Thermal well workover casing head and use method thereof

Abstract

The present invention relates to the technical field of casing heads, and in particular to a thermal well repair casing head and a method for using the same. The thermal well repair casing head comprises a casing head shell, wherein the casing head shell is provided with a circular cavity and a conical cavity from top to bottom, the side wall of the circular cavity is provided with a side hole connected to the casing annulus, the top is threadedly connected to the upper cover, a hanger for hanging the oil layer casing is provided inside, an upper joint is welded on the top of the oil layer casing, the upper joint comprises a flange portion engaged with the upper cover and a connecting portion passing through the upper cover, the hanger comprises a clamping portion welded to the oil layer casing, a supporting portion pressed on the top of the surface casing is provided at the bottom of the clamping portion, and a plurality of wedge-shaped slips capable of hanging on the inner wall of the conical cavity are equidistantly provided on the outer wall of the surface casing. The thermal well repair casing head provided by the present invention has simple installation and operation, high construction efficiency, high connection stability, and good construction safety.

Description

Technical Field

[0001] The invention relates to the technical field of casing heads, and in particular to a thermal recovery well workover casing head and a use method thereof. Background Art

[0002] Thermal recovery casing heads are mainly used in oil wells for "heavy oil thermal recovery", that is, high-temperature steam (generally 400°C) is injected into the well to heat the heavy oil at the bottom of the well and reduce its viscosity, making it easier to recover. Thermal recovery casing heads generally work in an intermittent system. During recovery, high-temperature steam of about 400°C is continuously injected into the well for about half a month, and then recovery is carried out. After the viscosity increases, high-temperature steam is injected into the well again, and the cycle continues. Since thermal recovery casing heads are in a harsh working environment with continuous changes from high temperature to low temperature, they are more prone to aging and damage. In Xinjiang, the casing heads of some old wells for heavy oil thermal recovery have aged and damaged, and need to be repaired and replaced, and new well repair casing heads installed to smoothly recover oil resources.

[0003] The patent with application number 201610336934.1 discloses a thermal recovery casing head for repairing old wells, including a flange joint, a suspension nipple, a threaded sleeve, a main body and an oil pipe nipple. The interior of the flange joint is in the shape of a step that is narrow at the top and wide at the bottom, and the exterior of the threaded sleeve is in the shape of a step that is narrow at the top and wide at the bottom. The suspension nipple is sleeved in the flange joint and the top is welded and fixed to the flange joint. An external thread is provided in the middle of the suspension nipple, and the threaded sleeve is fixedly installed on the outside of the suspension nipple through the external thread. The threaded sleeve is seated into the positioning step in the main body by threaded connection. The length of the thread of the flange joint and the main body controls the position of the suspension nipple, which is convenient for adjusting the height. This can avoid the situation in which the weld of the oil layer casing is damaged due to thermal expansion and contraction during frequent gas injection, causing oil and water leakage, and then polluting the environment. However, the above technical solution has the following problems:

[0004] 1. The thermal recovery casing head and the surface casing still use the traditional threaded connection method. However, in the process of repairing old wells, the threads of the oil layer casing and the surface casing are often damaged, or the oil layer casing and the surface casing need to be re-cut to meet the construction requirements, and the original threads on the surface casing will be cut off. Therefore, if the surface casing is to be threadedly connected with the casing head, new threads need to be re-processed on the surface casing, which is complicated and has low construction efficiency.

[0005] 2. The oil layer casing is directly coaxially welded to the bottom of the suspension nipple. During welding, workers need to manually align the two, which is difficult to operate, increases the labor intensity of workers, and reduces construction efficiency;

[0006] 3. When the oil layer casing expands and contracts, the weld between the oil layer casing and the suspension nipple will alternately bear the upward thrust and downward pull. The weld is very easy to break under the action of alternating stress, causing safety accidents;

[0007] 4. The axial elongation trend of the oil layer casing is suppressed by the threaded connection force between the flange joint and the body. It is only applicable to thermal recovery wells of conventional depth. When encountering deep wells with high pressure and great depth, the length of the oil layer casing is extremely large, and its thermal expansion and contraction degree is greatly aggravated, which can easily destroy the threaded connection between the flange joint and the body, causing the oil layer casing to run up, damaging the wellhead equipment such as the Christmas tree, and causing safety accidents;

[0008] In summary, there is an urgent need to provide a thermal well workover casing head with simple operation, high construction efficiency, high connection stability and good construction safety. Summary of the invention

[0009] In order to solve at least one of the above-mentioned technical problems, the present invention provides a thermal well repair casing head, including a casing head shell, the casing head shell is provided with a circular cavity and a conical cavity from top to bottom, the side wall of the circular cavity is provided with a side hole connected to the casing annulus, the top is threadedly connected to the upper cover, a hanger for hanging the oil layer casing is provided inside, an upper joint is welded on the top of the oil layer casing, the upper joint includes a flange portion engaged with the upper cover and a connecting portion passing through the upper cover, the hanger includes a clamping portion welded to the oil layer casing, the bottom of the clamping portion is provided with a supporting portion pressed above the surface casing, and the outer wall of the surface casing is circumferentially provided with a plurality of wedge-shaped slips that can be hung on the inner wall of the conical cavity at equidistant intervals.

[0010] Preferably, a first threaded portion is provided above the inner wall of the circular cavity, two side holes are equidistantly provided around the circumference and are respectively threadedly connected to plugs, the upper cover comprises a cylindrical cover body with an opening at the bottom end, a center hole is provided on the top of the cover body, a step groove is provided at the bottom of the center hole, a second threaded portion corresponding to the first threaded portion is provided below the outer wall, a plurality of baffles are equidistantly provided around the circumference above the outer wall, the flange portion is inserted into the step groove, the inner wall is provided with an annular groove for inserting the oil layer casing, the connecting portion extends out of the center hole, and a third threaded portion is provided on the inner wall.

[0011] Preferably, the clamping part is cylindrical, and its inner diameter is consistent with the outer diameter of the oil layer casing; the supporting part is cylindrical, and its outer diameter is consistent with the outer diameter of the clamping part, and its inner diameter is not larger than the inner diameter of the surface casing; the supporting part and the oil layer casing form an annular space connecting the casing annulus, and a plurality of connecting holes are equidistantly arranged on the circumference of the supporting part.

[0012] Preferably, there are three wedge-shaped slips, including an arc-shaped slip body, the outer side wall of the slip body is a wedge surface that can be seated on the conical cavity, and the inner side wall is cylindrical and provided with oblique teeth for holding the surface casing.

[0013] Preferably, an annular step portion is provided at the junction of the circular cavity and the conical cavity of the casing head shell, and a positioning mechanism is provided on the step portion. The positioning mechanism includes a positioning ring partially placed on the step portion, the outer diameter of the positioning ring is consistent with the inner diameter of the circular cavity, and the inner diameter is smaller than the outer diameter of the oil layer casing, and the upper end surface is coaxially provided with a first annular groove for inserting the support portion, and the lower end surface is coaxially provided with a second annular groove for inserting the surface casing.

[0014] Preferably, an annular locking groove is provided below the side wall of the circular cavity, a plurality of first locking holes are equidistantly provided circumferentially below the side wall of the support portion, a plurality of second locking holes are equidistantly provided circumferentially above the side wall of the surface casing, a plurality of slide grooves are equidistantly provided circumferentially on the upper end surface of the positioning ring, the outer wall of the slide groove is provided with a radial hole, the inner wall is provided with a connecting port connecting the first annular groove and the second annular groove, a first locking block and a second locking block are radially slidingly provided in the slide groove, the first locking block can pass through the radial hole and be inserted into the locking groove, and the second locking block can pass through the connecting port and be inserted into the first locking hole and the second locking hole at the same time.

[0015] Preferably, the first locking block includes a first sliding portion that can slide radially in the slide groove, and a plug-in block is provided on the outer side of the first sliding portion, and the plug-in block can slide through the radial hole and be inserted into the locking groove; the second locking block includes a second sliding portion that can slide radially in the slide groove and the connecting port, and a first plug rod that can be inserted into the first locking hole and a second plug rod that can be inserted into the second locking hole are provided on the inner side of the second sliding portion.

[0016] Preferably, a plurality of positioning blocks are equidistantly provided on the circumference of the lower end surface of the positioning ring, a positioning groove corresponding to the positioning block is provided on the step portion, a damping groove connected to the slide groove and the connecting port is provided on the positioning block, a first damping slider matching with the damping groove is provided on the lower end surface of the first sliding portion, and a second damping slider matching with the damping groove is provided on the lower end surface of the second sliding portion.

[0017] Preferably, an annular extension portion is provided at the bottom of the cover body, a plurality of filter holes are equidistantly provided on the circumference above the extension portion, a fourth threaded portion is provided below, the upper end surface of the positioning ring is provided with an annular thread groove corresponding to the extension portion, the thread groove passes through the slide groove and is consistent with the height of the slide groove, the inner wall of the thread groove is provided with a fifth thread portion corresponding to the fourth threaded portion, the free end of the first sliding portion is an arc shape consistent with the outer diameter of the thread groove, and the free end of the second sliding portion is an arc shape consistent with the inner diameter of the thread groove.

[0018] The present invention provides a method for using a thermal well workover casing head, which is characterized by comprising the following steps:

[0019] Step S100, dismantling the wellhead device on the old well, and cutting the surface casing and the oil layer casing to the target size;

[0020] Step S200, sleeve the casing head shell onto the surface casing, then lower it, and weld a plurality of wedge-shaped slips equidistantly around the outer wall of the surface casing, with the wedge-shaped slips maintaining a certain distance from the upper end surface of the surface casing;

[0021] Step S300, sleeve the hanger on the oil layer casing, press the support part of the hanger on the upper end surface of the surface casing, and then weld and fix the holding part to the oil layer casing;

[0022] Step S400, welding and fixing the flange portion of the upper joint to the oil layer casing, then putting the upper cover on the connecting portion of the upper joint and pressing the flange portion;

[0023] Step S500, lift the casing head shell, screw the upper cover, and make the casing head shell and the upper cover threadedly connected. During the threaded connection process, the casing head shell is continuously moved up until the wedge-shaped slip seat is hung in the conical cavity of the casing head shell, and finally the casing head shell and the surface casing are welded and fixed;

[0024] Step S600, threading the connection part of the Christmas tree and the upper joint, and connecting the side hole to the exhaust pipe.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] 1. The present invention directly welds the wedge-shaped slips to the outer side wall of the surface casing, and by screwing the upper cover threadedly connected to the casing head shell, the casing head shell is moved upward, and the wedge-shaped slips and the surface casing can be hung in the conical cavity of the casing head shell, which is convenient and quick to operate and has good suspension stability;

[0027] 2. The oil layer casing is welded to the upper joint and the hanger respectively, forming a double weld. In addition, the upper joint and the surface casing have a bidirectional inhibitory effect on the thermal expansion and contraction of the oil layer casing, which can effectively inhibit the axial size change and welding stability of the oil layer casing, greatly improving the construction safety during thermal recovery;

[0028] 3. An annular groove for inserting the oil layer casing is set at the bottom of the upper cover. When the oil layer casing is inserted into the annular groove, the oil layer casing and the upper cover are automatically coaxially aligned, which is simple to operate, reduces the labor intensity of workers, and improves construction efficiency;

[0029] 4. During the installation process, the positioning ring of the positioning mechanism is provided with a first annular groove for inserting the oil layer casing and a second positioning groove for inserting the surface layer casing, which can play a role in straightening the oil layer casing, so that the oil layer casing and the surface casing remain in a coaxial state, improve the installation efficiency of workers, and reduce the labor intensity of workers;

[0030] 5. The first locking block and the second locking block of the positioning mechanism can axially lock the casing head housing, the hanger, the oil layer casing and the surface casing, further improving the suppression effect of thermal expansion and contraction of the oil layer casing, effectively preventing the oil layer casing from rising, and is suitable for thermal recovery of heavy oil in high-pressure deep wells;

[0031] 6. The positioning block and the positioning groove cooperate to circumferentially lock the positioning ring and the casing head housing, and then circumferentially lock the hanger, the oil layer casing and the surface casing, to avoid circumferential slippage between the casing head housing, the oil layer casing and the surface casing. The first damping slider and the second damping slider can limit the sliding freedom of the first locking block and the second locking block, so that the positions of the first locking block and the second locking block are relatively stable and will not slide freely at will, thereby improving the installation efficiency;

[0032] 7. The extension of the upper cover is threadedly connected to the positioning ring of the positioning mechanism. First, it can improve the connection stability between the upper cover and the casing head shell, further improve the thermal expansion suppression effect of the oil layer casing, second, it can compress the first locking block and the second locking block, improve the plugging stability of the first locking block and the second locking block, and third, it can form a filtering structure to prevent large debris entering from the side hole from falling into the casing annulus;

[0033] In summary, the thermal well workover casing head provided by the present invention has simple installation operation, high construction efficiency, high connection stability and good construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the external structure of the present invention;

[0035] Figure 2 It is an exploded view of Example 1;

[0036] Figure 3 It is a schematic diagram of the overall structure of Example 1;

[0037] Figure 4 It is an exploded view of Example 2;

[0038] Figure 5 It is an exploded view of the positioning mechanism;

[0039] Figure 6 is a top view of the positioning ring;

[0040] Figure 7 This is a schematic diagram of the overall structure of Example 2.

[0041] Description of reference numerals:

[0042] 1. Casing head shell, 11. Circular cavity, 12. Conical cavity, 13. Side hole, 14. First threaded portion, 15. Step portion, 16. Locking groove, 17. Positioning groove, 2. Upper cover, 21. Cover body, 22. Center hole, 23. Step groove, 24. Second threaded portion, 25. Baffle, 26. Extension portion, 27. Filter hole, 28. Fourth threaded portion, 3. Upper joint, 31. Flange portion, 32. Connecting portion, 33. Third threaded portion, 34. Annular groove, 4. Hanger, 41. Holding portion, 42. Support portion, 43. Connecting hole, 44. First locking hole, 5. Wedge-shaped slip, 51. Slip body, 52. Bevel teeth, 6. Oil layer casing, 7. Surface casing, 71. Second locking hole, 8. Plug, 9. Positioning mechanism, 91. Positioning ring, 911. First annular groove, 912. Second annular groove, 913. Slide groove, 914. Radial hole, 915. Connecting port, 916. Threaded groove, 917. Fifth threaded portion, 92. First locking block, 921. First sliding portion, 922. Plug block, 923. First damping slider, 93. Second locking block, 931. Second sliding portion, 932. First plug rod, 933. Second plug rod, 934. Second damping slider, 94. Positioning block, 941. Damping groove. DETAILED DESCRIPTION

[0043] The specific implementation of the present invention is described below in conjunction with the accompanying drawings and embodiments:

[0044] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0045] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content. Example 1

[0046] Combined with Figures 1 to 3The present embodiment provides a thermal well repair casing head, including a casing head shell 1, wherein the casing head shell 1 is provided with a circular cavity 11 and a conical cavity 12 from top to bottom, the side wall of the circular cavity 11 is provided with a side hole 13 connected to the casing annulus, the top is threadedly connected to the upper cover 2, a hanger 4 for hanging the oil layer casing 6 is provided inside, an upper joint 3 is welded on the top of the oil layer casing 6, the upper joint 3 includes a flange portion 31 engaged with the upper cover 2 and a connecting portion 32 passing through the upper cover 2, the hanger 4 includes a clamping portion 41 welded to the oil layer casing 6, a supporting portion 42 pressed on the top of the surface casing 7 is provided at the bottom of the clamping portion 41, and a plurality of wedge-shaped slips 5 that can be hung on the inner wall of the conical cavity 12 are equidistantly provided on the circumference of the outer wall of the surface casing 7.

[0047] In the above technical scheme, casing annulus is a commonly used term in this field, which refers to the annular space formed by the oil layer casing 6 and the surface casing 7. During thermal recovery, high-temperature steam is injected into the oil layer casing 6, and the water vapor in the casing annulus is evaporated by heat. The side holes 13 are used to discharge the water vapor evaporated by heat in the casing annulus to ensure the pressure stability in the casing annulus; the wedge-shaped slip 5 is the slip tooth in the traditional slip hanger.

[0048] It should be noted that the length of the oil layer casing 6 is much longer than that of the surface casing 7, and during thermal recovery, high-temperature steam is directly injected into the oil layer casing 6. The heat of the high-temperature steam is greatly reduced after being transferred to the surface casing 7 through the casing annulus. Based on the above factors, during thermal recovery of heavy oil, the axial thermal expansion and contraction of the oil layer casing 6 is much greater than that of the surface casing 7. The dynamically changing height difference can easily cause the weld cracking of the wellhead device and damage the wellhead device such as the Christmas tree. Therefore, the casing head needs to effectively suppress the thermal expansion and contraction of the oil layer casing 6. In this embodiment, the connection portion 32 of the upper joint 3 can be connected to the wellhead device such as the Christmas tree after passing through the upper cover 2, and the flange portion 31 of the upper joint 3 is connected to the oil layer casing The pipe 6 is welded and fixed, and the flange portion 31 is pressed by the upper cover 2, which can suppress the axial elongation (i.e. thermal expansion) of the oil layer casing 6 when heated; the hanger 4 is used to hang the oil layer casing 6, and the clamping portion 41 of the hanger 4 is used to clamp the oil layer casing 6. The clamping portion 41 and the oil layer casing 6 are connected and fixed by welding, and the support portion 42 of the hanger 4 is pressed on the surface casing 7. The surface casing 7 axially supports the clamping portion 41 and the oil layer casing 6 through the support portion 42, which can suppress the axial shortening (i.e. cold shrinkage) of the oil layer casing 6 when cooled. The support portion 42 can adopt any suitable structure that can be supported by the surface casing 7, including but not limited to strip and cylindrical structures;

[0049] In the process of repairing old wells, the threads of the oil layer casing 6 and the surface casing 7 are often damaged, or in order to meet the construction requirements, the oil layer casing 6 and the surface casing 7 need to be re-cut, and the original threads on the surface casing 7 will be cut off. If the surface casing 7 is to be threadedly connected to the casing head, new threads need to be re-processed, and the process is complicated. If a traditional slip hanger is to be used to connect the surface casing 7 and the casing head, it is necessary to first lift the surface casing 7, then hang the slip hanger seat in the casing head, and finally lower the surface casing 7 so that the slip hanger holds the surface casing 7 tightly. However, in the old well to be repaired, the surface casing 7 has been cemented and cannot be lifted up, so it is difficult to use The surface casing 7 is suspended by a traditional slip hanger; in the present embodiment, the above-mentioned problem is solved by welding a wedge-shaped slip 5 on the side wall of the surface casing 7, and matching the casing head shell 1 and the upper cover 2 which are threadedly connected. When in use, the casing head shell 1 can be first inserted into the outer side of the surface casing 7, and then the wedge-shaped slip 5 can be directly welded to the outer side wall of the surface casing 7. Finally, by screwing the upper cover 2 which is threadedly connected to the casing head shell 1, the casing head shell 1 can be moved upward, so that the wedge-shaped slip 5 is hung in the conical cavity 12, thereby realizing the suspension of the surface casing 7. The operation is convenient and quick, and the suspension stability is good. In order to further improve the connection stability, the surface casing 7 and the casing head shell 1 can be welded and fixed after the suspension is completed.

[0050] In a specific technical scheme, a first threaded portion 14 is provided above the inner wall of the circular cavity 11, two side holes 13 are equidistantly provided around the circumference and are respectively threadedly connected to a plug 8, the upper cover 2 includes a cylindrical cover body 21 with an opening at the bottom end, a center hole 22 is provided at the top of the cover body 21, a step groove 23 is provided at the bottom of the center hole 22, a second threaded portion 24 corresponding to the first threaded portion 14 is provided below the outer wall, a plurality of baffles 25 are equidistantly provided around the outer wall, the flange portion 31 is inserted into the step groove 23, an annular groove 34 is provided on the inner wall for inserting the oil layer casing 6, the connecting portion 32 extends out of the center hole 22, and a third threaded portion 33 is provided on the inner wall.

[0051] In the above technical scheme, the first threaded portion 14 and the second threaded portion 24 can be arranged in any suitable manner. In this embodiment, the first threaded portion 14 is in the shape of a spiral groove, and the second threaded portion 24 is in the shape of a spiral protrusion; when the side hole 13 is provided with a thread, a plug 8 is used to protect the thread of the side hole 13; the baffle 25 is used to screw the upper cover 2; an annular groove 34 for inserting the oil layer casing 6 is provided at the bottom of the upper joint 3, and when the oil layer casing 6 is inserted into the annular groove 34, the oil layer casing 6 and the upper joint 3 are automatically coaxially aligned, which reduces the labor intensity of workers and improves construction efficiency.

[0052] In a specific technical solution, the clamping part 41 is cylindrical, and its inner diameter is consistent with the outer diameter of the oil layer casing 6; the support part 42 is cylindrical, and its outer diameter is consistent with the outer diameter of the clamping part 41, and its inner diameter is not greater than the inner diameter of the surface casing 7; the support part 42 and the oil layer casing 6 form an annular space communicating with the casing annulus; and a plurality of communicating holes 43 are equidistantly arranged on the circumference of the support part 42. In the above technical solution, two communicating holes 43 are preferably provided, corresponding to the side holes 13 one by one; the support part 42 is cylindrical, and is directly coaxially pressed (pressing in the present invention does not require connection and fixing, and the two can be abutted) on the upper end surface of the surface casing 7. On the one hand, the cylindrical support part 42 can be integrally formed with the cylindrical clamping part 41, which is convenient to process and has high structural strength; on the other hand, the cylindrical support part 42 can increase its contact area with the surface casing 7, improve the support stability and support strength, and the communicating holes 43 on the support part 42 can discharge the steam in the casing annulus. The clamping portion 41 in the present invention may also be strip-shaped support columns equidistantly arranged on the lower end surface of the clamping portion 41. When the clamping portion 41 is a strip-shaped support column, there is naturally an exhaust gap between adjacent support columns, so there is no need to open additional exhaust holes.

[0053] In a specific technical solution, the wedge-shaped cava 5 is provided with three, including an arc-shaped cava body 51, the outer wall of the cava body 51 is a wedge surface that can be seated on the conical cavity 12, and the inner wall is cylindrical and provided with oblique teeth 52 that clamp the surface casing 7.

[0054] The installation and use process and working principle of this embodiment are as follows: 1. Installation and use: ① Remove the wellhead device on the old well, cut the surface casing 7 and the oil layer casing 6 to the target size; ② Put the casing head shell 1 on the surface casing 7, and then lower it, and weld a plurality of wedge-shaped slips 5 at equal intervals on the circumference of the outer wall of the surface casing 7, and keep a certain distance between the wedge-shaped slips 5 and the upper end surface of the surface casing 7; ③ Put the hanger 4 on the oil layer casing 6, so that the support part 42 of the hanger 4 is pressed on the upper end surface of the surface casing 7, and then weld the clamping part 41 to the oil layer casing 6; ④ Weld the flange part 31 of the upper joint 3 to the oil layer casing 6, and then put the upper cover 2 on the connecting part 32 of the upper joint 3, and press the flange part 31; ⑤ Lift the casing head shell 1, screw the upper cover 2, so that the casing head shell 1 is threadedly connected with the upper cover 2. During the threaded connection process, the casing head shell The body 1 is continuously moved upward until the wedge-shaped slip 5 is hung in the conical cavity 12 of the casing head shell 1, and finally the casing head shell 1 is welded and fixed to the surface casing 7; ⑥ The connection part 32 of the Christmas tree and the upper joint 3 is threadedly connected, and the side hole 13 is connected to the exhaust pipe; 2. Working principle: ① During thermal recovery, high-temperature steam is injected into the oil layer casing 6, and the water vapor in the casing annulus is evaporated by heat and discharged from the side hole 13. The oil layer casing 6 expands due to heat, and the upper cover 2 presses the upper joint 3 and the oil layer casing 6 downward to suppress the axial elongation trend of the oil layer casing 6 and ensure the dimensional stability of the oil layer casing 6; ② After the thermal recovery is completed, the oil layer casing 6 cools and shrinks, the clamping part 41 of the hanger 4 clamps the oil layer casing 6, and the surface casing 7 applies an upward supporting force to the hanger 4 and the oil layer casing 6 through the support part 42, which suppresses the axial shortening trend of the oil layer casing 6 and ensures the dimensional stability of the oil layer casing 6. Example 2

[0055] Combined with Figures 4 to 7 This embodiment provides a thermal well repair casing head. On the basis of embodiment 1, a positioning mechanism 9 is added. The specific technical solution is as follows:

[0056] An annular step portion 15 is provided at the junction of the circular cavity 11 and the conical cavity 12 of the casing head shell 1, and a positioning mechanism 9 is provided on the step portion 15. The positioning mechanism 9 includes a positioning ring 91 partially placed on the step portion 15, and the outer diameter of the positioning ring 91 is consistent with the inner diameter of the circular cavity 11, and the inner diameter is smaller than the outer diameter of the oil layer casing 6. The upper end surface is coaxially provided with a first annular groove 911 for inserting the support portion 42, and the lower end surface is coaxially provided with a second annular groove 912 for inserting the surface casing 7.

[0057] When repairing an old well, the cut oil layer casing 6 is higher than the surface casing 7. In the initial state, the oil layer casing 6 will be in a skewed state and not coaxial with the surface casing 7. In Example 1, only when the upper cover 2 is threadedly connected to the casing head shell 1, the oil layer casing 6 and the surface casing 7 can maintain a coaxial state. However, in the actual operation process, especially the welding process, the oil layer casing 6 and the surface casing 7 must be coaxial to ensure the welding quality and installation stability. At this time, the workers are required to manually straighten the oil layer casing 6, which increases the labor intensity of the workers and reduces the labor efficiency. In this embodiment, the positioning mechanism 9 can play a straightening role on the oil layer casing 6, so that the oil layer casing 6 and the surface casing 7 remain coaxial, reduce the labor intensity of the workers, and improve the installation efficiency.

[0058] When in use, first insert the casing head shell 1 into the surface casing 7, then weld the wedge-shaped slip 5 on the outer wall of the surface casing 7, then insert the positioning mechanism 9, insert the surface casing 7 into the second annular groove 912 on the lower end face of the positioning ring 91, then insert the hanger 4 into the oil layer casing 6, and insert the support part 42 of the hanger 4 into the first annular groove 911 on the upper end face of the positioning ring 91. At this time, the surface casing 7, the hanger 4 and the oil layer casing 6 automatically enter a coaxial state, which greatly facilitates the subsequent welding and installation process, reduces the labor intensity of workers, and improves the installation efficiency.

[0059] In a specific technical scheme, an annular locking groove 16 is provided below the side wall of the circular cavity 11, a plurality of first locking holes 44 are equidistantly provided on the circumference below the side wall of the support portion 42, a plurality of second locking holes 71 are equidistantly provided on the circumference above the side wall of the surface casing 7, a plurality of slide grooves 913 are equidistantly provided on the circumference of the upper end surface of the positioning ring 91, the outer wall of the slide groove 913 is provided with a radial hole 914, and the inner wall is provided with a connecting port 915 connecting the first annular groove 911 and the second annular groove 912, a first locking block 92 and a second locking block 93 are radially slidably provided in the slide groove 913, the first locking block 92 can pass through the radial hole 914 and be inserted into the locking groove 16, and the second locking block 93 can pass through the connecting port 915 and be inserted into the first locking hole 44 and the second locking hole 71 at the same time.

[0060] In the above technical solution, the first locking block 92 and the second locking block 93 of the positioning mechanism 9 can axially lock the casing head housing 1, the hanger 4, the oil layer casing 6 and the surface casing 7, further improving the effect of suppressing the thermal expansion and contraction of the oil layer casing 6, and effectively preventing the oil layer casing 6 from moving upward.

[0061] Compared with conventional thermal recovery wells, high-pressure deep wells are deeper, the length of the oil layer casing 6 is longer, and its thermal expansion and contraction degree is aggravated. When thermal recovery is carried out in high-pressure deep wells, the tendency of axial extension of the oil layer casing 6 increases significantly, and the threaded connection between the upper cover 2 and the casing head shell 1 is subjected to a stronger upward thrust, which can easily cause damage to the first threaded portion 14 and the second threaded portion 24. Failure of the threaded connection will cause the oil layer casing 6 to move upward and damage the wellhead device. In this embodiment, the first locking block 92 of the positioning mechanism 9 axially locks the casing head shell 1 and the positioning ring 91, and the second locking block 93 axially locks the support portion 42 of the hanger 4 with the surface casing 7. Since the hanger 4 is welded to the oil layer casing 6 Therefore, the oil layer casing 6 and the surface casing 7 are also indirectly locked; during thermal recovery, the oil layer casing 6 has a large axial extension tendency, and the surface casing 7 has a small axial extension tendency. The first locking block 92 can suppress the axial extension tendency of the surface casing 7 in the casing head shell 1, so that no axial relative displacement occurs between the surface casing 7 and the casing head shell 1. The second locking block 93 can axially lock the hanger 4 and the surface casing 7, thereby suppressing the axial extension tendency of the oil layer casing 6. Under the joint action of the threaded connection force of the first locking block 92, the second locking block 93, the upper cover 2 and the casing head shell 1, the axial extension of the oil layer casing 6 at high temperature can be effectively prevented.

[0062] In a specific technical solution, the first locking block 92 includes a first sliding portion 921 capable of radially sliding in the slide groove 913, and a plug-in block 922 is provided on the outer side of the first sliding portion 921, and the plug-in block 922 can slide through the radial hole 914 and be inserted into the locking groove 16; the second locking block 93 includes a second sliding portion 931 capable of radially sliding in the slide groove 913 and the connecting port 915, and a first plug rod 932 capable of being inserted into the first locking hole 44 and a second plug rod 933 capable of being inserted into the second locking hole 71 are provided on the inner side of the second sliding portion 931.

[0063] In the above technical solution, the chute 913 and the connecting port 915 are directly connected. Figure 6 As shown, the specific positions of the two are indicated by dotted lines. Figure 6 The dotted line on the left side is a schematic diagram of the slide groove 913 and the connecting port 915 after the first locking block 92 and the second locking block 93 are taken out; the connecting port 915 is essentially a radial extension of the slide groove 913 to the first annular groove 911 and the second annular groove 912; the plug-in block 922 is preferably rectangular, and the height of the rectangle is greater than its width, so as to improve the plug-in stability, the first plug rod 932 and the second plug rod 933 can be cylindrical or rectangular, and the shape of the first locking hole 44 and the second locking hole 71 are consistent with the first plug rod 932 and the second plug rod 933.

[0064] In a specific technical solution, a plurality of positioning blocks 94 are equidistantly arranged on the circumference of the lower end surface of the positioning ring 91, a positioning groove 17 corresponding to the positioning block 94 is provided on the step portion 15, a damping groove 941 connected to the slide groove 913 and the connecting port 915 is provided on the positioning block 94, a first damping slider 923 matching with the damping groove 941 is provided on the lower end surface of the first sliding portion 921, and a second damping slider 934 matching with the damping groove 941 is provided on the lower end surface of the second sliding portion 931.

[0065] In the above technical scheme, the positioning block 94 and the positioning groove 17 cooperate with each other to circumferentially lock the positioning ring 91 and the casing head shell 1, and then circumferentially lock the hanger 4, the oil layer casing 6 and the surface casing 7, so as to avoid circumferential slippage between the casing head shell 1, the oil layer casing 6 and the surface casing 7; the damping groove 941, the first damping slider 923 and the second damping slider 934 can adopt any suitable damping sliding structure in the prior art, including but not limited to coating the damping sliding coating on the surface of the damping groove 941, the first damping slider 923 and the second damping slider 934, or setting damping patterns on the surfaces of the three, etc. The first damping slider 923 and the second damping slider 934 can limit the sliding freedom of the first locking block 92 and the second locking block 93, so that the position of the first locking block 92 and the second locking block 93 is relatively stable and will not slide freely at will, thereby improving the installation efficiency.

[0066] In a specific technical solution, an annular extension portion 26 is provided at the bottom of the cover body 21, a plurality of filter holes 27 are equidistantly provided on the circumference above the extension portion 26, and a fourth threaded portion 28 is provided at the bottom, and an annular threaded groove 916 corresponding to the extension portion 26 is provided on the upper end surface of the positioning ring 91, and the threaded groove 916 passes through the slide groove 913 and is consistent in height with the slide groove 913, and a fifth threaded portion 917 corresponding to the fourth threaded portion 28 is provided on the inner wall of the threaded groove 916, and the free end of the first sliding portion 921 is an arc shape consistent with the outer diameter of the threaded groove 916, and the free end of the second sliding portion 931 is an arc shape consistent with the inner diameter of the threaded groove 916.

[0067] In the above technical scheme, the extension portion 26 of the upper cover 2 is threadedly connected to the positioning ring 91 of the positioning mechanism 9. First, it can improve the connection stability between the upper cover 2 and the casing head shell 1, and further improve the thermal expansion suppression effect on the oil layer casing 6. Second, it can radially compress the first locking block 92 and the second locking block 93 to improve the plug-in stability of the first locking block 92 and the second locking block 93. Third, it can form a filtering structure through the filter hole 27 to prevent large debris entering from the side hole 13 from falling into the casing annulus. The filter hole 27 in this embodiment is preferably a strip-shaped axially slender through hole, which can effectively filter out large debris while ensuring structural strength and ventilation effect. Example 3

[0068] Combined with Figures 1 to 3 This embodiment provides a method for using a thermal well workover casing head, comprising the following steps:

[0069] Step S100, dismantling the wellhead device on the old well, and cutting the surface casing 7 and the oil layer casing 6 to the target size;

[0070] Step S200, sleeve the casing head shell 1 on the surface casing 7, then lower it, and weld a plurality of wedge-shaped slips 5 at equal intervals on the circumference of the outer wall of the surface casing 7, and keep a certain distance between the wedge-shaped slips 5 and the upper end surface of the surface casing 7;

[0071] Step S300, the hanger 4 is put on the oil layer casing 6, the support part 42 of the hanger 4 is pressed on the upper end surface of the surface casing 7, and then the holding part 41 is welded and fixed to the oil layer casing 6;

[0072] Step S400, the flange portion 31 of the upper joint 3 is welded and fixed to the oil layer casing 6, and then the upper cover 2 is put on the connecting portion 32 of the upper joint 3, and the flange portion 31 is pressed tightly;

[0073] Step S500, lift the casing head shell 1, screw the upper cover 2, and make the casing head shell 1 and the upper cover 2 threadedly connected. During the threaded connection process, the casing head shell 1 is continuously moved up until the wedge-shaped slip 5 is hung in the conical cavity 12 of the casing head shell 1, and finally the casing head shell 1 and the surface casing 7 are welded and fixed;

[0074] Step S600, the Christmas tree is threadedly connected to the connection portion 32 of the upper joint 3, and the side hole 13 is connected to the exhaust pipe.

[0075] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement modes and shall be included in the protection scope of the present invention.

Claims

1. A thermal well repair casing head, comprising a casing head shell (1), characterized in that: The casing head shell (1) is provided with a circular cavity (11) and a conical cavity (12) from top to bottom, the side wall of the circular cavity (11) is provided with a side hole (13) connected to the casing annulus, the top is threadedly connected to the upper cover (2), and a hanger (4) for hanging the oil layer casing (6) is provided inside, the top of the oil layer casing (6) is welded with an upper joint (3), the upper joint (3) comprises a flange portion (31) engaged with the upper cover (2) and a connecting portion (32) penetrating the upper cover (2), the hanger (4) comprises a clamping portion (41) welded to the oil layer casing (6), the clamping portion (41) is cylindrical, the inner diameter of which is consistent with the outer diameter of the oil layer casing (6), and the bottom is provided with a support portion (42) pressed on the top of the surface casing (7), and the outer wall of the surface casing (7) is provided with a plurality of wedge-shaped slips (5) that can be seated on the inner wall of the conical cavity (12) at equal intervals around the circumference; A first threaded portion (14) is provided above the inner wall of the circular cavity (11); the upper cover (2) comprises a cylindrical cover body (21) with an opening at the bottom; a center hole (22) is provided at the top of the cover body (21); a step groove (23) is provided at the bottom of the center hole (22); a second threaded portion (24) corresponding to the first threaded portion (14) is provided below the outer wall; a plurality of baffles (25) are provided equidistantly around the outer wall; the flange portion (31) is inserted into the step groove (23); an annular groove (34) is provided on the inner wall for inserting an oil layer casing (6); the connecting portion (32) extends out of the center hole (22); and a third threaded portion (33) is provided on the inner wall.

2. A thermal well workover casing head according to claim 1, characterized in that: Two side holes (13) are equidistantly arranged around the circumference and are respectively threadedly connected to the plug (8).

3. A thermal well workover casing head according to claim 2, characterized in that: The support portion (42) is cylindrical, with an outer diameter consistent with the outer diameter of the clamping portion (41), and an inner diameter no greater than the inner diameter of the surface casing (7). The support portion (42) and the oil layer casing (6) form an annular space communicating with the casing annulus, and a plurality of communicating holes (43) are equidistantly arranged on the circumference of the support portion (42).

4. A thermal well workover casing head according to claim 3, characterized in that: The wedge-shaped slips (5) are provided in three pieces, including an arc-shaped slip body (51), the outer side wall of the slip body (51) being a wedge surface capable of being seated on the conical cavity (12), and the inner side wall being cylindrical and provided with oblique teeth (52) for holding the surface casing (7).

5. A thermal well workover casing head according to claim 4, characterized in that: An annular step portion (15) is provided at the junction of the circular cavity (11) and the conical cavity (12) of the casing head shell (1), and a positioning mechanism (9) is provided on the step portion (15). The positioning mechanism (9) comprises a positioning ring (91) partially placed on the step portion (15), the outer diameter of the positioning ring (91) is consistent with the inner diameter of the circular cavity (11), and the inner diameter is smaller than the outer diameter of the oil layer casing (6), and the upper end surface is coaxially provided with a first annular groove (911) for inserting the support portion (42), and the lower end surface is coaxially provided with a second annular groove (912) for inserting the surface casing (7).

6. A thermal well workover casing head according to claim 5, characterized in that: An annular locking groove (16) is provided below the side wall of the circular cavity (11); a plurality of first locking holes (44) are equidistantly provided on the circumference below the side wall of the support portion (42); a plurality of second locking holes (71) are equidistantly provided on the circumference above the side wall of the surface sleeve (7); a plurality of sliding grooves (913) are equidistantly provided on the circumference of the upper end surface of the positioning ring (91); a radial hole (914) is provided on the outer wall of the sliding groove (913); a connecting port (915) connecting the first annular groove (911) and the second annular groove (912) is provided on the inner wall; a first locking block (92) and a second locking block (93) are radially slidably provided in the sliding groove (913); the first locking block (92) can pass through the radial hole (914) and be inserted into the locking groove (16); and the second locking block (93) can pass through the connecting port (915) and be simultaneously inserted into the first locking hole (44) and the second locking hole (71).

7. A thermal well workover casing head according to claim 6, characterized in that: The first locking block (92) comprises a first sliding portion (921) capable of radially sliding in the sliding groove (913), and an inserting block (922) is provided on the outer side of the first sliding portion (921), and the inserting block (922) is capable of sliding through the radial hole (914) and being inserted into the locking groove (16); the second locking block (93) comprises a second sliding portion (931) capable of radially sliding in the sliding groove (913) and the connecting port (915), and a first inserting rod (932) capable of being inserted into the first locking hole (44) and a second inserting rod (933) capable of being inserted into the second locking hole (71) are provided on the inner side of the second sliding portion (931).

8. A thermal well workover casing head according to claim 7, characterized in that: A plurality of positioning blocks (94) are equidistantly arranged on the circumference of the lower end surface of the positioning ring (91); a positioning groove (17) corresponding to the positioning block (94) is arranged on the step portion (15); a damping groove (941) connected to the slide groove (913) and the connecting port (915) is arranged on the positioning block (94); a first damping slider (923) matched with the damping groove (941) is arranged on the lower end surface of the first sliding portion (921); and a second damping slider (934) matched with the damping groove (941) is arranged on the lower end surface of the second sliding portion (931).

9. A thermal well workover casing head according to claim 8, characterized in that: The bottom of the cover body (21) is provided with an annular extension portion (26), a plurality of filter holes (27) are equidistantly arranged on the upper circumference of the extension portion (26), and a fourth threaded portion (28) is provided at the lower portion; the upper end surface of the positioning ring (91) is provided with an annular threaded groove (916) corresponding to the extension portion (26), the threaded groove (916) passes through the slide groove (913) and is at the same height as the slide groove (913); the inner wall of the threaded groove (916) is provided with a fifth threaded portion (917) corresponding to the fourth threaded portion (28); the free end of the first sliding portion (921) is in the shape of an arc that is consistent with the outer diameter of the threaded groove (916), and the free end of the second sliding portion (931) is in the shape of an arc that is consistent with the inner diameter of the threaded groove (916).

10. The method for using a thermal well workover casing head according to claim 1, characterized in that: The following steps are involved: Step S100, dismantling the wellhead device on the old well, and cutting the surface casing (7) and the oil layer casing (6) to the target size; Step S200, sleeve the casing head shell (1) onto the surface casing (7), then lower it, and weld a plurality of wedge-shaped slips (5) equidistantly around the outer wall of the surface casing (7), with the wedge-shaped slips (5) maintaining a certain distance from the upper end surface of the surface casing (7); Step S300, the hanger (4) is put on the oil layer casing (6), the support part (42) of the hanger (4) is pressed on the upper end surface of the surface casing (7), and then the holding part (41) is welded and fixed to the oil layer casing (6); Step S400, welding and fixing the flange portion (31) of the upper joint (3) and the oil layer casing (6), then sleeve the upper cover (2) onto the connecting portion (32) of the upper joint (3), and press the flange portion (31); Step S500, lifting the casing head shell (1), screwing the upper cover (2), so that the casing head shell (1) and the upper cover (2) are threadedly connected. During the threaded connection process, the casing head shell (1) is continuously moved upward until the wedge-shaped slip seat (5) is hung in the conical cavity (12) of the casing head shell (1), and finally the casing head shell (1) and the surface casing (7) are welded and fixed; Step S600, the Christmas tree is threadedly connected to the connecting portion (32) of the upper joint (3), and the side hole (13) is connected to the exhaust pipe.

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