Wellbore protection methods and apparatuses

Abstract

This invention relates to the field of oil and gas exploration and development technology, and discloses a wellbore protection method and device. The wellbore protection device is installed in the wellbore. The method includes, during the installation of the well casing hanger, causing the well casing hanger to press downwards and break the wellbore protection device into multiple fragments, which then fall below the wellhead. This invention enables the wellbore protection device to remain within the subsea wellhead body and subsea production tree body during the installation of casing strings and blind pipe screens, thus protecting the wellbore sealing surface.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and specifically to a wellbore protection method and wellbore protection device. Background Technology

[0002] Subsea wellheads and subsea production trees are key equipment for developing subsea oil and gas fields. They connect oil pipelines to underground producing formations and control the underground oil and gas production channels through components such as sealing modules, valves, and plugs. Subsea equipment is stored long-term on the seabed far from the surface, and its installation and retrieval require specialized vessels, equipment, and technicians, resulting in high installation and maintenance costs. Even slight wear on its sealing structure can lead to serious oil and gas leaks and environmental pollution, damaging the ecological environment and energy security.

[0003] The subsea wellhead body and subsea production tree body, as the main sealing and pressure-bearing components of the subsea wellhead and production tree, have a large area of ​​sealing surface on their inner surface. These surfaces, along with the sealing module, seal the annular channels to prevent oil and gas leakage. During drilling and completion, the rotation and downward movement of the drill bit, drill pipe, and casing can scratch and wear down the sealing surfaces of the subsea wellhead body and subsea production tree body, causing unreliable or failed seals. In existing technology, wellbore protection devices are installed inside the subsea wellhead body and subsea production tree body, serving as crucial devices for isolating the drill bit and drill pipe and protecting the sealing surfaces.

[0004] Because the wellbore protection device occupies the installation area of ​​the casing hanger and sealing module in the subsea wellhead and subsea production tree, the wellbore protection device needs to be retrieved before installing the casing hanger and sealing module. This results in the inner sealing surface of the subsea wellhead body and subsea production tree body being exposed during the installation of the casing string and blind screen. The rotation and downward movement of the casing string and blind screen will scratch and wear the sealing surface of the subsea wellhead body and subsea production tree body. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that the rotation and downward movement of casing strings and blind screens can scratch and wear the sealing surfaces of the subsea wellhead body and the subsea production tree body in the existing technology. This invention provides a wellbore protection method and device. The technical solution of this invention can remain in the subsea wellhead body and the subsea production tree body during the installation of casing strings and blind screens, thus protecting the wellbore sealing surfaces.

[0006] To achieve the above objectives, the present invention provides a wellbore protection method, wherein a wellbore protection device is installed in the wellbore. The method includes, when installing an oil well pipe hanger, causing the oil well pipe hanger to squeeze the wellbore protection device downward and break it into multiple fragments, and causing the multiple fragments to fall below the wellhead.

[0007] Another aspect of the present invention provides a well casing protection device, characterized in that the well casing protection device includes a thin-walled annular cylinder, and a cracking groove is formed on the wall surface of the thin-walled annular cylinder, the cracking groove being able to be squeezed and torn to break the thin-walled annular cylinder into multiple fragments.

[0008] In some embodiments, the thin-walled annular cylinder is made of a non-metallic material.

[0009] In some embodiments, the rupture groove extends from the top end to the bottom end of the thin-walled annular cylinder.

[0010] In some embodiments, the rupture grooves are parallel to the central axis of the thin-walled annular cylinder and are provided in multiples, with the multiple rupture grooves being distributed at equal intervals along the circumference of the thin-walled annular cylinder.

[0011] In some embodiments, the inner wall surface of the thin-walled annular cylinder is provided with a loading and unloading groove that cooperates with the loading and unloading tool.

[0012] In some embodiments, a plurality of loading and unloading slots are provided, and the plurality of loading and unloading slots are distributed at equal intervals along the circumference of the thin-walled annular cylinder.

[0013] In some embodiments, the loading and unloading groove is formed on the upper part of the inner wall surface of the thin-walled annular cylinder, and its orthographic projection shape on the wall surface of the thin-walled annular cylinder is J-shaped.

[0014] In some embodiments, the upper end of the inner wall surface of the thin-walled annular cylinder is formed with an outwardly inclined guide surface.

[0015] In some embodiments, a limiting inclined surface is formed at the bottom end of the outer wall of the thin-walled annular cylinder, and the limiting inclined surface cooperates with the inner wall of the well to position the thin-walled annular cylinder in the well; the diameter of the bearing inclined surface gradually decreases from top to bottom.

[0016] By adopting the above technical solution, the wellbore protection device of the present invention, compared with the prior art method of retrieving the wellbore protection device before installing the casing hanger and sealing module, can remain in the subsea wellhead body and subsea production tree body during the installation of casing string and blind pipe screen, protecting the wellbore sealing surface; after the wellbore protection device breaks, the wellbore protection device falls to the area below the lower wellhead body and subsea production tree body, saving the time of loading and unloading the wellbore protection device on the drill pipe under the platform. Attached Figure Description

[0017] Figure 1 This is a structural schematic diagram of a wellbore protection device used to illustrate specific embodiments of the present invention;

[0018] Figure 2 yes Figure 1Assembly diagram of the wellbore protection device at the high-pressure wellhead.

[0019] Explanation of reference numerals in the attached figures

[0020] 101 Guide surface; 102 Loading and unloading groove; 103 Rupture groove; 104 Limiting slope. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used to describe the relative positions of components in relation to the directions shown in the accompanying drawings or in relation to the vertical, perpendicular, or gravitational directions; "inner" and "outer" generally refer to the interior or exterior of the cavity relative to the chamber or the radial interior or exterior relative to the center of the circle.

[0023] Referring to the background art, wellbore protection devices (also known as core repair devices) are installed in subsea wellheads and subsea production trees, occupying the installation area of ​​casing hangers and sealing modules. Before installing casing hangers and sealing modules, the wellbore protection device needs to be retrieved. This results in the inner sealing surfaces of the subsea wellhead and subsea production tree being exposed during the installation of casing strings and blind pipe screens. The rotation and downward movement of the casing strings and blind pipe screens can scratch and wear down the sealing surfaces of the subsea wellhead and subsea production tree. Therefore, this invention provides a wellbore protection method. This method includes, during the installation of the casing hanger, using the casing hanger to crush the wellbore protection device downwards into multiple fragments, which then fall below the wellhead. In this way, during the installation of casing strings and blind pipe screens, the wellbore protection device remains within the subsea wellhead and subsea production tree, protecting the wellbore's sealing surfaces.

[0024] Based on the foregoing disclosure, the present invention provides another aspect of a wellbore protection device, which includes a thin-walled annular cylinder with a rupture groove 103 formed on the wall surface of the thin-walled annular cylinder. This groove is used to reduce the amount of external force required for the repair core to rupture, and at the same time, to cause the repair core to rupture at the location of the rupture groove. When the repair core is deformed by the external force applied by the well pipe hanger, the rupture groove 103 can be squeezed and torn to break the thin-walled annular cylinder into multiple fragments, which fall below the wellhead.

[0025] In some embodiments of the present invention, the thin-walled annular cylinder is made of non-metallic material. Using non-metallic materials results in lower strength and hardness. The high-pressure wellhead is made of metallic material. When the core is extruded, it breaks into several pieces. The broken core is pushed down below the high-pressure wellhead by a tool and falls into the casing without damaging the high-pressure wellhead during its descent. Furthermore, the low density of non-metallic materials results in a lightweight wellbore protection device, which can be pre-installed on land inside the wellhead body and subsea production tree, saving time spent installing the wellbore protection device on the drill pipe below the platform.

[0026] In some embodiments of the present invention, the rupture groove 103 extends from the top end to the bottom end of the thin-walled annular cylinder. The orientation of the rupture groove 103 on the wall surface of the thin-walled annular cylinder can be designed according to actual needs so that the core can be split into a predetermined shape. It is understood that multiple cuts penetrating the wall surface of the thin-walled annular cylinder can be made in the rupture groove, and the multiple cuts are spaced apart along the extension direction of the rupture groove to facilitate rupture when the rupture groove is subjected to force.

[0027] To minimize the size of the fragments formed when the wellbore protection device breaks, in some embodiments of the present invention, such as... Figure 1 As shown, the rupture grooves 103 are parallel to the central axis of the thin-walled annular cylinder and are arranged in multiples, with the multiple rupture grooves 103 being evenly distributed along the circumference of the thin-walled annular cylinder.

[0028] To facilitate the loading and unloading of the core, in some embodiments of the present invention, the inner wall surface of the thin-walled annular cylinder is provided with a loading and unloading groove 102 that cooperates with the loading and unloading tool.

[0029] To facilitate uniform force application, in some embodiments of the present invention, multiple loading and unloading slots 102 are provided, and the multiple loading and unloading slots 102 are distributed at equal intervals along the circumference of the thin-walled annular cylinder.

[0030] In some embodiments of the present invention, the loading / unloading groove 102 is formed on the upper part of the inner wall surface of the thin-walled annular cylinder, and its orthographic projection on the wall surface of the thin-walled annular cylinder is J-shaped. Prior art loading / unloading tools are provided with a protrusion that mates with the J-shaped loading / unloading groove on the inner surface of the core. Thus, the wellbore protection device can be installed and retrieved using the same loading / unloading tools as conventional wellbore protection devices.

[0031] In some embodiments of the present invention, an outwardly inclined guide surface 101 is formed at the upper end of the inner wall surface of the thin-walled annular cylinder. The guide surface 101 is used to guide the drill bit, drill string, centralizer and other components passing through the interior of the core, reducing the downward pressure and upward pulling force on the core during the passage of the drill string through the core, so as to avoid premature damage to the core or pushing the core upward to cause the core to leave the designed position.

[0032] In some embodiments of the present invention, a limiting inclined surface 104 is formed at the bottom end of the outer wall of the thin-walled annular cylinder. The limiting inclined surface 104 cooperates with the inner wall of the wellbore to hold the thin-walled annular cylinder in the wellbore. The diameter of the bearing inclined surface 104 gradually decreases from top to bottom. Under the action of downward extrusion force, when the thin-walled annular cylinder breaks into multiple pieces, the limiting inclined surface 104 can no longer provide support. The wellbore protection device falls to the area below the subsea wellhead body and the subsea production tree body, freeing up the installation area of ​​the casing hanger and sealing module.

[0033] The wellbore protection device of the present invention can be installed at the subsea wellhead and subsea production tree in two ways: land-based installation and underwater installation, as detailed below:

[0034] 1. Land-based wellbore protection devices include:

[0035] Land-based installation of underwater wellhead and shaft protection devices

[0036] With the submersible wellhead horizontal, remove the outer protective cover of the wellhead, check the wear of its inner sealing surface, lift the well casing protection device, insert it into the submersible wellhead, and push it into place.

[0037] Land-based installation of subsea wellbore protection devices

[0038] The subsea production tree is hoisted onto the inspection pile, the hoisting tools for the subsea wellhead production tree are removed, the wear of its inner sealing surface is checked, the wellbore protection device is lifted, vertically placed into the subsea production tree, and pressed into place.

[0039] In this way, the device can be pre-installed on land at the underwater wellhead and inside the underwater production tree, saving time spent installing wellbore protection devices on the drill pipe below the platform.

[0040] 2. The underwater installation of well shaft protection devices is as follows:

[0041] Install wellbore protection devices on drilling rig

[0042] After completing the installation of the subsea wellhead and subsea production tree, the wellbore protection device is placed vertically on the drilling platform. The loading and unloading tool is hoisted and moved above the wellbore protection device. By rotating the wellbore protection device, the loading and unloading slot of the wellbore protection device is connected to the protrusion of the loading and unloading tool, suspending the wellbore protection device onto the loading and unloading tool. The drill pipe is then connected to deliver the wellbore protection device into the subsea wellhead and subsea production tree. The drill pipe is rotated in the opposite direction to allow the protrusion of the loading and unloading tool to slide out of the loading and unloading slot of the wellbore protection device, thus separating the wellbore protection device from the loading and unloading tool.

[0043] 3. After installing the wellbore protection device at the subsea wellhead and subsea Christmas tree, perform the following operations:

[0044] Install sleeve string

[0045] Connect the casing string to the casing hanger, and then lock the casing string into the tool. Connect the drill pipe and send it above the casing hanger. Press down on the casing hanger until the wellbore protection device locks it in place.

[0046] Continue lowering the casing hanger until it crushes and breaks the wellbore protection device, causing it to fall below the underwater wellhead. Continue lowering the casing hanger until the bearing eaves at the bottom of the high-pressure wellhead catch it. By raising and lowering the casing hanger, the suspended weight on the drilling platform changes. Use the tidal rope to verify the installation depth of the casing hanger and confirm that it is installed correctly.

[0047] Install blind tube string

[0048] Connect the screen blind tubing string, connect the tubing hanger to the screen blind tubing string, and insert the screen blind tubing string into the tool and lock it in place. Connect the drill pipe to the top of the tubing hanger. Press down on the tubing hanger until the wellbore protection device locks it in place.

[0049] Continue lowering the tubing hanger until it squeezes and deforms the wellbore protection device, causing it to fall to the subsea wellhead. Continue lowering the tubing hanger until the high-pressure wellhead bottom bearing eaves catch it. By raising and lowering the tubing hanger, the suspended weight value on the drilling rig changes. Use the tidal rope to verify the installation depth of the blind pipe separator, confirming that the tubing hanger is installed correctly.

[0050] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A wellbore protection method, wherein a wellbore protection device is installed in the wellbore, characterized in that, The method involves, during the installation of the well pipe hanger, causing the well pipe hanger to press down and break the wellbore protection device into multiple fragments, which then fall below the wellhead.

2. A wellbore protection device, characterized in that, The well casing protection device includes a thin-walled annular cylinder with a rupture groove (103) formed on its wall surface. The rupture groove (103) can be squeezed and torn to break the thin-walled annular cylinder into multiple fragments.

3. The wellbore protection device according to claim 2, characterized in that, The thin-walled annular cylinder is made of non-metallic materials.

4. The wellbore protection device according to claim 2, characterized in that, The rupture groove (103) extends from the top end to the bottom end of the thin-walled annular cylinder.

5. The wellbore protection device according to claim 2 or 4, characterized in that, The rupture grooves (103) are parallel to the central axis of the thin-walled annular cylinder and are provided in multiples, with the multiple rupture grooves (103) being evenly distributed along the circumference of the thin-walled annular cylinder.

6. The wellbore protection device according to claim 2, characterized in that, The inner wall of the thin-walled annular cylinder is provided with a loading and unloading groove (102) that cooperates with the loading and unloading tools.

7. The wellbore protection device according to claim 6, characterized in that, The loading and unloading slots (102) are provided in multiple ways, and the multiple loading and unloading slots (102) are distributed at equal intervals along the circumference of the thin-walled annular cylinder.

8. The wellbore protection device according to claim 7, characterized in that, The loading and unloading groove (102) is located on the upper part of the inner wall of the thin-walled annular cylinder, and its orthographic projection on the wall of the thin-walled annular cylinder is J-shaped.

9. The wellbore protection device according to claim 2, characterized in that, The upper end of the inner wall of the thin-walled annular cylinder has an outwardly inclined guide surface (101).

10. The wellbore protection device according to claim 2, characterized in that, The bottom end of the outer wall of the thin-walled annular cylinder is formed with a limiting inclined surface (104), which cooperates with the inner wall of the well to position the thin-walled annular cylinder in the well; the diameter of the limiting inclined surface (104) gradually decreases from top to bottom.

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