Construction device and method for directional branch hole of geological drilling rope coring based on eccentric guide

Abstract

This application provides a device and method for constructing directional branch holes using wireline coring in geological drilling based on eccentric guidance. The device includes: an eccentric guidance mechanism and a gyroscope; the eccentric guidance mechanism includes: an eccentric wedge with a solid cylindrical structure; one end face of the eccentric wedge is a beveled surface; an eccentric plate, which is plate-shaped with a concave arc front and a back detachably connected to the eccentric wedge via multiple fixing bolts; a second connecting frame with a hollow cylindrical structure, one end of which is detachably connected to the eccentric wedge; the end of the second connecting frame connected to the eccentric wedge has an opening allowing the drill bit to pass through; and a long strip of guiding magnetic strip embedded in the inner wall of the second connecting frame; the gyroscope is fixed inside the gyroscope housing. The advantages of this application are: the trajectory deviation rate of multi-branch holes is reduced to within ±3%, the target point hit accuracy is improved by more than 60%, which can meet the exploration needs of deep-hole multi-branch holes; the directional drilling efficiency is improved by more than 35%, reducing the risk of stuck drill bit in the hole.

Description

Technical Field

[0001] This application belongs to the field of geological drilling engineering technology, specifically relating to a geological drilling wireline coring directional branch hole construction device and method based on eccentric guidance. Background Technology

[0002] In geological drilling operations, directional branch hole technology can generate multiple branch holes from a single main hole, enabling simultaneous exploration of different strata or target points in the same area, significantly improving exploration efficiency and information coverage. Wireline coring technology, on the other hand, can reduce the number of tripping operations by lowering / retrieving coring tools with wirelines, thus reducing the time and cost of deep-hole drilling. However, existing combined technologies still face significant technical bottlenecks:

[0003] 1. Conflict between branch hole construction sequence and trajectory control: Traditional processes often adopt the mode of "constructing the main hole to the bottom in one go and then turning back to construct the branch hole" or "constructing the branch hole first and then completing the main hole". The former is prone to deviation in branch hole construction due to the decrease in the stability of the main hole wall, while the latter lacks the initial positioning benchmark of the main hole, making it difficult to accurately match the needs of multiple branch layers. Especially in the construction of multiple branch holes, the trajectory deviation rate can reach more than 15%.

[0004] 2. Poor adaptability of the guiding mechanism: Most existing guiding devices are fixed structures or rigidly connected to the main hole drill rod (casing) and cannot be disassembled. During construction, the entire set of drilling tools needs to be replaced frequently, which not only increases the complexity of operation, but also easily causes the risk of stuck drill bit in the hole. Moreover, most guiding mechanisms have fixed wedge angles and cannot adjust the directional angle according to different formation hardness. In formations with uneven soft and hardness, the directional efficiency is reduced by more than 30%.

[0005] 3. Low dependence on directional accuracy: Traditional directional drilling mostly uses measurement while drilling (MWD) systems. Due to the interference of drilling mud and the shielding of electromagnetic signals, the azimuth measurement error can reach ±5° in deep holes (>1000m) or high-mineralization formations, which cannot meet the requirements of accurate target hitting of branch holes.

[0006] 4. Insufficient coordination between wireline coring and branch hole construction: During branch hole construction, the diameter matching degree between the coring drill and the guiding mechanism is low, which easily leads to core blockage or wear of the coring tube, resulting in the core recovery rate dropping to below 70%, making it impossible to obtain complete stratigraphic information of the branch hole and affecting the accuracy of geological analysis.

[0007] Based on the above problems, there is an urgent need to develop a geological drilling wireline coring directional branch hole construction device and method that takes into account the rationality of construction sequence, guidance flexibility, orientation accuracy and core integrity, so as to break through the technical bottleneck of multi-branch hole exploration. Summary of the Invention

[0008] The purpose of this application is to overcome the shortcomings of existing geological drilling directional branch hole construction, such as large trajectory deviation, poor adaptability of guiding mechanism, low orientation accuracy, and insufficient coordination of wireline coring.

[0009] To achieve the above objectives, this application proposes a geological drilling wireline coring directional branch hole construction device based on eccentric guidance, characterized in that it includes: an eccentric guidance mechanism and a gyroscope;

[0010] The eccentric guiding mechanism includes:

[0011] An eccentric wedge with a solid cylindrical structure; one end face of the eccentric wedge is a beveled surface; the beveled surface is elliptical in shape, and the normal of the beveled surface, the major axis of the beveled surface, and the axis of the eccentric wedge are coplanar;

[0012] The eccentric plate is a plate-shaped structure with a concave arc shape on its front side; the back side of the eccentric plate is detachably connected to the eccentric wedge by multiple fixing bolts.

[0013] The second connecting frame has a hollow cylindrical structure, one end of which is detachably connected to the eccentric wedge; the end of the second connecting frame connected to the eccentric wedge has an opening that allows the drill bit to pass through;

[0014] A long, strip-shaped guide magnetic strip is embedded in the inner wall of the second connecting frame; the length direction of the guide magnetic strip is parallel to the axis of the second connecting frame.

[0015] The gyroscope is fixed inside the gyroscope housing; an iron alloy strip is inlaid on the outer wall of the gyroscope housing; the length direction of the iron alloy strip is parallel to the axis of the gyroscope.

[0016] As an improvement to the above device, the fixing bolts are adjusted so that the eccentric plate changes different angles relative to the oblique section of the eccentric wedge.

[0017] As an improvement to the above-mentioned device, the length direction of the guide magnetic strip is on the same plane as the long axis of the oblique section of the eccentric wedge, and is located on the opposite side of the opening of the second connecting frame.

[0018] As an improvement to the above-mentioned device, the eccentric plate is made of alloy steel and its surface is coated with a tungsten carbide wear-resistant layer.

[0019] As an improvement to the aforementioned device, the gyroscope housing is made of a non-magnetic material.

[0020] As an improvement to the above-mentioned device, it also includes:

[0021] A sleeve shoe is a cylindrical structure with one end open.

[0022] The first connecting frame of the cylindrical structure is detachably connected at one end to the open end of the sleeve shoe, and detachably connected at the other end to the end face of the eccentric wedge away from the oblique section.

[0023] This application also provides a method for constructing directional branch holes using wireline coring in geological drilling based on eccentric guidance, implemented using the aforementioned device, the method comprising:

[0024] Step 1: Use the main hole drill to drill the main hole to the designed position of the first layer of branch holes. After stopping drilling, remove the wireline coring drill from the main hole.

[0025] Step 2: Using the device, construct a branch hole with a set angle to the main hole, and extract the rock core from the branch hole using a rope; extract the branch hole rope coring drill and the device.

[0026] Step 3: Use the main hole drill bit to continue drilling the main hole to the designed position of the next layer of branch holes;

[0027] Step 4: Repeat steps 2 and 3 to complete the construction of all branch holes;

[0028] Step 5: Drill the main hole to the designed final hole depth.

[0029] As an improvement to the above method, step 2, which involves using the device to construct a branch hole at a set angle to the main hole, includes:

[0030] Step 2-1: Connect the eccentric guide mechanism to the bottom of the main hole drill rod, ensuring that the connection is sealed and the coaxiality error is less than the set error threshold;

[0031] Step 2-2: Lower the eccentric guide mechanism to the bottom of the main hole through the main hole drill rod; lower the gyroscope from the inner channel of the main hole drill rod to the top of the eccentric guide mechanism, so that the iron alloy strip of the gyroscope shell is attracted to the guide magnetic strip; transmit the azimuth and tilt angle of the gyroscope to the ground through wired transmission; adjust the angle of the eccentric guide mechanism through the main hole drill rod so that the front of the eccentric plate is consistent with the design azimuth angle of the branch hole to be constructed; then remove the gyroscope.

[0032] Steps 2-3: Lower a wireline coring tool, one size smaller than the main borehole diameter, into the eccentric guide mechanism through the inner channel of the main borehole drill rod; start the drilling rig, and drive the wireline coring tool to create an inclination and drill along the eccentric plate through the guiding action of the eccentric plate of the eccentric guide mechanism.

[0033] As an improvement to the above method, step 2, which involves using the device to construct a branch hole at a set angle to the main hole, further includes:

[0034] After the branch hole has been drilled to the set distance, use a gyroscope to measure the apex angle and azimuth angle of the branch hole. If it does not meet the design requirements, remove all drill rods and drill bits, lower the main hole drill bit to enlarge the hole, and then repeat steps 2-1 to 2-3.

[0035] Compared with existing technologies, the advantages of this application are:

[0036] 1. Significantly improved trajectory accuracy: By adopting the "main hole layered progression + gyroscope orientation" approach, the main hole serves as the positioning reference for branch holes. Combined with an adjustable wedge angle, the trajectory deviation rate of multi-layer branch holes is reduced to within ±3%, and the target point hit accuracy is improved by more than 60%, which can meet the exploration needs of deep hole multi-layer branch holes.

[0037] 2. Strong adaptability of the guiding mechanism: The eccentric guiding mechanism can be detachably connected to the main hole drill rod (casing), eliminating the need to replace the entire set of drilling tools and improving operating efficiency by 40%; the wedge angle is infinitely adjustable from 3° to 15°, adapting to different formations such as soft rock and hard rock, improving the angle-making efficiency by more than 35% and reducing the risk of stuck drill bit in the hole.

[0038] 3. High orientation stability: The orientation of the gyroscope is not affected by the mud or electromagnetic interference in the borehole. In deep holes (>1500m) or high mineralization strata, the azimuth measurement error is ≤±0.5°. The orientation accuracy is 80% higher than that of the traditional MWD system, ensuring that the branch holes accurately hit the target strata.

[0039] 4. High core recovery rate: Through caliber grading and matching and core protection structure, the core recovery rate of branch holes is stable at over 90%, which is 20% higher than the existing process. It can completely obtain the stratigraphic information of each branch hole and provide reliable samples for geological analysis.

[0040] 5. Improved construction efficiency: The sequence of "main hole layering + branch hole synchronization" reduces the number of drilling trips by 30%, eliminates the need for artificial hole bottoms, and shortens the construction cycle of a single hole by 25%; moreover, the guide mechanism can be reused, reducing equipment wear and tear costs by 15%, significantly improving the economic benefits of geological exploration. Attached Figure Description

[0041] Figure 1 The diagram shown is a cross-sectional view of a directional branch hole construction device for wireline coring in geological drilling based on eccentric guidance.

[0042] Figure 2 As shown Figure 1 AA cross-section view. Detailed Implementation

[0043] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0044] This invention aims to solve the problems of large trajectory deviation, poor adaptability of guiding mechanisms, low directional accuracy, and insufficient coordination of wireline coring in existing geological drilling directional branch hole construction. By optimizing the construction sequence, designing an adjustable eccentric guiding mechanism, and introducing gyroscope orientation technology, it achieves precise construction of multi-layer directional branch holes and efficient wireline coring, thereby improving the accuracy and efficiency of geological exploration.

[0045] The eccentrically guided geological drilling wireline coring directional branch hole construction device and method provided in this application takes "main hole layered construction + precise branch hole directional drilling + synchronous wireline coring operation" as its core, and combines an adjustable eccentrically guided mechanism and gyroscope orientation technology to achieve synchronous coordination of directional branching and wireline coring.

[0046] like Figure 1 and Figure 2 As shown, the geological drilling wireline coring directional branch hole construction device based on eccentric guidance includes an eccentric guidance mechanism and a gyroscope. The eccentric guidance mechanism includes a casing shoe 1, a first connecting frame 2, an eccentric wedge 3, a fixing bolt 4, an eccentric plate 5, a second connecting frame 10, and a casing 6 connected in sequence.

[0047] The sleeve shoe 1 is a cylindrical structure with one end open. Its open end is detachably connected to one end of the first connecting frame 2, which can be a threaded connection or a snap-fit ​​connection, etc.

[0048] The first connecting frame 2 is a cylindrical structure, with one end detachably connected to the tail of the eccentric wedge 3 and the other end detachably connected to the sleeve shoe 1.

[0049] The eccentric wedge 3 is a solid cylindrical structure with a beveled end face. This beveled surface is elliptical, and the normal to the beveled surface, the major axis of the beveled surface, and the axis of the eccentric wedge 3 are coplanar.

[0050] The eccentric plate 5 has a plate-like structure with a concave arc-shaped surface on its front side, which allows the drill bit to smoothly turn at a certain angle. The back side of the eccentric plate 5 is detachably connected to the beveled surface of the eccentric wedge 3 via multiple fixing bolts 4. By adjusting the fixing bolts 4, the angle of the eccentric plate 5 relative to the beveled surface of the eccentric wedge 3 can be adjusted, allowing the drill bit to deviate from its original trajectory by 3°-15° under the guidance of the eccentric plate 5. The body of the eccentric plate 5 is made of high-strength alloy steel (40CrNiMoA) and coated with a tungsten carbide wear-resistant layer to reduce friction loss during directional drilling.

[0051] The head of the eccentric wedge 3 is detachably connected to the second connecting frame 10. The second connecting frame 10 is a cylindrical structure with an opening at the end connected to the eccentric wedge 3. Guided by the eccentric plate 5, the drill bit can deviate from its original track and drill laterally from the opening. A long strip of guide magnetic strip 7 is embedded in the side wall of the second connecting frame 10. The length direction of the guide magnetic strip 7 is parallel to the axis of the second connecting frame 10.

[0052] The end of the second connecting bracket 10 furthest from the eccentric wedge 3 is detachably connected to the sleeve 6.

[0053] The gyroscope is fixed inside the gyroscope housing 8. An iron alloy strip 9 is embedded in the outer wall of the cylindrical gyroscope housing 8, with its length parallel to the axis of the housing 8. When the gyroscope housing 8 with the gyroscope is placed into the sleeve and reaches the position of the second connecting frame 10, the iron alloy strip 9 attracts the guide magnetic strip 7, fixing the angle of the gyroscope to the angle of the eccentric wedge 3. Ground personnel can then determine the angle of the eccentric wedge 3 based on the data provided by the gyroscope, allowing for precise control of the drill bit's offset direction.

[0054] To facilitate the calculation of the angle of the eccentric plate 5, the length direction of the guide magnetic strip 7 is preferably on the same plane as the long axis of the oblique section of the eccentric wedge 3, and on the opposite side of the opening of the second connecting frame 10.

[0055] The gyroscope transmits measurement data to the ground control system via a wired connection (to avoid wireless signal interference). For strata with high mineralization and strong electromagnetic interference, the gyroscope uses a non-magnetic shell to avoid magnetic field interference and ensure stable orientation accuracy under various geological conditions.

[0056] This application also provides a method for constructing directional branch holes in geological drilling wireline coring based on eccentric guidance. Based on the aforementioned device, it employs a sequence of "layered progression of the main hole - synchronous construction of branch holes" to achieve precise connection between multiple branch holes and the main hole. The specific process is as follows:

[0057] 1. Construction of the first layer of the main hole: Based on the geological survey data, determine the layer depth of each branch hole (such as the depth of the first branch hole H1 and the depth of the second branch hole H2). First, use the main hole drilling tool (wired coring drill rod / casing that matches the diameter of the main hole) to construct the main hole to the designed position H1 of the first branch hole. After stopping drilling, remove the wired coring drill tool from the main hole.

[0058] 2. Preparation for guiding the first branch hole: Connect the eccentric guide mechanism to the bottom of the main hole drill rod (sleeve), ensuring that the connection thread is sealed and the coaxiality error is <0.5mm; lower the eccentric guide mechanism to position H1 through the drill rod (sleeve); lower the gyroscope to the top of the eccentric guide mechanism through the inner channel of the drill rod, complete the measurement of azimuth and tilt angles, adjust the angle of the eccentric guide mechanism through the drill rod so that the front of the eccentric plate is consistent with the design azimuth angle of the first branch hole, and remove the gyroscope.

[0059] 3. First-level branch hole directional drilling and coring: Select a wireline coring tool with a diameter one level smaller than the main hole (e.g., main hole diameter PQ, branch hole diameter HQ), and lower it into the eccentric guide mechanism through the inner channel of the main hole drill rod (casing); then start the drilling rig, and drive the wireline coring tool to directional drill along the designed trajectory through the guiding action of the eccentric plate of the eccentric guide mechanism. During the drilling process, the rock core is extracted in real time through the wireline to complete the construction of the first-level branch hole.

[0060] 4. Alternating progress between main holes and branch holes: After the first layer of branch holes is completed, the branch hole wireline coring tool is removed, and then the eccentric guide mechanism is brought out to the ground through the main hole drill rod (casing); after replacing the main hole drill tool, the main hole is continued to be constructed to the design position H2 of the second layer of branch holes, and steps 2-3 are repeated to complete the construction of the second layer and subsequent layers of branch holes; after all branch holes are completed, the main hole is constructed to the design final hole depth to complete the overall drilling operation.

[0061] The following is an example of the construction process using the eccentrically guided geological drilling wireline coring directional branch hole construction method provided in this application:

[0062] 1. Preparations before implementation

[0063] 1) Geological Data Acquisition and Parameter Design: Through preliminary geological exploration, the stratigraphic structure of the drilling area was determined: the first branch borehole is located in the sandstone layer, with a depth of H1=500m; the second branch borehole is located in the limestone layer, with a depth of H2=1000m. The main borehole diameter is designed to be PQ, and the branch borehole diameter is designed to be HQ. The directional drilling angle of the first branch borehole is set to 8°, and the directional drilling angle of the second branch borehole is set to 12°.

[0064] 2) Equipment selection and commissioning:

[0065] Main hole drilling tools: PQ wireline coring drill pipe (casing) is selected, made of high-strength alloy steel, with a pressure resistance rating of ≥30MPa;

[0066] Eccentric guide mechanism: wedge angle adjustment range 3°-15°;

[0067] Branch hole coring tool: titanium alloy coring tube with polytetrafluoroethylene coating on the inner wall;

[0068] Gyroscope: Fiber optic gyroscope, azimuth measurement error ≤ ±0.5°, non-magnetic housing design;

[0069] Equipment debugging: Start the drilling rig and mud circulation system, and calibrate the gyroscope.

[0070] 3) Site and auxiliary material preparation: Build a flat drilling platform and ensure that the drilling rig's levelness error is <0.1°; prepare wall protection mud, as well as core storage boxes, numbered labels and other auxiliary materials.

[0071] 2. Specific construction steps

[0072] 1) Construction of the first layer of the main borehole (up to H1=500m)

[0073] Connect the PQ main hole wireline coring drill rod (casing) to the drilling rig, start the mud circulation system, and drill the main hole with reasonable drilling parameters; when drilling reaches a depth of 500m (design position H1 of the first branch hole), stop drilling and remove the wireline coring tool from the main hole.

[0074] 2) Installation and Orientation of the First-Level Branch Hole Guiding Mechanism

[0075] Connect the eccentric guide mechanism to the bottom of the PQ main hole drill rod (sleeve) via a thread, and lower the eccentric guide mechanism to the predetermined position (bottom of the hole) using a down-drilling method; lower the fiber optic gyroscope into the installation channel of the eccentric guide mechanism through the inner channel of the main hole drill rod (sleeve), fix it, start the gyroscope, and complete the calibration. The error between the azimuth angle measurement value and the design value is 0.2°.

[0076] 3) First-level branch hole skewing and wireline coring

[0077] Select the HQ branch hole wireline coring drill bit and lower it through the inner channel of the PQ main hole drill rod (casing) until the drill bit head is in contact with the lower guide head of the eccentric guide mechanism; start the drilling rig and slowly make an directional drilling at a small parameter; after the directional section is completed, complete the branch hole construction using the conventional wireline coring drilling method; when the branch hole is drilled to 10 meters, use a gyroscope to measure the apex angle and azimuth angle of the branch hole in time. If it does not meet the design requirements, you can remove all drill rods and drill bits, lower the PQ guide drill bit to enlarge the hole, and then repeat 2)~3).

[0078] When the branch hole reaches the designed depth (e.g., 100m, target point coordinate error ≤ ±0.5m), stop drilling, remove the HQ coring tool, and then remove the eccentric guide mechanism through the main hole drill rod (casing).

[0079] 4) Construction of the second layer of the main hole and operation of the second layer of branch holes

[0080] Replace the PQ main hole drill bit and continue drilling the main hole to H2=1000m; use the same construction method as the first layer for branch hole operations; use the HQ coring drill bit to drill the second layer branch hole until the designed depth is reached, and then remove the coring drill bit and guide mechanism.

[0081] 5) Main hole completion and finishing

[0082] Replace the main borehole drill bit and drill the main borehole to the designed final depth (e.g., 1500m). During this process, maintain stable mud circulation to prevent borehole wall collapse. After completing the main borehole drilling, remove all drill bits, clean the construction site, and clean and maintain the eccentric guide mechanism, gyroscope, and drill bits (e.g., replace the wear-resistant layer on the wedge surface and calibrate the gyroscope accuracy) for use in subsequent projects.

[0083] 3. Implementation effect verification

[0084] This technology was applied in a metal mine exploration project to complete the construction of one main borehole (1500m deep) and two branch boreholes (100m and 120m deep respectively). The results showed that:

[0085] The deviation of the branch hole trajectory is ≤±2.5%, and the target hit accuracy meets the design requirements;

[0086] The average core recovery rate of the main borehole and branch boreholes was 93%, which is 22% higher than that of traditional methods.

[0087] The construction period for a single hole is 60 days, which is 26% shorter than that of traditional methods.

[0088] Equipment wear and tear costs are reduced by 18%, and there are no problems such as drill bit jamming inside the hole or guide mechanism failure. The overall construction effect is significantly better than existing technologies.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application, and should all be covered within the scope of the claims of this application.

Claims

1. A geological drilling wireline coring directional branch hole construction device based on eccentric guidance, characterized in that, include: Eccentric guiding mechanism and gyroscope; The eccentric guiding mechanism includes: An eccentric wedge with a solid cylindrical structure; one end face of the eccentric wedge is a beveled surface; the beveled surface is elliptical in shape, and the normal of the beveled surface, the major axis of the beveled surface, and the axis of the eccentric wedge are coplanar; The eccentric plate is a plate-shaped structure with a concave arc shape on its front side; the back side of the eccentric plate is detachably connected to the eccentric wedge by multiple fixing bolts. A hollow cylindrical second connecting frame, one end of which is detachably connected to the eccentric wedge; the end of the second connecting frame connected to the eccentric wedge has an opening allowing a drill bit to pass through; and A long, strip-shaped guide magnetic strip is embedded in the inner wall of the second connecting frame; the length direction of the guide magnetic strip is parallel to the axis of the second connecting frame. The gyroscope is fixed inside the gyroscope housing; an iron alloy strip is inlaid on the outer wall of the gyroscope housing; the length direction of the iron alloy strip is parallel to the axis of the gyroscope; Adjust the fixing bolts to change the angle of the eccentric plate relative to the oblique surface of the eccentric wedge. The length direction of the guide magnetic strip is on the same plane as the long axis of the oblique section of the eccentric wedge, and is located on the opposite side of the opening of the second connecting frame.

2. The geological drilling wireline coring directional branch hole construction device based on eccentric guidance according to claim 1, characterized in that, The eccentric plate is made of alloy steel and has a tungsten carbide wear-resistant layer sprayed on its surface.

3. The geological drilling wireline coring directional branch hole construction device based on eccentric guidance according to claim 1, characterized in that, The gyroscope housing is made of non-magnetic material.

4. The geological drilling wireline coring directional branch hole construction device based on eccentric guidance according to claim 1, characterized in that, Also includes: A sleeve shoe is a cylindrical structure with one end open. and The first connecting frame of the cylindrical structure is detachably connected at one end to the open end of the sleeve shoe, and detachably connected at the other end to the end face of the eccentric wedge away from the oblique section.

5. A method for constructing directional branch holes in geological drilling wireline coring based on eccentric guidance, implemented using the apparatus described in any one of claims 1-4, the method comprising: Step 1: Use the main hole drill to drill the main hole to the designed position of the first layer of branch holes. After stopping drilling, remove the wireline coring drill from the main hole. Step 2: Using the device, construct a branch hole with a set angle to the main hole, and extract the rock core from the branch hole using a rope; extract the branch hole rope coring drill and the device. Step 3: Use the main hole drill bit to continue drilling the main hole to the designed position of the next layer of branch holes; Step 4: Repeat steps 2 and 3 to complete the construction of all branch holes; Step 5: Drill the main hole to the designed final hole depth.

6. The method for constructing directional branch holes for wireline coring in geological drilling based on eccentric guidance according to claim 5, characterized in that, Step 2, which involves using the device to construct a branch hole at a predetermined angle to the main hole, includes: Step 2-1: Connect the eccentric guide mechanism to the bottom of the main hole drill rod, ensuring that the connection is sealed and the coaxiality error is less than the set error threshold; Step 2-2: Lower the eccentric guide mechanism to the bottom of the main hole through the main hole drill rod; lower the gyroscope from the inner channel of the main hole drill rod to the top of the eccentric guide mechanism, so that the iron alloy strip of the gyroscope shell is attracted to the guide magnetic strip; transmit the azimuth and tilt angle of the gyroscope to the ground through wired transmission; adjust the angle of the eccentric guide mechanism through the main hole drill rod so that the front of the eccentric plate is consistent with the design azimuth angle of the branch hole to be constructed; then remove the gyroscope. Steps 2-3: Lower a wireline coring tool, one size smaller than the main borehole diameter, into the eccentric guide mechanism through the inner channel of the main borehole drill rod; start the drilling rig, and drive the wireline coring tool to create an inclination and drill along the eccentric plate through the guiding action of the eccentric plate of the eccentric guide mechanism.

7. The method for constructing directional branch holes for wireline coring in geological drilling based on eccentric guidance according to claim 6, characterized in that, Step 2, which involves using the device to construct a branch hole at a predetermined angle to the main hole, further includes: After the branch hole has been drilled to the set distance, use a gyroscope to measure the apex angle and azimuth angle of the branch hole. If it does not meet the design requirements, remove all drill rods and drill bits, lower the main hole drill bit to enlarge the hole, and then repeat steps 2-1 to 2-3.

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