Drilling equipment for in-situ seabed exploitation of natural gas hydrates

Abstract

Drilling equipment for in-situ seabed exploitation of natural gas hydrates, the drilling equipment comprising a drilling module. The drilling module comprises a frame (1), wherein a door-shaped guide rail (2) and a manipulator (3) are mounted in the frame (1), a lower hydraulic tong (4) is mounted at the bottom of the frame (1), an upper hydraulic tong (5) is coaxially arranged above the lower hydraulic tong (4), and a coaxial section between the upper hydraulic tong (5) and the lower hydraulic tong (4) is a drill string placement position; the upper hydraulic tong (5) is mounted in a top drive (6), and the top drive (6) is fitted in the door-shaped guide rail (2), so as to vertically move in the direction of height of the door-shaped guide rail (2); and a pipe rack (8) is provided within the rotation range of the manipulator (3), the pipe rack (8) is configured to store and place drill strings (100), and the manipulator (3) is configured to grab a drill string and place same between the upper hydraulic tong (5) and the lower hydraulic tong (4). The drilling equipment can be transferred from an offshore platform to the seabed, thereby significantly increasing the drilling speed and reducing the exploitation cost.

Description

A drilling equipment for in-situ mining of natural gas hydrate on the seabed Technical field:

[0001] The present invention relates to natural gas hydrate mining equipment, in particular to natural gas hydrate seabed in-situ mining drilling equipment. Background technology:

[0002] So far, there is no mature in-situ mining technology and equipment for submarine natural gas hydrates in the world. A few companies, such as Germany's Bauer, Britain's BGS, and the United States' Williamson & Associates, have carried out research and development of submarine drilling sampling equipment. In my country, only Hunan University of Science and Technology has carried out research and development of submarine drilling sampling equipment. Internationally, submarine drilling sampling equipment is classified into the first generation submarine drilling rig, the second generation submarine drilling rig, the third generation submarine drilling rig, and the fourth generation submarine drilling rig.

[0003] (1) After the 1950s, submarine drilling rigs with the main characteristics of shallow water (water depth within 500m), shallow drilling (drilling depth within 10m), single function and low intelligence are classified as the first generation of submarine drilling rigs;

[0004] (2) After the 1990s, with the development and integration of drilling, electromechanical, measurement and control, communication, sensor and other technologies, submarine drilling rigs have made a qualitative leap in water depth, drilling depth, intelligence and other aspects. The water depth has reached 6000m; the drilling depth has been extended to 50m; in terms of energy supply, battery type, electric drive type and electro-hydraulic combination type have become the preferred options for most submarine drilling rigs in the world; in terms of communication, communication bus (connecting computer information systems, or information transmission lines between computers and other systems), optical fiber and acoustic communication methods have been adopted; visualization, attitude indicators, thrusters, leveling legs and other monitoring and control devices have been added, resulting in the second generation of submarine drilling rigs with deep sea, shallow drilling and intelligence as the main features;

[0005] (3) Since 2007, in order to improve the depth, efficiency and quality of seabed drilling coring, developed countries have upgraded and modified seabed drilling rigs with rope coring technology. Since rope coring does not require lifting the drill, it only needs to use a rope salvage device to circulate and salvage the core sample at the bottom. Therefore, no casing is required during operation, the quality of the coring sample is improved, the working time is significantly reduced, and the work efficiency is significantly improved. The application of rope coring technology makes it possible to conduct cable-type in-situ testing in the well. It is a common practice to use a rope salvage device to lower a self-contained in-situ tester to the bottom of the hole for testing. A more advanced method is to directly use an independent small underwater winch and a load-bearing cable to lower and recover the in-situ tester. The former is a storage and forwarding method, while the latter can achieve real-time display and recording. In addition, in order to obtain more drilling formation information, simple logging instruments while drilling, wellhead test and analysis instruments, and sample pressure treatment are also used. The technical upgrades and modifications during this period have formed the third generation of seabed drilling rigs with medium-deep drilling, rope coring, multi-functional testing and intelligent control as the main features. While third-generation subsea drilling rigs operate at depths comparable to second-generation rigs, they have already reached 125 meters and are expected to exceed 200 meters in the coming years. Prominent examples of third-generation subsea drilling rigs include Australia's PROD, Germany's MeBo, the United States' A-BMS, ACS, and ROVDrill, and Canada's CRD100.

[0006] Fourth-generation subsea drilling rigs are characterized by high investment, large size and weight, and deep drilling capabilities, reaching depths of 600 meters. Due to the rig's massive size, modular design is fully utilized. Each module can be loaded and transported on land using standard containers. Once lowered to the seabed, it can be assembled, replaced, and maintained entirely by an ROV. To enable fully automated drilling operations on the seabed, the rig also incorporates a customized set of automated operation software and an expert system for handling underwater faults, ensuring efficient and reliable operation. This fourth-generation subsea drilling rig is still in the design phase.

[0007] It can be seen that these current seabed drilling and sampling devices have seabed sampling as the primary goal and cannot be directly applied to the well construction process in the development of seabed natural gas hydrates. They cannot form stable wellbores and cannot carry out subsequent development technical links.

[0008] Summary of the invention:

[0009] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a natural gas hydrate seabed in-situ mining drilling equipment to realize the transfer of drilling equipment from the sea surface platform to the seabed, greatly speeding up the drilling speed and reducing the mining cost.

[0010] To achieve the above object, the technical solution of the present invention is:

[0011] A drilling device for in-situ extraction of natural gas hydrates from the seabed comprises a drilling module, the drilling module comprising a frame, a portal guide rail and a manipulator being installed in the frame, a lower hydraulic clamp being installed at the bottom of the frame, an upper hydraulic clamp being provided coaxially above the lower hydraulic clamp, and a coaxial section between the upper and lower hydraulic clamps being a drill string placement position; the upper hydraulic clamp being installed in a top drive, and the top drive being assembled in the portal guide rail so as to move up and down in a height direction of the portal guide rail; a pipe rack being provided within the rotation range of the manipulator, the pipe rack being used for storing and placing drill strings, and the manipulator being used for grabbing the drill strings between the upper and lower hydraulic clamps.

[0012] Furthermore, the pipe rack is a disc-type pipe rack; the manipulator rotates between the drill string placement position and the disc-type pipe rack to reciprocate back and forth to complete the transfer and discharge of the drill string.

[0013] Furthermore, when the drill string with the drill bit is transferred to the drill string placement position by the manipulator, the upper hydraulic clamp is clamped, the lower hydraulic clamp is opened, the top drive moves downward, the lower hydraulic clamp is clamped, the upper hydraulic clamp is opened, the top drive moves downward and the buckle is rotated, and the lower hydraulic clamp is opened to complete the drilling of the first drill string.

[0014] Furthermore, after the drilling of the first drill string is completed, the lower hydraulic clamp is clamped, the top drive is unfastened, and the top drive moves upward. After the subsequent drill string is transferred to the drill string placement position by the manipulator, the upper hydraulic clamp is clamped, the top drive moves downward, the top drive moves downward, the connecting buckle at the wellhead is rotated, the upper hydraulic clamp is opened, the top drive moves downward, the buckle is rotated, and the lower hydraulic clamp is opened to complete the drilling of the continuous drill string.

[0015] Furthermore, the drill string adopts casing drilling, and the casing drilling downhole drill string assembly is composed of a drill bit with a diameter smaller than the inner diameter of the casing and an expander that can pass through the inner diameter of the casing and expand the wellbore to the size of the casing.

[0016] Furthermore, the two sides of the door-shaped guide rail in the height direction are racks; the top drive includes a lifting motor and a rotary motor; the lifting motor is installed in the rack to achieve up and down movement; the rotary motor is connected to the upper hydraulic clamp and installed to drive the drill string to rotate.

[0017] Furthermore, supporting legs are installed on the four sides of the bottom of the frame, and the four supporting legs are driven by independent hydraulic motors to extend outwards.

[0018] Furthermore, the manipulator adopts a column-type structure, including a column, on which upper and lower clamping pliers are arranged. The upper and lower clamping pliers have both clamping and telescopic functions and can act synchronously to meet the needs of clamping the drill string; the column can rotate and rise and fall around its own central axis to meet the needs of transferring the drill string back and forth between different positions; the clamping and telescopic of the upper and lower clamping pliers and the lifting and lowering of the column are all driven by hydraulic cylinders; the rotation of the column is driven by a hydraulic motor.

[0019] Furthermore, the disc-type pipe rack adopts a double-layer / multi-layer arrangement, and the drill strings are fitted between the layers. When the outer drill string is taken out, the inner drill string can automatically shift to the outer layer; the pipe rack can rotate around its own central axis and is driven by a hydraulic motor.

[0020] Furthermore, the subsea in-situ natural gas hydrate extraction drilling equipment also includes a subsea circulation system. The seawater circulation system is used to circulate seawater and consists of a subsea pump, hoses, and connectors. The subsea pump is mounted on the frame structure of the subsea drilling and completion equipment body and is driven by a hydraulic motor. Rock cuttings circulated from the seabed to the wellhead are transported via the hose to the seabed at a distance from the wellhead.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention adopts a top drive + upper hydraulic clamp + lower hydraulic clamp to complete the connection and disconnection of the drill string, and a manipulator is used to complete the transfer of a single drill string between the center of the wellhead and the pipe rack. The manipulator is arranged between the center of the wellhead and the pipe rack. Less equipment is arranged at the wellhead and a small space is occupied, so that the entire seabed in-situ drilling and completion device is compact in space, and the drilling equipment can be transferred from the sea surface platform to the seabed, which greatly speeds up the drilling speed and reduces the mining cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic diagram of the overall structure of a drilling module of a natural gas hydrate seabed in-situ mining drilling equipment provided by an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of the layout of the manipulator;

[0025] Figure 3 is a flow chart of drill string transfer, connection and drilling operations;

[0026] FIG4 is a top view of a natural gas hydrate seabed in-situ mining drilling equipment provided by an embodiment of the present invention;

[0027] Figure 5 is a schematic diagram of the state of the leveling legs;

[0028] FIG6 is a schematic diagram of a pipe rack without a drill string installed;

[0029] FIG7 is a schematic diagram of a pipe rack with a drill string installed;

[0030] Figure 8 is a schematic structural diagram of the manipulator;

[0031] Figure 9 is a schematic diagram of the structure of the top drive;

[0032] Figure 10 is a schematic diagram of the structure of the upper hydraulic pliers and the lower hydraulic pliers;

[0033] FIG11 is a top view of the complete components of the submarine in-situ natural gas hydrate extraction drilling equipment;

[0034] In the figure: 1. Frame; 2. Door-type guide rail; 3. Manipulator; 4. Lower hydraulic clamp; 5. Upper hydraulic clamp; 6. Top drive; 7. Leveling legs; 8. Pipe rack; 31. Column; 32. Upper clamp; 33. Lower clamp; 61. Lifting motor; 62. Rotation motor; 100. Drill string. Specific implementation method:

[0035] Example:

[0036] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0037] Referring to Figure 1, the natural gas hydrate seabed in-situ extraction drilling equipment provided in this embodiment mainly includes a drilling module, which includes a frame 1, in which a portal guide rail 2 and a manipulator 3 are installed, a lower hydraulic clamp 4 is installed at the bottom of the frame 1, and an upper hydraulic clamp 5 is arranged coaxially above the lower hydraulic clamp 4. The coaxial section between the upper hydraulic clamp 5 and the lower hydraulic clamp 4 is the drill string placement position, that is, the center position of the wellhead; the upper hydraulic clamp 5 is connected to the center pipe of the top drive 6 and rotates with the center pipe. The top drive 6 is assembled in the portal guide 2 to move up and down in the height direction of the portal guide rail 2; a pipe rack 8 is provided within the rotation range of the manipulator, and the pipe rack 8 is used to store and place the drill string 100. The manipulator 3 is used to grab the drill string 100 between the upper hydraulic clamp 5 and the upper hydraulic clamp 4. As shown in Figure 2, a top drive, upper hydraulic clamp, and lower hydraulic clamp are used to connect and disconnect the drill string, and a manipulator is used to transfer a single drill string between the wellhead center and the pipe rack. The manipulator is arranged between the wellhead center and the pipe rack. Fewer devices are arranged at the wellhead, occupying less space, making the entire seabed in-situ drilling and completion device compact.

[0038] As shown in Figure 3, when the drill string with the drill bit is transferred by the manipulator to the drill string placement position, as shown in Figure 3a, the upper hydraulic clamp 5 is clamped and the lower hydraulic clamp 4 is opened. Then, as shown in Figure 3b, the top drive 6 descends, the lower hydraulic clamp 4 is clamped, the upper hydraulic clamp 5 is opened, and the top drive 6 descends to twist the thread. Subsequently, as shown in Figure 3c, the lower hydraulic clamp 4 is opened, the top drive advances, the lower hydraulic clamp is clamped, and the top drive is unthreaded, completing the drilling of the first drill string. After drilling the first drill string, as shown in Figure 3d, the top drive ascends, and the manipulator transfers the second drill string to the wellhead center. As shown in Figure 3e, the top drive descends, the upper hydraulic clamp is clamped, and the top drive descends to twist the thread at the wellhead. As shown in Figure 3f, the upper hydraulic clamp is opened, the top drive descends to twist the upper thread, and the lower hydraulic clamp 4 is opened, waiting for the transfer of the next drill string. This completes the drill string transfer, connection and unloading, and drilling process.

[0039] As a preferred embodiment of this embodiment, as shown in FIG4 , leveling legs 7 are further mounted on the four sides of the bottom of the frame 1. Each of the four leveling legs 7 is driven outward by an independent hydraulic motor. As shown in FIG5 , the leveling legs 7 are driven outward by an oil cylinder, allowing for a wide adjustment range and significantly expanding the contact area to increase stability, thereby providing chassis leveling and stable support. Thus, when the drilling equipment for in-situ extraction of natural gas hydrates is placed on the seabed, the four power-adjustable legs provide support and self-leveling, preventing lateral slippage or posture changes during subsequent movements of the equipment.

[0040] In one specific embodiment, as shown in Figures 6-7, the pipe rack 8 is a disc-type pipe rack, with two or more being provided. A manipulator 3 rotates back and forth between the drill string placement position and the disc-type pipe racks to transfer the drill string. By positioning the manipulator 3 between the two disc-type pipe racks 8, at the center of the entire device, drill string can be transferred back and forth between the two racks and the wellhead center, simplifying the subsea drilling rig structure. As shown in Figure 3, the disc-type pipe rack arranges the drill string in two layers, with each layer tightly fitted. Once the outer layer is removed, the inner layer automatically shifts to the outer layer. The pipe rack can rotate around its own central axis, driven by a hydraulic motor. This allows for automatic drill string discharge. The upper and lower hydraulic clamps have identical structures, employing three hydraulic cylinders that extend and retract to clamp the drill string. The three cylinders are evenly spaced at 120° angles and aligned in the same plane, and a synchronized motion mechanism ensures alignment during drill string clamping. In this way, the automatic connection and disconnection of the drill string can be achieved.

[0041] In a specific embodiment, as shown in Figure 8, the manipulator 3 adopts a column structure, including a column 31, on which an upper clamping clamp 32 and a lower clamping clamp 33 are provided. The upper and lower clamping clamps 32 and the lower clamping clamp 33 have both clamping and telescopic functions, and can act synchronously to meet the requirements of clamping the drill string; the column 31 can rotate and rise and fall around its own central axis to meet the requirements of transferring the drill string back and forth between different positions; the clamping and telescopic functions of the upper and lower clamping clamps 32 and the lower clamping clamp 33 and the lifting of the column are all driven by hydraulic cylinders; the rotation of the column is driven by a hydraulic motor.

[0042] In one embodiment, the drill string utilizes casing drilling. The downhole drill string assembly for casing drilling consists of a drill bit with a diameter smaller than the casing's inner diameter and an underreamer capable of penetrating the casing's inner diameter and expanding the wellbore to the casing's dimensions. This allows for simultaneous drilling and casing running, eliminating the risk of wellbore collapse and preventing casing running. The large outer diameter of the casing creates a small annulus with the wellbore, resulting in a high cuttings return velocity and reduced sedimentation, requiring a low subsea pump capacity.

[0043] In one embodiment, racks are provided on both sides of the portal guide rail 2 in the vertical direction. As shown in Figure 9, the top drive 6 includes a lifting motor 61 and a rotary motor 62. The lifting motor 61 is mounted within the rack of the portal guide rail 2 to achieve vertical movement. The rotary motor 62 is connected to the upper hydraulic clamp 5 to rotate the drill string. In other words, the top drive's vertical movement is driven by a hydraulic motor and a rack-and-pinion transmission, offering advantages such as a simple structure, smooth transmission, convenient pressurization, and ease of control.

[0044] In a specific embodiment, as shown in FIG10 , the upper hydraulic clamp 5 and the lower hydraulic clamp 4 have the same structural type, and three hydraulic cylinders are used to extend and retract the drill string for clamping. The three hydraulic cylinders are evenly distributed on the same plane at 120°, and a synchronous motion mechanism is provided to meet the centering requirements when clamping the drill string.

[0045] As a preferred embodiment of the subsea in-situ natural gas hydrate extraction drilling equipment, the equipment also includes a seawater circulation system. This system circulates seawater to cool the drill bit and carry rock cuttings. The system consists of a subsea pump, a hose, and a connector. The rock cuttings circulated from the seabed to the wellhead are transported via the hose to the seabed at a distance from the wellhead.

[0046] As a further preferred embodiment of the natural gas hydrate seabed in-situ mining drilling equipment of this embodiment, as shown in FIG11 , a pipe storage module, an additional module, a cementing module and a completion module can be connected around the drilling module to realize fully automated seabed mining.

[0047] In practical application, this in-situ subsea natural gas hydrate extraction drilling equipment is carried to the target sea area by a surface support vessel capable of deepwater equipment deployment. The equipment is deployed using the surface support vessel's deployment device. An umbilical cable with load-bearing capacity connects the drilling equipment to the surface support vessel, enabling the equipment to be transferred from the surface platform to the seabed. This significantly accelerates drilling speed and reduces extraction costs. Furthermore, subsea in-situ drilling is less susceptible to the effects of marine climate conditions, offering significant advantages and excellent feasibility.

[0048] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A natural gas hydrate seabed in-situ mining drilling equipment, characterized in that: The drilling module comprises a frame, a portal guide rail and a manipulator are installed in the frame, a lower hydraulic clamp is installed at the bottom of the frame, an upper hydraulic clamp is arranged coaxially above the lower hydraulic clamp, and the coaxial section between the upper hydraulic clamp and the lower hydraulic clamp is a drill string placement position; the upper hydraulic clamp is installed in a top drive, and the top drive is assembled in the portal guide rail to move up and down in the height direction of the portal guide rail; a pipe rack is arranged within the rotation range of the manipulator, the pipe rack is used to store and place the drill string, and the manipulator is used to grab the drill string between the upper hydraulic clamp and the lower hydraulic clamp.

2. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1, characterized in that: The pipe rack is a disc-type pipe rack; the manipulator rotates between the drill string placement position and the disc-type pipe rack to reciprocate back and forth to complete the transfer and discharge of the drill string.

3. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1 or 2, characterized in that: When the drill string with the drill bit is transferred to the drill string placement position by the manipulator, the upper hydraulic clamp is clamped, the lower hydraulic clamp is opened, the top drive moves downward, the lower hydraulic clamp is clamped, the upper hydraulic clamp is opened, the top drive moves downward and the buckle is turned, and the lower hydraulic clamp is opened to complete the drilling of the first drill string.

4. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 3, characterized in that: After the drilling of the first drill string is completed, the lower hydraulic clamp is clamped, the top drive is withdrawn, and the top drive moves upward. After the subsequent drill string is transferred to the drill string placement position by the manipulator, the upper hydraulic clamp is clamped, the top drive moves downward, the top drive moves downward, the connecting buckle at the wellhead is rotated, the upper hydraulic clamp is opened, the top drive moves downward and the buckle is rotated, and the lower hydraulic clamp is opened to complete the drilling of continuous drill strings.

5. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1, characterized in that: The drill string adopts casing drilling, and the casing drilling downhole drill string assembly is composed of a drill bit with a diameter smaller than the inner diameter of the casing and an expander that can pass through the inner diameter of the casing and expand the wellbore to the size of the casing.

6. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1, characterized in that: The two sides of the door-type guide rail in the height direction are racks; the top drive includes a lifting motor and a rotating motor; the lifting motor is installed in the rack to achieve up and down movement; the rotating motor is connected and installed with the upper hydraulic clamp to drive the drill string to rotate.

7. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1, characterized in that: Outriggers are installed on the four sides of the bottom of the frame, and the four outriggers are driven by independent hydraulic motors to extend outwards.

8. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1, characterized in that: The manipulator adopts a column-type structure, including a column, on which upper and lower clamping pliers are arranged. The upper and lower clamping pliers have both clamping and telescopic functions and can act synchronously to clamp the drill string; the column can rotate and rise and fall around its own central axis to transfer the drill string back and forth between different positions; the clamping and telescopic of the upper and lower clamping pliers and the lifting and lowering of the column are all driven by hydraulic cylinders; the rotation of the column is driven by a hydraulic motor.

9. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1, characterized in that: The disc-type pipe rack adopts a double-layer / multi-layer arrangement. When the outer drill string is taken out, the inner drill string can be automatically shifted to the outer layer; the pipe rack can rotate around its own central axis and is driven by a hydraulic motor.

10. The natural gas hydrate seabed in-situ mining drilling equipment according to claim 1, characterized in that: It also includes a seabed circulation system, which is used to circulate seawater and consists of a seabed pump, a hose and a joint; the seabed pump is installed on the frame structure of the seabed drilling and completion device body, and the seabed pump is driven by a hydraulic motor. The rock cuttings circulated from the seabed to the wellhead are transported to the seabed at a certain distance from the wellhead through the hose.

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