Method for tripping in electrical logging device of semi-submersible drilling platform

Abstract

The invention relates to the technical field of cable logging, in particular to a semi-submersible drilling platform electrical logging device tripping-in method which comprises the following steps that a sleeve with the matched size is tripped in an underwater borehole, well cementation is completed, an underwater simple wellhead is built, a protective sleeve with the certain length is installed below a rotary table face on a semi-submersible drilling platform, and the rotary table face is provided with a protective sleeve with the certain length; and the assembled electrical logging device is gradually lowered from the protection sleeve, meanwhile, the underwater ROV and the electrical logging instrument are kept to be lowered synchronously, the state of the electrical logging instrument string is monitored and adjusted in the whole process, and the electrical logging instrument is assisted to enter and exit from an underwater simple wellhead. An underwater blowout preventer and a marine riser do not need to be tripped in the electric logging operation period, the well building time of deepwater drilling operation is shortened, the tripping-in speed is increased, the influence of ocean current on an instrument string is eliminated, the problem that the electric logging instrument string in an open sea area is prone to deviating from a wellhead in the tripping-in process is solved, the operation requirement for drilling and cable logging in the open sea area is met, and the construction period is shortened. The purpose of safely, efficiently and reliably obtaining geological data is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of cable logging, and more specifically, to a method for lowering an electric logging device into a semi-submersible drilling platform. Background Art

[0002] The drilling and construction costs of ultra-deepwater wells on semi-submersible drilling platforms are often high due to the huge risks involved and the stringent performance requirements on various equipment. In deepwater wells, the burial depth of shallow gas is generally very shallow. If blowout preventers and risers are lowered according to normal well control requirements, the overall drilling cost will be greatly increased. Therefore, under the condition that technical means have matured in recent years, in order to reduce the well construction cycle of a single well and improve the operation efficiency, the exploration and development of shallow gas requires an open sea operation method without the use of underwater blowout preventers and risers. If there are no underwater blowout preventers and risers, the cables and instruments will be greatly affected by tides and ocean currents during the cable logging process. Since the cables are soft, they will be affected by ocean currents when the instruments enter the water. The logging instruments may collide with the underwater thrusters of the drilling platform due to the influence of ocean currents. At the same time, during the lowering of the instruments, the logging instruments may deviate far from the water turntable surface. In the dim environment of more than one thousand meters deep water, it is impossible to aim at the wellhead and cannot accurately enter and exit the wellhead, which means that the operation objectives cannot be completed, resulting in operation failure.

[0003] There is a Chinese invention with publication number CN116065961A, which discloses a pressure-controlled drilling system and drilling method for deep-water drilling in deep sea areas. The system includes a riser rotation control nipple, an MPD hydraulic control nipple, a riser annulus sealing device, a riser spool, etc., which are integrated on an independent drilling riser, and form a system with its corresponding ground key equipment: MPD throttling manifold, MPD hydraulic control manifold, MPD buffer manifold, MPD filter manifold, MPD mud gas separator and other equipment, and is used together with the riser booster pump, metering tank pump, turntable, mud diverter, riser expansion joint, riser tension ring, drilling riser, underwater blowout preventer group, seabed water turntable face head and other equipment of conventional deep-water drilling equipment. The present invention can be applied to deep-water (water depth of more than 300m) semi-submersible drilling platform, drilling ship and other equipment to implement pressure-controlled drilling and related drilling operations.

[0004] However, in the above technical solution, it is necessary to set up an underwater blowout preventer group and a drilling riser, which leads to a long well construction period and low operation efficiency, and is not suitable for shallow gas exploration. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for lowering an electrical logging device on a semi-submersible drilling platform. During the electrical logging operation, there is no need to lower an underwater blowout preventer and a watertight pipe, thereby reducing the well construction time of deep-water drilling operations, improving the lowering rate, and eliminating the influence of ocean currents on the instrument string. The problem that the electrical logging instrument string is easy to deviate from the wellhead during the lowering process solves the problem, meets the operational requirements of cable logging in open sea drilling, and achieves the purpose of safely, efficiently and reliably obtaining geological data.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for lowering an electrical measuring device of a semi-submersible drilling platform, comprising the following steps:

[0007] S100: Installing protective casing on the turntable surface of a semi-submersible drilling platform;

[0008] S200: lowering the electrical measuring device into the protective casing and placing the underwater ROV into the water;

[0009] S300: using the underwater ROV to detect the lowering position and state of the electric measuring device, and transmitting the lowering position and state information of the electric measuring device to the controller on the semi-submersible drilling platform;

[0010] S400: The controller controls the underwater ROV to adjust the lowering position and state of the electric measuring device according to the received lowering position and state information of the electric measuring device, until the electric measuring device is lowered into the underwater wellhead at the bottom of the water.

[0011] In the present technical solution, when the electric measuring device is lowered or lowered on the semi-submersible drilling platform, step S100 is first performed to install a protective casing on the turntable surface of the semi-submersible drilling platform, and the protective casing is directly inserted below the horizontal plane. Then step S200 is performed to lower the electric measuring device into the water through the casing, thereby preventing the electric measuring device from being affected by the ocean current during the process of directly entering the water, so that the electric measuring device is affected by the ocean current and it is difficult to control its movement direction, causing it to collide with the underwater propeller of the drilling platform. At the same time, the underwater ROV is put into the water, and then step S300 is performed. The underwater ROV is electrically connected to the controller. The underwater ROV has power and can autonomously approach the electric measuring device in the water to detect it and transmit the position information and status of the electric measuring device to the controller. Finally, step S400 is performed, and the controller controls the underwater ROV to work. The underwater ROV can adjust the movement direction of the electric measuring device by pushing the electric measuring device, thereby ensuring that the electric measuring device can move in the water in a preset direction, improving the accuracy of the electric measuring device, and the adjustment is flexible and simple, avoiding the electric measuring device being affected by the underwater ocean current and unable to control its movement direction, resulting in it not being able to accurately fall into the cementing casing at the bottom of the water. At the same time, there is no need to install underwater blowout preventers and risers, saving related parts and installation time, and improving logging efficiency. When the electric measuring device enters the cementing casing, the electric measuring operation in the well can be started.

[0012] Preferably, the step S100 specifically includes the following steps:

[0013] S101: The drilling depth needs to take into account the length of the electrical measuring device, and the drilling depth is deeper than the length of the electrical measuring device;

[0014] S102: After the drilling is completed, a cementing casing matching the well diameter of the water turntable surface is lowered into the well at the bottom of the water;

[0015] S103: The length of the protective sleeve installed on the turntable surface should be between 150m and 250m.

[0016] Preferably, the step S200 specifically includes the following steps:

[0017] S201: a derrick is arranged above the turntable surface, a first pulley block is installed on the derrick, a first driving member is further provided on the semi-submersible drilling platform, one end of the first pulley block is connected to the driving end of the first driving member, and the other end of the first pulley block is connected to the electrical measuring device;

[0018] S202: a second driving member is arranged on the semi-submersible drilling platform, a driving end of the second driving member is connected to one end of a cable, the other end of the cable is connected to the underwater ROV, and the second driving member drives the cable to be put into the water to place the underwater ROV to monitor the electrical measuring device;

[0019] S203: Testing whether the electrical measuring device works normally;

[0020] S204: The first driving member drives the first pulley block to place the electrical measuring device from the protective casing into water.

[0021] Preferably, the step S300 specifically includes the following steps:

[0022] S301: The controller controls the underwater ROV to approach the electrical measuring device;

[0023] S302: The underwater ROV detects the lowering position and status of the electrical measuring device and transmits the detection results to the controller.

[0024] Preferably, the step S400 further includes the following steps:

[0025] S500: pulling the electric measuring device up slowly to perform well logging on the target layer, and transmitting the measured data to the controller;

[0026] S600: After the well logging is completed, the electrical logging device is pulled back to the turntable surface on the semi-submersible drilling platform;

[0027] S700: Lifting the underwater ROV out of the water and back onto the semi-submersible drilling platform.

[0028] Preferably, the upper end of the cementing casing should be 2m to 3m higher than the bottom mud surface.

[0029] Preferably, the protective sleeve is formed by splicing a plurality of sleeves, each section of the sleeve is connected by a thread, and a white indicator line is provided at the threaded connection of each section of the sleeve along its axial direction.

[0030] Preferably, a C-shaped disc for clamping the electrical measuring device is provided at the upper end of the sleeve.

[0031] Preferably, a tension sensor is provided on the first pulley block, and the tension sensor is used to send tension information on the first pulley block to the controller.

[0032] Preferably, a white observation zone at least 1 m high is provided at the bottom of the electrical measuring device.

[0033] Compared with the prior art, the beneficial effects of the present invention are: there is no need to lower an underwater blowout preventer and a riser when lowering the electrical measuring device, which reduces the parts that need to be installed during lowering and increases the lowering rate. By providing a protective casing, the electrical measuring device is prevented from being deflected by currents and waves. An underwater ROV is also provided, which can detect and adjust the movement state of the electrical measuring device in the water in real time. It has high lowering accuracy and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of Embodiment 1 of the method for lowering an electric measuring device of a semi-submersible drilling platform according to the present invention;

[0035] Figure 2 It is a schematic diagram of a method for lowering an electric measuring device of a semi-submersible drilling platform according to the present invention.

[0036] In the attached drawings: 1. semi-submersible drilling platform; 2. turntable surface; 3. protective casing; 4. electrical measuring device; 5. underwater ROV; 6. controller; 7. underwater wellhead; 8. cementing casing; 9. derrick; 10. first pulley block; 11. first driving member; 12. second driving member; 13. cable. DETAILED DESCRIPTION

[0037] The drawings are only for illustrative purposes and cannot be construed as limiting the present invention. To better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged, or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are only for illustrative purposes and cannot be construed as limiting the present invention.

[0038] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "long", "short" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, they 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. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0039] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0040] Example 1

[0041] like Figure 1 , 2As shown, a method for lowering an electric measuring device of a semi-submersible drilling platform comprises the following steps:

[0042] S100: Install the protective casing 3 at the turntable surface 2 on the semi-submersible drilling platform 1; the protective casing 3 is directly inserted below the horizontal plane to form a channel for subsequently lowering the electric measuring device 4.

[0043] S200: lowering the electric measuring device 4 from the protective casing 3, and simultaneously placing the underwater ROV 5 into the water; the protective casing 3 protects the electric measuring device 4, and prevents the electric measuring device 4 from being affected by the ocean current when directly entering the water, so that the electric measuring device 4 is affected by the ocean current and cannot control its movement direction, causing it to collide with the underwater propeller of the semi-submersible drilling platform 1. At the same time, the underwater ROV 5 is placed into the water to assist the electric measuring device 4 in its underwater movement.

[0044] S300: Use the underwater ROV5 to detect the lowering position and status of the electric measuring device 4, and transmit the lowering position and status information of the electric measuring device 4 to the controller 6 on the semi-submersible drilling platform 1; the underwater ROV5 is electrically connected to the controller 6, and the underwater ROV5 has power, and can autonomously approach the electric measuring device 4 located in the water to detect it and transmit the position information and status of the electric measuring device 4 to the controller 6.

[0045] S400: The controller 6 controls the underwater ROV5 to adjust the lowering position and state of the electric measuring device 4 according to the received lowering position and state information of the electric measuring device 4, until the electric measuring device 4 is lowered into the underwater wellhead 7 at the bottom of the water. The controller 6 controls the underwater ROV5 to work, and the underwater ROV5 can adjust the movement direction of the electric measuring device 4 by pushing the electric measuring device 4, thereby ensuring that the electric measuring device 4 can move in the water in a preset direction, improving the accuracy of the lowering of the electric measuring device 4, and the adjustment is flexible and simple, avoiding the electric measuring device 4 being affected by the underwater ocean current and unable to control its movement direction, resulting in it not being able to accurately fall into the underwater wellhead 7 at the bottom of the water, and at the same time, there is no need to install an underwater blowout preventer and a watertight pipe, saving related parts and installation time, and improving the logging efficiency. When the electric measuring device 4 enters the cementing protection casing 3, the electric measuring operation in the well can be started.

[0046] like Figure 1 As shown, step S100 specifically includes the following steps:

[0047] S101: The drilling depth needs to take into account the length of the electric measuring device 4. The drilling depth is deeper than the length of the electric measuring device 4. The drilling should ensure that the electric measuring device 4 can be fully accommodated to avoid the electric measuring device 4 being unable to fully enter the drilling well, resulting in the data measured by the electric measuring device 4 not belonging to the data in the drilling well.

[0048] S102: After drilling is completed, a cementing casing 8 matching the diameter of the underwater wellhead 7 is lowered into the underwater well; the cementing casing 8 is used to support the well wall after drilling is completed to prevent the well wall from collapsing and burying the wellbore.

[0049] S103: The length of the protective sleeve 3 installed at the turntable surface 2 should be between 150m and 250m. The protective sleeve 3 with a length of 150m to 250m can be inserted from the semi-submersible drilling platform 1 to below the water surface, and play a protective and guiding role for the electric measuring device 4 within a considerable distance, thereby preventing the electric measuring device 4 from being affected by the ocean current when it directly enters the water, so that the electric measuring device 4 is affected by the ocean current and it is difficult to control its movement direction, causing it to collide with the underwater propeller of the drilling platform 1.

[0050] like Figure 2 As shown, step S200 specifically includes the following steps:

[0051] S201: A derrick 9 is arranged above the turntable surface 2, and a first pulley block 10 is installed on the derrick 9. A first driving member 11 is also arranged on the semi-submersible drilling platform 1. One end of the first pulley block 10 is connected to the driving end of the first driving member 11, and the other end of the first pulley block 10 is connected to the electric measuring device 4. The derrick 9 is used to hoist the first pulley block 10, and the first pulley block 6 is used to suspend the electric measuring device 4. This arrangement ensures that the electric measuring device 4 can be aligned with the turntable surface 2 from above and lowered into the protective casing 3. The two ends of the first pulley block 10 are respectively connected to the electric measuring device 4 and the first driving member 11. The first driving member 11 is installed on the semi-submersible drilling platform 1. The first driving member 11 can provide power for the first pulley block 10 to lift or lower the electric measuring device 4, so that the electric measuring device 4 does not need to be pulled manually, reducing the labor load of the manual labor. The first driving member 11 is connected to the controller 6, and the staff can control the first driving member 11 through the controller 6.

[0052] S202: A second driving member 12 is provided on the semi-submersible drilling platform 1, and a driving end of the second driving member 12 is connected to one end of a cable 13, and the other end of the cable 13 is connected to an underwater ROV5. The second driving member 12 drives the cable 13 to put the underwater ROV5 into the water to detect the electrical measuring device 4; the underwater ROV5 has its own power and can swim in the water, but it cannot rely on its own power to make the underwater ROV5 return to the semi-submersible drilling platform 1. At the same time, when the underwater ROV5 is lowered into the water, since the semi-submersible drilling platform 1 is at a certain height from the water surface, if the underwater ROV5 is directly dropped into the water from the semi-submersible drilling platform 1, the underwater ROV5 may collide with the water surface due to the excessive falling speed of the underwater ROV5, causing damage to the underwater ROV5. The semi-submersible drilling platform 1 is provided with a second driving member 12, the driving end of the second driving member 12 is connected to one end of a cable 13, and the other end of the cable 13 is connected to the underwater ROV5. The second driving member 12 provides power for lowering or lifting the underwater ROV5. The second driving member 12 can control the speed of releasing or retracting the cable 13 to control the speed of the underwater ROV5 entering the water or lifting it, so as to avoid damage caused by the underwater ROV5 entering the water too quickly. At the same time, the underwater ROV5 can be directly lifted from the water when the electrical measurement is completed.

[0053] S203: Testing whether the electric measuring device 4 works normally; in order to ensure the accuracy of the data measured by the electric measuring device 4, the working state of the electric measuring device 4 should be checked before it works to ensure that it can work normally.

[0054] S204: The first driving member 11 drives the first pulley block 10 to put the electric measuring device 4 into the water from the protective sleeve 3. The first driving member 11 controls the speed of releasing the first pulley block 10 and thus controls the falling speed of the electric measuring device 4, so as to prevent the electric measuring device 4 from falling too fast and colliding with the water surface and causing damage.

[0055] like Figure 2 As shown, step S300 specifically includes the following steps:

[0056] S301: The controller 6 controls the underwater ROV 5 to approach the electrical measuring device 4; the underwater ROV 5 has its own power, which can drive the underwater ROV 5 to move in the water.

[0057] S302: The underwater ROV5 detects the lowering position and status of the electric measuring device 4 and transmits them to the controller 6; a camera is provided on the underwater ROV5. When the underwater ROV5 approaches the electric measuring device 4, the camera can be used to observe the position and falling speed of the electric measuring device 4 and whether the surface of the electric measuring device 4 is damaged to determine the status of the electric measuring device 4.

[0058] like Figure 2 As shown, after step S400, the following steps are also included:

[0059] S500: Pull the electric measuring device 4 up slowly to measure the target layer, and transmit the measured data to the controller 6; the staff can obtain various data in the well through the controller 6 and analyze them.

[0060] S600: After the well logging is completed, the electric measuring device 4 is pulled back onto the turntable surface 2 on the semi-submersible drilling platform 1; the staff removes the electric measuring device 4 and stores it properly to prevent the electric measuring device 4 from being damaged.

[0061] S700: Lift the underwater ROV5 out of the water and back onto the semi-submersible drilling platform 1. The semi-submersible drilling platform 1 is above the horizontal plane, and the underwater ROV5 can only move in the water body by its own power and cannot climb back onto the semi-submersible drilling platform 1, so it is necessary to start the second driving member 12, and the second driving member 12 lifts the underwater ROV5 from the water back onto the semi-submersible drilling platform 1 through the cable 13.

[0062] Example 2

[0063] This embodiment is similar to the above-mentioned embodiment 1, except that: Figure 2 As shown, the upper end of the cementing casing 8 should be 2m to 3m above the bottom mud surface. After the drilling is completed and the cementing casing 8 is installed, the outside world can only observe the upper end of the cementing casing 8. In order to facilitate the determination of the position of the cementing casing 8, the upper end of the cementing casing 8 should be 2m to 3m above the bottom mud surface for easy observation.

[0064] like Figure 2 As shown, the protective sleeve 3 is formed by splicing a plurality of sleeves, and each sleeve section is connected by a thread, and a white indicator line is set at the threaded connection of each sleeve section along its axial direction. The length of the protective sleeve 3 is between 150m and 250m. If a whole protective sleeve 3 is used, it will cause installation difficulties, and it will also be difficult to place and store. Therefore, the protective sleeve 3 is spliced ​​by a plurality of sleeves, and each sleeve section is connected by a thread. A white indicator line is set at the threaded connection of each sleeve section along its axial direction. When each sleeve section is spliced, if the white indicator lines of the two adjacent short tubes are aligned, it means that the two sleeve sections are threaded in place. At the same time, after installation, during the working process of the protective sleeve 3, the staff can also observe whether the two adjacent sleeve sections rotate by observing the white indicator line to avoid the short tube from falling off.

[0065] like Figure 2 As shown, a C-shaped plate for clamping the electric measuring device 4 is provided at the upper end of the protective sleeve 3. When the electric measuring device 4 is hung on the first pulley block 10, the C-shaped plate can play a role of temporarily supporting the electric measuring device 4. After the electric measuring device 4 is hung, the C-shaped plate is pulled out horizontally, and the electric measuring device 4 can freely enter and exit the protective sleeve 3.

[0066] Example 3

[0067] This embodiment is similar to the above-mentioned embodiment 1, except that: Figure 2 As shown, a tension sensor is provided on the first pulley block 10, and the tension sensor is used to send the tension information on the first pulley block 10 to the controller 6. The first pulley block 10 is used to hoist the electrical measuring device 4. If the first pulley block 10 breaks, the electrical measuring device 4 will fall into the water or in the drilling, causing equipment damage. Therefore, it is necessary to detect the state of the first pulley block 10. The breakage of the first pulley block 10 is generally caused by the tension, which causes the first pulley block 10 to be broken. Whether the first pulley block 10 is in a safe state can be determined based on the tension information of the first pulley block 10. Therefore, a tension sensor is provided on the first pulley block 10, and the tension sensor can send the tension information on the first pulley block 10 to the controller 6. The staff can monitor the state of the first pulley block 10 through the controller 6 and determine whether to continue the electrical measurement work.

[0068] like Figure 2 As shown, a white observation belt at least 1m high is provided at the bottom of the electric measuring device 4. The underwater ROV 5 observes and determines the position of the electric measuring device 4 through a camera. The white color is more obvious in water and is easy to be observed. Therefore, a white observation belt 1m high is provided at the bottom of the electric measuring device 4 to facilitate the underwater ROV 5 to determine its position.

[0069] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for lowering an electrical measuring device into a semi-submersible drilling platform, characterized in that: The following steps are involved: S100: Installing a protective casing (3) on a turntable surface (2) of a semi-submersible drilling platform (1); S200: lowering the electrical measuring device (4) into the protective casing (3) and placing the underwater ROV (5) into the water; S300: Using the underwater ROV (5) to detect the lowering position and state of the electric measuring device (4), and transmitting the lowering position and state information of the electric measuring device (4) to the controller (6) on the semi-submersible drilling platform (1); S400: The controller (6) controls the underwater ROV (5) to adjust the lowering position and status of the electric measuring device (4) according to the received lowering position and status information of the electric measuring device (4), until the electric measuring device (4) is lowered into the underwater wellhead (7) at the bottom of the water.

2. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The step S100 specifically includes the following steps: S101: The drilling depth needs to take into account the length of the electrical measuring device (4), and the drilling depth is deeper than the length of the electrical measuring device (4); S102: After the drilling is completed, a cementing casing (8) matching the diameter of the underwater wellhead (7) is lowered into the underwater well; S103: The length of the protective sleeve (3) installed on the turntable surface (2) should be between 150m and 250m.

3. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The step S200 specifically includes the following steps: S201: A derrick (9) is arranged above the turntable surface (2), a first pulley block (10) is installed on the derrick (9), a first driving member (11) is also arranged on the semi-submersible drilling platform (1), one end of the first pulley block (10) is connected to the driving end of the first driving member (11), and the other end of the first pulley block (10) is connected to the electric measuring device (4); S202: A second driving member (12) is provided on the semi-submersible drilling platform (1), a driving end of the second driving member (12) is connected to one end of a cable (13), the other end of the cable (13) is connected to the underwater ROV (5), and the second driving member (12) drives the cable (13) to place the underwater ROV (5) into the water to monitor the electrical measuring device (4); S203: testing whether the electrical measuring device (4) works normally; S204: The first driving member (11) drives the first pulley block (10) to place the electrical measuring device (4) from the protective sleeve (3) into water.

4. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The step S300 specifically includes the following steps: S301: the controller (6) controls the underwater ROV (5) to approach the electrical measuring device (4); S302: The underwater ROV (5) detects the lowering position and status of the electrical measuring device (4) and transmits the information to the controller (6).

5. The method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The step S400 further includes the following steps: S500: pulling the electric measuring device (4) up slowly to perform well logging on the target layer, and transmitting the measured data to the controller (6); S600: After the well logging is completed, the electrical logging device (4) is pulled back onto the turntable surface (2) on the semi-submersible drilling platform (1); S700: Lift the underwater ROV (5) out of the water and lift it back onto the semi-submersible drilling platform (1).

6. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The upper end of the cementing casing (8) should be 2m to 3m above the bottom mud surface.

7. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The protective sleeve (3) is formed by splicing a plurality of sleeves, each section of the sleeve is connected by a thread, and a white indicator line is provided at the threaded connection of each section of the sleeve along its axial direction.

8. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The upper end of the sleeve (3) is provided with a C-shaped disc for clamping the electrical measuring device (4).

9. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 3, characterized in that: The first pulley block (10) is provided with a tension sensor, and the tension sensor is used to send tension information on the first pulley block (10) to the controller (6).

10. A method for lowering an electrical measuring device into a semi-submersible drilling platform according to claim 1, characterized in that: The bottom of the electrical measuring device (4) is provided with a white observation belt at least 1 m high.

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