Inner insertion pipe type well cementation wellhead sealing device structure

Abstract

The invention relates to gas / oil well mouth sealing equipment, in particular to an inner inserting pipe type well cementation well mouth sealing device structure which comprises a drill rod radish head, a first annular protrusion I, a second annular protrusion II, a sealing ring, a sealing ring, a sealing ring and an inner inserting pipe sealing ring, the outer cylindrical face of the drill rod radish head is provided with a first annular protrusion I, and the lower end face of the first annular protrusion I is a conical slope b; a second annular bulge II is arranged on the inner wall of the upper section part of the sleeve joint, and the upper end surface of the second annular bulge II is a conical inclined surface c; a central hole is formed in the pressing cap; the drill rod radish head seat is placed in the sleeve joint, the conical inclined surface b is adaptively propped against the conical inclined surface c, and a sealing ring is arranged between the conical inclined surface b and the conical inclined surface c; a pressing cap is arranged on the radish head of the drill rod from top to bottom in a sleeving mode, abuts against the conical slope a and is connected with the sleeve joint in a threaded fit mode; cement paste is injected into a well through the drill rod, and the cement paste directly enters a gap between the stratum well wall and the casing pipe from the lower end of the drill rod, so that well cementation is achieved. The sealing device has the beneficial effects that the sealing effect is excellent, and the situation of sealing failure is not prone to occurring; the structure is simple and cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of gas / oil wellhead sealing equipment, in particular to an inner-insertion-tube cementing wellhead sealing device structure. Background Art

[0002] When using casing cementing for deep / ultra-deep wells: 1. Due to the large size and length of the casing, and the large amount of cement slurry injected / replaced during cementing, if less cement slurry is injected, the annular cement return height may not meet the requirements, and if more cement is injected, too much cement slurry may be returned, resulting in waste; 2. In addition, the drilling fluid and cement slurry are seriously mixed during cementing in this type of well, affecting the cementing quality. Therefore, when using casing cementing for this type of deep / ultra-deep wells, the internal pipe cementing method is mostly used (which can solve the problem of injecting less or more cement).

[0003] The so-called internal pipe cementing method refers to inserting the drill pipe into the casing and using a sealing structure to seal the two (refer to the patent publication number CN111878028A for details of the relevant technology).

[0004] At present, the development situation of oil fields at home and abroad is that there are more and more deep wells and ultra-deep wells, which not only puts higher and higher requirements on cementing technology, but also on wellhead cementing tools. Faced with increasingly complex downhole conditions, any influencing factor such as well temperature, pressure, circulation displacement, circulation time, drilling fluid cleanliness, cement slurry cleanliness, etc. may affect the sealing performance of the tool.

[0005] Some conventional cementing methods using internal pipe cementing devices have the risk of poor sealing and failure of floating collars due to the upward force during cementing construction between the inserted sealing seat and the inserted sealing pipe, which can lead to backflow and continuous flow of liquid in the pipe after cementing, thus affecting the quality of cementing and even the life of the entire oil and gas well. Therefore, in the cementing process, tool quality, especially tool sealing, is a prerequisite for the success of cementing.

[0006] Based on this, this solution is specifically designed for cementing of deep wells / ultra-deep wells, and an inner-insert-tube cementing wellhead sealing device structure is designed. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an internal tube cementing wellhead sealing device structure, which solves the problem that the tube seat in the existing internal tube cementing device is prone to sealing failure, resulting in the inability to implement the internal tube cementing process, and the problem that the well cannot be shut down and the pressure cannot be held after the back pressure valve fails.

[0008] It should be noted that: Method 1: In the general plug-in cementing method, the casing is usually inserted into the well, and then cement slurry is injected into the casing. This method is ideal for small-sized casings, but not particularly ideal for large-sized casings. Specifically, 14 Take 3 / 8” casing (inner cannula) as an example. There is a lot of drilling fluid in the casing. When cement slurry is injected, the cement slurry is easily mixed with the drilling fluid, and the mixed cement cannot achieve cementing. Method 2: Therefore, a new method has been adopted in recent years: a cannula seat (sealing seat) is set at the lower end of the casing (cannula) and then the two are lowered into the well together (equivalent to the cannula seat being located in the well), and then the drill pipe is extended into the casing, and the lower end of the drill pipe is extended from the cannula seat (the drill pipe and the cannula seat are sealed, which is equivalent to turning the annulus cavity formed between the drill pipe and the casing into a closed cavity), and cement is directly injected through the drill pipe. The cement is located below the cannula seat, and then the cement enters between the formation well wall and the casing (cement slurry will not enter the annulus cavity between the drill pipe and the casing, so the cement slurry will not mix with the drilling fluid in the annulus cavity).

[0009] However, the problem 1 of the above method 2 is that the sealing of the tube seat is very easy to fail, so that the cement slurry will enter the annular space and bubble out, which makes it impossible to implement the internal tube cementing process, and the back pressure valve fails to shut down the well and hold the pressure for solidification, which will cause cementing failure or cementing accidents. There is no particularly good solution to the current technical problems in the above method 2; the generally adopted measures are: when the seal fails, it is necessary to drill out the tube seat with a drill pipe (the tube seat is made of aluminum material, and it is drilled into powder), and then re-insert the tube seat. It will take a lot of time to drill out the tube seat, and the whole re-construction will prolong the cementing time. In addition, the problem 2 of the above method 2 is that regardless of whether the seal fails, the tube seat needs to be drilled into powder, which will also increase the time of the whole construction.

[0010] Therefore, the present invention designs a sealing structure for inner-insertion pipe cementing to solve the problem of easy failure of the seal.

[0011] The purpose of the present invention is achieved through the following technical solutions: The structure of the inner-insertion-tube cementing wellhead sealing device comprises:

[0012] The drill rod has a first annular protrusion I on its outer cylindrical surface; the first annular protrusion I is a circular ring column, the upper end surface of the circular ring column is a conical inclined surface a, and the lower end surface is a conical inclined surface b;

[0013] The casing joint has a second annular protrusion II on the inner wall of the upper section thereof, and the upper end surface of the second annular protrusion II is a conical inclined surface c;

[0014] A pressure cap having a center hole therein;

[0015] The casing joint is arranged at the wellhead, the drill pipe turnip seat is placed in the casing joint, and the conical bevel b is adapted to abut against the conical bevel c, and a sealing ring is arranged between the conical bevel b and the conical bevel c; the pressure cap is put on the drill pipe turnip from top to bottom, and the pressure cap is abutted against the conical bevel a, and the pressure cap is threadedly connected with the casing joint; when the pressure cap is rotated, the conical surface b presses the sealing ring against the conical surface c to perform sealing;

[0016] The lower end of the casing joint is connected with a casing, and the drill rod head is fixed to the upper end of the drill rod; the drill rod extends into the casing joint and the casing; an annular cavity A is formed between the lower section of the casing joint and the drill rod head, and an annular cavity B is formed between the drill rod and the casing;

[0017] Cement slurry is injected into the well through the drill pipe. Since the drilling fluid in the annular cavity B cannot be discharged and is pressurized, the cement injected from the lower end of the drill pipe will directly enter the gap between the formation well wall and the casing to achieve cementing.

[0018] As a preferred technical solution of the present application, an annular groove A is formed on the conical inclined surface c of the casing joint; the annular groove A is coaxial with the casing joint. A plurality of vertical holes are formed in the circumferential direction on the bottom surface of the annular groove A; a large cavity is provided on the vertical hole near its lower end. A heart-shaped airbag is placed in the large cavity, a jacking assembly is provided in the vertical hole, and an annular pressure assembly is placed on the bottom surface of the annular groove A; the annular pressure assembly is coaxial with the casing joint. When cement is injected into the well, the drilling fluid at the annular cavity A will be pressurized, and the drilling fluid will exert an extrusion force on the heart-shaped airbag through the lower end of the vertical hole, causing the heart-shaped airbag to deform, thereby pushing the jacking assembly upward, and the jacking assembly squeezes the sealing ring through the annular pressure assembly, thereby causing the sealing ring to deform; even if the pressure cap and the casing joint are not tightened particularly tightly to cause the sealing ring to be greatly squeezed, a good seal can be achieved.

[0019] As a preferred technical solution of the present application, the lifting assembly includes a rubber plug head, which is adapted to the vertical hole. The annular pressure assembly includes an annular flat rubber ring, which has an inner cavity, and the inner cavity is filled with a liquid alloy that can solidify at a temperature below 65 degrees Celsius; the liquid alloy in the annular flat rubber ring is placed in the annular groove A when it is in a molten state, and then cooled and solidified to form a rigid part.

[0020] As a preferred technical solution of the present application, a bypass is also provided at the lower section of the sleeve joint, and the bypass is connected to the annular cavity A; bypass pressure relief or liquid injection is performed through the bypass.

[0021] As a preferred technical solution of the present application, the upper end of the sleeve joint is also matched with the outer cylindrical surface of the annular column, and a plurality of first O-type packings are arranged between the two. When leakage occurs at the sealing ring, the first O-type packings can be used for auxiliary sealing.

[0022] As a preferred technical solution of the present application, a handle is provided on the pressing cap, and the pressing cap is driven to rotate by the handle.

[0023] As a preferred technical solution of the present application, when the pressure cap is rotated, the distance between the conical surface b and the conical surface c can be adjusted, thereby realizing the squeezing of the conical surface c on the sealing ring / separation of the conical surface c from the sealing ring, thereby realizing the closure or opening of the wellhead.

[0024] As a preferred technical solution of the present application, the upper section of the casing joint is a small inner diameter section, and the lower section is a large inner diameter section. The lower inner diameter section has a second annular protrusion II on the inner wall at the lower end, and the middle and upper part of the small inner diameter section is adapted to the circular ring column and a first O-type packing is provided between the two. An annular cavity A is formed between the large inner diameter section and the drill rod carrot head, and a bypass is provided on the side wall of the large inner diameter section.

[0025] As a preferred technical solution of the present application, the pressure cap is in the shape of a bottle cap, and the diameter of its center hole is smaller than the diameter of the circular ring column, but greater than or equal to the outer diameter of the upper part of the drill rod carrot head; the outer cylindrical surface of the small inner diameter section of the casing joint is provided with an external thread, and the inner wall of the cap is provided with an internal thread, and the cap is threadedly fitted on the outer cylindrical surface of the small inner diameter section.

[0026] As a preferred technical solution of the present application, a bypass hole is opened on the side wall of the sleeve joint, and the bypass is in the shape of a tube; the bypass thread is screwed into the bypass hole and locked by a nut, and a second O-type packing is also provided between the bypass and the bypass hole.

[0027] 1. For ease of understanding, the installation of this solution at the wellhead is explained:

[0028] A casing is lowered into the well, and a casing joint is connected to the upper end of the casing, and the casing joint is located at the wellhead; the drill pipe carrot head is fixedly threaded on the upper end of the drill pipe, and then the drill pipe is lowered into the casing joint and the casing. As the drill pipe is lowered, the drill pipe carrot head is finally placed in the casing joint; then the pressure cap is buckled on the casing joint, and the pressure cap is twisted to make the pressure cap cooperate with the casing joint thread (this method can not only limit the upper top of the drill pipe, but also squeeze the sealing ring to achieve sealing).

[0029] 2. For ease of understanding, the working process and principle of this solution are explained:

[0030] During the internal pipe cementing operation, the drill pipe and the casing are sealed at the wellhead. When cement slurry is injected into the well through the drill pipe, the cement slurry is discharged from the lower end of the drill pipe. Since the drill pipe and the casing are sealed at the wellhead through the casing joint and the drill pipe head, the upper end of the annular cavity B between the drill pipe and the casing is blocked. Even if cement is injected at the lower end of the annular cavity B, the cement will not enter the annular cavity B and mix with the drilling fluid (there is drilling fluid in the annular cavity B. When cement is injected into the lower end of the annular cavity B, the injected cement will only squeeze the drilling fluid in the annular cavity B, causing the annular cavity B to be pressurized). The injected cement will directly enter the gap between the formation well wall and the casing, thereby achieving cementing.

[0031] According to the pressure in the well, the drilling fluid pressure in the annular chamber B is appropriately adjusted through the bypass;

[0032] During the cementing process, the cone surface b presses the sealing ring onto the cone surface c by relying on the weight of the drill pipe and the drill pipe head to achieve sealing; when cement slurry is injected into the drill pipe, the drill pipe will be subjected to an upward reaction force. Since the casing joint and the casing position remain basically unchanged (vibrating up and down invisible to the naked eye), the drill pipe is limited by the pressure cap (to prevent the drill pipe from moving upward);

[0033] If the pressure in the well is too high, the sealing ring may fail to seal. However, since the pressure cap is directly connected to the casing joint thread - the sealing structure formed by the drill pipe thread and the casing joint will never separate. Even if the sealing ring fails to seal, the resulting failure gap is extremely small (the failure gap is at most equivalent to the size of the sealing ring). Therefore, it still has a certain sealing effect (it will not cause a large amount of cement slurry to directly rush out from the seal). It can be said that no matter how high the pressure in the well is, a good seal can be achieved.

[0034] The present invention has the following advantages:

[0035] (1) Excellent sealing effect, and sealing failure is not likely to occur;

[0036] In the internal insertion cementing device and method used in recent years, a pipe inserting seat is set at the lower end of the casing, the pipe inserting seat and the casing are lowered into the well together, and then the drill pipe is inserted into the casing, and the lower end of the drill pipe is extended from the pipe inserting seat (so that a seal is formed between the drill pipe and the pipe inserting seat), and then cement is injected through the drill pipe; however, the seal between the pipe inserting seat and the drill pipe is easy to fail; once the seal fails, cement slurry will spray out from the annular cavity between the drill pipe and the casing, and cementing cannot be performed; it takes a long time to restore to the cementing state (and it also takes a long time during normal cementing);

[0037] In this scheme, since a casing joint is arranged at the upper end of the casing, the casing joint is located at the wellhead, and then the drill pipe head is fixed at the upper end of the drill pipe, when the drill pipe is extended into the casing, the drill pipe head will be seated in the casing joint, and then the casing joint is connected with a pressure cap, so that the drill pipe head is locked between the pressure cap and the casing joint; and, when sealing, the sealing is achieved by relying on the conical surface b of the drill pipe head and the conical inclined surface c of the casing joint; then the effects are: a. Even if the pressure in the well is high and the sealing fails, since the drill pipe head is locked between the pressure cap and the casing joint (the drill pipe head and the casing joint will not be separated), Then the failure gap caused by the seal failure is at most the size of the seal ring, and a good sealing effect is still maintained (a large amount of cement slurry will not flow out directly from the seal, and cementing work can still be continued to a certain extent); b. In addition, since this solution is set at the wellhead, even if the seal is not good, it can be replaced in time, and the normal inner tube cementing process can be quickly restored, saving time; c. Compared with the traditional inner tube cementing process, this cementing structure and cementing process of this solution do not need to drill the tube seat into powder with a drill bit during normal operation without seal failure, which can save time and improve cementing efficiency;

[0038] (2) Simple structure and low cost;

[0039] The solution has a simple structure, low production cost, and can be well matched with some existing sealing devices. Through field tests, the sealing is very reliable and the back pressure valve is well closed during the trial process of the entire construction site. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of the present invention;

[0041] Figure 2 for Figure 1 AA enlarged image in;

[0042] Figure 3 It is a structural schematic diagram of a casing joint;

[0043] Figure 4 for Figure 3 BB enlarged image in;

[0044] Figure 5 It is a schematic diagram of the structure arranged between the heart-shaped airbag, the lifting assembly, the annular pressure assembly, and the sealing ring;

[0045] Figure 6 It is a schematic diagram of the structure between the annular pressure component and the sealing ring;

[0046] In the figure: 1, drill pipe carrot head; 2, pressure cap; 3, first O-ring; 4, handle; 5, sealing ring; 6, second O-ring; 7, nut; 8, bypass; 9, casing joint; 1001, annular groove A; 1002, annular groove B; 1003-vertical hole, 1004, large cavity; 1005, vertical rod; 1006, rubber plug; 1007-heart-shaped airbag; 1008, resin annular ring; 1009-annular flat rubber ring; 10010, flexible rubber ring. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0048] It should be noted that the directions or positional relationships indicated by "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use, or are the directions or positional relationships commonly understood by those skilled in the art. Such terms are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0049] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0050] (Example 1)

[0051] like Figure 1 As shown, the structure of the internal plug-in cementing wellhead sealing device includes a drill pipe radish head 1, a casing joint 9, and a pressure cap 2. The casing joint 9 is installed at the upper end of the casing, and the casing joint 9 and the casing are inserted into the well together, and the casing joint 9 is located at the wellhead. The drill pipe radish head 1 is sleeved on the end of the drill pipe and fixed, and then the drill pipe is gradually inserted into the casing joint 9 and the casing, and finally the drill pipe radish head 1 is placed on the casing joint 9.

[0052] The outer cylindrical surface of the drill rod radish head 1 is provided with a first annular protrusion I, which is a circular column, and the upper end surface of the circular column is a conical inclined surface a, and the lower end surface is a conical inclined surface b. In addition, a second annular protrusion II is provided on the inner wall of the upper section of the casing joint 9, and the upper end surface of the second annular protrusion II is a conical inclined surface c. In addition, there is also a pressure cap 2, and a center hole is opened on the pressure cap 2.

[0053] When the drill pipe radish head 1, the casing joint 9, and the pressure cap 2 are installed in coordination: an annular groove A1001 is opened on the conical surface c, and a sealing ring 5 is placed in the annular groove A1001. When the drill pipe radish head 1 is placed in the casing joint 9, the conical surface b is against the conical surface c, and the sealing ring 5 is squeezed to achieve sealing; the pressure cap 2 is put on the drill pipe radish head 1 from top to bottom, so that the pressure cap 2 is against the conical inclined surface a, and then the pressure cap 2 is rotated so that the pressure cap 2 is connected with the casing joint 9 expert thread (when the pressure cap 2 is rotated, the conical surface b can also press the sealing ring 5 on the conical surface c). When the installation is completed, an annular cavity A is formed between the lower section of the casing joint 9 and the drill pipe radish head 1, and an annular cavity B is formed between the drill pipe and the casing.

[0054] During cementing work, cement slurry is injected into the well through the drill pipe. Since the drilling fluid in the annular cavity B cannot be discharged and is pressurized, the cement injected from the lower end of the drill pipe will directly enter the gap between the formation well wall and the casing to achieve cementing.

[0055] It should be noted that no matter how great the pressure in the well is, even if the sealing ring 5 fails to seal, due to the effect of the pressure cap 2, the drill pipe connector 1 and the casing joint 9 will not separate, and still have a certain sealing effect (will not cause a large amount of cement slurry to directly flow out from the seal).

[0056] In addition, it should be noted that when the pressure cap 2 is rotated, the distance between the conical surface b and the conical surface c can be adjusted, so that the conical surface c can squeeze the sealing ring 5 / separate the conical surface c from the sealing ring 5, thereby achieving the closure or opening of the wellhead.

[0057] See also Figure 1 In an advantageous embodiment, a bypass 8 is provided at the lower section of the casing joint 9, and the bypass 8 is connected to the annular cavity A; the bypass 8 is connected to the casing joint 9 and the cementing high-pressure pipeline. If there is any abnormality after construction, the pressure can be released, and mud can also be injected through the annular space of the bypass 8 to reduce cement in the pipe and reduce cementing risks.

[0058] See also Figure 1 In an advantageous embodiment, a plurality of additional annular grooves C are provided on the outer cylindrical surface of the annular column, and corresponding first O-type packings 3 are sleeved in these annular grooves C. When the drill pipe radish head 1 is placed in the casing joint 9, the inner wall of the upper end of the casing joint 9 is adapted to the outer cylindrical surface of the annular column, and sealing is achieved through the first O-type packing 3. If the sealing of the sealing ring 5 is not particularly tight, and leakage occurs, the first O-type packing 3 can still be used for auxiliary sealing.

[0059] See also Figure 1 In order to facilitate the rotation of the pressing cap 2, a handle 4 is provided on the outer wall of the pressing cap 2.

[0060] In this embodiment, the casing joint 9 is further optimized. Specifically, the upper section of the casing joint 9 is a small inner diameter section, and the lower section is a large inner diameter section. The lower inner diameter section has a second annular protrusion II on the inner wall at the lower end, and the middle and upper part of the small inner diameter section is adapted to the circular ring column and a first O-type packing 3 is provided between the two. An annular cavity A is formed between the large inner diameter section and the drill pipe carrot head 1, and a bypass 8 is provided on the side wall of the large inner diameter section.

[0061] Furthermore, for the casing joint 9, 35CrMo material is forged and machined, which is a common material for oil and gas field tools. Its main purpose is to achieve mutual sealing between the casing and the drill pipe connector 1.

[0062] In this embodiment, the drill rod radish head 1 is further optimized. The two ends of the drill rod radish head 1 use standard drill rod thread buckles, and the strength reaches P110 steel grade. The outer part is respectively designed with a limit slope surface and a sealing packing groove assembled with the casing joint 9. The structural design is stable and reliable. The drill rod radish head is made of 35CrMo steel, and its yield strength exceeds 830MPa after quenching and tempering.

[0063] In this embodiment, the pressure cap 2 is further optimized. The pressure cap 2 is in the shape of a bottle cap, and the diameter of the center hole is smaller than the diameter of the annular column, but greater than or equal to the outer diameter of the upper part of the drill rod carrot head 1; the outer cylindrical surface of the small inner diameter section of the casing joint 9 is provided with an outer thread, and the inner wall of the cap 2 is provided with an inner thread, and the cap 2 is threadedly fitted on the outer cylindrical surface of the small inner diameter section.

[0064] In this embodiment, the bypass 8 is further optimally designed. Specifically, a bypass hole is opened on the side wall of the sleeve joint 9, and the bypass 8 is in a tubular shape; the bypass 8 is screwed into the bypass hole and locked by a nut 7, and a second O-type packing 6 is also provided between the bypass 8 and the bypass hole.

[0065] It should be noted that: 1. When assembling the product, check the matching clearance between the matching surfaces separately, such as the internal sealing surface inspection of the casing joint, the sealing surface inspection of the drill pipe radish head, the matching inspection of the bypass and the casing joint, and the connection inspection of the drill pipe radish head, the casing joint and the pressure cap, and perform air-fitting operations to ensure that the clearance matching meets the design requirements; 2. In order to effectively improve the assembly efficiency and safe and quick on-site use, the design and use of convenient and safe auxiliary installation tools is also an important part of product research and development. Because the casing joint is large and bulky, it is not convenient to connect with the casing at the wellhead. It is necessary to drill holes and process threads on the shell to connect it with the connecting rod for easy lifting; 3. At room temperature, connect the pressure test plugs on both sides of the assembled finished product, and perform the overall sealing test and the test of overcoming the upper force respectively. Pressurize the pipe to 15Mpa, stabilize the pressure for 15min, and the pressure drop is ≤0.5MPa.

[0066] (Example 2)

[0067] It should be noted that, in the design of Example 1, when the drilling fluid pressure at the annular cavity A is not large, the sealing function of the sealing ring 5 is completely determined by the tightness of the threaded locking between the pressure cap 2 and the casing joint 9. If a good sealing effect is to be ensured at this time, the pressure cap 2 and the casing joint 9 need to be tightened. If they are tightened too tightly, the sealing ring 5 will be deformed during use, resulting in sealing failure (if there is a large pressure in the drilling fluid, the casing joint 9 is pushed upward by the drilling fluid, thereby squeezing and deforming the sealing ring 5).

[0068] To this end, Example 2 is based on the embodiment, and further optimizes the design. Figure 2-Figure 6 .

[0069] See also Figure 3 and Figure 4 An annular groove A1001 is formed on the conical surface c of the sleeve joint 9; an annular groove B1002 is formed on the bottom surface of the annular groove A1001, and the annular groove A1001 and the annular groove B1002 are coaxial with the sleeve joint 9; in addition, at least three vertical holes 1003 are formed in the circumferential direction on the bottom surface of the annular groove B1002; a large cavity 1004 is formed on the vertical hole 1003 near its lower end;

[0070] Also, see Figure 2 A heart-shaped air bag 1007 is placed in the large cavity 1004, a jacking assembly is arranged in the vertical hole 1003, and an annular pressure assembly is placed at the bottom surface of the annular groove A1001, and the annular pressure assembly is coaxial with the sleeve joint 9;

[0071] During operation, when cement is injected into the well, the drilling fluid in the annular cavity A will be pressurized, and the drilling fluid will generate an extrusion force on the heart-shaped airbag 1007 through the lower end of the vertical hole 1003, causing the heart-shaped airbag 1007 to deform, thereby pushing the jacking component upward, and the jacking component will squeeze the sealing ring 5 through the annular pressure component, thereby causing the sealing ring 5 to deform;

[0072] In this way, it can be achieved that: during the installation, there is no need to greatly tighten the pressure cap 2 and the casing joint 9 to cause the sealing ring 5 to be squeezed. When the pressure of the drilling fluid is not large, the heart-shaped airbag 1007 is deformed by squeezing the drilling fluid, so that the annular pressure-applying component squeezes and deforms the sealing ring 5 through the deformation of the heart-shaped airbag 1007. In this way, the deformation degree of the sealing ring 5 can be adaptively adjusted according to the pressure of the drilling fluid, and the sealing ring 5 does not need to be in a state of large squeezing all the time, so that it is not easy to fail during the sealing process.

[0073] See also Figure 2 and Figure 5 , the heart-shaped airbag 1007 is described.

[0074] It should be noted that the size of the heart-shaped airbag 1007 in the figure is only for illustration and does not meet the actual size standard (similarly, the sizes of the corresponding annular groove A1001, annular groove B1002, and vertical hole 1003 can also be adjusted as needed), so that the edge of the heart-shaped airbag 1007 can provide sufficient upward lifting force.

[0075] The heart-shaped airbag 1007 is heart-shaped, and has an upward depression at the bottom, and a gas nozzle at the depression. When the heart-shaped airbag 1007 is placed in the large cavity 1004, the internal gas is first released, then squeezed into the large cavity 1004, and then the gas is flushed through the gas nozzle.

[0076] It should be noted that the heart-shaped airbag 1007 can be sealed with the large cavity 1004. The principle is that when the bottom surface of the heart-shaped airbag 1007 is squeezed, its side wall and the large cavity 1004 are more closely attached, and only the top of the heart-shaped airbag 1007 bulges upward and deforms, and when the top bulges and deforms, it generates an upward force on the lifting component.

[0077] See also Figure 2 , Figure 4 and Figure 5 , further explanation is given to the lifting assembly and the annular pressure assembly.

[0078] The jacking assembly includes a vertical rod 1005, on which a plurality of rubber plugs 1006 are provided, and the rubber plugs 1006 are adapted to the vertical holes 1003. When the jacking assembly moves up and down in the vertical holes 1003, the rubber plugs 1006 act like pistons, further preventing the drilling fluid from flowing into the annular groove A1001 through the vertical holes 1003.

[0079] The annular pressure component includes a resin annular ring 1008, an annular flat rubber ring 1009, and a flexible rubber ring 10010, and all three are coaxial with the sleeve joint 9; the resin annular ring 1008 has a certain hardness and can be squeezed, deformed and restored, the annular flat rubber ring 1009 has an inner cavity, and the inner cavity is filled with a liquid alloy that can solidify below 65 degrees Celsius, and the upper surface of the flexible rubber ring 10010 is adapted to the bottom surface of the sealing ring 5 and is a flexible material; the resin annular ring 1008 is squeezed and deformed and placed in the annular groove A1001, and then the deformation is restored to provide certain support for the subsequent annular flat rubber ring 1009; then the liquid alloy is allowed to be in a molten state through high temperature, and the annular flat rubber ring 1009 is placed on the resin annular ring 1008 at this time, and then the annular flat rubber ring 1009 is cooled and formed into a rigid part; and then the flexible rubber ring 10010 is placed on the annular flat rubber ring 1009.

[0080] It should be noted that the sleeve joint 9 in this solution is a casting.

[0081] The above embodiments only express preferred implementation modes, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. The structure of the inner tube cementing wellhead sealing device is characterized by: include: The drill rod carrot head (1) has a first annular protrusion I on its outer cylindrical surface; The first annular protrusion I is a circular column, the upper end surface of the circular column is a conical inclined surface a, and the lower end surface is a conical inclined surface b; The sleeve joint (9) has a second annular protrusion II on the inner wall of its upper section, and the upper end surface of the second annular protrusion II is a conical inclined surface c; A pressure cap (2) having a central hole; The casing joint (9) is arranged at the wellhead, the drill pipe radish head (1) is seated in the casing joint (9), and the conical bevel surface b is adapted to abut against the conical bevel surface c, and a sealing ring (5) is arranged between the conical bevel surface b and the conical bevel surface c; the pressure cap (2) is put on the drill pipe radish head (1) from top to bottom, and the pressure cap (2) is abutted against the conical bevel surface a, and the pressure cap (2) is threadedly connected to the casing joint (9); when the pressure cap (2) is rotated, the conical surface b presses the sealing ring (5) against the conical surface c to perform sealing; The lower end of the casing joint (9) is connected to a casing, and the drill rod radish head (1) is fixed to the upper end of the drill rod; the drill rod extends into the casing joint (9) and the casing; an annular cavity A is formed between the lower section of the casing joint (9) and the drill rod radish head (1), and an annular cavity B is formed between the drill rod and the casing; Cement slurry is injected into the well through the drill pipe. Since the drilling fluid in the annular cavity B cannot be discharged and is pressurized, the cement injected from the lower end of the drill pipe will directly enter the gap between the formation well wall and the casing to achieve cementing.

2. The inner-insertion-tube cementing wellhead sealing device structure according to claim 1 is characterized in that: An annular groove A (1001) is formed on the conical inclined surface c of the sleeve joint (9); the annular groove A (1001) is coaxial with the sleeve joint (9); A plurality of vertical holes (1003) are circumferentially formed on the bottom surface of the annular groove A (1001); a large cavity (1004) is formed on the vertical hole (1003) near its lower end; A heart-shaped air bag (1007) is placed in the large cavity (1004), a lifting assembly is arranged in the vertical hole (1003), and an annular pressure assembly is placed on the bottom surface of the annular groove A (1001); the annular pressure assembly is coaxial with the sleeve joint (9); When cement is injected into the well, the drilling fluid in the annular cavity A will be pressurized, and the drilling fluid will generate an extrusion force on the heart-shaped airbag (1007) through the lower end of the vertical hole (1003), causing the heart-shaped airbag (1007) to deform, thereby pushing the lifting component upward, and the lifting component squeezes the sealing ring (5) through the annular pressure component, thereby causing the sealing ring (5) to deform; even if the pressure cap (2) and the casing joint (9) are not tightened particularly tightly to allow the sealing ring (5) to be greatly squeezed, a good seal can be achieved.

3. The inner-insertion-tube cementing wellhead sealing device structure according to claim 2 is characterized in that: The lifting assembly comprises a rubber plug (1006), and the rubber plug (1006) is adapted to the vertical hole (1003); The annular pressure-applying assembly comprises an annular flat rubber ring (1009), wherein the annular flat rubber ring (1009) has an inner cavity, and the inner cavity is filled with a liquid alloy that can solidify at a temperature below 65 degrees Celsius; the liquid alloy in the annular flat rubber ring (1009) is placed in an annular groove A (1001) when it is in a molten state, and then cooled and solidified to form a rigid part.

4. The inner-insertion-tube cementing wellhead sealing device structure according to claim 1 or 2, characterized in that: A bypass (8) is also provided at the lower section of the sleeve joint (9), and the bypass (8) is communicated with the annular cavity A; bypass pressure relief or liquid injection is performed through the bypass (8).

5. The inner-insertion-tube cementing wellhead sealing device structure according to claim 1 or 2, characterized in that: The upper end of the sleeve joint (9) is also adapted to fit the outer cylindrical surface of the annular column, and a plurality of first O-type packings (3) are arranged between the two. When leakage occurs at the sealing ring (5), auxiliary sealing can be performed through the first O-type packing (3).

6. The inner-insertion-tube cementing wellhead sealing device structure according to claim 1 or 2, characterized in that: The pressing cap (2) is provided with a handle (4), and the pressing cap (2) is driven to rotate by the handle (4).

7. The inner-insertion-tube cementing wellhead sealing device structure according to claim 1 or 2, characterized in that: When the pressure cap (2) is rotated, the distance between the conical surface b and the conical surface c can be adjusted, so that the conical surface c can squeeze the sealing ring (5) / separate the conical surface c from the sealing ring (5), thereby achieving the closure or opening of the wellhead.

8. The inner-insertion-tube cementing wellhead sealing device structure according to any one of claims 1 to 3, characterized in that: The upper section of the sleeve joint (9) is a section with a small inner diameter, and the lower section is a section with a large inner diameter; The lower inner diameter section has a second annular protrusion II on the inner wall at the lower end, and the middle and upper part of the small inner diameter section is adapted to the circular column and a first O-type packing (3) is arranged between the two. An annular cavity A is formed between the large inner diameter section and the drill rod turnip head (1), and a bypass (8) is provided on the side wall of the large inner diameter section.

9. The inner-insertion-tube cementing wellhead sealing device structure according to claim 8 is characterized in that: The pressing cap (2) is in the shape of a bottle cap, and the diameter of the central hole thereof is smaller than the diameter of the circular column, but greater than or equal to the outer diameter of the upper part of the drill rod carrot head (1); The outer cylindrical surface of the small inner diameter section of the sleeve joint (9) is provided with an external thread, and the inner wall of the cap (2) is provided with an internal thread, and the cap (2) is sleeved on the outer cylindrical surface of the small inner diameter section to be thread-matched.

10. The inner-insertion-tube cementing wellhead sealing device structure according to claim 9 is characterized in that: A bypass hole is provided on the side wall of the sleeve joint (9), and the bypass (8) is in the shape of a tube; the bypass (8) is screwed into the bypass hole and is locked by a nut (7), and a second O-type packing (6) is provided between the bypass (8) and the bypass hole.

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