A floating casing head

Abstract

The application provides a floating casing head, which comprises a casing head body, an oil layer casing and a casing hanger, both of which are located in the casing head body, an inner wall surface of the casing hanger movably sheaths the oil layer casing, an outer wall surface of the casing hanger is fixedly connected with the casing head body, so that the oil layer casing can slide upward relative to the casing hanger; wherein, a floating casing nipple located above the casing hanger is further fixedly sheathed outside the oil layer casing, the floating casing nipple slidably connects the oil layer casing with the casing head body, so that the oil layer casing can slide upward relative to the casing head body, the casing head provided by the application can automatically adjust the elongation of the oil layer casing according to the wellhead lifting condition and ensure the sealing effect of the wellhead, improve the utilization rate of the old well and the sealing timeliness of the wellhead of the newly drilled well, realize the integrity of the wellhead, and prolong the full life cycle of the oil and water well.

Description

Technical Field

[0001] This application relates to the field of oil and gas development equipment, and in particular to a floating casing head. Background Technology

[0002] In the later stages of oilfield development, wellhead uplift was discovered in oil and water wells one after another. The number of damaged wells increased year by year, leading to problems such as wellhead equipment elevation, process deviation, reduced pump efficiency, casing deformation and damage, and environmental pollution. The annulus lost its effective barrier, and there were significant safety hazards at the wellhead, which seriously affected the lifespan of oil and water wells and normal production.

[0003] Currently, wellhead lift mainly manifests as casing uplift, hanger uplift, and casing head uplift. The discovery time for wellhead lift is concentrated between 10 and 15 years ago, with severe wellhead lift occurring in second-stage wells, accounting for 96% of all wells with wellhead lift. In some wells, the casing uplift height even exceeds 50 cm. To ensure the development effect of the oilfield, improve the utilization rate of old wells in the block, and enhance the sealing efficiency of new wellheads, five methods are typically used to address the casing uplift problem: welding, lifting, cutting and lowering the casing, capping, and replacing the casing head. Among these methods, welding and lifting are simple to construct but have a high recurrence rate, requiring repeated treatment and failing to guarantee wellhead sealing. Cutting and lowering the casing method has limitations and cannot be used for wells with a wellhead lift of less than 50cm. The capping method provides a secure fixation, but the elastic stress of the casing cannot be released for a long time, posing a high safety risk and easily causing bending deformation of the casing, thus damaging the integrity of the wellbore. Conventional casing heads cannot automatically adjust the casing according to the elongation of the wellhead lift to ensure wellhead sealing, and the casing head needs to be replaced multiple times, which is cumbersome, costly, and poses a significant safety risk, seriously affecting the entire life cycle of oil and water wells. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a floating casing head, which has the advantages of avoiding stress deformation of the oil layer casing, preventing casing hanger and casing head from moving upwards, and ensuring wellhead sealing.

[0005] The technical solution of this invention is:

[0006] A floating casing head includes a casing head body, an oil layer casing, and a casing hanger, all located within the casing head body. The inner wall of the casing hanger is movably fitted over the oil layer casing, and the outer wall of the casing hanger is fixedly connected to the casing head body, allowing the oil layer casing to slide upward relative to the casing hanger.

[0007] A floating casing section is also fixedly fitted outside the oil layer casing and located above the casing hanger. The floating casing section slides to connect the oil layer casing to the casing head body, so that the oil layer casing can slide upward relative to the casing head body. When the oil layer casing moves upward, the oil layer casing drives the floating casing section to slide upward within the casing head body.

[0008] Optionally, the casing head body has a sliding space for the floating casing section to slide. The lower end of the floating casing section is connected to the oil layer casing. When the floating casing section slides upward in the sliding space, the section of the floating casing section located in the upper part of the sliding space can be replaced or cut.

[0009] Optionally, the sleeve head body includes a detachably connected upper body and a lower body, wherein the upper body constitutes the upper end portion of the sleeve head body, and the lower body constitutes the lower end portion of the sleeve head body.

[0010] Optionally, the floating sleeve section and the sliding space are located at the upper part of the sleeve head body, and the sleeve hanger is located at the lower part of the sleeve head body.

[0011] Optionally, the lower end of the casing head body is provided with a set screw and a set screw sealing device. The set screw extends laterally through the lower end and is used to fix the casing hanger and the lower end of the casing head body. The set screw sealing device is sleeved on the outer circumferential surface of the set screw and is used to seal between the set screw and the lower end of the casing head body.

[0012] Optionally, the casing hanger includes, from top to bottom, an upper pressure ring, a sealing element, a lower pressure ring, and a hanger body, wherein the sealing element seals the casing hanger to the lower end portion of the casing head body; wherein,

[0013] The upper pressure ring has a first conical surface at its outer apex, and the end of the set screw has a second conical surface that fits tightly with the first conical surface. The upper pressure ring is used to tighten and fix the set screw. The side wall of the hanger body has a third conical surface, and the lower end of the sleeve head body has a fourth conical surface that fits tightly with the third conical surface. The hanger body is used to improve the sealing between itself and the lower end of the sleeve head body.

[0014] Optionally, the set screw sealing device includes, from one side near the sleeve hanger to the other, a support ring, a rubber ring, a spacer ring, and a pressure ring in sequence; wherein the support ring and the pressure ring are pressure-bearing and corrosion-resistant structures used to protect the rubber ring and the spacer ring.

[0015] Optionally, the top of the sliding space has a limiting step to prevent the floating sleeve section from sliding further.

[0016] Optionally, a circular side hole is provided at the bottom of the lower body, and the circular side hole is sealed by a side hole flange. The center hole of the side hole flange is connected to the side hole plug, and the side hole flange is fixed to the lower body by several side hole caps.

[0017] Optionally, a watch sleeve conversion connector extending from the bottom end of the lower body is embedded inside the lower body, and a watch sleeve connecting flange is fitted outside the watch sleeve conversion connector. The top end of the watch sleeve connecting flange is detachably connected to the bottom end of the lower body; wherein,

[0018] The inner apex of the flange of the watch sleeve is provided with a fifth conical surface, and the side wall of the watch sleeve conversion joint is provided with a sixth conical surface that fits tightly with the fifth conical surface.

[0019] Compared with the prior art, this application has the following advantages:

[0020] This invention proposes a floating casing head, comprising a casing head body, an oil layer casing, and a casing hanger, all located within the casing head body. The inner wall of the casing hanger is movably fitted over the oil layer casing, while the outer wall of the casing hanger is fixedly connected to the casing head body, allowing the oil layer casing to slide upward relative to the casing hanger. A floating casing section is also fixedly fitted over the oil layer casing, positioned above the casing hanger. This floating casing section slidably connects the oil layer casing to the casing head body, allowing the oil layer casing to slide upward relative to the casing head body. When the oil layer casing moves upward, it drives the floating casing section to slide upward within the casing head body.

[0021] By adopting the technical solution of this application, the problems of casing run-through and wellhead sealing can be fundamentally solved, improving the utilization rate of old wells and the sealing time of new wells, and ensuring the integrity of the wellhead. When casing run-through occurs at the wellhead, the oil layer casing drives the floating casing section to move upward within the casing head body, automatically adjusting the casing elongation and avoiding stress deformation of the oil layer casing. As the oil layer casing drives the floating casing section upward, subsequent well workover operations are carried out by disassembling and assembling the casing head body, cutting off the floating casing section from the upper end of the casing hanger, and reinstalling the casing head body for continued use without replacing the casing. Therefore, the floating casing head provided by this invention solves the wellhead sealing problem of the casing head and the safety hazards caused by casing run-through. It has wide applicability, effectively reduces product investment and maintenance costs, has a simple process, and extends the entire life cycle of oil and water wells. Attached Figure Description

[0022] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a cross-sectional structural diagram of the floating sleeve head described in this application;

[0024] Figure 2 This is a cross-sectional structural schematic diagram of the set screw sealing device according to an embodiment of this application;

[0025] Figure 3 This is a cross-sectional structural schematic diagram of the sleeve hanger according to another embodiment of this application.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Double male short section; 2. Upper flange; 3. First sealing gasket ring; 4. Upper body; 5. Floating sleeve short section; 6. Upper double-ended stud; 7. Upper nut; 8. Second sealing gasket ring; 9. Support ring; 10. Top screw sealing device; 101. Rubber ring; 102. Spacer ring; 103. Pressure ring; 11. Top screw pressure cap; 12. Top screw; 13. Sleeve hanger; 131. Upper pressure ring; 132. Seal; 133. Lower pressure ring; 134. Hanger body; 14. Side hole pressure cap; 15. Side hole plug; 16. Side hole flange; 17. First O-ring seal; 18. Lower body; 19. Second O-ring seal; 20. Gauge sleeve connection flange; 21. Lower nut; 22. Lower double-ended stud; 23. Gauge sleeve adapter; 24. Oil layer sleeve. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] In the later stages of oilfield development, wellhead uplift has been increasingly observed in both oil and water wells. The number of damaged wells is increasing year by year, leading to problems such as wellhead equipment elevation, flow path deviation, reduced pump efficiency, casing deformation and damage, and environmental pollution. The annulus loses its effective barrier, posing significant safety hazards at the wellhead and severely impacting the lifespan and normal production of oil and water wells. The main reason for this phenomenon is that over time, surface subsidence causes the pressure outside the casing to exceed the pressure inside. Under this high pressure, the casing inside the casing moves upwards. Since modern casing heads are equipped with casing hangers 13, which are threadedly connected to the casing, the casing hangers 13 prevent upward movement of the casing. However, the casing is subjected to pressure for a long time, eventually causing the elastic stress of the casing to remain unreleased, resulting in bending deformation or even breakage. At the same time, the casing pulls the casing hangers 13 upwards, ultimately leading to the simultaneous occurrence of upward movement of the oil layer casing 24, upward movement of the casing hangers 13, and upward movement of the casing head.

[0030] In view of the above problems, the present invention aims to fundamentally solve the problems of wellhead lift and casing head wellhead sealing, and provides a floating casing head that automatically adjusts the elongation of the oil layer casing 24 according to the wellhead lift and ensures the sealing effect of the wellhead, improves the utilization rate of old wells and the sealing time of new wellheads, achieves wellhead integrity, and extends the entire life cycle of oil and water wells.

[0031] Reference Figure 1 As shown, Figure 1 A cross-sectional structural schematic diagram of the floating sleeve head of this application is shown.

[0032] A floating casing head includes a casing head body, an oil layer casing 24, and a casing hanger 13, all located within the casing head body. The inner wall of the casing hanger 13 is movably fitted over the oil layer casing 24, while the outer wall of the casing hanger 13 is fixedly connected to the casing head body, allowing the oil layer casing 24 to slide upwards relative to the casing hanger 13.

[0033] A floating casing section 5 is also fixedly fitted outside the oil layer casing 24 and located above the casing hanger 13. The floating casing section 5 slides to connect the oil layer casing 24 with the casing head body so that the oil layer casing 24 can slide upward relative to the casing head body. When the oil layer casing 24 moves upward, the oil layer casing 24 drives the floating casing section 5 to slide upward within the casing head body.

[0034] Specifically, the casing head body is a crucial connector in the wellhead assembly, connecting the production tree to the surface casing. The casing head internally supports the casing hanger 13, which supports the weight of all casing layers except the surface casing and seals the annular space between them. Each casing layer can be a technical casing or an oil layer casing 24 of different specifications. The oil layer casing 24 is the innermost casing in the oil and gas well casing sequence, extending from the wellhead through the oil and gas layer to provide a passage for oil and gas to the surface, isolating the oil and gas from the formation and ensuring no leakage of oil and gas pressure. Therefore, stress deformation of the oil layer casing 24 can severely affect wellhead safety and sealing time, shorten the lifespan of oil and water wells, and hinder safe production.

[0035] Specifically, the top of the casing head body is detachably connected to the upper flange 2, and a double male short section 1 extending from the top of the upper flange 2 is embedded inside the upper flange 2. The upper flange 2 and the casing head body are connected by several double-ended studs, with several nuts at each end of the studs. The upper flange 2 of the casing head is threaded to the Christmas tree via the double male short section 1. Different types of flanges can be configured on the upper part of the double male short section 1 to adapt to the Christmas tree and meet the usage requirements of the Christmas tree. Of course, the upper part of the casing head body can also be directly connected to the Christmas tree's main cross joint, which is safer and more reliable, reduces the wellhead height, and lowers product investment costs.

[0036] Specifically, in order to effectively solve the problem of stress deformation of the oil layer casing 24, this application movably sleeves the inner wall of the casing hanger 13 outside the oil layer casing 24, and fixes the outer wall of the casing hanger 13 to the casing head body, so that the oil layer casing 24 can slide upward relative to the casing hanger 13. This avoids the casing hanger 13 preventing the oil layer casing 24 from moving upward under the premise of achieving suspension and sealing, thus preventing the elastic stress of the casing from being released. This solves the problem of stress deformation of the oil layer casing 24 and the wellhead lift problem caused by the upward movement of the casing hanger 13 and the casing head body.

[0037] Thus, the oil layer casing 24 moves upward within the casing head body. To ensure the safety and sealing of the wellhead, maintain the integrity of the wellbore, and avoid the impact of surface subsidence on the wellhead of oil and water wells, it is necessary to cut the casing or replace the casing head to manage the wellhead. This application addresses this by setting a floating casing short section 5 to connect the oil layer casing 24 to the casing head body. This supports the weight of the oil layer casing 24 and automatically adjusts its elongation as it slides within the casing head body during upward movement. Only the floating casing short section 5 needs to be cut or replaced; the oil layer casing 24 does not need to be cut or replaced. Specifically, the floating casing short section 5 is threaded to the oil layer casing 24, and its shape is similar to that of the oil layer casing 24, being a hollow cylindrical structure that is easy to process, has a simple forming process, and is low in cost.

[0038] As a specific explanation of this embodiment, the movable sleeve of the casing hanger 13 and the oil layer casing 24, as well as the sliding connection between the floating casing section 5 and the casing head body, are all tight overlapping connections. The strength of the overlapping connection will not cause the oil layer casing 24 to drive the floating casing section 5 to move upward within the casing head body due to small pressure or ground vibration. Under the condition of large pressure generated by ground subsidence, the pressure is greater than the strength of the overlapping connection, thereby causing the oil layer casing 24 to drive the floating casing section 5 to move upward within the casing head body, automatically adjusting the casing elongation and avoiding stress deformation of the oil layer casing 24.

[0039] The structure and principle of the floating casing sub 5 will be further explained below. The casing head body has a sliding space for the floating casing sub 5 to slide. The lower end of the floating casing sub 5 is connected to the oil layer casing 24. When the floating casing sub 5 slides upward in the sliding space, the section of the floating casing sub 5 located in the upper part of the sliding space can be replaced or cut.

[0040] Specifically, the length of the slip space should be selected within an appropriate range. An excessively long slip space will result in an excessively long casing head, while a too-short slip space will limit the slip distance of the oil layer casing 24, making it difficult to adequately address the issue of replacing the oil layer casing 24. Considering the phenomenon of casing upward movement exceeding 50cm in some wells, it is preferable to set the slip space at a height of approximately 50cm. During casing head replacement, the floating casing section 5 is connected to the oil layer casing 24 and lowered as a whole into the lower body 18 of the casing head. When the oil layer casing 24 moves upward, it drives the floating casing section 5 upward within the upper body 4. During well workover operations, the upper part of the casing head body is removed, and the floating casing section 5 is cut off from the upper end of the casing hanger 13. After reinstalling the upper part of the casing head body, it can continue to be used without replacing the casing. When the cut surface moves upward again, well workover operations are required to replace the uppermost oil layer casing 24 and the floating casing section 5.

[0041] Correspondingly, the lower part of the floating casing sub 5 is threaded onto the oil layer casing 24, while the upper part of the floating casing sub 5 is located within the sliding space. By setting an appropriate height for the floating casing sub 5, when the oil layer casing 24 moves upwards, the floating casing sub 5 can be cut to avoid cutting the oil layer casing 24. When the oil layer casing 24 moves upwards a second time, the floating casing sub 5 can still be cut, or the remaining floating casing sub 5 and a small portion of the oil layer casing 24 can be cut to avoid replacing the oil layer casing 24. It can be understood that the height of the remaining floating casing sub 5 and the height of the small portion of the oil layer casing 24 are equal to the height of the upward movement of the oil layer casing 24. Therefore, the phenomenon of the oil layer casing 24 moving upwards occurs frequently, occurring every 10-15 years. By setting the floating casing sub 5, this application can extend the usable life of the casing head to at least 20-30 years, improve the utilization rate of old wells and the sealing efficiency of new wellheads, and ensure normal production of oil, gas and water wells.

[0042] In the technical solution of the present invention, which features a floating sleeve short section 5, both ends of the floating sleeve short section 5 are male threads, and the surface is heat-treated. The length of the floating sleeve short section 5 can be configured as needed, and the outer surface is sprayed with nickel-based alloy to prevent corrosion during long-term use and damage from impacts during installation, which could lead to sealing surface failure and delamination.

[0043] As a further improvement to the following embodiments, the sleeve head body includes a detachably connected upper body 4 and a lower body 18, wherein the upper body 4 constitutes the upper end portion of the sleeve head body and the lower body 18 constitutes the lower end portion of the sleeve head body.

[0044] Specifically, the double male short section 1 has an upper flange 2 at its lower part, and an upper body 4 at its lower part. A rigid first sealing gasket 3 ensures a steel-to-steel seal between the upper flange 2 and the upper body 4, guaranteeing the oil and gas sealing effect of the casing head. The first sealing gasket 3 has a symmetrical trapezoidal cross-section. The upper flange 2 and the upper body 4 are connected by several double-ended studs, each with several nuts at both ends. A lower body 18 is located at the lower part of the upper body 4. A rigid second sealing gasket 8 ensures a steel-to-steel seal between the upper body 4 and the lower body 18, connected by several upper double-ended studs 6, each with several upper nuts 7 at both ends.

[0045] Furthermore, the floating bushing section 5 and the sliding space are located at the upper part of the bushing head body, while the bushing hanger 13 is located at the lower part of the bushing head body. By detachably connecting the upper body 4 and the lower body 18, the floating bushing section 5 slides within the upper body 4. By disassembling and assembling the upper body 4, the floating bushing section 5 can be cut or replaced. The bushing head is easy to disassemble and assemble, and the floating bushing section 5 can be easily handled. It has a wide range of applications, strong practicality, and effectively reduces installation and maintenance costs.

[0046] As a further improvement of this embodiment, the lower end of the casing head body is provided with a set screw 12 and a set screw sealing device 10. The set screw 12 extends laterally through the lower end and is used to fix the casing hanger 13 and the lower end of the casing head body. The set screw sealing device 10 is sleeved on the outer circumferential surface of the set screw 12 and is used to seal the space between the set screw 12 and the lower end of the casing head body.

[0047] Specifically, the lower body 18 of the sleeve head has several symmetrical set screw holes arranged laterally on its upper end. Set screws 12 are placed in the set screw holes, and the set screws 12 are connected to the set screw holes of the lower body 18 by threads. The set screws 12 and the lower body 18 are sealed by a set screw sealing device 10. One end of the set screw 12 extending out of the lower body 18 is pressed by a set screw pressure cap 11, which is connected to the set screw hole of the lower body 18 by threads.

[0048] As a further improvement to this embodiment, refer to Figure 3 As shown, Figure 3 A cross-sectional structural schematic diagram of the casing hanger of this application is shown. The casing hanger 13 includes, from top to bottom, an upper pressure ring 131, a sealing element 132, a lower pressure ring 133, and a hanger body 134. The sealing element 132 seals the casing hanger 13 with the lower end of the casing head body. The upper pressure ring 131 has a first conical surface at its outer apex, and the end of the set screw 12 has a second conical surface that fits tightly with the first conical surface. The upper pressure ring 131 is used to tighten and fix the set screw 12. The side wall of the hanger body 134 has a third conical surface, and the lower end of the casing head body has a fourth conical surface that fits tightly with the third conical surface. The hanger body 134 is used to improve the sealing between the hanger body and the lower end of the casing head body.

[0049] Specifically, the casing hanger 13 of this application is composed of an upper pressure ring 131, a rubber seal 132, a lower pressure ring 133, and a body from top to bottom. The casing hanger 13 adopts a split sealing component structure. The rubber seal 132 is sealed to the lower body 18 of the casing head by tightening and pressurizing the top screw 12, thereby firmly installing the casing hanger 13 in the lower body 18. The pressure of the rubber seal 132 makes the connection between the casing hanger 13 and the oil layer casing 24 flexible and controllable, so that the oil layer casing 24 will not rise relative to the casing hanger 13 due to small pressure or surface vibration. Under the large pressure generated by surface subsidence, it will not prevent the release of elastic stress of the oil layer casing 24 and cause deformation of the oil layer casing 24.

[0050] More specifically, the upper pressure ring 131 has a first conical surface at its outer apex, and the end of the set screw 12 has a second conical surface that fits tightly with the first conical surface. The upper pressure ring 131 is used to tighten and fix the set screw 12. The side wall of the hanger body 134 has a third conical surface, and the lower body 18 has a fourth conical surface that fits tightly with the third conical surface, so that the conical surface of the casing hanger 13 body and the inner convex conical surface of the lower body 18 achieve a steel-to-steel seal, improving the sealing performance. Here, the conical surface refers to the edge of a conical structure. The end of the set screw 12 is a conical end, which extends laterally through the lower body 18. The end has a conical angle pointing towards the casing hanger 13. The angles of the first and second conical surfaces are both towards the central axis of the casing head body to achieve a steel-to-steel seal between the casing hanger 13 and the set screw 12. The angles of the third and fourth conical surfaces are preferably away from the central axis of the casing head body to achieve a steel-to-steel seal between the casing hanger 13 and the lower body 18.

[0051] Reference Figure 2 As shown, Figure 2 A cross-sectional structural schematic diagram of the top screw sealing device of this application is shown.

[0052] Furthermore, the top screw sealing device 10 includes, from one side near the sleeve hanger 13 to the other side, a support ring 9, a rubber ring 101, a spacer ring 102, and a pressure ring 103; wherein the support ring 9 and the pressure ring 103 are pressure-bearing and corrosion-resistant structures used to protect the rubber ring 101 and the spacer ring 102.

[0053] Specifically, the support ring 9, rubber ring 101, spacer ring 102, and pressure ring 103 of the set screw sealing device 10 are sequentially fitted onto the set screw 12 from left to right. The upper end of the set screw 12 is pressed by the set screw pressure cap 11, which is connected to the set screw hole of the lower body 18 by threads. Multiple sets of rubber rings 101 may be included, such as multiple sets of C-type rubber rings 101. Multiple sets of spacer rings 102 may be included, such as O-type spacer rings 102. The spacer rings 102 can be made of flexible sealing material. Both the rubber rings 101 and spacer rings 102 are used to seal the oil, gas, and water inside the sleeve head, preventing leakage. The support ring 9 and pressure ring 103 are preferably made of rigid sealing material. The support ring 9 is located on the innermost side for bearing pressure, and the pressure ring 103 is located on the outermost side for corrosion resistance. The support ring 9, rubber ring 101, spacer ring 102, and pressure ring 103 form a sandwich structure to protect the spacer ring 102 and rubber ring 101 in the middle. In this embodiment, if the sealing form of the top screw sealing device 10 is arbitrarily replaced, it will be difficult to ensure the sealing time and safety of the sleeve head body, resulting in the loss of the annulus barrier and unexpected events such as environmental pollution.

[0054] In another technical solution, the top of the sliding space has a limiting step to prevent the floating sleeve section 5 from continuing to slide.

[0055] Specifically, the inner diameter of the limiting step is smaller than the inner diameter of the floating casing sub 5. During casing head replacement, the casing hanger 13 is first installed on the floating casing sub 5, then the floating casing sub 5 is connected to the oil layer casing 24, and the entire assembly is lowered into the lower body 18 of the casing head. The entire casing string load is transferred to the lower body 18 through the casing hanger 13, and then tightened with the set screw 12 to complete the seal. When the oil layer casing 24 moves upwards, and the floating casing sub 5 moves upwards to the limiting step, a workover operation is performed. The upper body 4 is removed, and the floating casing sub 5 is cut off from the upper end of the casing hanger 13. After installing the upper body 4, the casing can continue to be used without replacing the casing. When the cut surface moves upwards again and reaches the limiting step, a workover operation is performed to replace the uppermost oil layer casing 24 and the floating casing sub 5.

[0056] In another technical solution, a circular side hole is provided at the bottom of the lower body 18. The circular side hole is sealed by a side hole flange 16. The center hole of the side hole flange 16 is connected to the side hole plug 15. The side hole flange 16 is fixed to the lower body 18 by several side hole pressure caps 14.

[0057] Specifically, the lower body 18 of the casing head has two symmetrical circular side holes at its lower part. These side holes are sealed by side hole flanges 16. The center hole of the side hole flange 16 is connected to a side hole plug 15 via threads. The side hole flange 16 is fixed to the lower body 18 by several side hole pressure caps 14. A seal is achieved between the side hole flange 16 and the lower body 18 through multiple sets of first O-ring seals 17. The circular side holes and the corresponding side hole flanges 16, side hole plugs 15, side hole pressure caps 14, and sealing rings at the bottom of the lower body 18 are used to form a new circulation channel after the hanger is inserted into the well and seated in the casing, thus enabling mud circulation during cementing operations.

[0058] In another technical solution, a watch sleeve conversion connector 23 extending from the bottom end of the lower body 18 is embedded inside the lower body 18. A watch sleeve connecting flange 20 is fitted onto the outside of the watch sleeve conversion connector 23. The top end of the watch sleeve connecting flange 20 is detachably connected to the bottom end of the lower body 18.

[0059] The inner top corner of the flange 20 is provided with a fifth conical surface, and the side wall of the adapter 23 is provided with a sixth conical surface that fits tightly with the fifth conical surface.

[0060] Specifically, the lower body 18 houses a gauge sleeve conversion joint 23, which is sealed to the lower body 18 by a second O-ring seal 19. A gauge sleeve connecting flange 20 is located at the lower part of the lower body 18. Several threaded holes are designed at the end of the lower body 18, and several lower double-ended studs 22 pass through the gauge sleeve connecting flange 20 and are fixed within the threaded holes of the lower body 18. Lower nuts 21 secure the lower body 18 to the gauge sleeve connecting flange 20. A steel-to-steel seal is achieved between the fifth conical surface of the gauge sleeve connecting flange 20 and the sixth conical surface of the gauge sleeve conversion joint 23. The angle between the fifth and sixth conical surfaces is away from the central axis of the sleeve head body. The lower part of the gauge sleeve conversion joint 23 is connected to the surface sleeve.

[0061] In summary, the floating sleeve head provided by the present invention mainly consists of a double male short section 1, an upper flange 2, a first sealing gasket ring 3, an upper body 4, a floating sleeve short section 5, an upper double-ended stud 6, an upper nut 7, a second sealing gasket ring 8, a support ring 9, a C-type rubber ring 101, a spacer ring 102, a pressure ring 103, a set screw cap 11, a set screw 12, an upper pressure ring 131, a rubber seal 132, a lower pressure ring 133, a hanger body 134, a side hole cap 14, a side hole plug 15, a side hole flange 16, a first O-ring seal 17, a lower body 18, a second O-ring seal 19, a gauge sleeve connecting flange 20, a lower nut 21, a lower double-ended stud 22, a gauge sleeve conversion joint 23, and an oil layer sleeve 24. The floating casing head can adjust the casing elongation by moving the oil layer casing 24 upwards within the upper body 4, causing the oil layer casing 24 to move upwards along with the floating casing sub. This automatically prevents casing deformation due to prolonged unreleased elastic stress, ensuring normal production in oil, gas, and water wells. Due to these key advantages, this invention is suitable for two-stage and three-stage wells, as well as for on-site casing head modifications. During the replacement of the floating casing head, only the floating casing sub 5 or part of the oil layer casing 24 needs to be replaced. The operation is safe, reliable, and widely applicable, reducing installation and maintenance costs.

[0062] Taking a two-stage well as an example, the usage steps and principle of the floating casing head provided by this invention are as follows:

[0063] During the replacement of the floating bushing head, the discarded bushing head is first cut off. The surface bushing and oil layer bushing 24 are then threaded and pressure tested. The bushing connection flange 20 is fitted onto the bushing adapter 23, and grease is applied to the conical surface of the bushing connection flange 20 and the O-ring seal of the bushing adapter 23. The sealing conical surface of the upper part of the bushing connection flange 20 and the O-ring seal of the bushing adapter 23 must be intact and undamaged. The double-ended stud is then inserted through the bushing connection flange 20 into the screw hole at the bottom of the lower body 18. At this point, the nut can be hand-tightened; after the body is installed, it should be tightened to the specified torque.

[0064] Next, hoist the lower body 18 of the casing head, carefully protecting the sealing surface during hoisting to avoid impact. After hoisting into place, tighten all nuts evenly in a diagonal sequence until the gap between the casing flange 20 and the lower body 18 disappears. Remove all set screws 12 (until the mark line of set screw 12 is exposed). First, install the casing hanger 13 on the floating casing section 5, then connect the floating casing section 5 to the oil layer casing 24, and lower the entire assembly into the lower body 18 of the casing head. The entire casing string load is transferred to the lower body 18 of the casing head through the hanger. Then tighten the set screws 12 to lock the casing hanger 13, completing the fixation and sealing. Install the rigid sealing gasket ring to the groove on the lower body 18 section. Hoist the upper body 4 of the casing head, carefully protecting the sealing surface during hoisting to avoid impact. After hoisting into place, tighten all nuts evenly in a diagonal sequence until the gap between the upper body 4 and the lower body 18 disappears. The flange 2 and the double male short section 1 are hoisted onto the casing head body 4, and the casing head is pressure tested. Finally, the wellhead is handed over after the production tree is installed according to the corresponding procedures.

[0065] Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the specific technical solutions in the above embodiments, or equivalent substitutions can be made to some of the technical features (for example, the O-ring can be replaced with other V-rings, U-rings, Y-rings, J-rings or TC-rings; or, the double-ended stud single-layer nut fastening can be replaced with a double-ended stud with a double-layer nut fastening form; or, the double male short section 1 can be a commonly used short section or other structural pipe joint that serves a sealing function; or, the sealing gasket can be a rigid sealing gasket, such as a metal sealing gasket, or other gaskets of different shapes or structures); and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the present invention.

[0066] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0067] It should also be noted that, in this document, the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor should they be construed as indicating or implying relative importance. Moreover, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device.

[0068] The above provides a detailed description of a floating sleeve head provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand this application, and the content of this specification should not be construed as a limitation of this application. Furthermore, those skilled in the art will recognize that various modifications may be made to the specific implementation methods and application scope based on this application. It is neither necessary nor possible to exhaustively list all implementation methods here, but obvious variations or modifications derived therefrom are still within the protection scope of this application.

Claims

1. A floating casing head, comprising a casing head body, an oil layer casing, and a casing hanger all located within the casing head body, characterized in that, The inner wall of the casing hanger is movably fitted over the oil layer casing, and the outer wall of the casing hanger is fixedly connected to the casing head body, so that the oil layer casing can slide upward relative to the casing hanger; wherein... A floating casing section is also fixedly fitted outside the oil layer casing and located above the casing hanger. The floating casing section slides to connect the oil layer casing to the casing head body, so that the oil layer casing can slide upward relative to the casing head body. When the oil layer casing moves upward, the oil layer casing drives the floating casing section to slide upward within the casing head body. The casing head body has a sliding space for the floating casing section to slide. The lower end of the floating casing section is connected to the oil layer casing. When the floating casing section slides upward in the sliding space, the section of the floating casing section located in the upper part of the sliding space can be replaced or cut. The lower end of the casing head body is provided with a set screw and a set screw sealing device. The set screw passes through the lower end laterally and is used to fix the casing hanger and the lower end of the casing head body. The set screw sealing device is sleeved on the outer circumferential surface of the set screw and is used to seal the space between the set screw and the lower end of the casing head body. The casing hanger, from top to bottom, includes an upper pressure ring, a sealing element, a lower pressure ring, and a hanger body. The sealing element seals the casing hanger to the lower end of the casing head body. The upper pressure ring has a first conical surface at its outer apex, and the end of the set screw has a second conical surface that fits tightly with the first conical surface. The upper pressure ring is used to tighten and fix the set screw. The side wall of the hanger body has a third conical surface, and the lower end of the sleeve head body has a fourth conical surface that fits tightly with the third conical surface. The hanger body is used to improve the sealing between itself and the lower end of the sleeve head body.

2. The floating sleeve head according to claim 1, characterized in that, The sleeve head body includes a detachably connected upper body and a lower body, wherein the upper body constitutes the upper end portion of the sleeve head body, and the lower body constitutes the lower end portion of the sleeve head body.

3. A floating sleeve head according to claim 1 or 2, characterized in that, The floating sleeve section and the sliding space are located at the upper part of the sleeve head body, and the sleeve hanger is located at the lower part of the sleeve head body.

4. A floating sleeve head according to claim 1, characterized in that, The top screw sealing device includes, from one side near the sleeve hanger to the other, a support ring, a rubber ring, a spacer ring, and a pressure ring; wherein the support ring and the pressure ring are pressure-bearing and corrosion-resistant structures used to protect the rubber ring and the spacer ring.

5. A floating sleeve head according to claim 1, characterized in that, The top of the sliding space has a limiting step to prevent the floating sleeve section from sliding further.

6. A floating sleeve head according to claim 2, characterized in that, The bottom of the lower body has a circular side hole, which is sealed by a side hole flange. The center hole of the side hole flange is connected to the side hole plug, and the side hole flange is fixed to the lower body by several side hole caps.

7. A floating sleeve head according to claim 2, characterized in that, The lower body has a watch sleeve conversion connector embedded inside, extending from the bottom end of the lower body. A watch sleeve connecting flange is fitted onto the outside of the watch sleeve conversion connector, and the top end of the watch sleeve connecting flange is detachably connected to the bottom end of the lower body. The inner apex of the flange of the watch sleeve is provided with a fifth conical surface, and the side wall of the watch sleeve conversion joint is provided with a sixth conical surface that fits tightly with the fifth conical surface.

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