A petroleum drilling casing head

Abstract

The present application relates to the technical field of casing head, and particularly relates to an oil drilling casing head, which comprises a casing head body and a wellhead pipeline connected with the casing head body, an external locking assembly is arranged on the wellhead pipeline, an internal locking assembly is arranged in the casing head body, and the casing head body and the wellhead pipeline are quickly locked and fixed through the external locking assembly and the internal locking assembly. The present application realizes the functions of bolt-free quick locking and dynamic unlocking through the arrangement of the internal locking assembly. The internal locking assembly adopts a phased locking design. When the wellhead pipeline is inserted into the casing head body, the internal locking assembly first enters an axial limiting stage. When the pipeline is completely positioned, the system is automatically switched to a longitudinal locking stage. A plurality of symmetrically arranged second wedge blocks are expanded in the radial direction under the action of the downward movement of the first wedge block, so that the second wedge blocks are inserted into the vertical section of the locking groove, and the insertion and fixation are realized.

Description

Technical Field

[0001] This invention relates to the field of casing head technology, specifically to an oil drilling casing head. Background Technology

[0002] Drilling casing head is an important connecting component between casing and wellhead equipment. It is used to connect different layers of casing, between casing and blowout preventer, and to connect to the production wellhead after well completion. Drilling casing head is the core component of the oil and gas wellhead system, undertaking the triple functions of connection, load-bearing, and sealing.

[0003] Chinese patent application CN118933641A discloses a plug-in type casing head for oil drilling, including a casing head body and a calibration sealing assembly. The main feature is the use of a matching calibration sealing assembly between the casing head and the wellhead, and between the casing head and the connector body, to ensure that the mounting holes on the connecting disc are aligned when using bolts for fixing. This improves the ease of connection and fixing of the first mounting bolt, thus positively impacting overall installation efficiency. Furthermore, the sealing ring engages with the sealing groove, and auxiliary components are provided on the auxiliary plug, which, while providing verification for the casing head installation, also improves the connection sealing performance, better meeting practical application requirements.

[0004] As mentioned in the above application, the drilling casing head, as a transition structure between the casing string and the wellhead equipment, is currently connected to equipment such as blowout preventers, Christmas trees, and wellhead pipelines via standardized flanges. The connection is made through flange nuts, which is inefficient. Frequent disassembly or downhole impact loads may cause wear on the threads of nuts, bolts, or flanges, reducing the reliability of the connection. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an oil drilling casing head.

[0006] The present invention adopts the following technical solution: an oil drilling casing head, comprising a casing head body and a wellhead pipe connected to the casing head body, wherein an external locking component is provided on the wellhead pipe and an internal locking component is provided inside the casing head body, and the casing head body and the wellhead pipe are quickly locked and fixed by the cooperation of the external locking component and the internal locking component.

[0007] As a further description of the above technical solution, a lower fixing plate is provided on the outer wall of the casing head body, and an upper fixing plate is provided on the outer wall of the wellhead pipe. When the bottom end of the wellhead pipe is inserted into the casing head body for connection, the upper fixing plate is fitted onto the lower fixing plate, and an O-ring is provided on the mating surface of the upper fixing plate and the lower fixing plate.

[0008] As a further description of the above technical solution, the casing head body is provided with a reduced diameter section inside, an inclined surface is formed on the reduced diameter section, a limiting groove is opened on the upper surface of the inclined surface, an L-shaped groove is opened on the inner bottom plate of the limiting groove, and a reduced diameter section is provided at the bottom end of the wellhead pipe to cooperate with the casing head body.

[0009] The internal locking assembly includes a locking block disposed on the outer wall of the reduced diameter section of the wellhead pipe. A driving block is disposed at the bottom end of the locking block. A limiting ring is rotatably disposed at the bottom end of the wellhead pipe. Multiple locking grooves are opened on the outer wall of the limiting ring. The multiple locking grooves are distributed in a ring with equal spacing and have an inverted L-shaped structure. A spiral blade is disposed on the inner wall of the limiting ring.

[0010] A first wedge block is movably disposed within the vertical section of the L-shaped groove, and a second wedge block is movably disposed within the horizontal section of the L-shaped groove.

[0011] As a further description of the above technical solution, a first slider is welded to the outer wall of the first wedge block. The first slider is slidably connected to a vertical groove opened on the inner wall of the L-shaped groove. A first spring is welded to the outer wall of the first slider. In the initial state, the first slider is pushed to move to the bottom end of the vertical groove under the elastic force of the first spring.

[0012] As a further description of the above technical solution, a second slider is welded to the lower surface of the second wedge block. The second slider is slidably connected to a horizontal groove opened on the inner wall of the L-shaped groove. A second spring is welded to the lower surface of the second slider. The second spring is a tension spring. In the initial state, under the tension of the second spring, the second slider is pushed to the middle of the horizontal groove, so that the second wedge block is separated from the locking groove.

[0013] As a further description of the above technical solution, the top of the limiting ring is welded with multiple arc-shaped sliders, and the lower surface of the wellhead pipe is provided with an arc-shaped groove for use with the arc-shaped sliders. The arc-shaped sliders are slidably connected to the arc-shaped grooves. An arc-shaped spring is welded to one side wall of the arc-shaped slider. In the initial state, the arc-shaped slider is pushed to one end of the arc-shaped groove by the elastic force of the arc-shaped spring. At this time, the vertical section of the locking groove opened on the limiting ring corresponds to the position of the second wedge block.

[0014] As a further description of the above technical solution, the external locking assembly includes multiple clamping seats and connecting rods circumferentially distributed around the outer perimeter of the upper fixed plate. The clamping seats have a concave structure, and a sliding seat is welded onto the clamping seats. A strip-shaped groove is formed on the upper fixed plate, and the sliding seat is slidably connected to the strip-shaped groove. A rotating seat is fitted onto the wellhead pipe. One end of the connecting rod is rotatably connected to the rotating seat, and the other end of the connecting rod is rotatably connected to the clamping seat. The rotating seat is driven to rotate by a driving mechanism, which in turn drives the connecting rod to move. The connecting rod then drives the clamping seat to move, thereby achieving clamping, fixing, or separation of the clamping seat.

[0015] As a further description of the above technical solution, a driving mechanism is also included. The driving mechanism includes a fixed ring, which is welded and fixed to the wellhead pipe. A driving nut is threadedly connected to the wellhead pipe above the fixed ring. A driving rod is welded to the bottom end of the driving nut. The bottom end of the driving rod is fixedly connected to the rotating seat. The rotating seat is driven to rotate by rotating the driving nut.

[0016] As a further description of the above technical solution, a total of multiple drive rods are provided, and the multiple drive rods are circumferentially distributed at equal intervals around the outside of the wellhead pipe. The fixing ring is provided with an arc-shaped through hole for use with the drive rods.

[0017] As a further description of the above technical solution, the outer diameter of the lower fixed plate is smaller than the outer diameter of the upper fixed plate.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention provides an oil drilling casing head that achieves boltless rapid locking and dynamic unlocking through an internal locking assembly. The internal locking assembly employs a staged locking design. When the wellhead pipe is inserted into the casing head body, the internal locking assembly first enters the axial limiting stage. During this process, the locking block is inserted into the limiting groove to eliminate the circumferential degree of freedom between the wellhead pipe and the casing head, ensuring that they do not rotate relative to each other. Once the pipe is fully in place, the system automatically switches to the longitudinal locking stage. Multiple symmetrically arranged second wedge blocks expand radially under the downward movement of the first wedge blocks, causing the second wedge blocks to insert into the vertical section of the locking groove, achieving insertion and fixation.

[0020] Furthermore, the locking power originates from the energy of the fluid within the wellhead pipeline. When drilling fluid or oil / gas flows through the pipeline, it drives the limiting ring to complete a phase rotation at a predetermined angle. During the rotation, as the limiting ring rotates, the second wedge block moves from the vertical section of the locking groove to the horizontal section, thereby longitudinally limiting the second wedge block. Through mechanical linkage, fluid energy is converted into locking force. This design abandons the traditional bolt connection method, avoids manual tightening operations, and the locking mechanism is completely built into the pipeline structure, which not only prevents external accidental contact but also improves system reliability. Attached Figure Description

[0021] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0022] Figure 1 This is a schematic diagram of the structure of an oil drilling casing head provided in an embodiment of the present invention;

[0023] Figure 2 A cross-sectional schematic diagram of an oil drilling casing head provided for an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of the sleeve head body provided in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the structure of the wellhead pipeline provided in an embodiment of the present invention;

[0026] Figure 5 A schematic diagram of the disassembled structure of the wellhead pipeline provided in an embodiment of the present invention;

[0027] Figure 6 Provided for embodiments of the present invention Figure 2 Enlarged view of area A in the image;

[0028] Figure 7 This is a schematic diagram of the internal locking assembly provided in an embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of the structure of the external locking assembly provided in an embodiment of the present invention;

[0030] Figure 9 Provided for embodiments of the present invention Figure 8 Enlarged view of area B in the image.

[0031] Reference numerals: 1. Casing head body; 11. Lower fixed plate; 12. Inclined surface; 13. Limiting groove; 14. L-shaped groove; 2. Wellhead pipe; 21. Upper fixed plate; 3. External locking assembly; 31. Clamping seat; 32. Sliding seat; 33. Strip-shaped slide groove; 34. Rotating seat; 35. Drive nut; 36. Fixing ring; 37. Arc-shaped through hole; 38. Drive rod; 39. Connecting rod; 4. Internal locking assembly; 41. Locking block; 42. Drive block; 43. Limiting ring; 431. Arc-shaped slider; 432. Arc-shaped spring; 433. Arc-shaped slide groove; 44. Locking groove; 45. Helical blade; 46. First wedge block; 47. First slider; 48. First spring; 49. Second wedge block; 410. Second slider; 411. Second spring. Detailed Implementation

[0032] To make the technical means, creative features, objectives, and effects of this invention readily understandable, the invention is further described below with reference to specific illustrations. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0033] Example 1

[0034] Please see Figures 1-9 The present invention provides a technical solution: an oil drilling casing head, including a casing head body 1 and a wellhead pipe 2 connected to the casing head body 1. An external locking component 3 is provided on the wellhead pipe 2, and an internal locking component 4 is provided inside the casing head body 1. The casing head body 1 and the wellhead pipe 2 are quickly locked and fixed through the external locking component 3 and the internal locking component 4.

[0035] A lower fixing plate 11 is provided on the outer wall of the casing head body 1, and an upper fixing plate 21 is provided on the outer wall of the wellhead pipe 2. When the bottom end of the wellhead pipe 2 is inserted into the casing head body 1 for connection, the upper fixing plate 21 is fitted onto the lower fixing plate 11, and an O-ring is provided on the mating surface of the upper fixing plate 21 and the lower fixing plate 11.

[0036] The casing head body 1 has a reduced diameter section inside, and an inclined surface 12 is formed on the reduced diameter section. A limiting groove 13 is opened on the upper surface of the inclined surface 12. An L-shaped groove 14 is opened on the inner bottom plate of the limiting groove 13. The bottom end of the wellhead pipe 2 is provided with a reduced diameter section that is used in conjunction with the casing head body 1.

[0037] The internal locking assembly 4 includes a locking block 41 disposed on the outer wall of the reduced diameter section of the wellhead pipe 2. A driving block 42 is disposed at the bottom end of the locking block 41. A limiting ring 43 is rotatably disposed at the bottom end of the wellhead pipe 2. Multiple locking grooves 44 are provided on the outer wall of the limiting ring 43. The multiple locking grooves 44 are distributed in a ring at equal intervals and have an inverted L-shaped structure. A spiral blade 45 is disposed on the inner wall of the limiting ring 43. The bottom end of the locking groove 44 extends to the bottom end of the reduced diameter section. The L-shaped groove 14 is disposed below the reduced diameter section.

[0038] A first wedge block 46 is movably disposed in the vertical section of the L-shaped groove 14, and a second wedge block 49 is movably disposed in the horizontal section of the L-shaped groove 14.

[0039] A first slider 47 is welded to the outer wall of the first wedge block 46. The first slider 47 is slidably connected to the vertical groove opened on the inner wall of the L-shaped groove 14. A first spring 48 is welded to the outer wall of the first slider 47. In the initial state, the first slider 47 is pushed to move to the bottom end of the vertical groove under the elastic force of the first spring 48.

[0040] The lower surface of the second wedge block 49 is welded with a second slider 410. The second slider 410 is slidably connected to the horizontal slide groove opened on the inner wall of the L-shaped groove 14. The lower surface of the second slider 410 is welded with a second spring 411. The second spring 411 is a tension spring. In the initial state, under the tension of the second spring 411, the second slider 410 is pushed to move to the middle of the horizontal slide groove, so that the second wedge block 49 is separated from the locking groove 44.

[0041] Multiple arc-shaped sliders 431 are welded to the top of the limiting ring 43. An arc-shaped groove 433 is provided on the lower surface of the wellhead pipe 2 to cooperate with the arc-shaped sliders 431. The arc-shaped sliders 431 are slidably connected to the arc-shaped grooves 433. An arc-shaped spring 432 is welded to one side wall of the arc-shaped slider 431. In the initial state, the arc-shaped slider 431 is pushed to one end of the arc-shaped groove 433 by the elastic force of the arc-shaped spring 432. At this time, the vertical section of the locking groove 44 opened on the limiting ring 43 corresponds to the position of the second wedge block 49.

[0042] Specifically, the internal locking assembly 4 has two working strokes, including a first working stroke and a second working stroke. The first working stroke is when the wellhead pipe 2 is inserted into the casing head body 1, so that the locking block 41 is inserted into the limiting groove 13, thereby axially limiting the wellhead pipe 2 and the casing head body 1 so that they do not rotate relative to each other. Secondly, in conjunction with the external locking assembly 3, the wellhead pipe 2 and the casing head body 1 are vertically limited, thereby achieving quick locking and fixing of the casing head body 1 and the wellhead pipe 2.

[0043] The second working stroke is as follows: when the locking block 41 is inserted into the limiting groove 13, the driving block 42 presses the first wedge block 46 downward, causing the first spring 48 to contract. The first wedge block 46 moves downward, causing the second wedge block 49 to move towards the axis of the wellhead pipe 2, so that the second wedge block 49 is inserted into the vertical section of the locking groove 44. When the fluid in the wellhead pipe 2 enters the limiting ring 43 and contacts the internally arranged spiral blade 45, the limiting ring 43 is driven to rotate. As the limiting ring 43 rotates, the second wedge block 49 moves from the vertical section of the locking groove 44 to the horizontal section, thereby longitudinally limiting the second wedge block 49, thereby realizing the vertical locking and fixing of the wellhead pipe 2 and the casing head body 1.

[0044] The internal locking assembly 4 axially limits the wellhead pipe 2 and the casing head body 1 during the first working stroke, preventing them from rotating relative to each other. During the second working stroke, it longitudinally limits the second wedge block 49, thereby achieving vertical locking and fixing of the wellhead pipe 2 and the casing head body 1.

[0045] The locking method is simple and quick, without the need for bolt fixing. The locking mechanism is set inside the wellhead pipe 2, making it difficult to be accidentally moved. Through the setting of the internal locking component 4, and without the need for a drive mechanism, the power generated by the fluid in the pipe is used to automatically drive the limit ring 43 to rotate. In conjunction with the set second wedge block 49, the vertical locking and fixing of the wellhead pipe 2 and the casing head body 1 is automatically completed.

[0046] When there is no fluid passing through the wellhead pipe 2, the arc-shaped spring 432 pushes the arc-shaped slider 431 to one end of the arc-shaped groove 433 under the reset force. At this time, the vertical section of the locking groove 44 opened on the limiting ring 43 corresponds to the position of the second wedge block 49, realizing automatic unlocking. The wellhead pipe 2 can be directly lifted upward to separate the wellhead pipe 2 from the casing head body 1.

[0047] In this embodiment, the internal locking component 4 enables boltless rapid locking and dynamic unlocking. The internal locking component 4 employs a staged locking design. When the wellhead pipe 2 is inserted into the casing head body 1, the internal locking component 4 first enters the axial limiting stage. During this process, the locking block 41 is inserted into the limiting groove 13 to eliminate the circumferential degree of freedom between the wellhead pipe 2 and the casing head body 1, ensuring that they do not rotate relative to each other. Once the pipe is fully in place, the system automatically switches to the longitudinal locking stage. Multiple sets of symmetrically arranged second wedge blocks 49 expand radially under the downward movement of the first wedge block 46, causing the second wedge blocks 49 to insert into the vertical section of the locking groove 44, achieving insertion and fixation.

[0048] The locking power comes from the energy of the fluid itself in the wellhead pipe 2. When drilling fluid or oil and gas flow through the pipe, it drives the limiting ring 43 to complete a phase rotation at a predetermined angle. During the rotation, as the limiting ring 43 rotates, the second wedge block 49 moves from the vertical section of the locking groove 44 to the horizontal section, thereby longitudinally limiting the second wedge block 49. The fluid energy is converted into locking force through mechanical linkage. This design abandons the traditional bolt connection method and avoids manual tightening operations. The locking mechanism is completely built into the pipe structure, which not only prevents external accidental contact but also improves the reliability of the system.

[0049] The unlocking process employs an intelligent triggering mechanism. When the fluid inside the pipe stops flowing, the arc-shaped spring 432, pre-installed in the slide groove, releases its stored energy, pushing the slider back to its initial position. At this point, the vertical section of the locking groove 44 of the limit ring 43 is precisely aligned with the wedge block, releasing the mechanical constraint. Operators only need to vertically lift the pipe to complete the separation operation; the entire process requires no special tools or complex operating procedures.

[0050] Example 2

[0051] Please see Figures 1-2 and Figures 8-9Based on the above embodiments, this embodiment further adds an external locking component 3. The external locking component 3 locks and fixes the wellhead pipe 2 and the casing head body 1 vertically from the outside, thereby further improving the stability of the locking and fixing of the wellhead pipe 2 and the casing head body 1.

[0052] The external locking assembly 3 includes multiple clamping seats 31 and connecting rods 39 circumferentially distributed around the outer periphery of the upper fixed plate 21. The clamping seats 31 have a concave structure and a sliding seat 32 is welded on the clamping seats 31. The sliding seat 32 is slidably connected to the strip-shaped sliding groove 33 opened on the upper fixed plate 21. A rotating seat 34 is sleeved on the wellhead pipe 2. One end of the connecting rod 39 is rotatably connected to the rotating seat 34, and the other end of the connecting rod 39 is rotatably connected to the clamping seat 31. The rotating seat 34 is driven to rotate by the driving mechanism, which drives the connecting rod 39 to move. The connecting rod 39 drives the clamping seat 31 to move, thereby realizing the clamping and fixing or separation of the clamping seat 31.

[0053] Specifically, based on Embodiment 1, when the bottom end of the wellhead pipe 2 is inserted into the casing head body 1 for connection, the upper fixing plate 21 is fitted onto the lower fixing plate 11, and an O-ring is provided on the mating surface of the upper fixing plate 21 and the lower fixing plate 11. The O-ring is provided to improve the sealing performance at the connection between the lower fixing plate 11 and the upper fixing plate 21.

[0054] After the upper fixing plate 21 is attached to the lower fixing plate 11, the upper fixing plate 21 and the lower fixing plate 11 are locked and fixed by the external locking component 3, so as to lock and fix the wellhead pipe 2 and the casing head body 1 in the vertical direction.

[0055] The locking and fixing method of the external locking component 3 is as follows: during use, the rotating seat 34 is driven to rotate by the drive mechanism. The rotating seat 34 drives the connecting rod 39 to move. The connecting rod 39 pulls the clamping seat 31 to move and is sleeved on the upper fixed plate 21 and the lower fixed plate 11, so as to realize the vertical locking and fixing of the wellhead pipe 2 and the casing head body 1. This fixing method eliminates the need to set bolts between the upper fixed plate 21 and the lower fixed plate 11, making the fixing more convenient and quick. It also overcomes the problem that the sealing performance is affected by the damage of the threads and the opening of the bolt holes when using sampling bolts and threaded connections.

[0056] In this embodiment, the driving mechanism can be a gear ring and a drive motor. The gear ring is fixed on the outer wall of the rotating seat 34, the drive motor is externally fixed, and the output shaft of the drive motor is fixed to the gear disk. The gear disk meshes with the gear ring. The drive motor drives the gear ring to rotate, thereby causing the rotating seat 34 to rotate. This embodiment achieves automatic driving. The drive motor, gear ring, and gear disk are not shown in the figure.

[0057] In this embodiment, the driving mechanism includes a fixed ring 36, which is welded and fixed to the wellhead pipe 2. A driving nut 35 is threadedly connected to the wellhead pipe 2 above the fixed ring 36. A driving rod 38 is welded to the bottom end of the driving nut 35. The bottom end of the driving rod 38 is fixedly connected to the rotating seat 34. The rotating seat 34 is driven to rotate by rotating the driving nut 35.

[0058] Multiple drive rods 38 are provided, and the multiple drive rods 38 are circumferentially distributed at equal intervals around the outside of the wellhead pipe 2. The fixing ring 36 is provided with an arc-shaped through hole 37 for use with the drive rods 38.

[0059] It should be noted that when the drive nut 35 is tightened and fits against the fixing ring 36, the drive rod 38 drives the rotating seat 34 to rotate, which in turn drives the connecting rod 39 to move. The connecting rod 39 then drives the clamping seat 31 to move, thus achieving the clamping and fixing of the clamping seat 31. Conversely, when the drive nut 35 is loosened in the opposite direction, the drive rod 38 drives the rotating seat 34 to rotate, which in turn drives the connecting rod 39 to move. The connecting rod 39 then drives the clamping seat 31 to move, causing the bottom horizontal end of the clamping seat 31 to separate from the lower fixing plate 11.

[0060] The outer diameter of the lower fixed plate 11 is smaller than the outer diameter of the upper fixed plate 21. It should be noted that the outer diameter of the upper fixed plate 21 is larger than that of the lower fixed plate 11, so that when the clamping seat 31 slides to the outer end of the strip groove 33 via the sliding seat 32, the bottom horizontal end of the clamping seat 31 can be separated from the lower fixed plate 11, which facilitates the disassembly between the wellhead pipe 2 and the casing head body 1.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An oil drilling casing head, comprising a casing head body (1) and a wellhead pipe (2) connected to the casing head body (1), characterized in that, An external locking assembly (3) is provided on the wellhead pipe (2), and an internal locking assembly (4) is provided inside the casing head body (1). The casing head body (1) and the wellhead pipe (2) are quickly locked and fixed by the cooperation of the external locking assembly (3) and the internal locking assembly (4). The casing head body (1) is provided with a reduced diameter section inside, and an inclined surface (12) is formed on the reduced diameter section. A limiting groove (13) is opened on the upper surface of the inclined surface (12). An L-shaped groove (14) is opened on the inner bottom plate of the limiting groove (13). The bottom end of the wellhead pipe (2) is provided with a reduced diameter section that is used in conjunction with the casing head body (1). The internal locking assembly (4) includes a locking block (41) disposed on the outer wall of the reduced diameter section of the wellhead pipe (2). A driving block (42) is disposed at the bottom end of the locking block (41). A limiting ring (43) is rotatably disposed at the bottom end of the wellhead pipe (2). Multiple locking grooves (44) are opened on the outer wall of the limiting ring (43). The multiple locking grooves (44) are distributed in a ring with equal spacing and have an inverted L-shaped structure. A spiral blade (45) is disposed on the inner wall of the limiting ring (43). A first wedge block (46) is movably disposed in the vertical section of the L-shaped groove (14), and a second wedge block (49) is movably disposed in the horizontal section of the L-shaped groove (14). The lower surface of the second wedge block (49) is welded with a second slider (410). The second slider (410) is slidably connected to the horizontal groove opened on the inner wall of the L-shaped groove (14). The lower surface of the second slider (410) is welded with a second spring (411). The second spring (411) is a tension spring. In the initial state, under the tension of the second spring (411), the second slider (410) is pushed to move to the middle of the horizontal groove, so that the second wedge block (49) is separated from the locking groove (44).

2. The oil drilling casing head according to claim 1, characterized in that, The casing head body (1) is provided with a lower fixing plate (11) on its outer wall, and the wellhead pipe (2) is provided with an upper fixing plate (21) on its outer wall. When the bottom end of the wellhead pipe (2) is inserted into the casing head body (1) for connection, the upper fixing plate (21) and the lower fixing plate (11) fit together, and the contact surfaces of the upper fixing plate (21) and the lower fixing plate (11) are provided with O-ring seals.

3. The oil drilling casing head according to claim 1, characterized in that, A first slider (47) is welded to the outer wall of the first wedge block (46). The first slider (47) is slidably connected to a vertical groove opened on the inner wall of the L-shaped groove (14). A first spring (48) is welded to the outer wall of the first slider (47).

4. The oil drilling casing head according to claim 1, characterized in that, The top of the limiting ring (43) is welded with multiple arc-shaped sliders (431), and the lower surface of the wellhead pipe (2) is provided with an arc-shaped groove (433) for use with the arc-shaped sliders (431). The arc-shaped sliders (431) are slidably connected to the arc-shaped grooves (433), and an arc-shaped spring (432) is welded on one side wall of the arc-shaped sliders (431).

5. The oil drilling casing head according to claim 2, characterized in that, The external locking assembly (3) includes multiple clamping seats (31) and connecting rods (39) circumferentially distributed around the outer periphery of the upper fixed plate (21). The clamping seats (31) are concave structures. A sliding seat (32) is welded on the clamping seat (31). A strip groove (33) is provided on the upper fixed plate (21). The sliding seat (32) is slidably connected to the strip groove (33). A rotating seat (34) is fitted on the wellhead pipe (2). One end of the connecting rod (39) is rotatably connected to the rotating seat (34), and the other end of the connecting rod (39) is rotatably connected to the clamping seat (31).

6. The oil drilling casing head according to claim 5, characterized in that, It also includes a drive mechanism, which includes a fixed ring (36) that is welded and fixed to the wellhead pipe (2). A drive nut (35) is threadedly connected above the fixed ring (36) on the wellhead pipe (2). A drive rod (38) is welded to the bottom end of the drive nut (35). The bottom end of the drive rod (38) is fixedly connected to the rotating seat (34).

7. The oil drilling casing head according to claim 6, characterized in that, Multiple drive rods (38) are provided, and the multiple drive rods (38) are circumferentially distributed at equal intervals around the outside of the wellhead pipe (2). The fixing ring (36) is provided with an arc-shaped through hole (37) for use with the drive rods (38).

8. The oil drilling casing head according to claim 2, characterized in that, The outer diameter of the lower fixed plate (11) is smaller than the outer diameter of the upper fixed plate (21).

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