A seabed strata trenchless excavation system and method of operation

Abstract

The application discloses a seabed stratum trenchless mining system and a working method, and belongs to the technical field of marine resource development. The system comprises a seabed stratum targeted mining system, an extended mining device and an underwater transfer station. The method comprises the following steps: arranging the seabed stratum targeted mining system on the seabed; drilling a guide well in the seabed stratum through the seabed stratum targeted mining system; mining the seabed soft bottom layer around the guide well through the extended mining device; and conveying the ore particles or ore slurry formed by the mining to the underwater transfer station for treatment through the circulation of the circulating fluid in the circulating loop. The working mode of the application is "extending the in-well mining device out of the guide well, disturbing or breaking the stratum, and returning the particle flow or ore slurry", which does not need to maintain a large-size permanent roadway for a long time, can effectively reduce the collapse risk under the seabed stratum environment, reduce the seabed surface disturbance and sediment plume diffusion, and realize the low-disturbance, high-directional and high-continuous mining of the seabed soft bottom layer mineral.

Description

Technical Field

[0001] This invention relates to the field of marine resource development technology, and in particular to a trenchless mining system and method for seabed strata. Background Technology

[0002] In the field of deep-sea mineral resource development, the commercial exploitation of seabed polymetallic nodules, cobalt-rich crusts, and hydrothermal sulfides has become a cutting-edge research focus in global marine engineering. Existing seabed mining technologies can be mainly categorized into the following three types: The first category is subsea mechanical mining systems. Current deep-sea mining commonly employs ore collection vehicles, hydraulic pumping and hoisting, mechanical cutting heads, and pipeline hoisting systems. These systems primarily target polymetallic nodules, seabed sulfides, and cobalt-rich crusts. The operational process involves the subsea ore collection vehicle moving forward, the mechanical head breaking up seabed minerals, hydraulic pumping to form slurry, and then transporting the slurry to the mother ship via riser. For example, deep-sea mining systems disclosed by companies such as Nautilus Minerals, Royal IHC, and SMD (Soil Machine Dynamics) typically use subsea ore collection vehicles to mechanically cut, disturb, and collect slurry on the seabed surface, then transport it to a surface platform via a riser system. This type of technology mainly targets surface mineral extraction, and its core method is "surface-based mobile mining," without addressing long-distance horizontal directional drilling or continuous drilling and pumping methods within soft seabed sedimentary layers. Furthermore, this type of approach is prone to causing large-scale seabed disturbance and sediment plume diffusion problems in soft seabed environments.

[0003] The second category is horizontal directional drilling (HDD). This technology is primarily used for oil and gas drilling, pipeline crossings, and shallow underground pipeline laying. Its core structure includes a directional drill bit, drill pipe, mud circulation system, and directional control system. The construction process involves directional drilling, reaming, and pullback. For example, HDD systems disclosed by companies such as Vermeer Corporation, Ditch Witch, and XCMG Group typically include a directional drill bit, drill pipe propulsion mechanism, mud circulation system, and attitude control system. Their primary purpose is to create underground horizontal channels, not for seabed mineral resource extraction. While this technology possesses long-distance horizontal drilling capabilities, it lacks a disturbance-based extraction structure in soft seabed sediment layers and fails to address the continuous slurry transport problem in soft subsurface environments. Therefore, its application is not suitable for seabed soft-layer mining scenarios.

[0004] The third category is subsea drilling and mining technology. While vertical wells, jet disturbance, and pumping methods are used in the extraction of subsea natural gas hydrates and shallow minerals, they generally lack the capability for long horizontal sections and continuous horizontal extraction, and are difficult to apply to large-scale extraction of soft seabed sediments. For example, literature on hydrate extraction discloses decompression extraction, hydraulic disturbance, and fluidized bed extraction techniques, but these are mainly for vertical wellbore operations or localized extraction, and have not developed into a directional drilling-pumping coupling system suitable for long horizontal sections of continuous extraction in soft seabed layers.

[0005] In summary, the existing technology has the following shortcomings: Firstly, existing seabed mining technologies mainly employ mechanical ore collection on the seabed surface and vertical suction, which cannot form stable, long-distance horizontal collection channels within the soft sedimentary layer of the seabed. Due to the low bearing capacity of the soft bottom layer and the ease with which the channels collapse, traditional drilling systems struggle to maintain effective transport space, further leading to decreased suction efficiency, increased risk of blockage, and insufficient continuous mining capacity.

[0006] Secondly, existing mining methods cause large disturbances, and surface ore collection operations on the seabed are prone to triggering large-scale seabed sediment plumes. Traditional vertical shaft mining has a limited coverage area and requires frequent well placement during operations. At the same time, mining using mechanical cutting methods also has the problem of high energy consumption.

[0007] Thirdly, while drilling operations are possible on land, there is currently no technology for excavating soil in soft strata through wells; in the field of drilling technology for shallow mudstone on the seabed, there is still a lack of technical solutions for drilling shallow horizontal holes; and there is absolutely no record of technology for drilling and excavating soil in soft sedimentary layers on the seabed.

[0008] Given the limitations of the existing technologies, there is an urgent need for a mining system and operation method that can achieve long-distance horizontal directional drilling, continuous sampling while drilling and pumping, and minimal disturbance to the seabed within soft sedimentary layers on the seabed. Summary of the Invention

[0009] The purpose of this invention is to provide a trenchless seabed strata mining system and operation method to solve the problems of existing seabed mining technologies, such as large surface disturbance of the seabed, easy to cause plume diffusion, difficulty in achieving long-distance continuous directional collection in soft sediment layers, easy collapse and blockage of slurry transport channels, easy leakage of circulating fluids, inability to develop mineral resources inside the strata below the ocean, and high energy consumption.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention discloses a trenchless mining system for seabed formations, including a pilot well, a targeted mining system for seabed formations, an extended mining device, and an underwater transfer station; The seabed strata targeted mining system is used to lower and retrieve the extended mining device, and to provide power to the extended mining device so that the extended mining device can carry out mining operations based on the pilot well; The extended mining device works in conjunction with the seabed strata targeted mining system to mine the seabed strata surrounding the pilot well; The underwater transfer station is connected to the seabed strata targeted mining system and is used to process or transport the mined ore particles or slurry.

[0011] Furthermore, this also includes service tubing or continuous tubing; The service string or continuous pipe is connected in front of the seabed formation targeted mining system; the extended mining device is located in front of the service string or continuous pipe, and the service string or continuous pipe is used to provide the extended mining device with a fluid transport channel, a solid particle transport channel and / or mining power.

[0012] Furthermore, a circulation loop is formed between the underwater transfer station and the seabed strata targeted mining system, and circulating fluid flows inside the circulation loop to transport the ore particles or slurry to the underwater transfer station.

[0013] Furthermore, the extended mining device is a three-dimensional mining arm, which is disposed at the front of the service string or the continuous pipe; the three-dimensional mining arm can extend outward along the radial direction of the service string or the continuous pipe to mine the soft seabed around the service string or the continuous pipe. The three-dimensional mining arm includes at least one deflection control mechanism, which is used to drive the three-dimensional mining arm to extend or deploy laterally toward the pilot well.

[0014] Furthermore, the three-dimensional mining arm also includes a telescopic control mechanism, which is used to control the telescopic feed of the three-dimensional mining arm.

[0015] Furthermore, the three-dimensional mining arm is connected to the traveling body, which is located inside the guide well hole of the guide well.

[0016] Furthermore, it also includes a propulsion mechanism, which is located on the side or rear of the traveling body and is used to propel the extended mining device to excavate, while also pulling the continuous pipe forward.

[0017] Furthermore, the extended mining device includes multiple sections, each section is connected by a hinge, and a crushing assembly is installed at the front end of the first section of the tubing at the foremost end. The crushing assembly includes a tunneling head, a suction assembly or a jet crushing assembly. A controllable deflection device is provided between the crushing assembly and the first section, or a controllable deflection device is provided between the first section and the second section. It also includes an azimuth rotation device, which is connected in series in the extended mining device or disposed behind the extended mining device, for driving the extended mining device to rotate along its own axis. The extended mining device utilizes its ability to bend laterally to drill laterally from the guide well and excavate the rock mass lateral to the guide well.

[0018] Furthermore, the front end or side of the extended mining device is provided with a suction assembly and / or a crushing assembly; The auger assembly is located at the front end of the extended mining device, and the extended mining device is provided with a return flow channel; the return flow channel is connected to the backflow channel inside the continuous tube, or the return flow channel is connected to the backflow channel inside the service string. Alternatively, when the crushing assembly is located at the front end or side of the extended mining device, the crushing assembly is a mechanical crushing assembly or a jet crushing assembly; The three-dimensional mining arm is connected to the traveling body and has an ore particle inlet. The ore particle inlet is connected to the backflow channel inside the continuous tube and is used to discharge the ore particles generated by crushing through the continuous tube. Alternatively, the front of the service column is provided with an ore particle inlet, which is connected to the backflow channel inside the service column, for discharging ore particles generated by disturbance and crushing through the service column.

[0019] Furthermore, the continuous pipe includes at least two continuous pipes; wherein, the first continuous pipe is used as a return flow channel for conveying the produced solid-liquid two-phase flow or slurry to the outside of the wellhead; the second continuous pipe is used as an injection flow channel, the front end of which is connected to the crushing assembly or the suction assembly for spraying jets onto the rock wall.

[0020] Furthermore, it also includes a pulping device, which is installed inside the extended mining device and is used to further grind and pulp the rock particles sucked into the extended mining device.

[0021] Furthermore, it also includes a ring drill bit, which is located at the rear of the extended mining device and is used to reverse-break the strata during the retrieval of the extended mining device to avoid jamming.

[0022] Furthermore, the seabed strata targeted mining system includes a pipe delivery mechanism for coordinating the lowering and retrieval of the continuous pipe; The service string is connected to the front end of the delivery mechanism, which drives the service string to move along the wellbore direction. The extended mining device is movable relative to the service string to mine the soft seabed strata surrounding the service string. The pipe delivery mechanism drives the three-dimensional mining arm to move along the wellbore by driving the service string. It also includes a feeding mechanism, which is disposed inside the service string or cooperates with the service string, for driving the extended mining device to move relative to the service string; The front of the service string is provided with a window for the extension mining device to extend or retract.

[0023] Furthermore, the pipe delivery mechanism is a pipe handling system, which includes a drill bit for connecting and disconnecting drill rods and pipe laying equipment for connecting, lowering or disassembling and recycling the service string.

[0024] Furthermore, the service string is provided with an annular bladder on the outside, and the annular bladder is provided with a filling space inside, which is used to achieve expansion by injecting fluid during mining operations.

[0025] Furthermore, the rear part of the extended mining device is located inside the pilot well, and is supported by the well wall, enabling the extended mining device to excavate the rock strata surrounding the pilot well; or, the rear part of the extended mining device is inserted into the service string, and is supported by the service string.

[0026] Furthermore, it also includes a base, on which an angle adjustment mechanism is provided. The pipe delivery mechanism is adjustablely mounted on the base and is used to push the service string into the seafloor strata at an inclined angle to form a wellbore with a controllable trajectory. The base is also provided with support legs at its lower part to stabilize the base; the base is also provided with a pipe-holding module to hold the pipe when it is being raised or lowered from the seabed.

[0027] Furthermore, the service string is equipped with an injection channel and a return channel. The injection channel is used to inject circulating fluid into the well, and the return channel is used to return the mined ore particles or slurry to the underwater transfer station. The front of the service string is provided with a window for ore particles to flow in. After the circulating fluid is ejected from the crushing assembly, it carries the ore particles into the window provided at the front of the service string and flows back to the subsea wellhead within the service string.

[0028] Furthermore, the service string adopts a dual-tube structure, which includes an outer tube and an inner tube. The circulating fluid is injected downhole through the annulus between the outer tube and the inner tube, and the slurry is returned through the inside of the inner tube.

[0029] Furthermore, the rear end of the service tubing or continuous tubing is connected to the inlet of the underwater transfer station via a pipeline; The underwater transfer station re-injects the separated seawater into the injection channel within the continuous pipe or the service string, forming a circulation loop with the seabed strata targeted mining system and the extended mining device. The circulating fluid flows within the circulation loop to transport the ore particles or slurry to the underwater transfer station.

[0030] Furthermore, it also includes a seabed monitoring and control system, which includes a location information transceiver system. The location information transceiver system includes a seabed-end location information transceiver system installed on the seabed surface and a downhole-end location information transceiver system installed on the extended mining device or the service string. The location information transceiver system includes at least one of a magnetic beacon, an acoustic emission device, or an electromagnetic wave emission device as a signal transmitting end, and / or includes at least one of a magnetic sensor, an acoustic sensor, or an electromagnetic wave sensor as a signal receiving end.

[0031] Furthermore, it also includes a surface service platform, which is connected to the seabed strata targeted mining system and the underwater transfer station by a power cable to provide power for seabed mining and underwater mineral processing.

[0032] Furthermore, the underwater transfer station is located on or near the seabed surface, and the underwater transfer station includes at least one of the following: an underwater ore particle crushing device, an underwater booster pump, an underwater ore particle flow stirring device, and / or an underwater ore particle flow pressure stabilizing device. The underwater ore particle crushing device is used to crush ore particles to the millimeter or sub-millimeter level to facilitate the formation of slurry, which is then transported to the lifting riser via an underwater booster pump. It also includes a lift-up riser and a service vessel, with the underwater transfer station connected to the service vessel via the lift-up riser.

[0033] A method for targeted wellbore mining operations in subsea formations, employing a trenchless subsea formation mining system, includes the following steps: The seabed strata targeted mining system is deployed on the seabed; A pilot well is formed in the seabed strata using the aforementioned targeted mining system. The extended mining device is used to excavate the soft seabed around the pilot well; The service string or coiled tubing is lowered into the pilot well through the subsea formation targeted mining system, and the extended mining device is sent into the pilot well through the service string or coiled tubing. The ore particles or slurry formed by mining are transported to the underwater transfer station for processing by circulating fluid flowing in the circulation loop.

[0034] Furthermore, the method employs a closed-loop retraction operation mode or a through-loop drag-back enlargement operation mode. In the closed-loop retraction operation mode, the service string adopts a single-tube structure or a double-tube structure. When using a single-tube structure, circulating fluid is injected downhole through the inside of the service string, and slurry is returned through the annulus between the service string and the borehole wall. When using a double-tube structure, circulating fluid is injected downhole through the annulus between the outer and inner tubes, and slurry is returned through the inside of the inner tube. The drill bit and the service string enter the target formation, move horizontally underground to the target area for flushing and collection, and then retreat along the original path after completion. In the through-pullback reaming operation mode, the drill bit penetrates the target formation and drills out from the other end of the seabed to form a second wellhead. A reaming and pullback device is installed at the outcrop end to perform rotary pullback reaming and mineral collection simultaneously during the pullback process. When the service string adopts a single-tube structure, slurry is pumped through the drill pipe, or assisted by pumping at the outcrop end, or high-pressure injection is used to enhance transportation. When the service string adopts a double-tube structure, the outer tube continuously provides hydraulic assistance, and the inner tube continuously transports slurry.

[0035] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1) Enables long-distance continuous mining of soft seabed layers. Existing seabed mining relies heavily on mechanical ore collection at the seabed surface, making it impossible to construct stable and continuous collection paths within soft sedimentary layers. This invention employs horizontal directional drilling technology, which can form long-distance horizontal collection channels in the soft seabed, enabling continuous directional mining and expanding the coverage area of ​​single-well operations. 2) Effectively reduces the risk of borehole collapse and blockage in soft seabed layers. Traditional drilling methods are prone to collapse in soft seabed layers due to prolonged exposure of the borehole. This invention adopts a synchronous continuous operation mode of "extending the guide hole - disturbing or breaking the strata - returning the particle flow or slurry." The slurry is pumped and transported immediately after its generation, eliminating the need to retain long-term permanent boreholes and significantly reducing the risk of borehole collapse and pipeline blockage. 3) Significantly reduces the range of seabed surface disturbance. Existing ore collection equipment mostly conducts large-area mechanical operations on the seabed surface. This invention addresses several issues: 1) It improves the continuity of mining operations and the stability of slurry transport by integrating disturbance nozzles and suction inlets at the drilling front end, enabling continuous drilling and mining operations while avoiding transport interruptions common in traditional intermittent mining. 2) It reduces energy consumption and equipment wear during mechanical cutting by using fluid disturbance to fluidize the sediment layer, replacing the traditional heavy machinery crushing and cutting mode, effectively reducing workload, equipment wear, and overall energy consumption. 3) It adapts to the development needs of large-scale seabed soft sediment resources by relying on a horizontally extended collection mode, which can meet the needs of large-scale continuous mining of widely distributed mineral resources such as rare earth mud, fine-grained minerals, and rich ore soft sediment layers. 4) The integrated service string and extended mining device of the seabed targeted mining system can form a highly integrated seabed mining equipment, which can greatly simplify seabed construction and minimize the size of equipment to be deployed to the seabed. 8) Using well shafts for mining facilitates the maintenance of the sealing of the mining system and allows mining operations to be carried out while being isolated from the marine water environment. Attached Figure Description

[0036] The present invention will be further described below with reference to the accompanying drawings.

[0037] Figure 1 This is a schematic diagram of the continuous pipe structure used in the trenchless mining system for seabed strata of the present invention; Figure 2 This is a schematic diagram of the propulsion mechanism, continuous tube, crushing assembly, and three-dimensional mining arm of the present invention. Figure 3 This is a schematic diagram of the structure of the seabed strata targeted mining system and extended mining device of the present invention; Figure 4 This is a schematic diagram of the structure of the seabed strata targeted mining system of the present invention; Figure 5 This is a schematic diagram of the pipe handling system and service pipe column of the present invention; Figure 6 This is a schematic diagram of the feeding mechanism, service string, and extended mining device of the present invention; Figure 7 This is a schematic diagram of the structure of the seabed strata targeted mining system of the present invention; Figure 8 This is a schematic diagram of the mining system for soft strata according to the present invention; Figure 9 This is a schematic diagram of another mining system for soft strata according to the present invention; Figure 10 This is a schematic diagram of the rake mechanism of the present invention; Figure 11 This is a partial structural schematic diagram of the rake mechanism of the present invention; Figure 12 This is a schematic diagram of the structure of the hopper of the present invention.

[0038] Explanation of reference numerals in the attached drawings: 11. Seabed strata; 12. Seabed surface; 14. Lifting riser; 15. Power cable; 16. Hopper; 2. Pilot well; 3. Subsea Targeted Excavation System; 31. Pipe Feeding Mechanism; 311. Continuous Tube Drum; 312. Tube Processing System; 32. Service String; 321. Return Flow Channel; 33. Base; 34. Support Leg; 35. String Reception Module; 36. Feeding Mechanism; 37. Scraping Mechanism; 371. Traction Cable; 372. Winch; 38. Propulsion Mechanism; 381. Support Piston; 382. Propulsion Piston; 383. Traveling Rail; 39. Continuous Tube; 4. Extended mining device; 41. Crushing assembly; 42. Three-dimensional mining arm; 421. Deflection control mechanism; 422. Telescopic control mechanism; 43. Azimuth rotation device; 431. Azimuth drive motor; 432. Centering bearing; 433. Fixing part; 434. Azimuth angle rotation part; 44. Excavation assembly; 441. High-pressure flow channel of excavator head; 442. Crushing structure; 45. Nozzle; 46. Conversion flow channel; 47. Annular partition. Detailed Implementation

[0039] like Figure 1-12 As shown, a trenchless seabed strata mining system mainly consists of three parts: a seabed strata targeted mining system 3, an extended mining device 4, and an underwater transfer station.

[0040] The seabed strata targeted mining system 3 is deployed on the seabed surface 12 and is used to drill a pilot well 2 in the seabed strata 11, and use this as the working base point to carry out directional drilling and mining towards the target mineral layer or soft sediment layer.

[0041] The seafloor strata targeted mining system 3 is used to lower and retrieve the extended mining device 4, and to provide power to the extended mining device 4, enabling it to carry out mining operations based on the guide well 2. The extended mining device 4 cooperates with the seafloor strata targeted mining system 3 to mine the seafloor strata surrounding the guide well 2. Specifically, the extended mining device 4 is connected to the front end of the seafloor strata targeted mining system 3, and under the pushing and guiding action of the targeted mining system 3, it enters the target strata along the guide well 2 to mine the soft seafloor strata surrounding the guide well 2.

[0042] The underwater transfer station is located on or near the seabed surface 12 and is connected to the seabed strata targeted mining system 3 via pipelines. It receives mined ore particles or slurry and performs preliminary processing, including pumping, agitation, and / or solid-liquid separation. The underwater transfer station can also be a discontinuous transfer station; for example, hopper 16 can also serve as a form of underwater transfer station. Mined ore temporarily falls into hopper 16, and the mining vessel lifts the hopper onto the vessel using a hoisting device, or other methods are used to lift the hopper onto the mining vessel.

[0043] During operation, the subsea strata targeted mining system 3 lowers the extended mining device 4 to the target stratum depth via service string 32 or continuous pipe 39. The extended mining device 4 deploys and mines at the target stratum. The mined ore particles or slurry are returned to the underwater transfer station via the return flow channel inside the service string 32 or continuous pipe 39. Simultaneously, circulating fluid forms a loop between the underwater transfer station, the subsea strata targeted mining system 3, and the extended mining device 4, enabling continuous mining-transportation-separation operations.

[0044] The pilot well 2 is a preliminary borehole extending from the seabed surface 12 into the interior of the seafloor strata 11. Its diameter is larger than the outer diameter of the service string 32 or the continuous tubing 39, and it is used to provide an initial passage and guiding reference for subsequent mining operations. The pilot well 2 can be a vertical well, a directional well, or a horizontal well, and its specific trajectory is determined according to the spatial distribution of the target ore layer.

[0045] like Figure 1 As shown, the seabed strata targeted excavation system 3 is first deployed at the predetermined operating location on the seabed surface 12. For example... Figure 4 As shown, the seabed strata targeted mining system 3 includes a base 33, with support legs 34 installed on the lower part of the base 33. The support legs 34 are used to stabilize the base, and the base 33 is stabilized to the seabed surface 12 by the support legs 34. The base 33 is provided with a pipe delivery mechanism 31, a pipe string receiving module 35, and a feeding mechanism 36. The pipe string receiving module 35 is used to receive the pipe string when it is being raised and lowered on the seabed.

[0046] It also includes a service string 32 or a continuous tubing 39; the service string 32 or the continuous tubing 39 is connected to the front of the subsea formation targeted mining system 3; the extended mining device 4 is disposed in front of the service string 32 or the continuous tubing 39, and is used to provide the extended mining device 4 with a fluid transport channel, a solid particle transport channel, and / or mining power. In this specific implementation, the extended mining device 4 can crawl inside the service string 32 to move to the front end of the service string 32, or be pushed to the front end of the service string 32 by other tubing, or the extended mining device 4 is fixedly disposed at the front end of the service string 32 and is lowered into the pilot well or drilling pilot well together with the service string 32.

[0047] As an optional implementation, to adapt to mineral layers with different occurrences, the base 33 is provided with an angle adjustment mechanism, and the pipe delivery mechanism 31 is adjustablely disposed on the base 33 for pushing the service string 32 into the seafloor strata 11 along an inclined angle to form a wellbore with a controllable trajectory.

[0048] The seabed strata targeted mining system 3 includes a pipe delivery mechanism 31, which is a continuous pipe drum 311, used to cooperate in lowering and retrieving the continuous pipe 39; the continuous pipe 39 is wound on the continuous pipe drum 311, and the lowering and retrieval of the continuous pipe 39 is achieved by the forward and reverse rotation of the drum, which has the characteristics of good operation continuity and fast lifting and lowering speed.

[0049] This system also includes a propulsion mechanism, which is located on the side or rear of the traveling body. This mechanism propels the extended mining device 4 to excavate and simultaneously pulls the continuous pipe 39 forward. Figure 2 As shown, the propulsion mechanism includes a support piston 381, a propulsion piston 382, ​​and a travel rail 383. When moving forward, the following steps are performed: (1) the rear support piston 381 presses against the well wall, and the front support piston 381 is in a relaxed loading state; (2) the propulsion piston 382 propels the three-dimensional mining arm 42 forward; (3) the front support piston 381 is driven to press against the well wall, and the rear support piston 381 returns to a relaxed state; the propulsion piston 382 is driven to reset.

[0050] The extended mining device 4 is a three-dimensional mining arm 42, which is located at the front of the service string 32 or the continuous pipe 39. The three-dimensional mining arm 42 can extend outward along the radial direction of the service string 32 or the continuous pipe 39 to mine the soft seabed around the service string 32 or the continuous pipe 39.

[0051] The three-dimensional mining arm 42 includes at least one deflection control mechanism 421, which is used to drive the three-dimensional mining arm 42 to extend or deploy laterally toward the pilot well.

[0052] In another embodiment, such as Figure 2 As shown, the three-dimensional mining arm 42 includes a deflection control mechanism 421 and a telescopic control mechanism 422. The deflection control mechanism 421 is used to control the three-dimensional mining arm 42 to extend or unfold laterally toward the guide shaft, and the telescopic control mechanism 422 is used to control the telescopic feed of the three-dimensional mining arm 42.

[0053] Specifically, the three-dimensional mining arm 42 is connected to the traveling body, which is located within the guide wellbore of the guide well 2. A deflection control mechanism 421, which is a hydraulic or electric cylinder, is provided between the three-dimensional mining arm 42 and the traveling body to control the extension of the three-dimensional mining arm 42 relative to the traveling body, thereby achieving the effect of breaking the rock mass surrounding the guide well. The telescopic control mechanism 422 adds a control variable to assist the feed of the drill bit.

[0054] As an optional implementation, the extended mining device 4 includes multiple sections, each section being hinged together. A crushing assembly 41 is installed at the front end of the foremost first section of the casing. The crushing assembly 41 includes a tunneling head, a suction assembly, or a jet crushing assembly. A controllable deflection device is provided between the crushing assembly 41 and the first section, or between the first and second sections. It also includes an azimuth rotation device 43, which is connected in series within the extended mining device 4 or located behind the extended mining device 4, for driving the extended mining device 4 to rotate along its own axis. The extended mining device 4 utilizes its ability to bend laterally to drill laterally from the pilot well, thereby mining the rock mass lateral to the pilot well. For soft formations and unformed formations, at least two sections are equipped with suction assemblies or jet fracturing assemblies, which can disturb the formation over a larger area and draw the fluidized formation into the extended mining device 4, and extract it along the service string 32.

[0055] The end of the extended mining device 4 is equipped with a mining head, the diameter of which is between 0.3 and 2 meters. It achieves mining effect by reciprocating lateral drilling based on the guide well 2.

[0056] The front end or side of the extended mining device 4 is provided with a suction assembly and / or a crushing assembly 41; specifically implemented in the following manner: (a) Implementation method for setting up the hinge assembly: The auger assembly is located at the front end of the extended mining device 4, and the extended mining device 4 is provided with a return flow channel 321 inside.

[0057] When the continuous tube 39 scheme is adopted, the return channel 321 is connected to the return flow channel inside the continuous tube 39. The ore particles enter the return flow channel of the continuous tube 39 through the return channel 321 and are returned to the seabed wellhead through the continuous tube 39.

[0058] When the service string 32 scheme is adopted, the return channel 321 is connected to the return flow channel inside the service string 32. The ore particles enter the return flow channel of the service string 32 through the return channel 321 and are returned to the subsea wellhead through the service string 32.

[0059] (II) Implementation method for setting up the crushing assembly: When the crushing assembly 41 is located at the front end or side of the extended mining device 4, the crushing assembly 41 is a mechanical crushing assembly or a jet crushing assembly.

[0060] When a mechanical fracturing assembly is used, it includes a rotary drill bit or cutter head, which breaks the formation into particles through rotary cutting. When a jet fracturing assembly is used, it includes a high-pressure nozzle, which impacts the formation with a high-pressure water jet, causing the formation to peel off in the form of particles.

[0061] like Figure 8 , 9 As shown, when the target of mining is an unformed soft stratum, the extended mining device 4 includes at least two sections, forming a three-dimensional mining arm 42 composed of two or more sections. The end of the three-dimensional mining arm 42 is equipped with a mining assembly 44, which includes... Figure 8 The mechanical excavator assembly shown can also be, for example... Figure 9 The jet excavation assembly shown is an example of a jet excavation assembly 44. The excavation assembly 44 is a type of the crushing assembly 41. The excavation assembly 44 is mainly used for softer unformed rock strata and is used to excavate unformed rock strata by means of water jet disturbance, mechanical agitation, or excavation. The crushing assembly 41 and the excavation assembly 44 are interchangeable.

[0062] The extended mining device 4 adopts a three-dimensional mining arm 42. The three-dimensional mining arm 42 includes, from back to front, an azimuth rotation device 43, a conversion channel 46, a deflection control mechanism 421, and a mining assembly 44. A nozzle 45 is provided on the front side wall. The rear end of the three-dimensional mining arm 42 is connected to the dual-channel service string 32.

[0063] The azimuth rotation device 43 includes a fixing part 433 and an azimuth angle rotation part 434. The fixing part 433 is connected to the service column 32, and the azimuth angle rotation part 434 is connected to the three-dimensional mining arm 42. The fixing part 433 and the azimuth angle rotation part 434 are rotatably connected by a centering bearing 432. The drive motor 431 built into the azimuth rotation device 43 is used to drive the azimuth angle rotation part 434 to rotate, thereby driving the three-dimensional mining arm 42 to rotate around the service column 32 as the axis.

[0064] The azimuth rotation device 43 is located at the rear of the three-dimensional mining arm 42, connected in series between the three-dimensional mining arm 42 and the dual-channel service string 32. It drives the components in front of it to rotate around the axis of the three-dimensional mining arm 42, adjusting the circumferential orientation of the excavation assembly 44. Both the injected and drained fluids pass through the outer annulus of the three-dimensional mining arm 42 itself. The azimuth rotation device 43 is equipped with a rotational sealing structure to keep the two halves of the annulus connected and prevent cross-flow during rotation.

[0065] The deflection control mechanism 421 is located in front of the azimuth rotation device 43 and is an articulated structure. It is driven by a hydraulic cylinder or an electric cylinder, causing the excavation assembly 44 to swing laterally relative to the rear section of the three-dimensional mining arm 42, extending laterally into the surrounding formation from the guide well 2. The azimuth rotation device 43 can change the azimuth angle of the deflection control mechanism 421, allowing it to move in different ranges in directions away from the axis of the service string 32.

[0066] The excavation assembly 44 is located at the foremost end of the three-dimensional mining arm 42. A crushing structure 442 is provided on its outer circumference, and a high-pressure flow channel 441 for the excavation head is located inside. The high-pressure flow channel 441 of the excavation head is connected to a hydraulic motor within the excavation assembly 44. The hydraulic motor can be a turbine type or a screw type. Pressurized mud drives the hydraulic motor through the high-pressure flow channel 441 of the excavation head, causing the excavation assembly 44 to rotate. The crushing structure 442 rotates and scrapes the strata, removing soft strata and fluidizing them. During operation, the three-dimensional mining arm 42 has three directional movements: the azimuth rotation device 43 rotates around its own axis to select the azimuth; the deflection control mechanism 421 oscillates laterally to control the extension depth and angle; and the feeding mechanism 36 moves along the borehole axis to transfer the mining position. These three mechanisms work together to achieve directional mining of the strata surrounding the guide well 2. (Example: Soil 8...) Figure 9 The proposed solution is primarily used for the excavation of soft seafloor strata, including deep-sea unformed sedimentary layers, seafloor sedimentary mud, and seafloor rare earth mud. The soft mud has low strength and can be easily peeled off using the rotating scraper of the crushing structure 442, without requiring extensive crushing and cutting. This results in lower energy consumption and torque, and it is less prone to forming mud bales. Combined with the jetting nozzle 45 and in-situ suction and return, it can minimize disturbance to the seabed.

[0067] The three-dimensional mining arm 42 has a double-layer pipe structure with an inner layer being an internal flow channel, and the outer annulus being divided into two unconnected halves by an annulus partition 47, with part being injected and part being returned.

[0068] The conversion channel 46 is located at the front end of the injection-side semi-annulus, transferring the mud in this semi-annulus into the internal channel, and then to the high-pressure channel 441 of the excavator head. The nozzle 45 is connected to the internal high-pressure channel, and pressurized mud is ejected through the nozzle 45 to help disturb and loosen the strata, and to carry the fluidized particles towards the return inlet, preventing particle accumulation and jamming of the excavator assembly 44. The fluid path is as follows: the mud is injected from the inner tube of the dual-channel service string 32, enters the tail of the three-dimensional mining arm 42, and then enters the injection-side semi-annulus, flows forward to the conversion channel 46 and enters the internal channel, and then flows to the nozzle 45 and the high-pressure channel 441 of the excavator head respectively; the mixed fluid of ore particles and mud generated during mining enters the return-side semi-annulus from the inlet at the rear of the excavator assembly 44, flows backward into the outer annulus of the dual-channel continuous pipe 39 or the dual-channel service string 32, and is returned to the seabed formation targeted mining system 3, and then transported to the underwater transfer station 5.

[0069] The ore particles formed from the crushing process shall be fed into the return flow channel in one of the following ways: Option 1, Continuous Tube Scheme: The three-dimensional mining arm 42 is connected to the traveling body and has an ore particle flow inlet. The ore particle flow inlet is connected to the return flow channel inside the continuous tube 39. The ore particles generated by crushing enter the interior of the continuous tube 39 through the ore particle flow inlet and are discharged to the seabed wellhead through the continuous tube 39.

[0070] Method 2, Service String Scheme: The front of the service string 32 is provided with an ore particle flow inlet, which is connected to the return flow channel inside the service string 32. The ore particles generated by crushing enter the interior of the service string 32 through the ore particle flow inlet and are discharged to the subsea wellhead through the service string 32.

[0071] The continuous pipe 39 includes at least two continuous pipes; wherein, the first continuous pipe is used as a return flow channel to transport the produced solid-liquid two-phase flow or slurry to the outside of the wellhead; the second continuous pipe is used as an injection flow channel, the front end of which is connected to the crushing assembly 41 or the suction assembly to spray jets onto the rock wall to achieve auxiliary rock breaking and circulation.

[0072] It also includes a pulping device, which is installed inside the extended mining device 4 and is used to further grind and pulp the rock particles sucked into the extended mining device 4 to facilitate transportation in the continuous pipe.

[0073] It also includes a ring drill bit, which is located at the rear of the extended mining device 4 and is used to reverse the formation during the recovery of the extended mining device 4 to avoid jamming.

[0074] This invention provides two delivery solutions: service tubing and continuous tubing. The two solutions differ in physical structure, operation method, and applicable scenarios, allowing users to choose according to their actual working conditions.

[0075] (I) Continuous Tube Scheme like Figure 1 As shown, when using a continuous tube 39 as the transport channel, the subsea formation targeted mining system 3 includes a continuous tube drum 311. The continuous tube 39 is wound around the continuous tube drum 311, and the continuous tube 39 is continuously pushed from the drum to the downhole by the rotation of the drum. The continuous tube 39 is provided with an injection channel and a return channel (which can be a concentric double-tube structure or a parallel multi-channel structure). The advantages of the continuous tube scheme are good operational continuity, fast tripping speed, and fewer connection joints, making it particularly suitable for scenarios requiring frequent tripping operations or long-distance horizontal section operations.

[0076] (II) Service Pipeline Scheme like Figure 4 , 5 As shown, when the service string 32 is used as the conveying channel, the pipe delivery mechanism 31 is a push-pull pipe delivery mechanism, which is used to realize the axial advancement and retraction of the service string 32, providing the service string 32 with pushing and pulling capabilities. This push-pull pipe delivery mechanism includes a propulsion drive mechanism, a push-pull guide rail, and a sliding propulsion seat that moves along the push-pull guide rail. The sliding propulsion seat is used to support the movement of the service string 32 along the mining direction. The propulsion drive mechanism provides axial propulsion power and can be one of a hydraulic push-pull cylinder, a chain propulsion mechanism, or a rack and pinion propulsion mechanism. Among these, the chain propulsion structure is suitable for long-distance continuous propulsion, while the rack and pinion structure is suitable for high-rigidity, heavy-duty propulsion. To adapt to the seabed environment, the propulsion mechanism preferably adopts a corrosion-resistant sealing structure and a structure to prevent sediment intrusion.

[0077] When using the service string 32 as the delivery channel, to achieve unmanned string delivery and retrieval operations in the seabed environment, the seabed formation targeted mining system 3 includes a pipe handling system 312. The pipe handling system 312 is an automatic pipe delivery and retrieval module. The pipe handling system 312 includes a drill pipe storage bin, an automatic pipe laying mechanism, a drill pipe holder for connecting and disconnecting drill pipes, an automatic coupling mechanism, and an automatic uncoupling mechanism. The pipe handling system is existing technology and will not be described in detail here. It constitutes a complete "automated string handling system" capable of connecting multiple drill pipes end-to-end to form the service string 32, lowering them downhole one by one, and disassembling and retrieving them one by one after the operation is completed.

[0078] The service string 32 is connected to the front end of the delivery mechanism 31, which drives the service string 32 to move along the wellbore direction. The feed mechanism 36 is located inside the service string 32 or works in conjunction with it to drive the extended mining device 4 relative to the service string 32. The front of the service string 32 has a window for the extended mining device 4 to extend or retract. After moving inside the service string 32 to the window position, the extended mining device 4 extends out of the window via a deflection control mechanism 421 to mine the formation surrounding the service string 32.

[0079] The advantages of the service string solution are its strong torque transmission capability, good support and protection for the formation, suitability for large-diameter drill bits and complex trajectory control, and particular suitability for scenarios requiring high-power mining or with poor formation stability.

[0080] The service string 32 can be a single-tube structure or a double-tube structure. The double-tube structure includes an outer tube and an inner tube. The circulating fluid is injected downhole through the annulus between the outer tube and the inner tube, and the slurry is returned through the inside of the inner tube.

[0081] The service string 32 is provided with an annular bladder on the outside, and the annular bladder has a filling space inside, which is used to expand by injecting fluid during mining operations; this structure is designed for mining deep-sea unformed rock formations or seabed sediments rich in metal resources. The annular bladder can effectively support the formation and prevent the service string from being wrapped by the deep-sea unformed rock formations or seabed sediments, thus preventing the service string from being pulled back.

[0082] The service string 32 serves to provide a prefabricated channel, meaning the main channel is protected, which offers a significant advantage for development in soft strata. The service string 32 provides an alternative support method for the extension mining device 4 and offers better protection for it. The rear of the extension mining device 4 is located within the pilot well 2, supported by the well wall, enabling the extension mining device 4 to excavate the rock strata surrounding the pilot well 2. Alternatively, the rear of the extension mining device 4 can be inserted into the service string 32, which provides support for it.

[0083] Whether using service tubing 32 or continuous tubing 39, both have internal injection and return channels. The injection channel is used to inject circulating fluid into the well, while the return channel is used to return mined ore particles or slurry to the underwater transfer station.

[0084] When using the service string scheme, the front of the service string 32 is provided with a window for ore particles to flow in. After the circulating fluid is ejected from the crushing assembly 41, it carries the ore particles into the window provided at the front of the service string 32 and flows back to the subsea wellhead within the service string 32.

[0085] The rear end of the service string 32 or the continuous pipe 39 is connected to the inlet of the underwater transfer station via a pipeline. Its function is to directly input the extracted rock fragments or slurry into a closed ore flow transport system, preventing its diffusion into the ocean water. The underwater transfer station re-injects the separated seawater into the injection channel within the continuous pipe 39 or the service string 32, forming a circulation loop with the seabed strata targeted mining system 3 and the extended mining device 4. The circulating fluid flows within this loop to transport the ore particles or slurry to the underwater transfer station, achieving fully enclosed continuous operation.

[0086] The mining operation of this invention relies on the continuous flow of circulating fluid in the circulation loop to transport ore particles or slurry.

[0087] When using the continuous tube scheme, the circulation loop is as follows: underwater transfer station outlet → continuous tube 39 injection channel → crushing assembly / screw suction assembly → mining face → return channel 321 → continuous tube 39 return discharge channel → underwater transfer station inlet.

[0088] When using the service tubing scheme, the circulation loop is as follows: underwater transfer station outlet → service tubing 32 injection channel → crushing assembly / screw assembly → mining face → service tubing 32 front ore particle flow inlet → service tubing 32 return channel → underwater transfer station inlet.

[0089] The circulating fluid can be seawater, mud, or a mixture of both, and is driven by an underwater booster pump. By adjusting the pump's displacement and pressure, the flow rate and volume of the circulating fluid can be controlled, thereby regulating the conveying capacity of the ore particles.

[0090] The underwater transfer station is located on or near the seabed surface 12, and includes at least one of the following: an underwater ore particle crushing device, an underwater booster pump, an underwater ore particle flow stirring device, and / or an underwater ore particle flow pressure stabilizing device. The underwater ore particle crushing device is used to crush ore particles to the millimeter or sub-millimeter level to facilitate the formation of slurry, which is then transported to the lifting riser via an underwater booster pump. The system also includes a lift riser 14 and a service vessel, and the underwater transfer station is connected to the service vessel through the lift riser 14.

[0091] The system also includes a seabed measurement and control system, which includes a location information transceiver system. The location information transceiver system includes a seabed end location information transceiver system installed on the seabed surface and a downhole end location information transceiver system installed on the extended mining device 4 or the service string 32. The location information transceiver system includes at least one of a magnetic beacon, an acoustic emission device, or an electromagnetic wave emission device as a signal transmitting end, and / or includes at least one of a magnetic sensor, an acoustic sensor, or an electromagnetic wave sensor as a signal receiving end.

[0092] The system also includes a surface service platform, which is connected to the seabed strata targeted mining system 3 and the underwater transfer station by a power cable 15, which is used to provide power for seabed mining and underwater mineral processing.

[0093] A method for targeted wellbore mining operations in subsea formations, employing a trenchless subsea formation mining system, includes the following steps: The seabed strata targeted mining system 3 is deployed on the seabed; The pilot well 2 is formed in the seabed strata 11 by the seabed strata targeted mining system 3; The extended mining device 4 is used to excavate the soft seabed around the guide well 2. The service string 32 or continuous tubing 39 is lowered into the pilot well through the subsea strata targeted mining system 3, and the extended mining device 4 is sent into the pilot well through the service string 32 or continuous tubing 39. The ore particles or slurry formed by mining are transported to the underwater transfer station for processing by circulating fluid flowing in the circulation loop.

[0094] The method employs either a closed-loop retraction operation mode or a through-pulling and expanding hole operation mode. In the closed-loop retraction operation mode, the service string 32 adopts a single-tube structure or a double-tube structure. When the single-tube structure is adopted, the circulating fluid is injected into the well through the inside of the service string 32, and the slurry is returned through the annulus between the service string 32 and the borehole wall. When the double-tube structure is adopted, the circulating fluid is injected into the well through the annulus between the outer tube and the inner tube, and the slurry is returned through the inside of the inner tube. The drill bit and the service string 32 enter the target formation, move horizontally underground to the target area for flushing and collection, and then retreat along the original path after completion. In the described through-pulling reaming operation mode, the drill bit penetrates the target formation and drills out from the other end of the seabed to form a second wellhead. A reaming and reaming device is installed at the outcrop end for rotating reaming and reaming, and mineral collection is carried out simultaneously during the reaming process. When the service string 32 adopts a single-tube structure, slurry is pumped through the drill pipe, or assisted by pumping at the outcrop end, or high-pressure injection is used to enhance transportation. When the service string 32 adopts a double-tube structure, the outer string continuously provides hydraulic assistance, and the inner string continuously transports slurry.

[0095] like Figure 10-12 As shown, a crushing device is provided at the front end of the extended mining device 4, and a rake mechanism 37 is provided inside the service column 32. The rake mechanism 37 reciprocates along the service column 32 under the traction of the traction cable 371, and the winch 372 is used to traction the rake mechanism to reciprocate.

[0096] In this embodiment, at the underwater transfer station hopper 16, ore is transferred to the top of the hopper and slides down from the service column 32 into the hopper 16. The ore that slides down into the hopper 16 can be transported to the ship by mechanical means such as winches or transport robots, or it can be pulped by other secondary crushing equipment and then pumped to the ship through riser pumps.

[0097] In this embodiment, the crushing device is preferably an impact crushing device.

[0098] The advantage of this invention lies in its operational method of "extension of the guide shaft from the well-mining device—disturbance or fracturing of the strata—return flow of granular fluid or slurry," which eliminates the need for long-term maintenance of large-scale permanent tunnels and effectively reduces the risk of collapse in marine geological environments. Combined with secondary crushing and slurry preparation at the underwater transfer station, it achieves the technical effect of cascaded granular development. Through well-mining, fluidized mining of metallic deposits beneath the seabed can be achieved without damaging the seabed.

[0099] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A trenchless mining system for seafloor strata, characterized in that: It includes a pilot well (2), a seabed strata targeted mining system (3), an extended mining device (4), and an underwater transfer station; The seabed strata targeted mining system (3) is used to lower and retrieve the extended mining device (4) and provide power to the extended mining device (4) so ​​that the extended mining device (4) can carry out mining operations based on the pilot well (2); The extended mining device (4) works in conjunction with the seabed strata targeted mining system (3) to mine the seabed strata around the guide well (2); The underwater transfer station is connected to the seabed strata targeted mining system (3) and is used to process or transport the mined ore particles or slurry.

2. The trenchless mining system for seafloor strata according to claim 1, characterized in that: It also includes service tubing (32) or continuous tubing (39); The service string (32) or continuous pipe (39) is connected in front of the seabed formation targeted mining system (3); the extended mining device (4) is located in front of the service string (32) or continuous pipe (39), and the service string (32) or continuous pipe (39) is used to provide the extended mining device (4) with a fluid transport channel, a solid particle transport channel and / or mining power.

3. The trenchless mining system for seafloor strata according to claim 1 or 2, characterized in that: The underwater transfer station and the seabed strata targeted mining system (3) form a circulation loop, and the circulating fluid flows inside the circulation loop to transport the ore particles or slurry to the underwater transfer station.

4. The trenchless mining system for seafloor strata according to claim 2, characterized in that: The extended mining device (4) is a three-dimensional mining arm (42), which is located at the front of the service string (32) or the continuous pipe (39); the three-dimensional mining arm (42) can extend outward along the radial direction of the service string (32) or the continuous pipe (39) to mine the soft bottom of the seabed around the service string (32) or the continuous pipe (39); The three-dimensional mining arm (42) includes at least one deflection control mechanism (421) for driving the three-dimensional mining arm (42) to extend or deploy laterally toward the pilot well.

5. The trenchless mining system for seafloor strata according to claim 4, characterized in that: The three-dimensional mining arm (42) also includes a telescopic control mechanism (422), which is used to control the telescopic feed of the three-dimensional mining arm (42).

6. The trenchless mining system for seafloor strata according to claim 4, characterized in that: The three-dimensional mining arm (42) is connected to the traveling body, which is located in the guide well hole of the guide well (2).

7. The trenchless mining system for seafloor strata according to claim 6, characterized in that: It also includes a propulsion mechanism, which is located on the side or rear of the traveling body and is used to propel the extended mining device (4) to mine and at the same time to pull the continuous pipe (39) to follow forward.

8. The trenchless mining system for seafloor strata according to claim 2, characterized in that: The extended mining device (4) includes multiple sections, each section is connected by a hinge, and the front end of the first section of the pipe is equipped with a crushing assembly (41), which includes a tunneling head, a hinge suction assembly or a jet crushing assembly. A controllable deflection device is provided between the crushing assembly (41) and the first section, or a controllable deflection device is provided between the first section and the second section. It also includes an orientation rotation device (43), which is connected in series in the extended mining device (4) or set behind the extended mining device (4) to drive the extended mining device (4) to rotate along its own axis. The extended mining device (4) utilizes its ability to bend laterally to drill laterally from the guide well and excavate the rock mass lateral to the guide well.

9. The trenchless mining system for seafloor strata according to claim 4 or 8, characterized in that: The front end or side of the extended mining device (4) is provided with a suction assembly and / or a crushing assembly; The auger assembly is located at the front end of the extended mining device (4), and the extended mining device (4) is provided with a return flow channel (321); the return flow channel (321) is connected to the return flow channel inside the continuous pipe (39), or the return flow channel (321) is connected to the return flow channel inside the service string (32); Alternatively, when the crushing assembly (41) is located at the front end or side of the extended mining device (4), the crushing assembly (41) is a mechanical crushing assembly or a jet crushing assembly; The three-dimensional mining arm (42) is connected to the traveling body and has an ore particle inlet. The ore particle inlet is connected to the return flow channel inside the continuous tube (39) and is used to discharge the ore particles generated by crushing through the continuous tube (39). Alternatively, the front of the service column (32) is provided with an ore particle inlet, which is connected to the return flow channel inside the service column (32) for discharging the ore particles generated by the disturbance crushing through the service column (32).

10. The trenchless mining system for seafloor strata according to claim 2, characterized in that: The continuous pipe (39) includes at least two continuous pipes; wherein, the first continuous pipe is used as a return flow channel for conveying the extracted solid-liquid two-phase flow or slurry to the outside of the wellhead; the second continuous pipe is used as an injection flow channel, the front end of which is connected to the crushing assembly (41) or the suction assembly for spraying jets onto the rock wall.

11. The trenchless mining system for seafloor strata according to claim 4, characterized in that: It also includes a pulping device, which is located inside the extended mining device (4) and is used to further grind and pulp the rock particles sucked into the extended mining device (4).

12. The trenchless mining system for seafloor strata according to claim 4, characterized in that: It also includes a ring drill bit, which is located at the rear of the extended mining device (4) and is used to reverse the formation during the recovery of the extended mining device (4) to avoid jamming.

13. The trenchless mining system for seafloor strata according to claim 2, characterized in that: The seabed strata targeted mining system (3) includes a pipe delivery mechanism (31) for cooperating in the lowering and retrieval of the continuous pipe (39). The service string (32) is connected to the front end of the pipe delivery mechanism (31), and the pipe delivery mechanism (31) is used to drive the service string (32) to move along the wellbore direction; The extended mining device (4) is movable relative to the service string (32) to mine the soft seabed strata surrounding the service string (32); The pipe delivery mechanism (31) drives the three-dimensional mining arm (42) to move along the wellbore by driving the service string (32); It also includes a feeding mechanism (36), which is disposed inside the service column (32) or cooperates with the service column (32) to drive the extended mining device (4) to move relative to the service column (32); The front of the service string (32) is provided with a window for the extension mining device (4) to extend or retract.

14. The trenchless mining system for seafloor strata according to claim 13, characterized in that: The pipe delivery mechanism (31) is a pipe processing system (312), which includes a drill bit for connecting and disconnecting drill rods and pipe laying equipment for connecting and lowering or disassembling and recycling the service string (32).

15. The trenchless mining system for seafloor strata according to claim 13, characterized in that: The service string (32) is provided with an annular bladder on the outside and a filling space inside the annular bladder for expansion by injecting fluid during mining operations.

16. The trenchless mining system for seafloor strata according to claim 4 or 8, characterized in that: The rear part of the extended mining device (4) is located inside the pilot well (2) and is supported by the well wall of the pilot well (2), enabling the extended mining device (4) to excavate the rock strata around the pilot well (2); or, the rear part of the extended mining device (4) is inserted into the service string (32) and is supported by the service string (32).

17. The trenchless mining system for seafloor strata according to claim 4 or 8, characterized in that: It also includes a base (33), on which an angle adjustment mechanism is provided, and the pipe delivery mechanism (31) is set at an adjustable angle on the base (33) for pushing the service string (32) into the seabed strata (11) at an inclined angle to form a wellbore with a controllable trajectory; The base (33) is also provided with a support leg (34) at the bottom to stabilize the base; the base (33) is also provided with a pipe column receiving module (35) to receive the pipe column when it is raised and lowered on the seabed.

18. The trenchless mining system for seafloor strata according to claim 2, characterized in that: The service string (32) is provided with an injection channel and a return channel. The injection channel is used to inject circulating fluid into the well, and the return channel is used to return the ore particles or slurry formed by mining to the underwater transfer station. The front of the service string (32) is provided with a window for ore particles to flow in. After the circulating fluid is ejected from the crushing assembly (41), it carries the ore particles into the window provided at the front of the service string (32) and flows back to the subsea wellhead in the service string.

19. The trenchless mining system for seafloor strata according to claim 2, characterized in that: The service string (32) adopts a double-pipe structure, which includes an outer pipe and an inner pipe. The circulating fluid is injected downhole through the annulus between the outer pipe and the inner pipe, and the slurry is returned through the inside of the inner pipe.

20. The trenchless mining system for seafloor strata according to claim 2, characterized in that: The rear end of the service string (32) or continuous pipe (39) is connected to the inlet of the underwater transfer station via a pipeline; The underwater transfer station re-injects the separated seawater into the injection channel within the continuous pipe (39) or the service string (32), forming a circulation loop with the seabed strata targeted mining system (3) and the extended mining device (4). The circulating fluid flows within the circulation loop to transport the ore particles or slurry to the underwater transfer station.

21. The trenchless mining system for seafloor strata according to claim 2, characterized in that: It also includes a seabed measurement and control system, which includes a location information transceiver system. The location information transceiver system includes a seabed end location information transceiver system set on the seabed surface and a downhole end location information transceiver system set on the extended mining device (4) or the service string (32). The location information transceiver system includes at least one of a magnetic beacon, an acoustic emission device or an electromagnetic wave emission device as a signal transmitting end, and / or includes at least one of a magnetic sensor, an acoustic sensor or an electromagnetic wave sensor as a signal receiving end.

22. The trenchless mining system for seafloor strata according to claim 1, characterized in that: It also includes a surface service platform, which is connected to the seabed strata targeted mining system (3) and the underwater transfer station by a power cable (15) to provide power for seabed mining and underwater mineral processing.

23. The trenchless mining system for seafloor strata according to claim 1, characterized in that: The underwater transfer station is located on the seabed surface (12) or near the seabed, and the underwater transfer station includes at least one of the following: an underwater ore particle crushing device, an underwater booster pump, an underwater ore particle flow stirring device and / or an underwater ore particle flow pressure stabilizing device. The underwater ore particle crushing device is used to crush ore particles to the millimeter or sub-millimeter level to facilitate the formation of slurry, which is then transported to the lifting riser via an underwater booster pump. It also includes a lift riser (14) and a service vessel, the underwater transfer station being connected to the service vessel via the lift riser (14).

24. A method for targeted wellbore mining operations in subsea formations, employing a trenchless subsea formation mining system as described in any one of claims 1-23, characterized in that: Includes the following steps: The seabed strata targeted mining system (3) is deployed on the seabed; A pilot well (2) is formed in the seabed strata (11) using the seabed strata targeted mining system (3). The soft seabed around the guide well (2) is excavated using the extended excavation device (4); The service string (32) or continuous pipe (39) is lowered into the pilot well through the subsea strata targeted mining system (3), and the extended mining device (4) is sent into the pilot well through the service string (32) or continuous pipe (39). The ore particles or slurry formed by mining are transported to the underwater transfer station for processing by circulating fluid flowing in the circulation loop.

25. The method for targeted wellbore mining operations in subsea formations according to claim 24, characterized in that: The method employs either a closed-loop retraction operation mode or a through-pulling and expanding hole operation mode. In the closed-loop operation mode, the service string (32) adopts a single-pipe structure or a double-pipe structure; when the single-pipe structure is adopted, the circulating fluid is injected into the well through the inside of the service string (32), and the slurry is discharged back through the annulus between the service string (32) and the borehole wall; when the double-pipe structure is adopted, the circulating fluid is injected into the well through the annulus between the outer pipe and the inner pipe, and the slurry is discharged back through the inside of the inner pipe; the drill bit and the service string (32) enter the target formation, move horizontally underground to the target area for flushing and collection, and then withdraw along the original path after completion; In the through-pulling and reaming operation mode, the drill bit penetrates the target formation and drills out from the other end of the seabed to form a second wellhead. A reaming and reaming device is installed at the outcrop end to perform rotary reaming and reaming, and mineral collection is carried out simultaneously during the reaming process. When the service string (32) adopts a single-pipe structure, slurry is pumped through the drill rod, or pumped with the assistance of the outcrop end, or high-pressure injection is used to enhance transportation. When the service string (32) adopts a double-pipe structure, the outer string continuously provides hydraulic assistance, and the inner string continuously transports slurry.

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