Method for deep-sea drilling and coring using an armored cable type electromechanical drill

Abstract

The present invention discloses a method for deep-sea coring using an armored cable-type electric mechanical drill tool, comprising the following steps: installing the drill tool; lowering a seabed base plate; lowering the drill tool to the surface of a seabed mud layer: using an armored cable as a sling, the drill tool is hoisted above a moon pool on an offshore platform; by controlling the angle and position of two ROV underwater cable-controlled robots, the drill tool enters a drilling channel on the seabed base plate; when the drill tool is lowered to the surface of the seabed mud layer, the lowering is stopped; drilling a hole in the seabed mud layer; lifting the drill tool and removing the hollow drill rod; drilling a hole in the seabed rock layer; drilling and sampling: after reaching the core sampling area, drilling and sampling the rock and soil in the core sampling area is initiated; lifting the drill tool and retrieving the core. In the coring method of the present invention, the cable replaces the drill rod, and the ROV underwater cable-controlled robot is used to provide assistance, which greatly saves the time of lifting and lowering the drill tool, thereby improving construction efficiency and reducing construction costs.

Description

Technical Field

[0001] The present invention relates to the technical field of deep sea drilling and coring, in particular to a method for deep sea drilling and coring using an armored cable type electric mechanical drilling tool. Background Art

[0002] Since launching the Moho Drilling Program in the late 1950s, the United States has successively implemented the Deep Sea Drilling Program (DSDP), the Ocean Drilling Program (ODP), the Integrated Ocean Drilling Program (IODP), and the International Ocean Discovery Program (IODP) since 1968. Over the past 60 years of global ocean scientific drilling, nearly 4,000 wells have been drilled in the world's oceans, yielding over 600,000 meters of core and a wealth of data. This geological data has provided crucial insights into seafloor spreading and plate tectonics, revealing patterns of climate evolution, studying seafloor sedimentation and mineral distribution, and discovering the deep biosphere and methane hydrate.

[0003] Ocean drilling faces many difficulties and challenges not encountered in continental scientific drilling. Due to the high cost of offshore operations, improving the efficiency of ocean drilling operations has become a matter of great international concern. To improve the efficiency of drilling and coring in ocean drilling, rope coring drilling is often used. A characteristic of rope coring drilling is that it does not require the entire drill string to be removed from the borehole. A specialized fishing device with a steel wire rope is used to lift the bottom-of-hole inner tube containing the core to the surface through the center hole of the drill string to obtain the core sample. This reduces the number of drill string lifts and lowers and the auxiliary time required to raise and lower the drill string, thereby improving drilling efficiency. However, rope coring drilling also requires lowering and lifting the entire drill string during the initial lowering and final raising of the drill string, which significantly increases operation time. During ocean scientific drilling operations, operations often occur between October and February in the Northern Hemisphere. Typhoons are common during this period, and the offshore construction window is short, often only a few days. For subsea drilling operations at a water depth of 2,000 meters, lowering and raising the drill pipe alone often takes at least three days. The harsh environment and short operating window increase operational difficulties, sometimes forcing operations to be terminated and rescheduled for the following year. Furthermore, offshore construction costs can reach several million RMB per day. Therefore, reducing the time required to lower and raise the drill pipe can significantly reduce operating costs.

[0004] Therefore, in ocean scientific drilling, especially during the short operating window from October to February in the Northern Hemisphere (corresponding to April to August in the Southern Hemisphere), deep water depths (over 1000m), and shallow seabed drilling depths (below 500m), conventional seabed sampling operations are likely to fail due to the long time required to connect, lower, and lift the drill pipe. Therefore, it is necessary to design a drilling tool that uses a cable instead of a drill pipe to deliver the coring device to the seabed, simultaneously drive the bottom drill bit for drilling, and then, after sampling, lift it from the bottom of the hole to the operating platform along with the sampling tube. Furthermore, a corresponding operating method should be designed based on this drilling tool. This drilling tool and method can not only significantly save ocean drilling operation time and improve operational efficiency, but also largely determine the success of operations at a specific time and depth. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for deep-sea coring by using an armored cable-type electric mechanical drilling tool, which improves construction efficiency and reduces construction costs.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for deep-sea coring using an armored cable-type electric mechanical drilling tool comprises the following steps:

[0008] S1. Drilling tool installation: The drilling tool includes a cable locking connector, slip ring assembly, pressure seal cabin, anti-torque assembly, counterweight, drive circulation device, cuttings tube, core sampling tube, and coring drill bit, which are connected in sequence. The armored cable winch is installed on the offshore platform. One end of the armored cable on the armored cable winch is connected to the cable connector of the drilling tool, and a hollow drill pipe is installed between the counterweight and the drive circulation device.

[0009] S2. Lowering the seabed base: Lower the seabed base to the surface of the seabed mud layer through the offshore platform;

[0010] S3. Lowering the drill tool to the surface of the seabed mud layer: Using an armored cable as a lifting rope, the drill tool is lowered to the moon pool on the offshore platform. The manipulators of two ROV underwater cable-controlled robots then grasp the drill tool. The armored cable winch and the ROV winches of the two ROV underwater cable-controlled robots are then activated. The two ROV underwater cable-controlled robots and the drill tool move downward synchronously. By controlling the angles and positions of the two ROV underwater cable-controlled robots, the drill tool enters the drilling channel on the seabed base. When the drill tool reaches the surface of the seabed mud layer, the lowering is stopped.

[0011] S4. Drilling in the seabed mud layer: The manipulator of one ROV underwater cable-controlled robot continues to grasp the drill tool to keep it in a vertical position. The manipulator of the other ROV underwater cable-controlled robot grasps the anti-torque component on the drill tool and starts the drilling motor in the drive circulation device. The drill tool begins drilling on the seabed. As the drill tool moves down, the armored cable is lowered synchronously. The two ROV underwater cable-controlled robots move down synchronously. After the drill tool penetrates the medium-hard rock layer on the seabed for a distance, the drilling motor is turned off and drilling stops. If the anti-torque component of the drill tool moves to the seabed base plate and further drilling is required, the drill tool should be raised and a hollow drill pipe should be installed before continuing drilling.

[0012] S5. Lift the drill tool and remove the hollow drill pipe: After drilling the seabed mud layer, reel in the armored cable on the armored cable winch, lift the drill tool to the offshore platform, remove the hollow drill pipe from the drill tool, and then connect the counterweight to the drive circulation device;

[0013] S6. Drilling in the seabed rock formation: The drill tool, after removing the hollow drill pipe, is lowered. When the anti-torsion assembly moves to the seabed base plate, the manipulators of the two ROV underwater cable-controlled robots release the drill tool, allowing the drill tool to pass through the seabed base plate and lower to the bottom of the hole in the seabed mud layer. At this time, the anti-torsion assembly is located in the medium-hard rock formation. Under the action of the medium-hard rock formation hole wall, the anti-torsion assembly is prevented from rotating. The drilling motor is started and the seabed rock formation drilling is continued until the drill tool reaches the seabed core sampling area.

[0014] S7, drilling sampling: after arriving at the core sampling area, start drilling sampling of the rock and soil in the core sampling area;

[0015] S8. Lift the drill tool and take out the core: After drilling and sampling are completed, lift the drill tool to the offshore platform, take out the core, and complete the core sampling work.

[0016] Furthermore, the offshore platform is a drilling ship or an offshore drilling platform.

[0017] Furthermore, the slip ring assembly includes a hollow shaft, an outer tube, an upper slip ring shaft, a lower slip ring shaft, a ball bearing and a tapered roller bearing. The ball bearing and the tapered roller bearing are installed between the hollow shaft and the outer tube. A locking nut is provided on the external threaded section of the hollow shaft, and the locking nut supports the tapered roller bearing. The upper slip ring shaft is connected to the upper end of the hollow shaft and is larger than the outer diameter of the hollow shaft. The cable locking connector is installed on the upper slip ring shaft. The lower slip ring shaft is connected to the lower end of the hollow shaft and is larger than the outer diameter of the hollow shaft, and extends into the upper port of the pressure sealing cabin. The lower end of the outer tube is connected to the upper port of the pressure sealing cabin.

[0018] Furthermore, a temperature sensor, a pressure sensor and an azimuth sensor are placed in the pressure-sealed cabin.

[0019] Furthermore, the anti-twist assembly includes more than three anti-twist knives, a connecting rod, an upper fixed frame, a compression spring, a lower movable frame, a screw and an adjusting nut. The upper end of the screw is connected and fixed to the lower end of the pressure sealing cabin, the upper fixed frame and the lower movable frame are located on the screw, the upper fixed frame is against the lower end of the pressure sealing cabin, the compression spring is sleeved on the screw and is located between the upper fixed frame and the lower movable frame, the adjusting nut is screwed on the screw to support the lower movable frame, and the upper and lower ends of the anti-twist knife are respectively hinged to the upper fixed frame and the lower movable frame through two connecting rods.

[0020] Furthermore, the middle portion of the anti-twisting blade bulges outwards to form an arc-shaped structure.

[0021] Furthermore, the counterweight includes a counterweight cabin and a plurality of counterweight blocks, the plurality of counterweight blocks are arranged in the counterweight cabin, and the counterweight cabin is connected to the pressure sealing cabin through a connecting piece.

[0022] Furthermore, the drive circulation device includes a drilling motor, a reducer, a water pump and a cylindrical shell. The motor, reducer and water pump are located in the cylindrical shell. The motor is connected to the reducer, and the reducer is used to provide power to the coring drill bit; the water pump is used to collect the drilling fluid carrying cuttings through the circulation channel into the cuttings chamber of the cuttings tube through the pumping action.

[0023] Furthermore, the upper port of the cuttings tube is docked with the lower port of the cylindrical shell, a filter is provided at the upper port of the cuttings tube, the inner cavity of the cuttings tube is a cuttings chamber, a center tube is provided in the cuttings chamber, an umbrella-shaped cuttings stopper is designed at the top of the center tube, the drilling fluid carries the cuttings into the cuttings chamber from the lower end of the center tube, and is discharged into the cuttings chamber through the guide hole on the lower end surface of the umbrella-shaped cuttings stopper, the lower port of the cuttings tube is connected to the core sampling tube, and the lower end of the core sampling tube is connected to the coring drill bit.

[0024] Furthermore, the core drill bit adopts a roller drill bit when the seabed to be drilled is soft rock or medium hardness rock formation; and adopts a diamond drill bit when the seabed to be drilled is hard rock formation.

[0025] The beneficial effects of the present invention are:

[0026] In the coring method of the present invention, the cable replaces the drill pipe and is assisted by two ROV underwater cable-controlled robots, which greatly saves the time of lifting and lowering the drill tool, thereby improving construction efficiency and reducing construction costs, providing more technical support for achieving China's ocean scientific drilling goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not limit the present invention in any way. A person skilled in the art can derive other drawings based on the following drawings without inventive effort.

[0028] Figure 1 This is a flow chart of the deep sea drilling coring method of the present invention;

[0029] Figure 2 for Figure 1 The structural diagram of the drilling tool shown;

[0030] Figure 3 for Figure 1 The diagram shows the state where the seabed template is lowered to the surface of the seabed mud layer;

[0031] Figure 4 for Figure 1 The drilling tool is shown as it is lowered to the surface of the seabed mud layer;

[0032] Figure 5 for Figure 1 The drilling tool is shown as being lowered to the bottom of a hole drilled in a seabed mud layer;

[0033] Figure 6 for Figure 1 The diagram shows the state of drilling a hole in the seabed rock formation and the drilling tool reaching the seabed core sampling area;

[0034] Figure 7 for Figure 2 A schematic diagram of the slip ring assembly shown;

[0035] Figure 8 for Figure 2 A schematic diagram of the anti-torque assembly shown;

[0036] Figure 9 for Figure 2 Schematic diagram of the drive circulation device and cuttings tube shown.

[0037] In the figure: 1. Drilling tool; 2. Cable locking connector; 3. Slip ring assembly; 4. Pressure sealing chamber; 5. Anti-torque assembly; 6. Counterweight; 7. Drive circulation device; 8. Cuttings tube; 9. Core sampling tube; 10. Coring drill bit; 11. Armored cable winch; 12. Offshore platform; 13. Living cabin; 14. ROV winch; 15. Drilling tower; 16. Overhead crane; 17. Control cabin; 18. Moon pool; 19. Armored cable; 20. Seabed base; 21. Seabed mud layer; 22. ROV underwater cable-controlled robot; 23. Drilling channel; 24. Medium-hard rock formation; 25. Bottom of the hole drilled in the seabed mud layer; 26. Wall of the hole in the medium-hardness rock layer; 27. Core sampling area; 28. Hollow shaft; 29. Outer tube; 30. Upper slip ring shaft; 31. Lower slip ring shaft; 32. Ball bearing; 33. Tapered roller bearing; 34. Locking nut; 35. Anti-twist cutter; 36. Connecting rod; 37. Upper fixed frame; 38. Compression spring; 39. Lower movable frame; 40. Screw; 41. Adjusting nut; 42. Drilling motor; 43. Reducer; 44. Water pump; 45. Cylindrical casing; 46. Filter; 47. Cuttings chamber; 48. Center tube; 49. Umbrella-shaped cuttings stop. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other unless there is a conflict.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper surface", "lower surface", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "forward", "reverse", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0040] like Figure 1 As shown, a method for deep-sea coring using an armored cable-type electric mechanical drilling tool comprises the following steps:

[0041] S1. Drilling tool installation: Figure 2As shown, the drilling tool 1 includes a cable locking connector 2, a slip ring assembly 3, a pressure sealing cabin 4, an anti-torque assembly 5, a counterweight 6, a drive circulation device 7, a cuttings tube 8, a core sampling tube 9, and a coring drill bit 10, which are connected in sequence. An armored cable winch 11 is provided on an offshore platform 12. The offshore platform 12 is provided with a living cabin 13, two ROV winches 14, a drilling tower 15, a crown block 16, a control cabin 17, and a moon pool 18. The drilling tower 15 is located above the moon pool 18, and the two ROV winches 14 are located on both sides of the drilling tower 15. One end of the armored cable 19 on the armored cable winch is passed around the crown block 16 at the top of the drilling tower 15, extended downward into the drilling tower 15, and connected to the cable connector 2 of the drilling tool 1. A hollow drill pipe is installed between the counterweight 6 and the drive circulation device 7. The offshore platform 12 is a drilling ship. The armored cable 19 contains several power lines and signal lines, which are wrapped in a high-pressure and corrosion-resistant sealed nylon layer in the middle and steel wire wrapped on the outside; the power lines pass through the cable locking connector 2, the slip ring assembly 3, the pressure sealing cabin 4, the anti-torsion assembly 5, and the counterweight 6 in sequence until they are connected to the drilling motor 42 inside the drive circulation device 7 to drive the lower cuttings tube 8, the core sampling tube 9 and the coring drill bit 10 to rotate; the signal lines pass through the cable locking connector 2 and the slip ring assembly 3 in sequence until they are connected to various sensors and other components in the pressure sealing cabin 4.

[0042] S2, lowering the seabed base plate 20: Figure 3 As shown, a seabed template 20 is lowered to the surface of a seabed sediment layer 21 through an offshore platform 12, and a drilling channel 23 is provided on the seabed template 20;

[0043] S3. The drilling tool is lowered to the surface of the seabed mud layer: Figure 2 As shown, the drill tool is hoisted onto the moon pool on the offshore platform 12 using the armored cable 18 as a hoisting rope. Then, the manipulators of two ROV underwater cable-controlled robots 22 grasp the drill tool 1. Then, the armored cable winch 11 and the ROV winches 14 of the two ROV underwater cable-controlled robots are started. The two ROV underwater cable-controlled robots 22 and the drill tool 1 move downward synchronously. The operator in the control cabin 17 controls the angles and positions of the two ROV underwater cable-controlled robots 22 to make the drill tool 1 enter the drilling channel 23 on the seabed base plate 20. When the drill tool 1 reaches the surface of the seabed mud layer 21, the lowering is stopped. Figure 4 As shown;

[0044] S4, drilling in the seabed mud layer: the manipulator of one ROV underwater cable-controlled robot 22 continues to grasp the drill tool 1, so that the drill tool 1 is protected in a vertical state, and the manipulator of the other ROV underwater cable-controlled robot 22 grasps the anti-torsion component 5 on the drill tool 1, starts the drilling motor in the drive circulation device 7, and the drill tool 1 starts drilling on the seabed. As the drill tool moves down, the armored cable is lowered synchronously. The two ROV underwater cable-controlled robots 22 move down synchronously. After the drill tool drills a distance into the seabed mud layer 21, the drilling motor is turned off and the drilling is stopped. If the anti-torsion component of the drill tool moves to the seabed base plate 20 and it is necessary to continue drilling, the drill tool 1 should be lifted and a hollow drill rod should be installed before continuing drilling. Because the anti-torsion component 5 cannot be fixed after entering the seabed base plate 20, it moves down into the seabed mud layer, and the seabed mud layer cannot fix the anti-torsion component 5, so a hollow drill rod needs to be installed.

[0045] S5. Lifting the drill tool and removing the hollow drill pipe: After the drill tool has passed through the seabed mud layer 21 and reached a certain distance from the medium-hardness rock layer 24, the armored cable on the armored cable winch is reeled in, and the drill tool 1 is lifted onto the offshore platform 12. The hollow drill pipe on the drill tool 1 is removed, and the counterweight 6 is connected to the drive circulation device 7.

[0046] S6. Drilling in submarine rock formations: The submarine rock formations include hard mud layers and medium-hard rock layers. The drill tool 1 is lowered after the hollow drill rod is removed. When the anti-torsion assembly moves to the submarine base plate, the manipulators of the two ROV underwater cable-controlled robots release the drill tool, allowing the drill tool to pass through the submarine base plate and be lowered to the bottom 25 of the hole drilled in the submarine mud layer. At this time, the anti-torsion assembly 5 is located in the medium-hard rock layer 24. Under the action of the hole wall 26 of the medium-hard rock layer, the anti-torsion assembly 5 cannot rotate. Figure 5 shown.

[0047] Start the drilling motor and drill the seabed rock until the drilling tool 1 reaches the core sampling area 27 on the seabed. Figure 6 As shown;

[0048] S7, drilling sampling: after arriving at the core sampling area 27, start drilling sampling of the rock and soil in the core sampling area 27;

[0049] S8. Lifting the drill tool and taking out the core: After the drilling and sampling is completed, the drill tool is lifted to the offshore platform 12, and the core is taken out to complete the core sampling work.

[0050] like Figure 7As shown, the slip ring assembly 3 includes a hollow shaft 28, an outer tube 29, an upper slip ring shaft 30, a lower slip ring shaft 31, a ball bearing 32 and a tapered roller bearing 33. The ball bearing 32 and the tapered roller bearing 33 are installed between the hollow shaft 28 and the outer tube 29. A locking nut 34 is provided on the external thread section of the hollow shaft 28. The locking nut 34 supports the tapered roller bearing 33. The upper slip ring shaft 30 is connected to the upper end of the hollow shaft 28 and is larger than the outer diameter of the hollow shaft 28. The cable locking connector 2 is installed on the upper slip ring shaft 30. The lower slip ring shaft 31 is connected to the lower end of the hollow shaft 28 and is larger than the outer diameter of the hollow shaft 28, and extends into the upper port of the pressure sealing cabin 4. The lower end of the outer tube 29 is connected to the upper port of the pressure sealing cabin 4. The slip ring assembly 3 can ensure that when the drill tool portion at the lower portion of the slip ring assembly rotates, the upper components will not rotate along with the lower drill tool, thereby avoiding entanglement of the armored cable and damage to the cable.

[0051] The pressure-sealed chamber 4 houses temperature sensors, pressure sensors, and azimuth sensors, as well as some equipment for monitoring bottomhole conditions. This prevents leakage in high-pressure liquid environments, preventing damage to circuit boards caused by drilling fluid intrusion. It also reduces the pressure-resistant requirements for electronic components. Signals from these sensors are connected via the signal cables and transmitted to a control console in a control cabin 17 on the offshore platform 12.

[0052] like Figure 8 As shown, the anti-twist assembly 5 includes more than three anti-twist knives 35, a connecting rod 36, an upper fixed frame 37, a compression spring 38, a lower movable frame 39, a screw 40 and an adjusting nut 41. The upper end of the screw 40 is connected and fixed to the lower end of the pressure sealing cabin 4, the upper fixed frame 37 and the lower movable frame 39 are located on the screw 40, the upper fixed frame 37 is against the lower end of the pressure sealing cabin 4, the compression spring 38 is sleeved on the screw 40 and is located between the upper fixed frame 37 and the lower movable frame 39, the adjusting nut 41 is screwed on the screw 40 to support the lower movable frame 39, and more than three anti-twist knives 35 are evenly distributed on the periphery of the screw, and the upper and lower ends of the anti-twist knife 35 are hinged to the upper fixed frame 37 and the lower movable frame 39 through two connecting rods 36 respectively. The anti-twist blade 35 has an outwardly bulging, arc-shaped center portion, facilitating entry and exit from the drill hole. This facilitates movement of the anti-twist assembly 5 into and out of the seabed template 20 and the secondary drilling path, thus facilitating the lifting and lowering of the drill string. To balance the torque generated during drilling, the radial extension of the anti-twist blade can be adjusted using an adjustment nut 41 and compression spring 38 at the bottom.

[0053] The counterweight 6 includes a counterweight compartment and a plurality of counterweight blocks. The counterweight blocks are located within the counterweight compartment and are connected to the pressure-sealed compartment via connectors. The counterweight compartment can be equipped with a different number of counterweight blocks as needed to adjust the maximum weight-on-bit during each drilling operation.

[0054] like Figure 9 As shown, the driving circulation device 7 includes a drilling motor 42, a reducer 43, a water pump 44 and a cylindrical shell 45. The motor 42, the reducer 43 and the water pump 44 are located in the cylindrical shell 45. The motor 42 is connected to the reducer 43. The reducer 43 is used to provide power to the coring drill bit; the water pump 44 is used to collect the drilling fluid carrying cuttings into the cuttings chamber of the cuttings pipe 8 through a circulation channel through a pumping action.

[0055] The upper end of the cuttings tube 8 is connected to the lower end of the cylindrical shell 45. A filter screen 46 is provided at the upper end of the cuttings tube 8. The inner cavity of the cuttings tube 8 is a cuttings chamber 47. A central tube 48 is provided in the cuttings chamber 47. An umbrella-shaped cuttings stopper 49 is designed at the top of the central tube 48. The drilling fluid carries cuttings and flows into the cuttings chamber 47 from the lower end of the central tube 48 through the guide hole on the lower end surface of the umbrella-shaped cuttings stopper 49. The lower end of the cuttings tube 8 is connected to the core sampling tube 9. The drilling fluid, carrying cuttings, returns from the annular gap between the core barrel and the core and enters the central tube 48 through the reducer. Passing through the umbrella-shaped cuttings stop 49 at the top of the central tube, the drilling fluid, carrying cuttings, generates a downward flow velocity component after passing through the umbrella cap. However, since the drilling fluid outlet reserved for the cuttings chamber 47 is located above the cuttings chamber, the drilling fluid's flow direction in the cuttings chamber 47 changes 180 degrees after passing through the umbrella cap. Since the cuttings particles are denser than the drilling fluid, the difference in flow direction between the cuttings particles and the drilling fluid allows the cuttings to settle better within the cuttings chamber 47. A filter 46 is fixed to the drilling fluid outlet above the cuttings chamber 47, which can perform secondary filtration on the drilling fluid, effectively ensuring that the cuttings are collected in the cuttings chamber and preventing the cuttings from entering the water pump 44 with the drilling fluid, thereby causing wear on the water pump 44.

[0056] The lower end of the core sampling tube 9 is connected to the coring drill bit 10. The coring drill bit 10 adopts a roller drill bit when the seabed to be drilled is soft rock or medium hardness rock formation; and adopts a diamond drill bit when the seabed to be drilled is hard rock formation.

[0057] In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent. Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for deep-sea coring using an armored cable-type electric mechanical drill, characterized in that: The following steps are involved: S1. Drilling tool installation: The drilling tool includes a cable locking connector, slip ring assembly, pressure seal cabin, anti-torque assembly, counterweight, drive circulation device, cuttings tube, core sampling tube, and coring drill bit, which are connected in sequence. The armored cable winch is installed on the offshore platform. One end of the armored cable on the armored cable winch is connected to the cable connector of the drilling tool, and a hollow drill pipe is installed between the counterweight and the drive circulation device. S2. Lowering the seabed base: Lower the seabed base to the surface of the seabed mud layer through the offshore platform; S3. Lowering the drill tool to the surface of the seabed mud layer: Using an armored cable as a lifting rope, the drill tool is lowered to the moon pool on the offshore platform. The manipulators of two ROV underwater cable-controlled robots then grasp the drill tool. The armored cable winch and the ROV winches of the two ROV underwater cable-controlled robots are then activated. The two ROV underwater cable-controlled robots and the drill tool move downward synchronously. By controlling the angles and positions of the two ROV underwater cable-controlled robots, the drill tool enters the drilling channel on the seabed base. When the drill tool reaches the surface of the seabed mud layer, the lowering is stopped. S4. Drilling in the seabed mud layer: The manipulator of one ROV underwater cable-controlled robot continues to grasp the drill tool to keep it vertical. The manipulator of the other ROV underwater cable-controlled robot grasps the anti-torque component on the drill tool and starts the drilling motor in the drive circulation device. The drill tool begins drilling on the seabed. As the drill tool moves down, the armored cable is lowered synchronously. The two ROV underwater cable-controlled robots move down synchronously. After the drill tool penetrates the medium-hard rock layer on the seabed for a distance, the drilling motor is turned off and drilling stops. If the anti-torque component of the drill tool moves to the seabed base plate and further drilling is required, the drill tool should be raised and a hollow drill pipe should be installed before continuing drilling. S5. Lift the drill tool and remove the hollow drill pipe: After drilling the seabed mud layer, reel in the armored cable on the armored cable winch, lift the drill tool onto the offshore platform, remove the hollow drill pipe from the drill tool, and then connect the counterweight to the drive circulation device. S6. Drilling in the seabed rock formation: The drill tool, after removing the hollow drill pipe, is lowered. When the anti-torsion assembly moves to the seabed base plate, the manipulators of the two ROV underwater cable-controlled robots release the drill tool, allowing the drill tool to pass through the seabed base plate and lower to the bottom of the hole in the seabed mud layer. At this time, the anti-torsion assembly is located in the medium-hard rock formation. Under the action of the medium-hard rock formation hole wall, the anti-torsion assembly is prevented from rotating. The drilling motor is started and the seabed rock formation drilling is continued until the drill tool reaches the seabed core sampling area. S7, drilling sampling: after arriving at the core sampling area, start drilling sampling of the rock and soil in the core sampling area; S8. Lift the drill tool and take out the core: After drilling and sampling are completed, lift the drill tool to the offshore platform, take out the core, and complete the core sampling work.

2. The method for deep-sea coring using an armored cable-type electric mechanical drill tool according to claim 1, characterized in that: The offshore platform is a drilling ship or an offshore drilling platform.

3. The method for deep-sea coring using an armored cable-type electric mechanical drill tool according to claim 1, characterized in that: The slip ring assembly includes a hollow shaft, an outer tube, an upper slip ring shaft, a lower slip ring shaft, a ball bearing and a tapered roller bearing. The ball bearing and the tapered roller bearing are installed between the hollow shaft and the outer tube. A locking nut is provided on the external threaded section of the hollow shaft, and the locking nut supports the tapered roller bearing. The upper slip ring shaft is connected to the upper end of the hollow shaft and is larger than the outer diameter of the hollow shaft. The cable locking connector is installed on the upper slip ring shaft. The lower slip ring shaft is connected to the lower end of the hollow shaft and is larger than the outer diameter of the hollow shaft, and extends into the upper port of the pressure sealing cabin. The lower end of the outer tube is connected to the upper port of the pressure sealing cabin.

4. The method for deep-sea coring using an armored cable-type electric mechanical drill tool according to claim 3, characterized in that: A temperature sensor, a pressure sensor and an azimuth sensor are placed in the pressure sealing cabin.

5. The method for deep-sea coring using an armored cable-type electric mechanical drill tool according to claim 4, characterized in that: The anti-twist assembly includes more than three anti-twist knives, a connecting rod, an upper fixed frame, a compression spring, a lower movable frame, a screw and an adjusting nut. The upper end of the screw is connected and fixed to the lower end of the pressure sealing cabin, the upper fixed frame and the lower movable frame are located on the screw, the upper fixed frame is against the lower end of the pressure sealing cabin, the compression spring is sleeved on the screw and is located between the upper fixed frame and the lower movable frame, the adjusting nut is screwed on the screw to support the lower movable frame, and more than three anti-twist knives are evenly distributed on the periphery of the screw, and the upper and lower ends of the anti-twist knife are respectively hinged to the upper fixed frame and the lower movable frame through two connecting rods.

6. The method for deep-sea coring using an armored cable-type electric mechanical drill tool according to claim 5, characterized in that: The middle part of the anti-twisting knife bulges outwards and presents an arc-shaped structure.

7. The method for deep-sea coring using an armored cable-type electric mechanical drill tool according to claim 6, characterized in that: The counterweight comprises a counterweight cabin and a plurality of counterweight blocks. The plurality of counterweight blocks are arranged in the counterweight cabin. The counterweight cabin is connected to the pressure sealing cabin via a connecting piece.

8. The method for deep-sea coring using an armored cable-type electric mechanical drill tool according to claim 7, characterized in that: The drive circulation device includes a drilling motor, a reducer, a water pump and a cylindrical shell. The motor, reducer and water pump are located in the cylindrical shell. The motor is connected to the reducer, and the reducer is used to provide power to the coring drill bit; the water pump is used to collect the drilling fluid carrying cuttings through the circulation channel into the cuttings chamber of the cuttings tube through the pumping action.

9. The method for deep-sea coring using an armored cable-type electric mechanical drilling tool according to claim 8, characterized in that: The upper end of the cuttings tube is connected to the lower end of the cylindrical shell. A filter is provided at the upper end of the cuttings tube. The inner cavity of the cuttings tube is a cuttings chamber. A central tube is provided in the cuttings chamber. An umbrella-shaped cuttings stopper is designed at the top of the central tube. The drilling fluid carries cuttings and flows into the cuttings chamber from the lower end of the central tube and is discharged into the cuttings chamber through the guide hole on the lower end surface of the umbrella-shaped cuttings stopper. The lower end of the cuttings tube is connected to the core sampling tube, and the lower end of the core sampling tube is connected to the coring drill bit.

10. The method for deep-sea coring using an armored cable-type electric mechanical drilling tool according to claim 9, characterized in that: The core drill bit adopts a roller drill bit when the seabed to be drilled is soft rock or medium hardness rock formation; and adopts a diamond drill bit when the seabed to be drilled is hard rock formation.

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