Drilling and fixing integrated drilling device and method for deep sea natural gas hydrate exploitation system

Abstract

The invention discloses a drilling and fixing integrated drilling device and method for a deep sea natural gas hydrate exploitation system. The drilling device comprises a hollow drill rod, a plurality of continuous pipe separation units and a hollow drill bit which are fixedly connected from top to bottom in the axial direction, and according to the method, the multi-well guiding suction anchor, the rope soil taking equipment, the drilling device and the seabed drilling machine are lowered to a seabed to be positioned and leveled through a small and medium-sized workboat and are fixedly connected with the multi-well guiding suction anchor; the seabed drilling machine controls the drilling device to drill along the multi-well guide suction anchor, and the rope soil taking equipment takes soil; and the pipe is replaced until the target depth is drilled, the drilling device conducts self well cementation and well completion through the self-expansion packer and the pre-filled gravel screen pipe, and the drilling device is completed after equipment is recycled. The device has continuous and integrated operation capacity of well drilling, soil taking, well cementation and well completion, the cost is effectively reduced, the efficiency is remarkably improved, rapid construction, convenient well cementation and economic well completion of a deep sea hydrate mining system are achieved, and a new thought and method are provided for safe and efficient mining of deep sea hydrates.

Description

Technical Field

[0001] This invention belongs to the fields of energy engineering and geotechnical engineering technology, and relates to a drilling method for deep-sea natural gas hydrate extraction, specifically to a drilling and cementing integrated self-forming well drilling tool and method for deep-sea natural gas hydrate extraction systems. Background Technology

[0002] Natural gas hydrate is an ice-like crystalline compound formed from water and natural gas (mainly methane) under low temperature and high pressure conditions. It is widely distributed in deep-sea sediments and permafrost zones. As a clean energy source with abundant reserves and high energy density, natural gas hydrate is hailed as one of the most promising alternative energy sources of the 21st century. However, its extraction has always faced severe technical challenges. In recent years, successful trial production of offshore natural gas hydrate has been achieved, but it faces problems such as low gas production rates and high operating costs.

[0003] Current deep-sea natural gas hydrate pilot production mainly draws on conventional offshore oil and gas drilling technology, typically employing drilling platforms or drilling vessels. The process involves multiple independent stages, including drilling, casing installation, cementing, and well completion. This segmented approach suffers from high equipment dependence, long operation cycles, and high costs. Furthermore, deep-sea natural gas hydrate reservoirs are characterized by low strength and high deformability, making conventional offshore oil and gas drilling methods prone to wellbore instability and gas leakage, further complicating their application in deep-sea hydrate reservoir drilling. These issues severely hinder the commercial development of deep-sea natural gas hydrates.

[0004] Currently, wireline coring technology has been explored and applied in the field of drilling coring. This technology allows the inner core tube to be retrieved via a wire rope without removing the drill pipe, thus improving coring efficiency. While this technology is convenient for reservoir drilling and coring and highly efficient, it cannot be used for cementing and completion operations in oil and gas production wells. Furthermore, existing cementing processes mostly employ cement slurry injection, which has a long solidification time and slow strength development in the deep-sea, low-temperature environment where natural gas hydrates are present. It also often disturbs the reservoir, inducing instability, posing significant challenges to the application of conventional cementing methods in this field.

[0005] Therefore, existing technologies lack a drilling and cementing integrated drilling method suitable for deep-sea natural gas hydrate extraction systems. Summary of the Invention

[0006] To address the problems existing in the background technology, this invention aims to provide an economical and efficient drilling structure and method. Based on wireline coring drilling, a self-expanding packer and a pre-filled gravel screen are developed, enabling drilling, soil sampling, cementing, and well completion to be completed in one go without removing the drill pipe, thus achieving "drilling-cementing integration" and reducing drilling costs. In particular, when implemented with a "one-anchor-multiple-well mining system", it can significantly improve work efficiency.

[0007] The technical solution adopted in this invention is: I. A drilling and cementing integrated drilling tool for deep-sea natural gas hydrate extraction systems: The subsea drilling rig is equipped with a drilling tool for drilling. The self-forming drilling tool mainly consists of a hollow drill rod, several cementing and completion units, and a hollow drill bit, which are fixedly connected from top to bottom along the axial direction. The hollow drill rod is connected to a preset interface of the subsea drilling rig. The subsea drilling rig drives the drilling tool to drill downwards, and the hollow drill bit breaks through the overlying layer and hydrate reservoir to drill into the underlying gas layer. Hollow boreholes are opened on the central axis of the hollow drill rod, the several cementing and completion units, and the hollow drill bit. The underwater soil in the overlying layer, hydrate reservoir, and underlying gas layer is transported and extracted through the hollow boreholes.

[0008] The cementing and completion unit is mainly composed of a self-expanding packer and a pre-filled gravel screen connected coaxially from top to bottom along the axial direction. The hollow drill pipe and the cementing and completion unit, the cementing and completion unit and the hollow drill bit, and the self-expanding packer and the pre-filled gravel screen are all connected coaxially by threads. Hollow drill holes are opened on the self-expanding packer and the pre-filled gravel screen.

[0009] The self-expanding packer includes a tubular inner rod and a water-swellable rubber sleeve. It is mainly composed of the inner rod and the rubber sleeve from the inside out. The inner rod has the same inner and outer diameter as the hollow drill rod. An annular groove is arranged on its outer circumference, and the water-swellable rubber sleeve is installed in the groove. A hydrolytic protective film tightly wraps around the outer circumference of the rubber sleeve. Under dry conditions, the outer diameter of the water-swellable rubber sleeve is no greater than the outer diameter of the inner rod. The hydrolytic protective film hydrolyzes upon contact with water underwater, and the water-swellable rubber sleeve expands after a preset time underwater. The outer diameter of the expanded water-swellable rubber sleeve is no less than [number] times that of the hollow drill rod.

[0010] The pre-filled gravel screen tube includes an inner screen tube, a pre-filled gravel layer, an outer screen tube, and a water-repellent plug. The inner screen tube is coaxially fitted inside the outer screen tube. The annular gap between the inner and outer screen tubes is fixedly filled with a pre-filled gravel layer. Multiple radially penetrating perforations are arranged in an array on the circumferential surface of the inner and outer screen tubes. A water-repellent plug is provided at each perforation. The hydrolytic sealant is temporarily plugged at the perforations of the inner and outer screen tubes. The hydrolytic sealant blocks the perforations under dry conditions, and hydrolyzes after a preset time when it comes into contact with water underwater, thus ensuring the smooth flow of the perforations in the pre-filled gravel screen tubes.

[0011] Self-expanding packers may be installed in the hydrate reservoir or overlying layer, or in both the hydrate reservoir and overlying layer.

[0012] The water-swellable rubber sleeve can expand on its own when it comes into contact with water or other soluble liquids, or can expand on its own after a preset time; the hydrolyzable protective film can hydrolyze when it comes into contact with water or other soluble liquids, or can dissolve on its own after a preset time.

[0013] The hydrolytically degradable sealant is hydrolyzable when it comes into contact with water or other soluble liquids, or it can self-dissolve after a preset time. It is a hydrolyzable material such as polyvinyl alcohol (PVOH / PVA), sodium polyacrylate, or polyglycolic acid (PGA).

[0014] The hollow drill bit includes a drill wall and an annular cutting blade; an open slot is provided at the top of the drill wall of the hollow drill bit for connecting with the soil sampling inner tube, and the annular cutting blade is provided at the bottom of the drill wall.

[0015] II. A drilling-solidification integrated drilling method for deep-sea natural gas hydrate extraction: The equipment used in the method includes multi-well directional suction anchors, subsea drilling rigs, wireline soil removal equipment, drilling tools, and small and medium-sized work vessels.

[0016] The small and medium-sized work vessel is connected to the multi-well directional suction anchor and the subsea drilling rig via an umbilical cable. The subsea drilling rig controls the drilling of the self-drilling well, and the rope-assisted soil removal equipment is installed inside the drill. The method is specifically carried out as follows: Step 1: Secure the suction anchor Small and medium-sized work vessels use umbilical cables to control the lowering of multi-well directional suction anchors to the seabed, position and level the multi-well directional suction anchors, and then penetrate them to the preset depth; Step 2: Fix the drilling rig The rope soil extraction equipment, drilling tools and subsea drilling rigs are combined in sequence, and the subsea drilling rig is lowered using a small and medium-sized work vessel via an umbilical cable. The rig is then connected and fixed to a multi-well directional suction anchor at a preset angle. Step 3: Directional Drilling The subsea drilling rig controls the drilling tool to drill along the preset direction of the guide pipes of the inclined guide pipe and the straight guide pipe set in the multi-well guide suction anchor; Step 4: Using ropes to collect soil After the drilling rig reaches the preset depth, the amount of soil stored in the rope soil removal equipment reaches the preset limit. The subsea drilling rig then controls the drilling rig to stop drilling and uses the rope soil removal equipment to remove soil and replace the pipe. Afterward, the subsea drilling rig controls the drilling rig to continue drilling. Step 5: Repeat drilling If the drilling tool does not drill to the preset depth, repeat steps 3-4; If drilling has reached the preset depth, the subsea drilling rig controls the drilling tool to stop drilling, and the rope soil removal equipment controls itself to detach from the drilling tool. Step 6: Cementing Completion The drilling tool can automatically cement and complete the well at a preset depth. The drilling tool can drill to the overlying layer, hydrate reservoir or underlying layer. Step 7: Repeat drilling Small and medium-sized work vessels control the seabed drilling rig to adjust its angle via umbilical cables, connect and fix it to other preset angles of the multi-well directional suction anchor, and repeat steps 3-6 to complete multiple drilling, cementing and well completion processes of the drilling rig. Step 8: Recover the drilling rig Small and medium-sized work vessels retrieve seabed drilling rigs via umbilical cables; Step 9: Prepare for mining Small and medium-sized work vessels are lowered and drilling equipment is installed, at which point the drilling tool is ready for extraction. This method can also be used as a drilling-and-soldering integrated drilling method for deep-sea energy drilling and extraction, such as offshore oil, natural gas, and hydrogen, as needed.

[0017] The multi-well guide suction anchor includes a top cover and an outer cylindrical body. The top cover is fixedly to the upper end of the outer cylindrical body to form an integral cylindrical shell structure with an open lower end and a closed upper end. Inclined guide pipes, straight guide pipes, and stiffening plates are installed inside the cylindrical shell structure. The multi-well guide suction anchor has straight guide pipes arranged on the central axis of the cylindrical shell structure. The upper ends of both the straight guide pipes and the inclined guide pipes are fixed to the top cover. Multiple inclined guide pipes are arranged around the straight guide pipes. Each inclined guide pipe is arranged at an incline and is evenly spaced along the circumference. The inclined guide pipes are arranged symmetrically about the straight guide pipes, so that each inclined guide pipe is radially distributed and extends from top to bottom. The upper side of each inclined guide pipe is fixedly connected to the inner wall of the top cover and the outer cylindrical body through vertical stiffening plates to form a force-bearing unit. The multi-well guide suction anchor has pre-set support leg slots on the top cover near the openings of the inclined guide pipes and the straight guide pipes for connecting and fixing the support legs of the subsea drilling rig.

[0018] The aforementioned rope-driven soil extraction equipment includes a mechanical gripper, a retrieval rope, and a soil extraction inner tube. The mechanical gripper extends into a hollow borehole inside the drilling rig and is connected to the subsea drilling rig via the retrieval rope. The soil extraction inner tube is located within the hollow borehole inside the drilling rig, and its upper end has a gripping groove for engaging with the mechanical gripper. The top of the hollow drill bit of the drilling rig has an open slot for engaging with the soil extraction inner tube, and the lower end of the soil extraction inner tube is connected to the hollow drill bit of the drilling rig via the open slot. The mechanical gripper includes a mechanical inner unit and multiple gripping arms. The mechanical inner unit has gripping arms evenly distributed circumferentially on at least two sides. Each gripping arm is mainly composed of a gripping upper arm, a gripping lower arm, and a gripping claw connected sequentially at the front and rear.

[0019] Step 4 includes: when the mechanical gripper descends to retrieve the soil-collecting inner pipe, it descends at a preset speed; after the lower end of the mechanical gripper is connected to the soil-collecting inner pipe through the gripping groove, the mechanical gripper moves upward at a preset speed; after the soil-collecting inner pipe is removed using the mechanical gripper, it is placed on the storage rack of the subsea drilling rig, and a new soil-collecting inner pipe is connected to the lower end of the mechanical gripper for pipe replacement, and then moves downward at a preset speed; and when the drilling rig is drilling, the soil-collecting inner pipe is connected to the hollow drill bit of the drilling rig through the open slot, and disconnected when collecting soil, so as to realize soil collection during the drilling process.

[0020] Step 6 includes: after drilling to a preset depth, the self-expanding packer and pre-filled gravel screen in the drill bit are completely buried in the hydrate reservoir. After a preset time, the hydrolytic protective film on the self-expanding packer is completely hydrolyzed, and the water-infected self-expanding rubber sleeve begins to expand. After another preset time, the water-infected self-expanding rubber sleeve is fully expanded, achieving the effect of not expanding during drilling and self-expanding after drilling is completed, thus fixing the drill bit in the hydrate reservoir; at the same time, the hydrolytic plug in the pre-filled gravel screen is completely hydrolyzed, and the perforations of the outer and inner screens are unobstructed, ensuring the smooth subsequent extraction of natural gas hydrates.

[0021] This invention utilizes a small to medium-sized work vessel to sequentially lower a specially designed multi-well directional suction anchor, a rope-assisted soil removal device, a self-drilling well drill, and a subsea drilling rig to the seabed for positioning and leveling. The subsea drilling rig is then connected and fixed to the multi-well directional suction anchor. The subsea drilling rig controls the self-drilling well drill to drill along the preset direction of the multi-well directional suction anchor to a predetermined depth, and soil is removed using the rope-assisted soil removal device. The above steps are repeated, with pipe replacements as needed, until the target depth is reached. The self-drilling well drill automatically cements and completes the well using a self-expanding packer and pre-filled gravel screen. The subsea drilling rig is controlled by an umbilical cable to adjust its angle, and the above steps are repeated to complete the drilling, cementing, and completion processes for self-drilling well drills at different angles. The subsea drilling rig is retrieved via the umbilical cable, and extraction equipment is lowered and installed, completing the rapid deployment of a deep-sea natural gas hydrate extraction system.

[0022] This invention has the capability of continuous and integrated operation of drilling, soil extraction, cementing, and well completion, effectively reducing costs and significantly improving efficiency. It enables rapid construction, convenient cementing, and economical well completion of deep-sea hydrate mining systems, providing new ideas and methods for the safe and efficient mining of deep-sea hydrates.

[0023] The beneficial effects of this invention are: This invention achieves continuous, integrated drilling, soil sampling, cementing, and well completion operations by modularly integrating hollow drill pipe, self-expanding packers, and pre-filled gravel screens. This overcomes the technical bottlenecks of traditional deep-sea drilling, which involves multiple separate stages, reliance on large platforms, long cycles, and high costs. Its innovative self-responsive cementing and completion mechanism effectively adapts to the engineering challenges of low-temperature, high-pressure deep-sea environments and the weak cementation and easy disturbance of hydrate reservoirs, avoiding reservoir disturbance and solidification delays caused by cement slurry cementing.

[0024] This invention significantly improves the overall efficiency and operational safety of deep-sea drilling from an engineering application perspective. By using wireline soil removal equipment, it achieves "continuous soil removal without drilling," reducing the number of trips and ensuring operational continuity. The self-expanding packer and pre-filled gravel screen's self-responsive cementing and completion mechanism eliminates the risks of fluid injection pressure and chemical contamination, reducing the probability of wellbore instability and gas leakage. This provides a practical and feasible technical path for the safe, economical, and large-scale exploitation of deep-sea natural gas hydrates in my country, possessing significant engineering application and strategic value.

[0025] This invention possesses continuous and integrated operation capabilities for drilling, soil extraction, cementing, and well completion, enabling rapid construction, convenient cementing, and economical and efficient well completion of deep-sea natural gas hydrate extraction systems. It is a prerequisite for breaking through the threshold of commercial extraction of deep-sea natural gas hydrates. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a drilling-and-soldering integrated drilling method for deep-sea natural gas hydrate extraction systems according to the present invention: wherein, Figure 1 (a) Steps 1-2: fixing the suction anchor and fixing the drilling rig; Figure 1 (b) is step 3, directional drilling; Figure 1 (c) is step 4, using ropes to collect soil; Figure 1 (d) is step 5, drilling to the preset depth; Figure 1 (e) is step 6, sealing the plug hydrolysis and packer self-expansion cementing; Figure 1 (f) refers to steps 7-8, multi-angle drilling and rig recovery; Figure 2 This is a schematic diagram of the rope-based soil extraction process in this invention: where, Figure 2 (a) is the process of the mechanical gripper descending to retrieve the inner pipe for soil removal; Figure 2(b) is the upward process after the mechanical clamp is connected to the inner pipe of the soil extraction device; Figure 2 (c) is the process of the mechanical clamp being connected to the new soil extraction inner pipe and descending; Figure 3 This is a cross-sectional view of the integrated drilling and cementing hydrate well in this invention; Figure 4 This is a schematic diagram of the integrated drilling and solidification hydrate well sealing hydrolysis and packer self-expansion in this invention; Figure 4 (a) Schematic diagram of well sealing, plugging, hydrolysis, and self-expansion cementing before production well; Figure 4 (b) is a schematic diagram of the wellhead after hydrolysis of the sealing plug and self-expansion cementing; Figure 4 (c) is a schematic diagram of the self-expanding packer before self-expansion; Figure 4 (d) is a schematic diagram of the self-expanding packer after self-expansion; Figure 4 (e) is a schematic diagram of the pre-filled gravel screen pipe before hydrolysis; Figure 4 (f) is a schematic diagram of the pre-filled gravel screen after hydrolysis; Figure 5 This is a schematic diagram of the multi-well directional suction anchor structure in this invention; wherein, Figure 5 (a) is a top view of a multi-well directional suction anchor; Figure 5 (b) is a radial cross-sectional view of a multi-well directional suction anchor; Figure 5 (c) is a front view of a multi-well directional suction anchor; Figure 6 This is a flowchart of a drilling and cementing integrated drilling method for deep-sea natural gas hydrate extraction systems according to the present invention.

[0027] In the picture: 1-Multi-well directional suction anchor, 11-Guide pipe, inclined guide pipe 102, straight guide pipe 103, suction anchor outer wall 104, suction anchor inner wall 105, stiffening plate 106, pre-set support leg slot 107; 2-Subsea drilling rig, 21-Storage pipe rack; 3- Rope-based soil extraction equipment; 31- Mechanical clamp; 311- Mechanical internal unit; 312- Clamping boom; 313- Clamping forearm; 314- Clamping claw; 32- Salvage rope; 33- Soil extraction inner tube; 331- Clamping groove; 332- Soil collection; 34- Hollow drill bit; 341- Drill wall; 342- Ring cutting blade; 343- Opening slot. 4-Drilling tool; 41-Hollow drill pipe; 42-Self-expanding packer; 421-Inner rod of self-expanding packer; 422-Water-swellable rubber sleeve; 423-Hydrolytic protective membrane; 43-Pre-filled gravel screen; 431-Outer screen; 432-Pre-filled gravel layer; 433-Inner screen; 434-Hydrolytic sealant; 435-Protective net; 436-Perforation. 5-Small and medium-sized working vessels, 6-Umbilical cable, 7-Seawater, 8-Seabed, 9-Overlying layer, 10-Hydrate reservoir, 101-Underlying layer. Detailed Implementation

[0028] The invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] The subsea drilling rig 2 has a storage pipe rack 21, and the storage pipe rack 21 is equipped with a guide pipe 11 for drilling multi-well guide suction anchor 1, a guide pipe 11 for drilling, and a self-forming well drilling tool 4.

[0030] like Figure 2 As shown, the integrated drilling and cementing hydrate self-forming well drill 4 mainly consists of a hollow drill rod 41 fixedly connected from top to bottom along the axial direction, several consecutive cementing and completion units, and a hollow drill bit 34. The hollow drill rod 41 is connected to a preset interface of the subsea drilling rig 2. The subsea drilling rig 2 drives the self-forming well drill 4 to drill downwards, breaking through the overlying layer 9 and the hydrate reservoir 10 through the hollow drill bit 34 to drill into the underlying gas layer 101. Hollow boreholes are opened on the central axis of the hollow drill rod 41, the several consecutive cementing and completion units, and the hollow drill bit 34. The underwater soil of the overlying layer 9, the hydrate reservoir 10, and the underlying gas layer 101 is transported and extracted through the hollow boreholes.

[0031] like Figure 3 and Figure 4 As shown, the cementing completion unit is a repeatable modular unit structure, mainly composed of a self-expanding packer 42 and a pre-filled gravel screen 43 connected coaxially from top to bottom along the axial direction. The self-expanding packer 42 is located at the upper end of the pre-filled gravel screen 43. The hollow drill pipe 41 and the cementing completion unit, the cementing completion unit and the hollow drill bit 34, and the self-expanding packer 42 and the pre-filled gravel screen 43 are all connected coaxially by threads. Hollow drill holes are opened on both the self-expanding packer 42 and the pre-filled gravel screen 43.

[0032] The drilling tools for vertical and inclined wells of the integrated drilling and cementing hydrate are all assembled in a specified order by hollow drill pipe 41, self-expanding packer 42, pre-filled gravel screen 43 and hollow drill bit 34. Based on the automatic drill pipe connection and unloading technology of the subsea drilling rig 2, the hollow drill pipe 41, self-expanding packer 42 and pre-filled gravel screen 43 are connected in different sections according to the mining requirements. The drill pipe is drilled along the inclined guide pipe and the guide pipe 11 of the multi-well guide suction anchor 1 until it reaches the specified depth of the hydrate reservoir 10 or the underlying gas layer 101, and finally forms the integrated drilling and cementing hydrate vertical and inclined wells.

[0033] Hollow drill pipe 41, self-expanding packer 42, pre-filled gravel screen 43, and hollow drill bit 34 can be connected and disassembled. In specific implementation, based on the automatic drill pipe connection and disassembly technology of the subsea drilling rig 2, different combinations can be selected for assembly and drilling as needed. After drilling, there is no need to retrieve the casing, and cementing and well completion can be carried out directly, finally forming a suitable self-forming well drill 4. The self-forming well drill 4 can be set with functions as needed. After drilling, it can be used as a depressurization well, gas or liquid injection well, chemical reagent injection well, hydrothermal injection well, monitoring well, etc.

[0034] like Figure 4 As shown, the self-expanding packer 42 includes a tubular self-expanding packer inner rod 421 and a water-swellable rubber sleeve 422. The self-expanding packer 42 is mainly composed of the self-expanding packer inner rod 421 and the water-swellable rubber sleeve 422 from the inside to the outside. The inner rod 421 of the self-expanding packer has the same inner and outer diameter as the hollow drill rod 41. An annular groove is provided on the outer circumferential surface. The water-swellable rubber sleeve 422 is installed in the annular groove. The hydrolyzable protective film 423 tightly wraps around the outer circumferential surface of the water-swellable rubber sleeve 422.

[0035] The self-expanding packer 42 is installed in the hydrate reservoir 10 or the overlying layer 9 as needed, or in both the hydrate reservoir 10 and the overlying layer 9. In the self-expanding packer 42, the outer diameter of the water-inducing rubber sleeve 422 under dry conditions is not greater than the outer diameter of the inner rod 421 of the self-expanding packer. The hydrolyzable protective film 423 hydrolyzes after encountering water underwater, and the water-inducing rubber sleeve 422 can self-expand after encountering water underwater for a preset time. The outer diameter of the expanded water-inducing rubber sleeve 422 is not less than 1.1 times that of the hollow drill pipe 41, thereby achieving the fixation of the well pipe and effectively blocking natural gas leakage during the extraction process.

[0036] The water-swellable rubber sleeve 422 can expand on its own when it comes into contact with water or other soluble liquids, or can expand on its own after a preset time; the hydrolyzable protective film 423 can hydrolyze when it comes into contact with water or other soluble liquids, or can dissolve on its own after a preset time.

[0037] like Figure 4As shown, the pre-filled gravel screen 43 has the same inner and outer diameter as the hollow drill rod 41, and includes an inner screen 433, a pre-filled gravel layer 432, an outer screen 431, and a water-removable plug 434. The pre-filled gravel screen 43 is mainly composed of the inner screen 433, the pre-filled gravel layer 432, and the outer screen 431 from the inside out. The inner screen 433 and the outer screen 431 are arranged inside and outside, with the inner screen 433 coaxially fitted inside the outer screen 431. The annular gap between the inner screen 433 and the outer screen 431 is fixedly filled with the pre-filled gravel layer 432, which is composed of gravel in the inner screen 433. The space between the inner screen 433 and the outer screen 431 is filled and compacted, and fixed by the friction between the gravel. Multiple radially penetrating perforations 436 are arranged in the same array on the circumferential surface of the inner screen 433 and the outer screen 431. The perforations 436 are evenly distributed on the outer screen 431 and the inner screen 433. The multiple perforations 436 are arranged in two rows and columns along the circumferential and axial directions on the circumferential surface, and are arranged in the same array on the circumferential surface of the inner screen 433 and the outer screen 431. A water-soluble plug 434 is provided at each perforation 436. The water-soluble plug 434 can prevent soil particles from clogging the pre-filled gravel screen 43 during drilling.

[0038] The outer surface of the outer screen tube 431 is provided with a protective net 435, which wraps around the outside of the pre-filled gravel screen tube 43 to ensure that the gravel in the pre-filled gravel layer 432 will not fall out.

[0039] The hydrolytic sealant 434 is used to temporarily plug the perforations 436 of the inner screen tube 433 and the outer screen tube 431 to prevent soil particles from clogging the pre-filled gravel screen tube 43 during drilling. The hydrolytic sealant 434 plugs the perforations 436 under dry conditions, and hydrolyzes after encountering water underwater for a preset time, so as to ensure the smooth flow of the perforations 436 in the pre-filled gravel screen tube 43, which facilitates the subsequent smooth extraction of natural gas hydrates.

[0040] The hydrolytic sealant 434 is hydrolyzable upon contact with water or other soluble liquids, or it can self-dissolve after a preset time. The hydrolytic sealant 434 can be made of hydrolyzable materials such as polyvinyl alcohol (PVOH / PVA), sodium polyacrylate, or polyglycolic acid (PGA). These materials can dissolve in seawater 7 after a certain period of time, effectively inhibiting soil particle intrusion during drilling and ensuring the unobstructed flow of perforations 436 in the pre-filled gravel screen 43.

[0041] The seabed consists of seawater 7, overlying layer 9, hydrate reservoir 10, and underlying gas layer 101 from top to bottom. Multi-well directional suction anchor 1 is anchored on the overlying layer 9. Vertical and inclined wells extend from the overlying layer 9 downwards to the hydrate reservoir 10 and the underlying gas layer 101.

[0042] like Figure 1As shown, the small and medium-sized work vessel 5 is connected and fixed to the subsea drilling rig 2 and the multi-well directional suction anchor 1 in sequence via the umbilical cable 6. The small and medium-sized work vessel 5 can control the multi-well directional suction anchor 1 and the subsea drilling rig 2 to be lowered to the preset position. After being lowered and fixed, the multi-well directional suction anchor 1 is fixed on the seabed 8, and the subsea drilling rig 2 is fixed on the multi-well directional suction anchor 1. The subsea drilling rig 2 controls the self-drilling well drill 4 to drill, and the rope soil removal equipment 3 is set inside the self-drilling well drill 4.

[0043] The subsea drilling rig 2 is connected to the medium and small working vessel 5 via the umbilical cable 6. The subsea drilling rig 2 is fixed on the top of the multi-well directional suction anchor 1. Multiple drilling wells, including vertical and inclined wells, are set in the multi-well directional suction anchor 1. The medium and small working vessel 5 controls the subsea drilling rig 2 through the umbilical cable 6 to complete the drilling and layout of the drilling-solidification integrated hydrate wells in the multi-well directional suction anchor 1. The vertical and inclined wells are connected to the multi-tube production tree arranged on the multi-well directional suction anchor 1. After the multi-tube production tree is connected to the subsea booster electric submersible pump and the production and transportation pipeline, a radial well cluster high-efficiency production and transportation path for natural gas hydrate is formed by one machine and multiple wells.

[0044] In the integrated drilling and cementing well completion process of this invention, after the multi-well directional suction anchor 1 is installed, the subsea drilling rig 2 is lowered into the top of the multi-well directional suction anchor 1 and fixed by a small-to-medium-sized work vessel 5 and a winch; the small-to-medium-sized work vessel 5 controls the subsea drilling rig 2 to complete the drilling and laying of the integrated drilling and cementing hydrate vertical well through the umbilical cable 6; after the drilling and laying of the integrated drilling and cementing hydrate vertical well is completed, the new storage pipe rack 21 is replaced on the subsea drilling rig 2, the subsea drilling rig 2 is adjusted to the position of the inclined guide pipe opening, and the extension of the drilling rig legs is adjusted so that the subsea drilling rig drills and lays the inclined well according to the set inclination angle; the above process is repeated until all production wells are drilled, the subsea drilling rig 2 is retrieved, and a multi-tube production tree and a subsea booster electric submersible pump are lowered.

[0045] In this invention, the radial well cluster production system connects vertical and inclined wells to the gas pipeline via a multi-tube wellhead and a subsea booster pump, forming a highly efficient radial well cluster production and transportation path for natural gas hydrates.

[0046] The hollow drill bit 34 includes a drill wall 341 and an annular cutting blade 342; an open slot 343 is provided at the top of the drill wall 341 of the hollow drill bit 34 for connecting with the soil sampling inner tube 33, which can realize the connection and disconnection with the soil sampling inner tube 33; the annular cutting blade 342 is provided at the bottom of the drill wall 341. When the annular cutting blade 342 drills downward, the collected soil 332 is transported upward from the hollow drill hole inside the drill wall 341 to the soil sampling inner tube 33, realizing soil sampling while drilling.

[0047] like Figure 5As shown, the multi-well guide suction anchor 1 specifically implemented includes a top cover and a cylindrical outer shell. The top cover can be welded to the upper end of the outer shell to form an integral shell structure with an open lower end and a closed upper end. An inclined guide tube 102, a straight guide tube 103, and a stiffening plate 106 are installed inside the shell structure. A straight guide tube 103 is arranged on the central axis of the shell structure of the multi-well guide suction anchor 1. The straight guide tube 103 is vertically arranged along the direction of gravity. The upper ends of both the straight guide tube 103 and the inclined guide tube 102 can be welded to the bottom surface of the top cover. A set of... Multiple inclined guide pipes 102 are arranged at an angle, and the inclined guide pipes 102 are evenly distributed circumferentially to form an approximate spiral array. The inclined guide pipes 102 and the straight guide pipes 103 are spaced apart and do not contact each other. The inclined guide pipes 102 are arranged rotationally symmetrically with the straight guide pipe 103 as the center, so that the inclined guide pipes 102 of each inclined well 314 are distributed and extended radially from top to bottom. The inclined guide pipes 102 are staggered from each other, and their extension directions point sequentially to the adjacent wellhead positions. The straight guide pipe 103 of the straight well 311 is arranged at the center of each inclined guide pipe 102. Thus, a radial well cluster structure of "central straight well + circumferential inclined well" is formed in the anchor body of a multi-well guide suction anchor 1.

[0048] Each inclined guide tube 102 is fixedly connected to the top and outer sides of the top cover and the inner wall of the outer peripheral cylinder (i.e., the inner wall 105 of the suction anchor) by a vertical stiffening plate 106 to form a force-bearing unit. The stiffening plate 106 is located on a vertical plane parallel to gravity and is used to maintain the stability of the relative position between the inclined guide tube 102 and the cylindrical shell structure of the multi-well guide suction anchor 1. The multi-well guide suction anchor 1 has a pre-set support leg slot 107 on the top cover near the opening of the inclined guide pipe 102 and the opening of the straight guide pipe 103 for connecting and fixing the support legs of the subsea drilling rig 2. The pre-set support leg slot 107 is used to connect with the bottom of the subsea drilling rig 2, so as to realize the rapid connection and separation of the subsea drilling rig 2 and the multi-well guide suction anchor 1.

[0049] In specific implementation, inclined guide pipes 102 are evenly arranged at specified intervals from the central axis of the straight guide pipe 103. Each inclined guide pipe 102 is inclined in a direction that is not parallel to the radial, axial and circumferential directions of the outer peripheral cylinder. The upper end of each inclined guide pipe 102 points to the pipe opening of the adjacent inclined guide pipe 102 according to a preset inclination angle. The straight guide pipe 103 and the inclined guide pipe 102 are used for drilling guidance of the drilling tool of the subsea drilling rig 2.

[0050] The outer wall and inner wall of the outer peripheral cylinder serve as the outer wall 104 and inner wall 105 of the suction anchor, respectively. The inner wall 105 of the suction anchor is connected to the inclined guide tube 102 through a stiffening plate 106, which is arranged along the direction of the inclined guide tube 102.

[0051] The stiffening plate 106 is welded to the surface of the inclined guide tube 102 on one side and to the bottom surface of the top cover and the inner wall of the outer peripheral cylinder (i.e., the inner wall 105 of the suction anchor) on the other side. Each inclined guide tube 102 has a vertically upward through slotted structure at the position of the stiffening plate 106 above itself and the position of the adjacent inclined guide tube 102 and its corresponding stiffening plate 106, forming an interlocking fit. The adjacent inclined guide tubes 102 and their corresponding stiffening plates 106 are inserted into the slotted structure and welded to each other for fixation.

[0052] Thus, multiple guide pipes 11 are arranged inside the multi-well guide suction anchor 1 at a preset angle, consisting of a vertical straight guide pipe 11 at the center of the multi-well guide suction anchor 1 and multiple inclined guide pipes 11 arranged at intervals around the straight guide pipe 11. In step 3, the preset direction is the direction of the guide pipes 11 set in the multi-well guide suction anchor 1 itself.

[0053] The subsea drilling rig 2 is equipped with a storage rack 21. The assembly method in step 2 is as follows: the drilling equipment 4, consisting of a preset number of hollow drill rods 41, self-expanding packers 42, pre-filled gravel screens 43, soil sampling inner tubes 33, and hollow drill bits 34, is placed in the storage rack 21 in the subsea drilling rig 2 in a preset order.

[0054] The rope-assisted soil extraction device 3 includes a mechanical clamp 31, a retrieval rope 32, and a soil extraction inner tube 33. The mechanical clamp 31 extends into the hollow borehole inside the drill rig 4, and its upper end is connected to the subsea drilling rig 2 via the retrieval rope 32, allowing it to move up and down inside the drill rig 4. The soil extraction inner tube 33 is located in the hollow borehole inside the drill rig 4, and its upper end has a clamping groove 331 for engaging with the lower end of the mechanical clamp 31, allowing it to connect or disconnect from the mechanical clamp 31. The top of the hollow drill bit 34 of the drill rig 4 has an open slot 343 for engaging with the soil extraction inner tube 33, allowing it to connect or disconnect from the soil extraction inner tube 33. The lower end of the soil extraction inner tube 33 is connected to the hollow drill bit 34 of the drill rig 4 via the open slot 343. The mechanical gripper 31 includes a mechanical inner unit 311 and multiple gripping arms. The mechanical inner unit 311 is provided with gripping arms evenly distributed along the circumference on at least two sides. Each gripping arm is mainly composed of a gripping upper arm 312, a gripping lower arm 313, and a gripping claw 314 connected in sequence with the first and second arms hinged together. The mechanical inner unit 311 controls the gripping upper arm 312, the gripping lower arm 313, and the gripping claw 314 to rotate at a preset angle to achieve connection or disconnection with the soil sampling inner tube 33.

[0055] like Figure 1 and Figure 6 As shown, the steps of the present invention are as follows: Step 1: Secure the multi-well directional suction anchor 1. (Example) Figure 1As shown in (a), the small and medium-sized work vessel 5 controls the multi-well guide suction anchor 1 through the umbilical cable 6 and lowers it into the seawater 7. When the multi-well guide suction anchor 1 is about to contact the seabed 8, the small and medium-sized work vessel 5 positions and levels the multi-well guide suction anchor 1, and then uses the self-weight penetration and pumping penetration methods to penetrate it to the preset depth in the hydrate overlying layer 9.

[0056] Step 2: Secure the subsea drilling rig 2. (e.g.,) Figure 1 As shown in (a), the subsea drilling rig 2 is equipped with a storage rack 21. Before lowering the subsea drilling rig 2, a preset number of hollow drill rods 41, self-expanding packers 42, pre-filled gravel screens 43, soil sampling inner tubes 33, and hollow drill bits 34 are stored in the storage rack 21 of the subsea drilling rig 2 in a preset order. The small and medium-sized work vessel 1 controls the subsea drilling rig 2 through the umbilical cable 6 and lowers it into the seawater 7. When the subsea drilling rig 2 is about to contact the seabed, the small and medium-sized work vessel 1 controls it to move above the multi-well guide suction anchor 1, so that it is connected and fixed to the multi-well guide suction anchor 1 at a preset angle.

[0057] Step 3: Directional drilling. For example... Figure 1 As shown in (b), multiple guide pipes 11 are set inside the multi-well guide suction anchor 1 at a preset angle; the subsea drilling rig 2 controls the drilling tool 4 to drill along one of the multi-angle guide pipes 11 of the multi-well guide suction anchor 1 at a preset speed.

[0058] Step 4: Use ropes to collect soil. (For example...) Figure 1 (c) Figure 2 As shown, after the drilling-solid integrated hydrate extraction well 4 reaches the preset depth, the soil storage volume of the rope soil removal equipment 3 reaches the preset limit. The subsea drilling rig 2 controls the drilling tool 4 to stop drilling, and the rope soil removal equipment 3 performs soil removal and pipe replacement. Specifically, the mechanical clamp 31 descends at a preset speed to retrieve the soil-collecting inner tube 33. After the mechanical clamp 31 and the soil-collecting inner tube 33 are connected through the clamping groove 331, the mechanical clamp 31 ascends at a preset speed to retrieve the soil-collecting inner tube 33 filled with collected soil 332. After that, it is stored in the pipe rack 21 of the subsea drilling rig 2. A new soil-collecting inner tube 33 is then connected to the mechanical clamp 31 and descends at a preset speed to replace the tube. When the soil-collecting inner tube 33 descends to the bottom of the drill rig 4 and is connected to the hollow drill bit 34 through the open slot 343, the mechanical clamp 31 disconnects from the soil-collecting inner tube 33 and ascends, completing the soil collection and tube replacement. After the soil collection and tube replacement by the rope soil collection device 3 is completed, the subsea drilling rig 2 controls the drill rig 4 to continue drilling.

[0059] Step 5: Repeat drilling. (For example...) Figure 1(d) If the drill bit 4 has not drilled to the preset depth in the hydrate reservoir 10, steps 3-4 are repeated; if it has drilled to the preset depth in the hydrate reservoir 10, the subsea drilling rig 2 controls the drill bit 4 to stop drilling, and the rope-assisted soil removal device 3 controls itself to detach from the drill bit 4; specifically, the hollow drill bit 34 is disconnected from the drill bit 4 through the drill rod automatic connection and disconnection technology, and at the same time disconnected from the soil removal inner tube 33; the mechanical clamp 31 descends at a preset speed to retrieve the soil removal inner tube 33. After the mechanical clamp 31 and the soil removal inner tube 33 are connected through the clamping groove 331, the mechanical clamp 31 ascends at a preset speed. After the soil removal inner tube 33 is retrieved, it is stored in the storage rack 21 of the subsea drilling rig 2, and the mechanical clamp 31 no longer descends.

[0060] Step 6: Seal the packer through hydrolysis and self-expanding cementing. (For example...) Figure 1 (f) Figure 4 As shown, after drilling rig 4 reaches a preset depth, the self-expanding packer 42 and the pre-filled gravel screen 43 are completely buried in the hydrate reservoir 10. After a preset time, the hydrolytic protective film 423 on the self-expanding packer 42 is completely hydrolyzed, and the water-involved self-expanding rubber sleeve 422 begins to expand. After another preset time, the water-involved self-expanding rubber sleeve 422 is fully expanded, thus fixing the drilling rig 4 in the hydrate reservoir 10. At the same time, the hydrolytic plug 434 in the pre-filled gravel screen 43 is completely hydrolyzed, and the perforations 436 of the outer screen 431 and inner screen 433 are unobstructed, ensuring smooth subsequent extraction of natural gas hydrates. Drilling rig 4 can drill to the overlying layer 9, the hydrate reservoir 10, or the underlying layer 101.

[0061] Step 7: Repeat drilling. (e.g.) Figure 1 As shown in (e), the small and medium-sized operation vessel 5 controls the subsea drilling rig 2 to adjust the angle at the top of the multi-well guide suction anchor 1 through the umbilical cable 6, connects and fixes it with other preset angles of the multi-well guide suction anchor 1, and repeats steps 3-6.

[0062] Step 8: Recover the drilling rig. (For example...) Figure 1 As shown in (e), the small and medium-sized work vessel 5 controls the seabed drilling rig 2 to disconnect from the multi-well guide suction anchor 1 and retrieves the seabed drilling rig 2 through the umbilical cable 6.

[0063] Step 9: Prepare for mining. The small and medium-sized work vessel 5 is lowered and mining equipment is installed. At this point, the integrated drilling and solidification hydrate mining well 4 is ready for mining.

[0064] As can be seen from the implementation, this invention innovatively introduces a self-expanding packer and a pre-filled gravel screen into the wireline coring drilling method, realizing the integration of drilling, soil sampling, cementing, and well completion. It has the advantages of novel method, simple operation, and clear process, providing a new method for the economical and efficient exploitation of deep-sea natural gas hydrates, and can solve the problems of high cost and low efficiency in natural gas hydrate exploitation.

[0065] It should be noted that the embodiments of this application are preferred for implementation and are not intended to limit the application in any way. The technical features or combinations of technical features described in the embodiments of this application should not be considered isolated; they can be combined with each other to achieve better technical effects. The scope of the preferred embodiments of this application may also include other implementations, and this should be understood by those skilled in the art to which the embodiments of this application pertain.

[0066] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of exemplary embodiments may have different values.

[0067] The accompanying drawings in this application are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this application, and are not intended to limit the implementation conditions of this application. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this application can produce, should be within the scope covered by the technical content disclosed in this application.

[0068] The above description is merely a description of preferred embodiments of this application and is not intended to limit the scope of this application in any way. Any changes or modifications made by those skilled in the art based on the above-disclosed technical content should be considered as equivalent and valid embodiments and fall within the scope of protection of the technical solution of this application.

Claims

1. A drill-and-ground integrated drilling tool for deep-sea natural gas hydrate extraction systems, characterized in that: The subsea drilling rig (2) is equipped with a drilling tool (4) for drilling. The drilling rig (4) is mainly composed of a hollow drill pipe (41) fixedly connected from top to bottom along the axial direction, a series of cementing and completion units and a hollow drill bit (34); the hollow drill pipe (41) is connected to the preset interface of the subsea drilling rig (2), and the subsea drilling rig (2) drives the drilling rig to drill downwards, and the hollow drill bit (34) breaks through the overlying layer (9) and the hydrate reservoir (10) to drill into the underlying gas layer (101). Hollow boreholes are coaxially connected on the central axis of the hollow drill pipe (41), several cementing and completion units and the hollow drill bit (34), and the underwater soil of the overlying layer (9), hydrate reservoir (10) and underlying gas layer (101) is transported out through the hollow boreholes.

2. The drilling and cementing integrated drilling tool for deep-sea natural gas hydrate extraction systems according to claim 1, characterized in that: The cementing completion unit is mainly composed of a self-expanding packer (42) and a pre-filled gravel screen (43) connected coaxially from top to bottom along the axial direction. The hollow drill pipe (41) and the cementing completion unit, the cementing completion unit and the hollow drill bit (34), and the self-expanding packer (42) and the pre-filled gravel screen (43) are all connected coaxially by threads. Hollow drill holes are opened on the self-expanding packer (42) and the pre-filled gravel screen (43).

3. The drilling and cementing integrated drilling tool for deep-sea natural gas hydrate extraction systems according to claim 2, characterized in that: The self-expanding packer (42) includes a tubular self-expanding packer inner rod (421) and a water-swellable rubber sleeve (422). It is mainly composed of the self-expanding packer inner rod (421) and the water-swellable rubber sleeve (422) from the inside to the outside. The inner rod (421) of the self-expanding packer has the same inner and outer diameter as the hollow drill rod (41). An annular groove is provided on the outer circumferential surface. The water-swellable rubber sleeve (422) is installed in the annular groove. The hydrolyzable protective film (423) tightly wraps the outer circumferential surface of the water-swellable rubber sleeve (422). The outer diameter of the water-swellable rubber sleeve (422) under dry conditions is not greater than the outer diameter of the inner rod (421) of the self-expanding packer; the hydrolyzable protective film (423) hydrolyzes after encountering water underwater; the water-swellable rubber sleeve (422) can self-expand after encountering water underwater for a preset time; the outer diameter of the expanded water-swellable rubber sleeve (422) is not less than (1) times that of the hollow drill rod (41).

4. A drilling and cementing integrated drilling tool for deep-sea natural gas hydrate extraction systems according to claim 2, characterized in that: The pre-filled gravel screen tube (43) includes an inner screen tube (433), a pre-filled gravel layer (432), an outer screen tube (431), and a water-repellent plug (434). The inner screen tube (433) is coaxially fitted inside the outer screen tube (431). The annular gap between the inner screen tube (433) and the outer screen tube (431) is fixedly filled with the pre-filled gravel layer (432). Multiple radially penetrating perforations (436) are arranged in the same array on the circumferential surface of the inner screen tube (433) and the outer screen tube (431). A water-repellent plug (434) is provided at each perforation (436). The water-soluble plug (434) is used to temporarily plug the perforations (436) of the inner screen tube (433) and the outer screen tube (431). The water-soluble plug (434) plugs the perforations (436) under dry conditions and hydrolyzes after encountering water underwater for a preset time, thereby ensuring the smooth flow of the perforations (436) in the pre-filled gravel screen tube (43).

5. A drilling and cementing integrated drilling tool for deep-sea natural gas hydrate extraction systems according to claim 1, characterized in that: The hollow drill bit (34) includes a drill wall (341) and an annular cutting blade (342); an open slot (343) is provided on the top of the drill wall (341) of the hollow drill bit (34) for connecting with the soil sampling inner tube (33), and the annular cutting blade (342) is provided on the bottom of the drill wall (341).

6. A drilling method for deep-sea natural gas hydrate extraction using a drilling-solid integrated drilling tool as described in any of claims (1-5), characterized in that: The small and medium-sized working vessel (5) is connected to the multi-well directional suction anchor (1) and the subsea drilling rig (2) via an umbilical cable (6). The subsea drilling rig (2) controls the drilling tool (4) to drill. The rope soil removal equipment (3) is installed inside the drilling tool (4). The method is specifically carried out as follows: Step 1: Secure the suction anchor Small and medium-sized work vessels (5) control the lowering of multi-well guide suction anchors (1) to the seabed via umbilical cables (6), position and level the multi-well guide suction anchors (1), and then penetrate them to the preset depth; Step 2: Fix the drilling rig The rope soil extraction equipment (3), drilling rig (4) and subsea drilling rig (2) are combined in sequence. The subsea drilling rig (2) is lowered by the medium and small working vessel (5) through the umbilical cable (6). It is then connected and fixed to the multi-well guide suction anchor (1) at a preset angle. Step 3: Directional Drilling The subsea drilling rig (2) controls the drilling tool (4) to drill along the preset direction of the guide pipe (11) set in the multi-well guide suction anchor (1); Step 4: Using ropes to collect soil After the drilling rig (4) drills to the preset depth, the amount of soil stored in the rope soil removal device (3) reaches the preset limit. The subsea drilling rig (2) controls the drilling rig (4) to stop drilling and uses the rope soil removal device (3) to remove soil and replace pipes. Then the subsea drilling rig (2) controls the drilling rig (4) to continue drilling. Step 5: Repeat drilling If the drilling tool (4) fails to drill to the preset depth, repeat steps 3-4; If the drilling has reached the preset depth, the subsea drilling rig (2) controls the drilling tool (4) to stop drilling, and the rope soil removal equipment (3) controls itself to detach from the drilling tool (4). Step 6: Cementing Completion The drilling tool (4) performs cementing and well completion at a preset depth; Step 7: Repeat drilling Small and medium-sized work vessels (5) control the seabed drilling rig (2) to adjust the angle through the umbilical cable (6), connect and fix it with other preset angles of the multi-well guide suction anchor (1), repeat steps 3-6, and complete the drilling, cementing and well completion process of the drilling rig (4) multiple times. Step 8: Recover the drilling rig Small and medium-sized work vessels (5) retrieve the seabed drilling rig (2) via umbilical cable (6); Step 9: Prepare for mining Small and medium-sized work vessels (5) are lowered and mining equipment is installed. At this time, the drilling rig (4) is ready for mining. This method can also be used as a drilling and cementing integrated drilling method for deep-sea energy drilling and extraction such as offshore oil, natural gas, and hydrogen, as needed.

7. The drilling-solidification integrated drilling method according to claim 6, characterized in that: The multi-well directional suction anchor (1) includes a top cover and an outer cylindrical body. The top cover is fixed to the upper end of the outer cylindrical body to form an integral cylindrical shell structure with an open lower end and a closed upper end. An inclined guide tube (102), a straight guide tube (103), and a stiffening plate (106) are arranged inside the cylindrical shell structure. A straight guide tube (103) is arranged on the central axis of the cylindrical shell structure of the multi-well directional suction anchor (1). The upper ends of the straight guide tube (103) and the inclined guide tube (102) are fixed to the top cover. Multiple inclined guide tubes (102) are arranged around the straight guide tube (103). Each inclined guide tube (102) is arranged at an angle. The guide pipes (102) are evenly distributed circumferentially, and each inclined guide pipe (102) is arranged symmetrically around the straight guide pipe (103) as the center, so that each inclined guide pipe (102) is radially distributed and extends from top to bottom; the upper side of each inclined guide pipe (102) is fixedly connected to the top cover and the inner wall of the outer peripheral cylinder through a vertical stiffening plate (106) to form a force-bearing unit; the multi-well guide suction anchor (1) is provided with a preset support leg slot (107) for connecting and fixing the support legs of the subsea drilling rig (2) on the top cover near the pipe opening of the inclined guide pipe (102) and the pipe opening of the straight guide pipe (103).

8. The drilling-solidification integrated drilling method according to claim 6 or 7, characterized in that: The rope-driven soil extraction device (3) includes a mechanical clamp (31), a retrieval rope (32), and a soil extraction inner tube (33). The mechanical clamp (31) extends into the hollow borehole inside the drill bit (4), and the mechanical clamp (31) is connected to the subsea drilling rig (2) via the retrieval rope (32). The soil extraction inner tube (33) is installed in the hollow borehole inside the drill bit (4), and the upper end of the soil extraction inner tube (33) is provided with a clamping groove (331) for cooperating with the mechanical clamp (31). The hollow drill bit (33) of the drill bit (4) 4) An open slot (343) is provided at the top for connecting with the soil sampling inner tube (33). The lower end of the soil sampling inner tube (33) is connected to the hollow drill bit (34) of the drilling tool (4) through the open slot (343). The mechanical clamp (31) includes a mechanical inner machine (311) and multiple clamping arms. The mechanical inner machine (311) is provided with clamping arms evenly distributed on at least two sides along the circumference. Each clamping arm is mainly composed of a clamping upper arm (312), a clamping lower arm (313), and a clamping claw (314) connected in sequence by hinges.

9. The drilling-solidification integrated drilling method according to claim 6, characterized in that: Step 4 includes: When the mechanical gripper (31) descends to retrieve the soil-collecting inner pipe (33), it descends at a preset speed; after the lower end of the mechanical gripper (31) is connected to the soil-collecting inner pipe (33) through the gripping groove (331), the mechanical gripper (31) moves upward; after the soil-collecting inner pipe (33) is taken out using the mechanical gripper (31), it is placed on the pipe storage rack (21) of the subsea drilling rig (2), and a new soil-collecting inner pipe (33) is connected to the lower end of the mechanical gripper (31) to replace the pipe, and then it moves downward again; Furthermore, when the drilling rig (4) is drilling, the soil extraction inner tube (33) is connected to the hollow drill bit (34) of the drilling rig (4) through the open slot (343), and is disconnected when extracting soil, so as to extract soil during the drilling process.

10. The drilling-solidification integrated drilling method according to claim 6, characterized in that: Step 6 includes: After drilling to the preset depth, the self-expanding packer (42) and the pre-filled gravel screen (43) in the drill bit (4) are completely buried in the hydrate reservoir (10). After a preset time, the hydrolytic protective film (423) on the self-expanding packer (42) is completely hydrolyzed. The self-expanding rubber sleeve (422) starts to expand when it comes into contact with water. After another preset time, the self-expanding rubber sleeve (422) expands completely when it comes into contact with water, thus achieving the goal of not expanding during drilling and expanding after drilling is completed, thereby fixing the drill bit (4) in the hydrate reservoir (10). At the same time, the hydrolytic blockage (434) in the pre-filled gravel screen tube (43) is completely hydrolyzed, and the perforations (436) of the outer screen tube (431) and the inner screen tube (433) are unobstructed.

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