond between the rubber layer and the casing body;

[0023] S4. According to the relevant design requirements of the groove, use a shield with the same shape as the groove along its length to shield the outer wall of the vulcanized rubber layer; spray heat insulation material on the outer wall of the rubber layer, and after curing, form a heat insulation layer; then spray wear-resistant material on the heat insulation layer, and after curing, form a wear-resistant layer.

[0024] S5, remove the obstructions on the outer wall of the rubber layer to expose the uncoated rubber layer and perform grooving to obtain the rubber assembly sleeve.

[0025] The beneficial effects of the present invention are: the preparation method of the present invention is simple to operate and easy to implement. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the cross-sectional structure of the rubber composite sleeve for preventing sleeve deformation according to the present invention;

[0027] Figure 2 This is a schematic diagram of the longitudinal section of the rubber composite sleeve for preventing sleeve deformation according to the present invention;

[0028] Figure 3 This is a block diagram illustrating the preparation method of the rubber composite sleeve for preventing sleeve deformation according to the present invention;

[0029] Figure 4 The effect of different rubber layer thicknesses on the deformation of the casing body;

[0030] Figure 5 Finite numerical simulation of rubber-insulated casing being run into the wellbore;

[0031] Figure 6 This shows the stress distribution of the rubber composite sleeve.

[0032] The attached diagram lists the components represented by each number as follows:

[0033] 1. Sleeve body; 2. Rubber layer; 3. Heat insulation layer; 4. Wear-resistant layer; 5. Inner end groove width; 6. Outer end groove width; 7. Groove thickness; 8. Female thread; 9. Male thread; 10. Distance between male thread end and rubber layer; 11. Distance between female thread end and rubber layer. Detailed Implementation

[0034] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0035] like Figure 1 and Figure 2 As shown, this embodiment of a rubber composite sleeve for preventing sleeve deformation includes a sleeve body 1 and a rubber layer 2. Two rubber layers 2 are fixed on the outer wall of the sleeve body 1 by vulcanization. The two rubber layers 2 are arranged at intervals along the axial direction of the sleeve body 1, and the interval formed between the two rubber layers 2 is a first blank segment, which is located in the middle of the sleeve body 1. The outer wall of the rubber layer 2 is provided with a plurality of grooves arranged at intervals along the circumference of the sleeve body 1. The grooves extend along the axial direction of the sleeve body 1, and a rubber rib is formed between two adjacent grooves. A heat insulation layer 3 and a wear-resistant layer 4 are sequentially provided on the outer peripheral sidewall of the rubber rib.

[0036] Specifically, in this embodiment, the casing body 1 has a cylindrical structure. The rubber layer 2 has the characteristic of not swelling when exposed to oil but expanding rapidly when exposed to water. The rubber layer 2 is located on the outside of the casing body 1 and is bonded to the casing body 1 by vulcanization. The rubber layer 2 has evenly spaced grooves, which increases its flexibility and expansion performance. The heat insulation layer 3 is on the outer surface of the rubber reinforcement, which can effectively prevent the rubber layer from softening in the high-temperature wellbore environment, thereby maintaining the structure and function of the rubber layer 2. The wear-resistant layer 4 can protect the rubber layer 2 during the running process, preventing wear caused by contact with the well wall and ensuring the reliability of the rubber composite casing in harsh downhole environments.

[0037] In this embodiment, the rubber material used in rubber layer 2 is a non-swellable rubber that expands when exposed to oil but expands when exposed to water. The casing installation process is carried out with the wellbore filled with oil-based drilling fluid. During this process, the rubber layer must not expand prematurely upon contact with oil; otherwise, premature expansion can easily lead to wellbore blockage, making it impossible to ensure the safe completion of the casing installation and causing construction risks. During cementing after casing installation, the rubber layer in the groove area, lacking heat insulation and wear-resistant materials, can expand upon contact with pre-cementing fluid and cement slurry, further increasing the rubber's ability to absorb displacement loads and maximizing the prevention of casing deformation. The rubber is bonded to the casing body via high-temperature vulcanization. After vulcanization, the maximum thickness of the rubber layer is 10-20 mm, with options including 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, and 20 mm.

[0038] like Figure 1 and Figure 2 As shown, in this embodiment, the two ends of the groove along the length direction are respectively arranged to penetrate the rubber layer 2.

[0039] Optionally, the groove can be a straight groove or a spiral groove, and the spiral angle of the spiral groove is 15° to 30°, specifically 15°, 17°, 19°, 20°, 22°, 24°, 26°, 28°, or 30°. The groove structure can be either along the axis of the sleeve body or spirally around the axis of the sleeve body. For conventional sleeve installation methods, a rubber composite sleeve with grooves along the axis is used; for rotating sleeve installation methods, a rubber composite sleeve with spiral grooves is used. This spiral structure, consistent with the rotation direction, further protects the rubber layer compared to the groove structure along the axis.

[0040] like Figure 1 As shown, the cross-section of the groove in this embodiment is a fan-shaped structure. The outer end groove width 6 of the fan-shaped structure is 10-20mm, and can be selected from 12mm, 14mm, 16mm, 18mm, 20mm, etc.; the inner end groove width 5 of the fan-shaped structure is 5-10mm, and can be selected from 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.; the groove opening thickness 7 is 5-10mm, and can be selected from 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.

[0041] For the groove design along the axial direction of the casing body, the groove adopts an outer-wide, inner-narrow groove design. Compared with equally spaced grooves, this ensures that the internal rubber has a larger surface area, allowing it to absorb more water from the cement slurry and expand fully. For the spiral groove design along the axial direction of the casing body, the spiral angle is 15°-30° with the axial angle. This further reduces frictional resistance during the rotating and lowering of the casing, preventing casing bending and increasing the risk of contact between the rubber and the well wall.

[0042] like Figure 1 As shown, the width of the outer peripheral sidewall of the rubber band in this embodiment is 80-90mm, and can be selected from 80mm, 82mm, 84mm, 86mm, 88mm, 90mm, etc.

[0043] like Figure 2 As shown, in this embodiment, a second blank section is formed between one end face of the rubber layer 2 and the adjacent end face of the casing body 1, and a third blank section is formed between the other end face of the rubber layer 2 and the adjacent end face of the casing body 1. By setting the second and third blank sections, it can be used for hoisting and installation at the wellhead, and can further reduce the friction and wear of the rubber layer at both ends of the casing body.

[0044] Specifically, the length of the first blank segment can be 0.5m to 1m, and can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, etc.; the length of the second blank segment (i.e., the distance 10 between the male end and the rubber layer) can be 0.5m to 0.8m, and can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc.; the length of the third blank segment (i.e., the distance 11 between the female end and the rubber layer) can be 0.5m to 0.8m, and can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc.

[0045] A distance of 0.5m-0.8m is reserved at both ends of the casing body (male and female threads) for hoisting and installation at the wellhead, preventing damage to the rubber layer. Because each casing body is quite long, exceeding 9m, the middle section of the casing experiences the highest deformation due to its weight and the buckling of the tubing string during casing installation, posing a high risk of contact with the wellbore. Three-dimensional finite element numerical simulations also indicate that the middle section of the casing eventually contacts the wellbore, and the presence of rubber significantly increases the risk of installation. Therefore, based on the numerical simulation results, such as... Figure 5 As shown, the middle of the casing contacts the well wall, and the contact force is greatest in the middle of the casing, that is, in the section of the well with an inclination of 45°-90°, the middle of the casing contacts the well wall. Figure 5 The center is red, indicating the greatest contact force. Figure 6 The study indicates that the casing bending stress is greatest during the build-up section, specifically between 45° and 90° inclination. It is recommended to leave a 0.5–1m section of casing body in the middle, without vulcanizing the rubber. Furthermore, the contact force between the rubber-coated casing and the wellbore is greatest when the casing string passes through the latter half of the build-up section (45°–90° inclination), resulting in a higher degree of casing bending. The faster the casing is run, the greater the bending. Therefore, during casing running, when the rubber casing passes through the 45°–90° inclination section, each casing should be run for at least 50 seconds to avoid excessive contact between the rubber and the wellbore due to high speed. Figure 5 and Figure 6It is based on the commercial software ABAQUS platform to perform finite element modeling of the three-dimensional casing. Figure 5 It is mainly used to illustrate that the middle part of the rubber casing is prone to contact with the well wall; Figure 6 It is mainly used to illustrate that rubber casing is most easily contacted in the deviated well section.

[0046] Specifically, the thickness of the rubber layer 2 is 10-20mm, and can be 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, etc.; the thickness of the heat insulation layer 3 is 0.3-0.8mm, and can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, etc.; the thickness of the wear-resistant layer 4 is 0.3-1mm, and can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, 0.9mm, 1mm, etc.; the sum of the thicknesses of the heat insulation layer 3 and the wear-resistant layer 4 is not greater than 1-1.5mm.

[0047] Specifically, in this embodiment, the pull-out test value of the heat insulation layer 3 is not less than 10 MPa, the pull-out test value of the wear-resistant layer 4 is not less than 10 MPa, the Shore hardness of the wear-resistant layer 4 is not less than 50D, the tear strength of the wear-resistant layer 4 is not less than 120 N / mm, and the tensile strength of the wear-resistant layer 4 is not less than 25 MPa.

[0048] Figure 4 A graph showing the relationship between the rubber layer thickness and the sleeve deformation is provided. Figure 4 As shown, the thicker the rubber layer 2, the smaller the casing deformation. However, if the thickness is too thick, the casing cannot be smoothly lowered into the wellbore. Therefore, in this embodiment, the thickness of the rubber layer is set to 10-20 mm, which can ensure the smooth lowering of the casing and also ensure that the casing deformation is small.

[0049] In this embodiment, the insulation layer 3 is made of polyurethane and is applied by spraying to the rubber surface, exhibiting strong adhesion (requiring a pull-out test value of greater than 10 MPa for the rubber-insulation coating). The coating thickness is relatively thin, ranging from 0.3 to 0.8 mm. The insulation coating serves to insulate against formation temperature, protecting the rubber from softening in high-temperature environments. The insulation coating is only sprayed on the outer side of the protruding rubber ribs in contact with the wellbore; the inner rubber is not sprayed, allowing for later water absorption and expansion. The insulation layer should not be too thick, as excessive thickness increases the overall outer diameter of the casing body, increasing the risk of casing installation.

[0050] In this embodiment, the wear-resistant layer is made of high-strength polyurea or ceramic material, applied by spraying and bonded to the insulation layer. It requires strong adhesion (pull-out test value of the insulation layer-wear-resistant coating greater than 10 MPa), Shore hardness greater than 50D, tear strength greater than 120 N / mm, tensile strength greater than 25 MPa, and temperature resistance of 90–200℃. The coating thickness is relatively thin, ranging from 0.3 to 1 mm. The wear-resistant coating protects the overall structure. Since the rubber casing inevitably comes into contact with the wellbore during installation, this wear-resistant coating structure protects the internal rubber from wear. Temperature resistance primarily prevents failure under high-temperature conditions. The insulation coating cannot be too thick, as excessive thickness increases the overall outer diameter of the casing body, increasing the risk of casing installation. The overall thickness of the insulation and wear-resistant layers should not exceed 1–1.5 mm. The sprayed material is only applied to the outer side of the protruding rubber ribs in contact with the wellbore; the inner rubber is left uncoated for later water absorption and expansion.

[0051] This embodiment of the rubber-assembled casing for preventing casing deformation utilizes a grooved rubber layer and a heat-insulating layer sprayed onto the protruding parts in contact with the wellbore to prevent the rubber from softening in the high-temperature wellbore environment. A wear-resistant layer is sprayed onto the outermost layer of the rubber layer to protect it from wear caused by contact with the wellbore during installation. In short, the combination of grooves, a heat-insulating layer, and a wear-resistant layer ensures safe installation of the rubber-assembled casing in high-temperature environments, effectively preventing deformation of deep and ultra-deep casing and improving the overall efficiency of shale oil and gas development. A first blank section is provided in the middle of the casing body, where the rubber is not vulcanized, to reduce friction and wear of the rubber layer in these areas.

[0052] This embodiment also provides a method for preparing the above-mentioned rubber composite sleeve for preventing sleeve deformation, such as... Figure 3 As shown, it includes the following steps:

[0053] S1. Perform surface pretreatment on the surface of the casing body 1; perform surface cleaning and sandblasting on the casing body 1 to remove oil, rust and impurities, increase surface roughness, and ensure the adhesion between the rubber and the casing.

[0054] S2. Two rubber layers are wrapped around the surface of the casing body 1, leaving a first blank section between the two rubber layers 2. Second and third blank sections are left at both ends of the casing body 1 for installing the male thread 9 and female thread 8, respectively. When wrapping the rubber layers, a certain space (0.5-0.8 meters) is left at both ends (male and female thread ends) and in the middle of the casing without rubber wrapping. These blank sections are used for wellhead hoisting, installation, and subsequent running-in to prevent damage to the rubber in critical areas. Then, a rubber layer with a thickness of 10-30mm is evenly wrapped around the outside of the casing body. This rubber layer does not expand when exposed to oil but expands rapidly when exposed to water.

[0055] S3. The rubber layer 2 is vulcanized to firmly bond it to the casing body 1. The wrapped casing is then vulcanized under high temperature conditions to firmly bond the rubber layer to the casing body. High-temperature vulcanization can enhance the physical properties of the rubber, ensuring its stability and high strength in high-temperature wellbore environments.

[0056] S4. According to the relevant design requirements of the groove, use a shielding material with the same shape as the groove along its length to shield the outer wall of the vulcanized rubber layer 2; spray heat insulation material onto the outer wall of the rubber layer 2, and after curing, form heat insulation layer 3. Then, spray wear-resistant material onto the heat insulation layer 3, and after curing, form wear-resistant layer 4. According to the designed groove shape and size parameters, use strip-shaped or spiral-shaped rubber sheeting or other shielding materials to shield the surface of the vulcanized rubber to ensure that the grooves processed later have accurate shape and size. Treat the unshielded rubber surface by spraying an ultra-thin heat insulation material (polyurethane) with a thickness of 0.3-0.8 mm, and then curing it to ensure that the heat insulation layer meets the mechanical performance requirements. Spray a high-strength wear-resistant material (polyurea or ceramic material) with a thickness of 0.3-1 mm onto the heat insulation layer to ensure that the wear-resistant layer has high Shore hardness (greater than 50D), tear strength (greater than 120 N / mm), tensile strength (greater than 25 MPa), and temperature resistance (90-200℃). After spraying, curing is carried out until the wear-resistant layer meets the performance requirements to ensure that it can effectively protect the rubber layer.

[0057] S5, remove the obstructions on the outer wall of rubber layer 2 to expose the uncoated rubber layer 2 and perform a grooving operation to obtain the rubber assembly sleeve. The grooving operation forms a groove structure along or around the axial direction, ensuring a groove design that is wider on the outside and narrower on the inside. Finally, the processed rubber assembly sleeve is cured and tested to ensure that its various properties meet the design requirements, and mechanical properties and temperature resistance properties are tested to ensure that the rubber layer, heat insulation layer, and wear-resistant layer all meet the usage standards.

[0058] The preparation method described in this embodiment is simple and easy to implement. The high-temperature resistant, high-strength rubber composite casing obtained is designed to solve the deformation and safety problems that traditional rubber casings are prone to under high-temperature and complex wellbore conditions. Through a specially designed rubber layer structure and refined surface treatment technology, softening and wear of the casing in high-temperature environments are effectively prevented, thus ensuring its stability and safety in the downhole environment. The rubber layer uses a material that does not expand when exposed to oil but expands rapidly when exposed to water. The grooved structure and spiral design reduce frictional resistance and the risk of tubing bending during casing installation. During processing, blank sections are reserved at both ends and the middle of the casing to ensure that the rubber in critical areas is not damaged during installation and operation. Furthermore, by controlling the running speed, especially in inclined sections and complex wellbore conditions, the risk of contact between the rubber and the wellbore is effectively reduced, further improving overall operational efficiency and safety.

[0059] The rubber composite casing of the present invention can withstand high temperatures or maintain high strength during the running process, reduce the contact between the rubber layer and the well wall, and take into account the effective water absorption and expansion function of the rubber layer, so as to achieve efficient prevention of casing deformation in unconventional reservoirs such as shale oil and gas.

[0060] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention.

[0061] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0064] In the description of this specification, the 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 present 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A rubber composite sleeve for preventing sleeve deformation, characterized in that, The casing includes a casing body and a rubber layer. Two rubber layers are fixed to the outer wall of the casing body by vulcanization. The two rubber layers are arranged at intervals along the axial direction of the casing body, and the interval between the two rubber layers is a first blank segment. The first blank segment is located in the middle of the casing body. The outer wall of the rubber layer is provided with a plurality of grooves arranged at intervals along the circumference of the casing body. The grooves extend along the axial direction of the casing body, and a rubber rib is formed between two adjacent grooves. A heat insulation layer and a wear-resistant layer are sequentially provided on the outer peripheral sidewall of the rubber rib.

2. The rubber composite sleeve for preventing sleeve deformation according to claim 1, characterized in that, The rubber layer is arranged so that both ends of the groove in the length direction are respectively connected to the rubber layer.

3. The rubber composite sleeve for preventing sleeve deformation according to claim 1, characterized in that, The groove is a straight groove or a spiral groove, and the spiral angle of the spiral groove is 15° to 30°.

4. The rubber composite sleeve for preventing sleeve deformation according to claim 1, characterized in that, The groove has a fan-shaped cross-section, with the outer end groove width being 10-20 mm, the inner end groove width being 5-10 mm, and the groove opening thickness being 5-10 mm.

5. The rubber composite sleeve for preventing sleeve deformation according to claim 1, characterized in that, The width of the outer peripheral sidewall of the rubber band is 80-90 mm.

6. The rubber composite sleeve for preventing sleeve deformation according to claim 1, characterized in that, A second blank segment is formed between one section of rubber layer and one end face of the adjacent casing body, and a third blank segment is formed between another section of rubber layer and the other end face of the adjacent casing body.

7. The rubber composite sleeve for preventing sleeve deformation according to claim 6, characterized in that, The length of the first blank segment is 0.5m to 1m, the length of the second blank segment is 0.5m to 0.8m, and the length of the third blank segment is 0.5m to 0.8m.

8. The rubber composite sleeve for preventing sleeve deformation according to claim 1, characterized in that, The thickness of the rubber layer is 10-20 mm, the thickness of the heat insulation layer is 0.3-0.8 mm, the thickness of the wear-resistant layer is 0.3-1 mm, and the sum of the thicknesses of the heat insulation layer and the wear-resistant layer is not greater than 1-1.5 mm.

9. The rubber composite sleeve for preventing sleeve deformation according to claim 1, characterized in that, The pull-out test value of the heat insulation layer is not less than 10 MPa, the pull-out test value of the wear-resistant layer is not less than 10 MPa, the Shore hardness of the wear-resistant layer is not less than 50D, the tear strength of the wear-resistant layer is not less than 120 N / mm, and the tensile strength of the wear-resistant layer is not less than 25 MPa.

10. A method for preparing a rubber composite sleeve for preventing sleeve deformation as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1, perform surface pretreatment on the surface of the casing body; S2, wrap two rubber layers around the surface of the casing body, leaving a first blank section between the two rubber layers, and leaving a second blank section and a third blank section at both ends of the casing body respectively. S3, vulcanize the rubber layer to ensure a firm bond between the rubber layer and the casing body; S4. According to the relevant design requirements of the groove, use a shield with the same shape as the groove along its length to shield the outer wall of the vulcanized rubber layer; spray heat insulation material on the outer wall of the rubber layer, and after curing, form a heat insulation layer; then spray wear-resistant material on the heat insulation layer, and after curing, form a wear-resistant layer. S5, remove the obstructions on the outer wall of the rubber layer to expose the uncoated rubber layer and perform grooving to obtain the rubber assembly sleeve.

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