A special casing head for oil well

Abstract

The present invention discloses a casing head for oil wells, and relates to the technical field of casing heads. The casing head for oil wells comprises a flange shell, a top screw with a conical head, and a slip hanger arranged in the flange shell, wherein the slip hanger comprises: a slip shell, wherein the slip shell has an extrusion cavity; a slip tooth component, wherein the slip tooth component is provided with at least four groups, wherein the slip tooth component comprises a slip tooth body located in the extrusion cavity, an upper extension portion arranged at the upper inner edge of the slip tooth body, and a force plane arranged at the upper outer edge of the slip tooth body; a pressure block, and the casing head for oil wells is provided with the function of the pressure block, and the pressure block is limited circumferentially and radially, so that it can be ensured that the slip hanger does not generate circumferential rotation when it is hung, that is, does not generate side slip, thereby ensuring that the slip tooth body is evenly distributed on the periphery of the oil layer casing, and improving the force uniformity of the oil layer casing.

Description

Technical Field

[0001] The invention relates to the technical field of casing heads, in particular to a special casing head for oil wells. Background Art

[0002] The casing head is used to fix the wellhead of the drilled well, connect the wellhead casing string, support the gravity of the technical casing and the oil layer casing, seal the annular space between the layers of pipes, provide a transition connection for the installation of the blowout preventer, tubing head, and Christmas tree, and through the two side ports on the casing head body, operations such as squeezing mud, monitoring, and adding balancing fluid can be carried out.

[0003] The casing head generally includes a flange housing and a hanger. The hanger generally includes a slip hanger and an axis hanger. It is an important component used to hang the pipe string in oil and gas drilling operations. The slip hanger is mainly composed of a slip seat and a slip tooth. Among them, the slip tooth is the most critical component, which directly affects the clamping state of the slip tooth and the pipe string and the degree of damage to the pipe string.

[0004] The outer side of the existing slip teeth is set to an inverted conical surface to cooperate with the slip seat, which can better hold the pipe string when in use, not only has a limiting effect, but also can stop the pipe string from moving axially. However, during actual drilling, the force on the pipe string is relatively complex, and the slip teeth and the slip seat are prone to side slipping, that is, relative rotation, causing wear, reducing the service life of the slip teeth, affecting the continued use of the hanger, and even causing the pipe string to slip. Especially when the top screw is screwed in, there is a large friction between the conical head of the top screw and the conical surface of the slip teeth, causing the conical head of the top screw to generate a tangential thrust on the slip teeth, causing the slip teeth to further side slip.

[0005] In order to solve the problem of side sliding of the cava teeth, a cava hanger is proposed in the patent with publication number CN213144426U, which can fix the first arc-shaped tooth body, the second arc-shaped tooth body and the cava seat respectively through the set threaded lock holes and slots, thereby preventing them from rotating and side sliding during use, preventing wear, improving the service life and anti-slip performance of the cava teeth, and ensuring the normal use of the hanger.

[0006] However, during the actual hanging process, after the cava tooth is subjected to the downward force of the top screw, it will produce axial movement along the cava shell, and the above-mentioned method of fixing the first arc-shaped tooth body, the second arc-shaped tooth body and the cava seat will prevent the cava tooth from moving downward. If the above-mentioned first arc-shaped tooth body, the second arc-shaped tooth body and the cava seat are separated during the hanging stage, the entire construction process will become too cumbersome. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a casing head dedicated to oil wells.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: a casing head dedicated to oil wells, comprising a flange shell, a top screw with a conical head and a slip hanger arranged in the flange shell, wherein the slip hanger comprises: a slip shell having an extrusion chamber; a slip tooth component, wherein the slip tooth component is provided with at least four groups, wherein the slip tooth component comprises a slip tooth body located in the extrusion chamber, an upper extension portion provided at the upper inner edge of the slip tooth body and a force-bearing plane provided at the upper outer edge of the slip tooth body; a pressure block, wherein the pressure block is provided at the periphery of the upper extension portion, and the pressure block has a conical surface, and the pressure block is limited in the circumferential direction and radial direction of the flange shell, so that when the conical surface of the pressure block is subjected to force, the pressure block can only move in the axial direction of the flange shell, forming a state in which the force-bearing plane is subjected to only axial force; the upper end height of the slip shell is greater than the height of the pressure block, and a first hole is radially opened at a position relative to the slip shell and the pressure block; wherein, after the top screw is screwed into the flange shell and the first hole, the conical head provides pressure to the conical surface of the pressure block.

[0009] Further, the pressure block includes an arc-shaped pressure plate 1, which includes: an upper ring portion, which is located at the periphery of the upper extension portion, the outer surface of the upper ring portion is set as a conical surface, and the lower surface of the upper ring portion is set as a plane, the plane is in contact with the force-bearing plane, and the plane protrudes outward from the force-bearing plane; a limiting rod, which is arranged on the lower surface of the upper ring portion protruding from the force-bearing plane, and a plug is provided at the lower end of the limiting rod, and a flat cut surface 1 is provided at the periphery of the upper end of the extrusion cavity, and a guide hole matched with the plug is opened on the flat cut surface 1, and the guide hole cooperates with the plug to limit the upper ring portion in the circumferential direction and radial direction.

[0010] Furthermore, a fixed plate is fixedly provided on the upper surface of the first planar section, and a through hole for accommodating a limiting rod is provided on the fixed plate, and a diameter of the through hole is smaller than a diameter of the plug.

[0011] Furthermore, the pressure block is an arc-shaped annular structure, and the arc-shaped annular structure is located at the periphery of the upper extension part, and the arc-shaped annular structure is a 90° arc, and four arc-shaped annular structures form a complete ring structure, and the four annular structures mutually restrict their respective radial movements; the arc-shaped annular structure also has a circumferential limiter, which can limit the circumferential displacement of each arc-shaped annular structure.

[0012] Furthermore, the arc-shaped annular structure includes an arc-shaped pressure frame, which is a hollow structure composed of an upper side wall, an inner side wall, a lower side wall and an outer side wall, and the conical surface is arranged on the upper surface of the lower side wall: the circumferential limiter includes: an axial long hole is opened in the middle part of the outer side wall, and the top screw passes through the first hole and the axial long hole to press down the conical surface of the lower side wall, and the lower side wall cooperates with the top screw to limit the circumferential rotation of the lower side wall.

[0013] Furthermore, the arc-shaped annular structure includes an arc-shaped pressure plate 2, which includes a plate body 2, and the plate body 2 is located at the periphery of the upper extension part, and the conical surface is arranged on the upper surface of the plate body 2; the circumferential limiting member includes a limiting ridge, and two limiting ridges are provided. After the top screw passes through the first hole, it is located between the two limiting ridges, and the limiting ridge and the top screw cooperate to limit the circumferential rotation of the upper side wall.

[0014] Furthermore, an upper convex portion is provided at the upper end of the plate body 2, and the upper end of the limiting ridge extends to the height of the upper convex portion, so that the height of the limiting ridge is always greater than the height of the top screw.

[0015] Furthermore, a guide slider is fixedly provided on the lower surface of the pressure block, and a guide groove is opened on the upper surface of the force-bearing plane. The guide groove and the guide slider are arranged in cooperation to enable only radial relative displacement to occur between the cava tooth component and the pressure block.

[0016] Furthermore, the kava tooth body is a W-shaped structure or a V-shaped structure.

[0017] Furthermore, the cava shell is composed of two semi-annular structures, the lower end of the cava shell is provided with a cava seat composed of two semi-annular structures, the lower end of the cava seat is provided with a support seat composed of two semi-annular structures, and when the connecting seam of the cava shell is aligned with the connecting seam of the cava seat, the cava hanger can be in a separated state.

[0018] The present invention has the following beneficial effects:

[0019] (1) The special casing head for oil wells is provided with a pressure block, and the pressure block is limited circumferentially and radially, so that the pressure block can only exert downward pressure on the main body of the cava tooth, thereby ensuring that the cava hanger does not produce circumferential rotation when it is hung, that is, no side slipping, thereby ensuring that the main body of the cava tooth is evenly distributed on the periphery of the oil layer casing, improving the uniformity of force on the oil layer casing, and the overall hanging process is similar to the hanging process in the prior art, and does not produce a cumbersome process.

[0020] (2) The casing head specially used for oil wells has a guide slider fixed on the lower surface of the pressure block and a guide groove opened on the upper surface of the force-bearing plane. The guide groove and the guide slider cooperate to enable only radial relative displacement to occur between the cava tooth component and the pressure block, thereby further ensuring that the cava tooth component can only move axially and radially. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the internal structure of Embodiment 1 of the present invention;

[0022] Figure 2 It is a structural schematic diagram of the flange housing of the present invention;

[0023] Figure 3 The slip hanger in the first embodiment of the present invention without the first handle and the second handle assembled;

[0024] Figure 4 Schematic diagram of the internal structure of the slip hanger in the first embodiment of the present invention;

[0025] Figure 5 A slip hanger with handle 1 and handle 2 assembled in Embodiment 1 of the present invention;

[0026] Figure 6 The slip hanger after seaming in the first embodiment of the present invention;

[0027] Figure 7 The internal structure of the single half slip hanger of the present invention is shown in FIG. Figure 1 ;

[0028] Figure 8 The internal structure of the single half slip hanger of the present invention is shown in FIG. Figure 2 ;

[0029] Fig. 9 It is a schematic diagram cut along the midline of the first embodiment of the present invention;

[0030] Fig.10 For the present invention Fig. 9 A magnified image of area A;

[0031] Fig.11 For the present invention Fig. 9 A magnified view of area A (the main body of the kava tooth is retracted);

[0032] FIG. 12 (a) shows the cooperation between the slip tooth component and the arc pressure plate 1 of the present invention Figure 1 ;

[0033] FIG. 12 (b) shows the cooperation between the slip tooth component and the arc-shaped pressure plate of the present invention. Figure 2 ;

[0034] FIG. 13 (a) is a disassembled view of the slip tooth component and the arc-shaped pressure plate of the present invention. Figure 1 ;

[0035] FIG. 13 (b) is a disassembled view of the slip tooth component and the arc-shaped pressure plate of the present invention. Figure 2 ;

[0036] Fig.14 Schematic diagram of the internal structure of the slip housing in the first embodiment of the present invention;

[0037] Fig.15 for Fig.14 Exploded diagram of

[0038] Fig.16 This is an assembly diagram of the arc-shaped pressing frame in the second embodiment of the present invention;

[0039] Fig.17 for Fig.16 The main view of

[0040] Fig.18 for Fig.17 Schematic diagram of the main body of the middle kava tooth being retracted;

[0041] Fig.19 It is a schematic diagram of the structure of four arc-shaped pressing frames in the second embodiment of the present invention;

[0042] Fig. 20 It is a schematic diagram of a cutaway single arc-shaped pressing frame according to the second embodiment of the present invention;

[0043] Fig.21 for Fig.19 Bottom view of ;

[0044] Fig. 22 It is an assembly diagram of the arc-shaped pressing plate 2 in the second embodiment of the present invention;

[0045] Fig.23 For the present invention Fig. 22 A magnified view of area B;

[0046] Fig.24 It is a schematic structural diagram of a single arc-shaped pressing plate 2 in the second embodiment of the present invention;

[0047] Fig.25 It is an assembly diagram of the present invention during installation and use.

[0048] In the figure, 1, top screw; 101, conical head; 2, pressure cap; 3, flange shell; 31, flange body; 32, pipe connection part; 33, flange hole; 34, pressure cap hole; 35, top screw hole; 36, hollow cavity; 5, slip shell; 51, extrusion cavity; 52, fixed plate; 521, through hole; 53, first hole; 54, guide hole; 55, plane section 1; 6, slip tooth component; 61, upper extension; 62, slip tooth body; 63, force plane; 64, guide groove; 7, arc C-shaped pressure plate one; 71, upper ring; 72, limiting rod; 73, plug; 8, support seat; 81, second hole; 9, handle one; 10, handle two; 11, cava seat; 12, guide slide block; 13, arc-shaped pressure frame; 131, upper side wall; 132, inner side wall; 133, axial long hole; 134, lower side wall; 135, outer side wall; 14, arc-shaped pressure plate two; 141, plate body two; 142, limiting ridge; 143, upper convex part; 15, C-shaped pressure plate; 16, C-shaped plate. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] According to the following Figure 1-Figure 25 The special casing head for oil wells provided by an embodiment of the present invention is described.

[0051] Embodiment 1

[0052] See also Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a casing head for oil wells, including a flange housing 3, the flange housing 3 including a flange body 31 and a connecting pipe 32, the flange body 31 and the connecting pipe 32 have a hollow cavity 36 therein for accommodating a slip hanger to hang the oil layer casing. A flange hole 33 is provided on the upper part of the flange body 31 for connecting a secondary casing head.

[0053] The four sides of the flange body 31 are radially provided with top screw holes 35 , into which the top screws 1 are screwed, and at the outer ends of the top screw holes 35 , there are press cap holes 34 for accommodating the press caps 2 .

[0054] Combination Figure 3-Figure 6 As shown, the above-mentioned slip hanger should be a two-half coupled hanger, specifically including a slip shell 5, a slip seat 11 located at the lower end of the slip shell 5, and a support seat 8 located at the lower end of the slip seat 11. The slip shell 5, the slip seat 11 and the support seat 8 are all composed of two semi-annular structures. Specifically, the support seat 8 and the slip seat 11 are mutually engaged, so that the support seat 8 and the slip seat 11 form an integral body and can move synchronously. A track is set on the upper surface of the slip seat 11, and the slip shell 5 can rotate on the track.

[0055] A first hole 53 is radially provided near the upper portion of the slip housing 5. Two first holes 53 are provided on each slip housing 5. The arc between the two first holes 53 is equal to the arc length corresponding to the 90° angle. A second hole 81 is provided in the middle of each semi-annular structure constituting the support seat 8. Four handles 1 9 can be inserted into the four first holes 53, and two handles 2 10 can be inserted into the two second holes 81. When the slip hanger is not in use, the slip hanger is usually in a Figure 5 Status shown.

[0056] When it is necessary to hang, the two halves of the coupled slip hanger need to be separated first. During operation, the support seat 8 is controlled to be unable to operate circumferentially by the handle 2 10, and the slip shell 5 is rotated 90° by the handle 1 9 to make the slip shell 5 and the support seat 8 axially aligned to form a Figure 6 The state shown in FIG. 1 is then followed by radially separating the two halves of the coupled hanger, and then separating the handle 1 9 and the handle 2 10 from the hanger, thereby forming a state as shown in FIG. Figure 7 The status shown can then be carried out.

[0057] Combination Figure 3-Figure 8 As shown, the above-mentioned cava hanger also includes a cava tooth component 6 and a pressure block. An extrusion chamber 51 is formed in the two half-coupled cava shells 5. There are at least four groups of cava tooth components 6. There are two groups of cava tooth components 6 in one half of the cava shell 5. The four cava tooth components 6 are just distributed in the two half cava shells 5. The cava tooth component 6 includes a cava tooth body 62 located in the extrusion chamber 51.

[0058] Optionally, the Cava tooth component 6 is a W-shaped structure or a V-shaped structure, and the extrusion chamber 51 is also a W-shaped structure or a V-shaped structure, so that when the Cava tooth body 62 is subjected to a downward thrust, it can be displaced downward. When it is displaced downward, the extrusion chamber 51 can gradually squeeze the Cava tooth body 62, so that the Cava tooth body 62 can hold the oil layer casing tightly to achieve sitting and hanging.

[0059] Combination Figure 7-Figure 11 As shown, an integral upper extension 61 is provided on the upper inner edge of the cava tooth body 62, a force-bearing plane 63 is provided on the upper outer edge of the cava tooth body 62, a pressure block is provided on the periphery of the upper extension 61, and the pressure block has a conical surface, the pressure block is limited in the circumferential and radial directions of the flange shell 3, the upper end height of the cava shell 5 is greater than the height of the pressure block, and a first hole 53 is radially opened at the position relative to the cava shell 5 and the pressure block, and after the top screw 1 is screwed into the flange shell 3 and the first hole 53, the conical head 101 provides pressure on the conical surface of the pressure block, so that when the conical surface of the pressure block is subjected to pressure, the pressure block can only move axially in the flange shell 3, so that the force-bearing plane 63 is only subjected to the force generated by the pressure block in the axial direction, so that the entire cava tooth body 62 is only subjected to downward pressure, avoiding the cava tooth body 62 from rotating in the circumferential direction, ensuring that the cava tooth body 62 is evenly distributed on the periphery of the oil layer casing when hanging, and improving the uniformity of force on the oil layer casing.

[0060] Therefore, the special casing head for oil wells provided in the embodiment of the present invention can ensure that the cava tooth body 62 does not produce circumferential rotation when sitting and hanging due to the role of the pressure block, thereby ensuring that the cava tooth body 62 is evenly distributed on the periphery of the oil layer casing, thereby improving the uniformity of force on the oil layer casing.

[0061] Combination Figure 7 , Figure 8 , Figure 10-Figure 14 As shown, specifically, in this embodiment, the pressure block includes an arc-shaped pressure plate 7, and the arc-shaped pressure plate 7 includes an upper ring portion 71 and a limiting rod 72. The upper ring portion 71 is located at the periphery of the upper extension portion 61, and the outer surface of the upper ring portion 71 is set as a conical surface, and the lower surface of the upper ring portion 71 is set as a plane. The plane is in contact with the force plane 63, and the plane protrudes outward from the force plane 63. The limiting rod 72 is arranged on the lower surface of the upper ring portion 71 protruding from the force plane 63, and a plug 73 is provided at the lower end of the limiting rod 72. A plane cut surface 55 is provided at the periphery of the upper end of the extrusion cavity 51, and a guide hole 54 adapted to the plug 73 is opened on the plane cut surface 55. The guide hole 54 cooperates with the plug 73 to limit the upper ring portion 71 in the circumferential and radial directions.

[0062] In the present embodiment, when the top screw 1 is screwed in, the conical head 101 can generate radial and axial thrusts on the conical surface of the upper ring portion 71, and when the conical head 101 is screwed in, the friction between the conical outer surface and the conical surface when rotating will also generate a tangential thrust on the conical surface. However, since the limiting rod 72 and the plug 73 can only produce axial displacement in the axial direction of the guide hole 54, the entire upper ring portion 71 can only produce axial displacement, so that the upper ring portion 71 can only produce axial pressure on the force plane 63 of the cava tooth body 62. This axial pressure will cause the cava tooth body 62 to produce axial displacement. At the same time, due to the extrusion effect of the extrusion chamber 51, the cava tooth body 62 will produce radial displacement, but will not rotate, thereby achieving the purpose of each cava tooth body 62 evenly holding the oil layer casing.

[0063] In addition, a fixed plate 52 is fixed to the upper surface of the flat cut surface 55. Preferably, the fixed plate 52 is fixed to the upper surface of the flat cut surface 55 by countersunk bolts. The fixed plate 52 is provided with a through hole 521 for accommodating the limit rod 72. The diameter of the through hole 521 is smaller than the diameter of the plug 73, so that the plug 73 cannot be pulled out from the through hole 521, thereby realizing the integrated design of the arc pressure plate 7 and the cava shell 5.

[0064] As shown in Figures 13 (a) and 13 (b), in order to further ensure that the cava tooth body 62 cannot rotate, a guide slider 12 is fixedly provided on the lower surface of the pressure block. In this embodiment, the guide slider 12 is fixed to the lower surface of the upper ring portion 71, and a guide groove 64 is provided on the upper surface of the force-bearing plane 63. The guide groove 64 cooperates with the guide slider 12 to allow only radial relative displacement to occur between the cava tooth component 6 and the pressure block.

[0065] In this embodiment, after the conical head 101 applies pressure to the upper ring portion 71, the cooperation between the upper ring portion 71 and the extrusion cavity 51 can cause the upper ring portion 71 to undergo radial and axial displacements, and at this time, the guide groove 64 and the guide slider 12 can produce relative displacements, such as Figure 10-11 status.

[0066] It is worth noting that, in fact, the limit rod 72 and the guide slider 12 are not on the same plane. Fig.10 and Fig.11 The limiting rod 72 and the guide slider 12 are drawn on the same plane only to better reflect the relative position change between the upper ring portion 71 and the slip tooth body 62 .

[0067] The following steps are included in the use: 1) first assemble the flange housing 3 with the blowout preventer, and then install the slip hanger after cementing. However, if the cement return height is greater than 300m, install the slip hanger after the cement is completely solidified 24 hours after cementing. No couplings shall appear one meter above and two meters below the installation position of the slip hanger.

[0068] 2) When installing the slip hanger, first remove the bolts between the BOP group and the flange housing, completely release the hanging weight of the oil layer casing, measure and record the lowering distance of the oil layer casing, then lift up and lock and stabilize the BOP group. Note that the lifting height must be no less than 45 cm, and support three columns or jacks between the flange housing 3 and the BOP group to support and fix the BOP group.

[0069] 3) Clean the top surface of flange housing 3.

[0070] 4) Separate the two halves of the coupled slip hanger and operate Figure 5 In the state shown, the circumferential operation of the support seat 8 is controlled by the handle 2 10, and the slip housing 5 is rotated 90° by the handle 1 9, so that the slip housing 5 and the support seat 8 are axially aligned to form a Figure 6 The state shown, followed by radial separation of the two coupled hanger halves;

[0071] 5) Use two halves of C-shaped plates 16 to support the top surface of flange housing 3, and dock the two halves of the slip hanger on the oil layer casing protruding from the top surface of flange housing 3. When docking, the first hole 53 should be opposite to the top screw hole 35. Use handle 2 10 to control the support seat 8 to not operate circumferentially, and use handle 1 9 to reversely rotate the slip housing 5 90° to stagger the seam between the slip housing 5 and the support seat 8 again, so that the slip hanger hugs the oil layer casing to form a Fig.25 Status shown.

[0072] 6) Disassemble handle 1 9 and handle 2 10, and remove the C-shaped plate 16, so that the slip hanger moves down into the flange housing 3.

[0073] 7) Manually measure and adjust the slip hanger to be concentric with the flange housing 3, and use two C-shaped pressure plates 15 to place on the fixed plate 52 (a certain gap should be reserved between the periphery of the pressure block and the slip housing 5 for placing the C-shaped pressure plates 15, refer to Figure 4The assembly position of the C-shaped pressure plate 15 can be better understood), the three columns or jacks are removed, and the blowout preventer group is gradually moved downward, and the gravity of the blowout preventer group is used to force the slip hanger to descend into place in the flange housing 3, and the anti-blowout group is lifted to the original position, and the three columns or jacks are used again to support the anti-blowout group, and then the two C-shaped pressure plates 15 are removed.

[0074] 8) Screw in each jack screw 1 respectively, so that the jack screw 1 enters the first hole 53, but the jack screw 1 does not contact the slip tooth body 62, so as to prevent the jack screw 1 from locking the slip tooth body 62 and causing the entire slip to be suspended and taken out when the oil layer casing is lifted in the next step.

[0075] 9) Lift up the oil layer casing and keep it in the lifting state. The net pulling force for the oil layer casing is 50-60 tons. During the whole process, since the slip teeth body 62 cannot rotate along the slip shell 5, the gap between the slip teeth body 62 will not change.

[0076] 10) Tighten the four top screws 1 respectively. When the top screws 1 are screwed in, the conical head 101 can generate radial and axial thrusts on the conical surface of the upper ring part 71, and when the conical head 101 is screwed in, the friction between the rotation of the conical outer surface and the conical surface will also generate a tangential thrust on the conical surface. However, since the limit rod 72 and the plug 73 can only produce axial displacement in the axial direction of the guide hole 54, the entire upper ring part 71 can only produce axial displacement, so that the upper ring part 71 can only produce axial pressure on the force plane 63 of the cava tooth body 62. This axial pressure will cause the cava tooth body 62 to produce axial displacement. At the same time, due to the extrusion effect of the extrusion chamber 51, the cava tooth body 62 will produce radial displacement, but will not rotate, and at this time, the guide groove 64 and the guide slider 12 can produce relative displacement, such as Figure 10-11 state, so that each slip tooth body 62 can evenly hold the oil layer casing tightly.

[0077] 11) Release the hanging weight of the oil layer casing to zero, and apply the weight of the casing to the main body 62 of the slip teeth to make it hold the oil layer casing tightly. Note that the sliding distance of the oil layer casing relative to the slip teeth should not be greater than 10mm, otherwise it needs to be re-hung.

[0078] Embodiment 2

[0079] Combination Figure 16-Figure 24 As shown, the difference between this embodiment and the first embodiment is that the pressure block is an arc-shaped annular structure, and the arc-shaped annular structure is located at the periphery of the upper extension portion 61, and the arc-shaped annular structure is a 90° arc, so that the four arc-shaped annular structures can form a complete ring structure, so the four annular structures mutually restrict their respective radial movement, so that the radial positions of the four annular structures can be locked. In addition, the arc-shaped annular structure is also separately provided with a circumferential limiter to limit the circumferential displacement of each arc-shaped annular structure.

[0080] This embodiment provides two arc-shaped ring structures.

[0081] Reference Figure 16-Figure 21 This is the specific content of the first arc-shaped ring structure.

[0082] The arc-shaped annular structure here includes an arc-shaped pressing frame 13, which is a hollow structure composed of an upper side wall 131, an inner side wall 132, a lower side wall 134 and an outer side wall 135. The conical surface is arranged on the upper surface of the lower side wall 134. The above-mentioned circumferential limiter includes: an axial long hole 133 is opened in the middle of the outer side wall 135, and the top screw 1 passes through the first hole 53 and the axial long hole 133 and then presses down the conical surface. The lower side wall 134 cooperates with the top screw 1 to limit the circumferential rotation of the lower side wall 134.

[0083] In this embodiment, four 90° arc pressure frames 13 can form a complete pressure frame and limit the radial movement of each arc pressure frame 13. When the top screw 1 is screwed in, the top screw 1 passes through the axial long hole 133. The top screw 1 itself can limit the rotation of the arc pressure frame 13 through the axial long hole 133, thereby realizing the circumferential positioning of the arc pressure frame 13. Therefore, when the top screw 1 is screwed in, the pressure of the top screw 1 acts on the conical surface of the upper surface of the lower side wall 134, so that the entire arc pressure frame 13 can only be displaced downward. The downward displacement can push the cava tooth body 62 downward to move the cava tooth body 62 downward. Due to the extrusion effect of the extrusion chamber 51, each cava tooth body 62 can be retracted, and due to the guiding effect of the guide groove 64 and the guide slider 12, it can be ensured that the cava tooth body 62 is evenly distributed on the periphery of the oil layer casing, ensuring that the oil layer casing is clamped in a uniform and tight posture.

[0084] The steps of this scheme when in use are basically the same as those of Example 1, with the difference being that in step 10): four top screws 1 are tightened respectively, and the pressure of the top screws 1 acts on the conical surface of the upper surface of the lower side wall 134, so that the entire arc-shaped pressure frame 13 can only be displaced downward, and its downward displacement can push the cava tooth body 62 downward, so that the cava tooth body 62 moves downward, and due to the extrusion effect of the extrusion chamber 51, each cava tooth body 62 can be retracted, and due to the guiding effect of the guide groove 64 and the guide slider 12, it can be ensured that the cava tooth body 62 is evenly distributed on the periphery of the oil layer casing, ensuring that the oil layer casing is clamped in a uniform and tight posture.

[0085] Reference Figure 22-Figure 24 This is the specific content of the second arc-shaped ring structure.

[0086] The arc-shaped annular structure includes an arc-shaped pressure plate 14, which includes a plate body 141. The plate body 141 is located at the periphery of the upper extension portion 61, and a conical surface is arranged on the upper surface of the plate body 141; the circumferential limiting member includes a limiting ridge 142, and two limiting ridges 142 are provided. The top screw 1 is located between the two limiting ridges 142, and the limiting ridge 142 cooperates with the top screw 1 to limit the circumferential rotation of the arc-shaped pressure plate 14.

[0087] In this embodiment, four 90° arc pressure plates 14 can form a complete pressure plate and limit the radial movement of each arc pressure plate 14. When the top screw 1 is screwed in, the top screw 1 enters between the two limiting ridges 142. The two limiting ridges 142 cooperate with the top screw 1 to achieve the circumferential positioning of the arc pressure plate 14. Therefore, when the top screw 1 is screwed in, the pressure of the top screw 1 acts on the conical surface of the upper surface of the plate body 141, so that the entire arc pressure plate 14 can only be displaced downward. The downward displacement can push the cava tooth body 62 downward to move the cava tooth body 62 downward. Due to the extrusion effect of the extrusion chamber 51, each cava tooth body 62 can be retracted, and due to the guiding effect of the guide groove 64 and the guide slider 12, it can be ensured that the cava tooth body 62 is evenly distributed on the periphery of the oil layer casing, ensuring that the oil layer casing is clamped in a uniform and tight posture.

[0088] Preferably, an upper protrusion 143 is provided at the upper end of the second plate body 141, and the upper end of the limiting ridge 142 extends to the height of the upper protrusion 143, so that the height of the limiting ridge 142 is always greater than the height of the top screw 1. Therefore, when the top screw 1 pushes the second plate body 141 downward, due to the downward movement of the second plate body 141, the top screw 1 reaches the height of the second plate body 141 relatively. At this time, the limiting ridge 142 can still cooperate with the top screw 1 to limit the rotation of the second plate body 141.

[0089] The steps of this scheme when in use are basically the same as those of Example 1, except that, in step 10): four top screws 1 are tightened respectively, and when the top screw 1 is screwed in, the top screw 1 enters between the two limiting ridges 142, and the two limiting ridges 142 cooperate with the top screw 1 to realize the circumferential positioning of the arc pressure plate 2 14, so when the top screw 1 is screwed in, the pressure of the top screw 1 acts on the conical surface of the upper surface of the plate body 2 141, so that the entire arc pressure plate 2 14 can only be displaced downward, and its downward displacement can push the cava tooth body 62 downward, so that the cava tooth body 62 moves downward, and due to the extrusion effect of the extrusion chamber 51, each cava tooth body 62 can be retracted, and due to the guiding effect of the guide groove 64 and the guide slider 12, it can be ensured that the cava tooth body 62 is evenly distributed on the periphery of the oil layer casing, ensuring that the oil layer casing is clamped in a uniform and tight posture.

Claims

1. A casing head for oil wells, comprising a flange housing (3), a top screw (1) having a conical head (101), and a slip hanger arranged in the flange housing (3), characterized in that ； Wherein, the slip hanger comprises: A slip housing (5), wherein the slip housing (5) has an extrusion chamber (51); A slip tooth component (6), wherein the slip tooth component (6) is provided with at least four groups, and the slip tooth component (6) comprises a slip tooth body (62) located in the extrusion cavity (51), an upper extension (61) provided at the upper inner edge of the slip tooth body (62), and a force-bearing plane (63) provided at the upper outer edge of the slip tooth body (62): A pressure block, the pressure block being arranged at the periphery of the upper extension portion (61), and having a conical surface, the pressure block being limited in the circumferential direction and radial direction of the flange housing (3), and when the conical surface of the pressure block is subjected to force, the pressure block can only move in the axial direction of the flange housing (3), forming a state in which the force-bearing plane (63) is subjected to only axial force; The upper end height of the slip housing (5) is greater than the height of the pressure block, and a first hole (53) is radially provided at a position of the slip housing (5) opposite to the pressure block; After the top screw (1) is screwed into the flange housing (3) and the first hole (53), the conical head (101) provides pressure to the conical surface of the pressure block.

2. The special casing head for oil wells according to claim 1, characterized in that: The pressure block comprises an arc-shaped pressure plate 1 (7), and the arc-shaped pressure plate 1 (7) comprises: An upper ring portion (71), the upper ring portion (71) being located at the periphery of the upper extension portion (61), the outer surface of the upper ring portion (71) being a conical surface, the lower surface of the upper ring portion (71) being a plane, the plane being in contact with the force-bearing plane (63), and the plane being protruded outwardly from the force-bearing plane (63); A limiting rod (72) is arranged on the lower surface of the upper ring portion (71) protruding from the force-bearing plane (63), and a plug (73) is arranged at the lower end of the limiting rod (72). A plane cut surface (55) is arranged on the outer periphery of the upper end of the extrusion cavity (51), and a guide hole (54) adapted to the plug (73) is opened on the plane cut surface (55), and the guide hole (54) cooperates with the plug (73).

3. The special casing head for oil wells according to claim 2, characterized in that: A fixed plate (52) is fixedly provided on the upper surface of the first planar section (55), and a through hole (521) for accommodating a limiting rod (72) is provided on the fixed plate (52), and the diameter of the through hole (521) is smaller than the diameter of the plug (73).

4. The special casing head for oil wells according to claim 1, characterized in that: The pressure block is an arc-shaped ring structure, and the arc-shaped ring structure is located at the periphery of the upper extension (61), and the arc-shaped ring structure is a 90° arc, and four arc-shaped ring structures form a complete ring structure, and the four ring structures mutually restrict their respective radial movements; The arc-shaped annular structure also has a circumferential limiter, which can limit the circumferential displacement of each arc-shaped annular structure.

5. The special casing head for oil wells according to claim 4, characterized in that: The arc-shaped annular structure comprises an arc-shaped pressing frame (13), wherein the arc-shaped pressing frame (13) is a hollow structure consisting of an upper side wall (131), an inner side wall (132), a lower side wall (134) and an outer side wall (135), wherein the conical surface is arranged on the upper surface of the lower side wall (134): The circumferential limiting member comprises: an axial long hole (133) is opened in the middle of the outer side wall (135), and the top screw (1) passes through the first hole (53) and the axial long hole (133) and then presses down the conical surface of the lower side wall (134).

6. The special casing head for oil wells according to claim 4, characterized in that: The arc-shaped annular structure comprises an arc-shaped pressing plate 2 (14), the arc-shaped pressing plate 2 (14) comprises a plate body 2 (141), the plate body 2 (141) is located at the periphery of the upper extension portion (61), and the conical surface is arranged on the upper surface of the plate body 2 (141); The circumferential limiting member comprises a limiting ridge (142), two limiting ridges (142) are provided, and the top screw (1) is located between the two limiting ridges (142) after passing through the first hole (53).

7. The special casing head for oil wells according to claim 6, characterized in that: An upper convex portion (143) is provided at the upper end of the second plate body (141), and the upper end of the limiting ridge (142) extends to the height of the upper convex portion (143).

8. The casing head for oil wells according to any one of claims 1 to 7, characterized in that: A guide slide block (12) is fixedly provided on the lower surface of the pressure block, and a guide groove (64) is provided on the upper surface of the force-bearing plane (63), wherein the guide groove (64) is arranged in cooperation with the guide slide block (12).

9. The special casing head for oil wells according to claim 8, characterized in that: The slip tooth body (62) is a W-shaped structure or a V-shaped structure.

10. The special casing head for oil wells according to claim 1, characterized in that: The slip shell (5) is composed of two semi-annular structures, a slip seat (11) composed of two semi-annular structures is provided at the lower end of the slip shell (5), and a support seat (8) composed of two semi-annular structures is provided at the lower end of the slip seat (11), and when the connecting seam of the slip shell (5) is aligned with the connecting seam of the slip seat (11), the slip hanger can be in a separated state.

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