Radially expandable pressure test plug, wellhead pressure testing device and wellhead pressure testing method

Abstract

The application provides a radial expansion type pressure test plug, which comprises a plug body, the plug body comprising an arbor and a disc-shaped seat fixedly connected to the lower end of the arbor, the outer diameter of the disc-shaped seat being larger than the outer diameter of the arbor; an elastic body sleeved on the arbor; an annular pressing block sleeved on the arbor, the elastic body being located between the disc-shaped seat and the annular pressing block in the axial direction; and a reset element, one end of the reset element being fixedly connected to the elastic body and the other end extending upward through the annular pressing block; wherein the annular pressing block can exert axial pressure on the elastic body to make the elastic body radially expand until the elastic body is in contact with the inner cavity of a casing head in a wellhead mechanism and forms a seal, so that the wellhead mechanism can be subjected to pressure test, and the elastic body can be axially stretched by lifting the reset element to make the elastic body radially shrink and reset. The application also provides a wellhead pressure test device and a wellhead pressure test method.

Description

Technical Field

[0001] This invention belongs to the field of wellhead pressure testing technology for oil and gas wells, specifically relating to a radial expansion type pressure testing plug, a wellhead pressure testing device, and a wellhead pressure testing method. Background Technology

[0002] During drilling operations, before each drilling operation, it is necessary to pressure test the wellhead components, such as the blowout preventer (BOP) assembly, to ensure that the well can be shut in in case of abnormal situations such as encountering gas formations. Currently, BOP pressure testing generally uses the method of running a plug. After the plug is inserted into the inlet through the drill pipe and placed inside the casing head, the pressure test is carried out after a seal is achieved.

[0003] With the increase in ultra-deep wells, the use of large-size and non-standard casing is gradually increasing, leading to higher requirements for blowout preventer (BOP) models and specifications. For example, some common wellhead installations use the FZ35-70 BOP assembly. This FZ35-70 assembly has an inner diameter of Ф346.1mm, while its casing head inner diameter is Ф420mm. When a Ф365.1mm casing is installed, the wellhead mechanism's diameter is "smaller at the top and larger at the bottom." Due to the limitation of the BOP's inner diameter, the plug can only be installed with a maximum diameter of Ф346.1mm. Its outer diameter is smaller than the casing head's inner diameter, making it impossible to form a seal and failing to meet pressure testing requirements. In such cases, a segmented pressure testing method is generally adopted on-site. The entire BOP assembly is lifted, the pressure testing plug is installed, and then the BOP is reinstalled. Pressure testing is then performed on the components above the casing head. After the pressure test is completed, the wellhead mechanism is disassembled, and the plug is removed. This method is not only complicated to operate, but it also cannot pressure test the connection between the blowout preventer and the casing head, and the integrity of the wellbore cannot be guaranteed. In particular, it cannot meet the pressure testing requirements for high-pressure oil and gas wells with high well control risks. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a radial expansion pressure testing plug, which can perform pressure testing on wellhead devices with different borehole diameter combinations without replacing the wellhead. It is simple to operate, safe and reliable, and has a wide range of applications.

[0005] Therefore, according to a first aspect of the present invention, a radially expanding pressure testing plug is provided, comprising: a plug body, the plug body including a mandrel and a disc-shaped seat fixedly connected to the lower end of the mandrel, the outer diameter of the disc-shaped seat being larger than the outer diameter of the mandrel; an elastic body sleeved on the mandrel; an annular pressure block sleeved on the mandrel, the elastic body being located axially between the disc-shaped seat and the annular pressure block; and a reset element, one end of the reset element being fixedly connected to the elastic body, and the other end extending upward through the annular pressure block; wherein the annular pressure block is capable of applying axial pressure to the elastic body to cause the elastic body to expand radially until it contacts the inner cavity of the casing head in the wellhead mechanism and forms a seal, thereby enabling pressure testing of the wellhead mechanism; by lifting the reset element, the elastic body can be axially stretched to cause the elastic body to contract radially and reset.

[0006] In one embodiment, the upper end of the mandrel is configured as a male threaded connector.

[0007] In one embodiment, the reset element is configured to include a hollow tube and an annular plate fixedly connected to the lower end of the hollow tube.

[0008] The annular plate is fixedly connected to the upper end of the elastomer, the hollow tube is sleeved on the mandrel, and the upper end of the hollow tube extends upward through the annular space between the annular pressure block and the mandrel.

[0009] In one embodiment, the upper end of the hollow tube is configured as a conical connecting buckle.

[0010] In one embodiment, the elastomer is a corrugated metal tube.

[0011] According to a second aspect of the present invention, a wellhead pressure testing apparatus is provided, comprising:

[0012] The radial expansion type pressure test plug as described above;

[0013] A double female connector is used to connect the drill pipe and the mandrel to lower the radial expansion pressure test plug into the casing head in the wellhead mechanism;

[0014] A pressure cylinder, used to connect the drill pipe and apply axial pressure to the elastomer to cause the elastomer to expand radially; and

[0015] A scooping tube is used to connect the drill rod and the reset element, and to lift the elastic element to reset it.

[0016] In one embodiment, the lower end of the double female connector is configured as a first female connector that can be adapted to the male connector at the upper end of the mandrel, and the upper end of the double female connector is configured as a second female connector that can be adapted to the drill pipe.

[0017] In one embodiment, the pressure cylinder is configured to include a first cylindrical body and a third female connector disposed at the upper end of the first cylindrical body.

[0018] The inner diameter of the first cylindrical body is larger than the outer diameter of the mandrel, and the first cylindrical body can apply axial force to the annular pressure block. The third female threaded connector is used for fitting and connecting with the drill pipe.

[0019] In one embodiment, the retrieval cylinder is configured to include a second cylindrical body and a fourth female connector disposed at the upper end of the second cylindrical body. The lower end of the second cylindrical body is configured as a negative conical connector. The inner diameter of the second cylindrical body is larger than the outer diameter of the mandrel, and the second cylindrical body can be adapted to connect with the positive conical connector at the upper end of the reset element through the negative conical connector. The fourth female connector is used to adapt to connect with the drill pipe.

[0020] According to a third aspect of the present invention, a wellhead pressure testing method is provided, comprising the following steps:

[0021] Provide wellhead pressure testing equipment as described above;

[0022] The radial expansion pressure test plug is connected to the lower end of the drill pipe through the double female connector, and the radial expansion pressure test plug is placed into the inside of the casing head of the wellhead mechanism;

[0023] Disconnect the double female connector from the radial expansion pressure test plug, and remove the drill pipe and the double female connector;

[0024] The pressure cylinder is connected to the drill pipe and lowered into the wellhead to press on the annular pressure block. The pressure cylinder is pressurized to axially compress the elastic body, causing the elastic body to expand radially to contact the inner cavity of the casing head and form a seal.

[0025] The drill rod is lifted to remove the pressure cylinder for pressure testing.

[0026] The retrieval cylinder is connected to the drill pipe and lowered into the wellhead until the retrieval cylinder and the reset element are fitted together. Lifting the drill pipe can drive the reset element to axially stretch the elastic body, so that the elastic body is reset and the radial expansion pressure test plug is removed.

[0027] Compared with the prior art, the advantages of this application are:

[0028] The radially expanding pressure-testing plug according to the present invention can achieve radial expansion under compression to meet the sealing requirements during pressure testing. By changing the size and degree of compression of the elastomer, the radial expansion degree of the elastomer can be controlled, achieving sealing for different inner diameters and expanding the application range of the expanding pressure-testing plug. Compared with the traditional packer-based pressure testing method, the elastomer can recover its original size after axial stretching, ensuring the safe removal of the expanding pressure-testing plug and solving the problem of some packers being unable to be released. In addition, the expanding pressure-testing plug can solve the pressure testing problem of well control devices with different diameter combinations without disassembling the wellhead equipment, ensuring wellbore integrity, and is characterized by simple operation and high reliability. Attached Figure Description

[0029] The present invention will now be described with reference to the accompanying drawings.

[0030] Figure 1 The structure of the radial expansion pressure test plug according to the present invention is schematically shown.

[0031] Figure 2 The diagram schematically illustrates the pressure expansion state of a radial expansion test plug.

[0032] Figure 3 The diagram schematically illustrates the tension reset state of the radial expansion test plug.

[0033] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0034] The present invention will now be described with reference to the accompanying drawings. It should be noted that these descriptions are provided merely to illustrate the principles of the invention and do not limit the scope of the invention.

[0035] For ease of understanding, the directional terms or qualifiers used in this application, such as "up" and "down," are all specific to the referenced appendix. Figure 1 The references to this invention are merely for the purpose of facilitating description and simplification, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0036] Figure 1 The structure of the radial expansion type pressure test plug 10 according to the present invention is schematically shown. Figure 1As shown, the radial expansion pressure-testing plug 10 includes a plug body 1, an elastic body 2, an annular pressure block 3, and a reset element 4. The plug body 1 includes a spindle 11 and a disc-shaped seat 12 fixedly connected to the lower end of the spindle 11. The outer diameter of the disc-shaped seat 12 is larger than the outer diameter of the spindle 11, thus forming a limiting step 121 on the upper end surface of the disc-shaped seat 12. The elastic body 2 is sleeved on the spindle 11 and rests on the limiting step 121. The annular pressure block 3 is sleeved on the spindle 11, and the elastic body 2 is located axially between the disc-shaped seat 12 and the annular pressure block 3. One end of the reset element 4 is fixedly connected to the upper end surface of the elastic body 2, and the other end extends upward through the annular space between the annular pressure block 3 and the spindle 11. The annular pressure block 3 applies axial pressure to the elastic body 2, causing the annular pressure block 3 and the limiting step 121 to jointly generate an axial force on the elastic body 2, thereby axially compressing the elastic body 2. This causes the elastic body 2 to expand radially until it contacts the inner cavity (not shown) of the casing head in the wellhead mechanism and forms a seal, thus enabling pressure testing of the wellhead mechanism. Simultaneously, after the pressure test, the elastic body 2 can be axially stretched by lifting the reset element 4, causing the elastic body 2 to radially contract and reset.

[0037] In one embodiment, such as Figure 1 As shown, the upper end of the mandrel 11 is configured as a male threaded connector 111 for connecting the drill pipe (not shown).

[0038] According to one embodiment of the present invention, the reset element 4 is configured to include a hollow tube 41 and an annular plate 42 fixedly connected to the lower end of the hollow tube 41. The lower end face of the annular plate 42 is fixedly connected to the upper end face of the elastic body 2. The inner diameter of the hollow tube 41 is larger than the outer diameter of the mandrel 11, and the inner and outer diameters of the hollow tube 41 are smaller than the central hole of the annular pressure block 3. The hollow tube 41 is sleeved on the mandrel 11, and the upper end of the hollow tube 41 extends upward through the annular space between the annular pressure block 3 and the surface of the mandrel 11.

[0039] In one embodiment, the upper end of the hollow tube 41 is configured as a conical connecting buckle 411 for adapting to and connecting other components, such as the scooping cylinder 7 (see...). Figure 3 ).

[0040] As an alternative or addition, the annular pressure block 3 and the reset element 4 can be constructed as a single unit.

[0041] According to one embodiment of the present invention, the elastomer 2 is made of a corrugated metal tube. The corrugated metal tube has good elasticity and sealing performance, which is very beneficial to realizing radial expansion and contraction reset, and can effectively ensure the working performance of the radial expansion type pressure test plug 10.

[0042] According to the present invention, a wellhead pressure testing device is also provided, comprising a radial expansion pressure testing plug 10, a double female connector 5, a pressure cylinder 6, and a retrieval cylinder 7 as described above. The double female connector 5, the pressure cylinder 6, and the retrieval cylinder 7 can be connected to a drill pipe (not shown) to perform corresponding actions. The double female connector 5 is used to connect the drill pipe and the mandrel 11 to lower the radial expansion pressure testing plug 10 into the casing head of the wellhead mechanism. The pressure cylinder 6 is used to connect the drill pipe and apply axial pressure to the elastic body 2 to cause the elastic body 2 to expand radially. The retrieval cylinder 7 is used to connect the drill pipe and the reset element 4 to lift the elastic body 2 and reset it.

[0043] like Figure 1 As shown, the lower end of the double female connector 5 is configured as a first female connector 51 that can be adapted to the male connector 111 at the upper end of the mandrel 11, and the upper end of the double female connector 5 is configured as a second female connector 52 that can be adapted to the drill pipe. During operation, the radial expansion pressure test plug 10 is fixedly connected to the lower end of the drill pipe through the double female connector 5, and then the radial expansion pressure test plug 10 can be lowered into the wellhead until it reaches the inner cavity of the casing head in the wellhead mechanism. Furthermore, by rotating the drill pipe, the male connector 111 at the upper end of the mandrel 11 of the double female connector 5 can be disengaged, and the drill pipe can be lifted out of the wellhead, thereby leaving the radial expansion pressure test plug 10 in the inner cavity of the casing head.

[0044] like Figure 2 As shown, the pressure cylinder 6 is constructed including a first cylindrical body 61 and a third female connector 62 disposed at the upper end of the first cylindrical body 61. The inner diameter of the first cylindrical body 61 is larger than the outer diameter of the mandrel 11, and the first cylindrical body 61 can apply axial force to the annular pressure block 3. The third female connector 62 is used for fitting and connecting with the drill pipe. The inner diameter of the first cylindrical body 61 is larger than the outer diameter of the central tube 41 of the reset element 4. During operation, the pressure cylinder 6 is connected to the lower end of the drill pipe through the third female connector 62, and then the pressure cylinder 6 can be lowered into the wellhead through the drill pipe, and the pressure cylinder 6 is fitted around the outer periphery of the mandrel 2 and the central tube 41 of the reset element 4, so that the lower end face of the pressure cylinder 6 abuts against the upper end face of the annular pressure block 3. Pressing down the pressure cylinder 6 can apply axial pressure to the annular pressure block 3 to axially compress the elastic body 2, thereby causing the elastic body 2 to expand radially.

[0045] like Figure 3As shown, the retrieval cylinder 7 is constructed including a second cylindrical body 71 and a fourth female connector 72 disposed at the upper end of the second cylindrical body 71. The lower end of the second cylindrical body 71 is constructed as a negative conical connector 73. The inner diameter of the second cylindrical body 71 is larger than the outer diameter of the mandrel 11, and the second cylindrical body 71 can be adapted to connect with the positive conical connector 411 at the upper end of the reset element 4 through the negative conical connector 73. The fourth female connector 72 is used to adapt to connect with the drill pipe. During operation, the retrieval cylinder 7 is connected to the lower end of the drill pipe through the fourth female connector 72, and then the retrieval cylinder 7 is lowered into the wellhead through the drill pipe, so that the retrieval cylinder 7 is fitted around the outer circumference of the mandrel 2, and then the second cylindrical body 71 is adapted to connect with the positive conical connector 411 at the upper end of the reset element 4 through the negative conical connector 73. Then, lifting the drill pipe can axially stretch the elastic body 2 through the reset element 4, so that the elastic body 2 can achieve radial contraction and reset.

[0046] The present invention also provides a wellhead pressure testing method, which includes the following steps.

[0047] First, a wellhead pressure testing device according to the present invention is provided, and the outer diameter of the plug body 1 of the radial expansion type pressure testing plug 10 is set according to the blowout preventer diameter and the inner diameter of the casing head in the wellhead mechanism.

[0048] Next, the radial expansion pressure test plug 10 is connected to the lower end of the drill pipe via the double female connector 5, and the radial expansion pressure test plug 10 is placed inside the casing head of the wellhead mechanism. Then, the double female connector 5 is disengaged from the radial expansion pressure test plug 10 by rotating the drill pipe, and the drill pipe and double female connector 5 are then pulled out of the wellhead.

[0049] Next, the double female connector 5 is removed, the pressure cylinder 6 is connected to the drill pipe, and lowered into the wellhead until the pressure cylinder 6 presses on the annular pressure block 3. Then, pressure is applied to the pressure cylinder 6 so that the annular pressure block 3 axially compresses the elastic body 2, thereby causing the elastic body 2 to expand radially until it contacts the inner cavity of the casing head to form a seal.

[0050] Next, the drill pipe is lifted to raise the pressure cylinder 6 for pressure testing. After the pressure test is completed, the pressure cylinder 6 is removed.

[0051] Next, connect the retrieval cylinder 7 to the drill pipe and lower it into the wellhead until the negative conical connecting buckle 73 at the lower end of the retrieval cylinder 7 is properly engaged with the positive conical connecting buckle 411 at the upper end of the reset element 4. Then, lift the drill pipe to axially stretch the elastic body 2, causing the radial dimension of the elastic body 2 to shrink until it is reset. The elastic body 2 separates from the inner cavity of the casing head. Continue lifting the drill pipe to retrieve the radial expansion type pressure test plug 10. Thus, the pressure test operation is completed, and normal construction resumes.

[0052] The radially expanding pressure-testing plug 10 according to the present invention can achieve radial expansion under compression to meet the sealing requirements during pressure testing. By changing the size and degree of compression of the elastomer 2, the radial expansion degree of the elastomer 2 can be controlled, achieving sealing for different inner diameters and expanding the application range of the expanding pressure-testing plug 10. Compared with the traditional packer-based pressure testing method, the elastomer 2 can recover its original size after axial stretching, ensuring the safe removal of the expanding pressure-testing plug 10 and solving the problem of some packers being unable to be unsealed. In addition, the expanding pressure-testing plug 10 can solve the pressure testing problem of well control devices with different diameter combinations without disassembling the wellhead equipment, ensuring wellbore integrity and featuring simple operation and high reliability.

[0053] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0054] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] Furthermore, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wellhead pressure testing method, using a wellhead pressure testing device, the wellhead pressure testing device comprising a radial expansion pressure testing plug, the radial expansion pressure testing plug comprising: The plug body (1) includes a spindle (11) and a disc seat (12) fixedly connected to the lower end of the spindle. The outer diameter of the disc seat is larger than the outer diameter of the spindle. An elastic body (2) fitted onto the mandrel; An annular pressure block (3) is sleeved on the mandrel, and the elastic body is located between the disc-shaped seat and the annular pressure block in the axial direction; as well as Reset element (4), one end of which is fixedly connected to the elastic body, and the other end extends upward through the annular pressure block; Specifically, pressing the annular pressure block down through the pressure cylinder from the wellhead can apply axial pressure to the elastomer, causing the elastomer to expand radially until it contacts the inner cavity of the casing head in the wellhead mechanism and forms a seal. Then, the pressure cylinder is removed, thereby enabling the wellhead mechanism to be pressure tested. By lifting the reset element, the elastomer can be axially stretched, causing the elastomer to contract radially and reset. The wellhead pressure testing device also includes: Double female connector (5) is used to connect the drill pipe and the mandrel to lower the radial expansion pressure test plug into the casing head in the wellhead mechanism; Pressure cylinder (6), used to connect the drill pipe and apply axial pressure to the elastomer to cause the elastomer to expand radially; and The scooping tube (7) is used to connect the drill rod and the reset element, and to lift the elastic element to reset the elastic element; Wellhead pressure testing methods include the following steps: The radial expansion pressure test plug is connected to the lower end of the drill pipe through the double female connector, and the radial expansion pressure test plug is placed into the inside of the casing head of the wellhead mechanism; Disconnect the double female connector from the radial expansion pressure test plug, and remove the drill pipe and the double female connector; The pressure cylinder is connected to the drill pipe and lowered into the wellhead to press on the annular pressure block. The pressure cylinder is pressurized to axially compress the elastic body, causing the elastic body to expand radially to contact the inner cavity of the casing head and form a seal. The drill rod is lifted to remove the pressure cylinder for pressure testing. The retrieval cylinder is connected to the drill pipe and lowered into the wellhead until the retrieval cylinder and the reset element are fitted together. Lifting the drill pipe can drive the reset element to axially stretch the elastic body, so that the elastic body is reset and the radial expansion pressure test plug is removed.

2. The wellhead pressure testing method according to claim 1, characterized in that, The upper end of the mandrel is configured as a male threaded connector (111).

3. The wellhead pressure testing method according to claim 1 or 2, characterized in that, The reset element is configured to include a hollow tube (41) and an annular plate (42) fixedly connected to the lower end of the hollow tube. The annular plate is fixedly connected to the upper end of the elastomer, the hollow tube is sleeved on the mandrel, and the upper end of the hollow tube extends upward through the annular space between the annular pressure block and the mandrel.

4. The wellhead pressure testing method according to claim 3, characterized in that, The upper end of the hollow tube is constructed as a conical connecting buckle (411).

5. The wellhead pressure testing method according to claim 1, characterized in that, The elastomer is made of corrugated metal tubing.

6. The wellhead pressure testing method according to claim 1, characterized in that, The lower end of the double female connector is configured to be a first female connector (51) that can be adapted to the male connector at the upper end of the mandrel, and the upper end of the double female connector is configured to be a second female connector (52) that can be adapted to the drill pipe.

7. The wellhead pressure testing method according to claim 1, characterized in that, The pressure cylinder is configured to include a first cylindrical body (61) and a third female connector (62) disposed at the upper end of the first cylindrical body. The inner diameter of the first cylindrical body is larger than the outer diameter of the mandrel, and the first cylindrical body can apply axial force to the annular pressure block. The third female threaded connector is used for fitting and connecting with the drill pipe.

8. The wellhead pressure testing method according to claim 1, characterized in that, The scooping tube is configured to include a second cylindrical body (71) and a fourth female buckle connector (72) disposed at the upper end of the second cylindrical body, and the lower end of the second cylindrical body is configured as a negative cone-shaped connecting buckle (73). The inner diameter of the second cylindrical body is larger than the outer diameter of the mandrel, and the second cylindrical body can be adapted to the positive conical connecting buckle at the upper end of the reset element through the negative conical connecting buckle. The fourth female connector is used to adapt to the drill pipe.

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