Efficient wire-line coring drilling tool combined device capable of preventing coal dust from holding drill and using method of efficient wire-line coring drilling tool combined device

Abstract

The invention relates to the technical field of wire-line coring drilling, in particular to an efficient wire-line coring drilling tool combination device capable of preventing coal dust from holding a drill and a using method.The efficient wire-line coring drilling tool combination device comprises a drill bit, a lower reamer, an outer pipe, an upper reamer, an inner pipe assembly, a drill collar and a drill rod, the bottom end of the lower reamer is connected with the drill bit, and the bottom of the outer pipe is in threaded connection with the top end of the lower reamer; the bottom end of the upper reamer is in threaded connection with the top of the outer pipe, the bottom end of the drill collar is connected with the top end of the upper reamer, the bottom end of the drill rod is in threaded connection with the top end of the drill collar, the lower reamer, the outer pipe, the upper reamer, the drill collar and the drill rod are matched to form a drilling tool inner cavity, and the inner pipe assembly is arranged in the drilling tool inner cavity. The drill bit comprises an inner cutting part, a middle cutting part and an outer cutting part, the diameters of the cutting parts are sequentially increased, the cutting parts are in a step shape, the advanced slotting guiding effect is achieved, the number of the compacts in each cutting part is small, the specific pressure of the compacts is high, rock cutting of the compacts is facilitated, and the drilling efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rope coring drilling, and in particular to a high-efficiency rope coring drill tool assembly device for preventing coal dust from holding the drill, and a use method thereof. Background Art

[0002] The rope coring drilling process realizes coring without lifting the drill, greatly shortens the time of lifting the coal core to the surface, improves the gas measurement accuracy, and reduces labor intensity. Therefore, it has become the preferred drilling process for coalbed methane parameter well construction. Since the inner tube assembly needs to be dropped from the drill pipe during drilling, the drill pipe wall of rope coring is thin and has low strength. In order to reduce the accident of drill pipe breakage, small-diameter drilling is generally used, and a "full-eye" drilling tool combination is used, that is, the drill bit diameter is the same as the outer tube diameter and close to the drill pipe diameter, and the gap between the drill pipe or outer tube and the hole wall is small, which reduces the bending of the drill pipe during drilling and achieves the purpose of reducing the accident of drill pipe breakage. In addition, due to the small annular gap between the hole wall and the drill tool, the hole inclination of the drill hole is small, and the strength of the drill pipe is low. Unlike ordinary drilling processes, rope coring drilling generally does not set a drill collar between the drill pipe and the outer tube;

[0003] For example, the diameter of the S95 series drill bit is 95mm or 98mm, and the diameter of the drill rod and outer tube are both 89mm. The diameter difference between the drill hole and the drill rod or outer tube is only 9mm. The small annular gap between the hole wall and the drill rod limits the amount of rock dust collected during drilling. Therefore, wireline coring drilling is generally used to drill hard rock formations with low rock dust content. The drill bits used are generally diamond drill bits with small blades that crush the rock by abrasive means.

[0004] Since the lithology of coal-bearing strata is relatively soft and the amount of rock cuttings is large, especially in pulverized coal strata with low mechanical strength, a large amount of coal powder will quickly flow into the borehole under the action of ground pressure and gas pressure, filling the gap between the drill tool and the hole wall. During the construction of conventional rope coring drilling technology, the rotation of the drill tool is easily obstructed, resulting in coal powder "holding the drill", and the drilling efficiency of diamond drill bits in soft rock formations is low. Therefore, an efficient rope coring drill assembly device with anti-coal powder holding the drill is proposed. Summary of the Invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a high-efficiency rope coring drill assembly device and a method of using the assembly.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a high-efficiency wireline coring drill assembly device for preventing coal dust from holding a drill, comprising a drill bit, a lower reamer, an outer tube, an upper reamer, an inner tube assembly, a drill collar, and a drill rod;

[0007] The bottom end of the lower reamer is connected to the drill bit, the bottom of the outer tube is threadedly connected to the top of the lower reamer, the bottom end of the upper reamer is threadedly connected to the top of the outer tube, the bottom end of the drill collar is connected to the top of the upper reamer, and the bottom end of the drill rod is threadedly connected to the top of the drill collar. The lower reamer, outer tube, upper reamer, drill collar and drill rod cooperate to form the inner cavity of the drill tool, and the inner tube assembly is arranged in the inner cavity of the drill tool.

[0008] Preferably, the drill bit includes a drill bit body, the end of which is formed with three groups of cutting part mounting areas, with three groups of both the outer and inner cutting parts being provided. Each group of cutting part mounting areas is provided with a group of inner cutting parts at the upper portion, and a group of outer cutting parts is provided at the lower portion of each group of cutting part mounting areas. A middle cutting part is formed between two adjacent groups of cutting part mounting areas. Preferably, the operating diameters of the inner, middle, and outer cutting parts increase in stages, and the inner, middle, and outer cutting parts are arranged in a staggered manner, forming a mud reflux channel between the staggered inner, middle, and outer cutting parts. The surfaces of the inner, middle, and outer cutting parts are all inlaid with a plurality of composite pieces for cutting and crushing rock.

[0009] Preferably, a plurality of water holes of different diameters are provided in each group of the cutting portion installation areas, and the outer bevel angle of the water holes is 10°.

[0010] Preferably, the surfaces of the inner cutting part, the middle cutting part and the outer cutting part are all provided with outer diameter-maintaining grooves, and each group of outer diameter-maintaining grooves is inlaid with strip-shaped polycrystalline diamonds.

[0011] Preferably, the inner wall surface of the end portion of the drill bit body is provided with a plurality of groups of inner diameter-keeping grooves, and each group of inner diameter-keeping grooves is inlaid with strip-shaped polycrystalline diamonds.

[0012] Preferably, the diameters of the lower reamer and the upper reamer are larger than the diameter of the drill bit, and continuous reaming teeth are formed on the outside of the lower reamer and the upper reamer.

[0013] Preferably, the diameter of the drill bit is larger than the outer diameter of the drill rod, and the difference between the diameter of the drill bit and the outer diameter of the drill rod is greater than 33 mm.

[0014] The method for using the high-efficiency wireline coring drill assembly device for preventing coal dust from holding the drill comprises the following steps:

[0015] Step S1, assembling and connecting the drill bit, the lower reamer, the outer tube, the upper reamer, the drill collar and the drill pipe;

[0016] Step S2, after the inner tube assembly is assembled on the ground, the inner tube assembly is dropped from the inner cavity of the drill tool to the bottom of the inner cavity of the drill tool;

[0017] Step S3: Determine the drilling pressure based on the ultimate compressive strength of the rock, the compressive strength of the composite sheets, and the total number of composite sheets. The calculation formula for determining the bottom hole drill pressure P based on the ultimate compressive strength of the rock is:

[0018] P=qm

[0019] Where q is the ultimate pressure that a single effective composite sheet can withstand, and m is the number of effective composite sheets;

[0020] Step S4, determine the speed n, the calculation formula of the speed n is:

[0021]

[0022] Where n is the drill bit speed, V is the drill bit linear speed, and D is the drill bit outer diameter;

[0023] Step S5: Determine the pumping pressure of the mud before drilling and flushing. The pressure loss during the circulation of the flushing fluid depends on the total length of the circulation channel, the flow velocity in the channel, the specific gravity of the fluid, the rheological parameters, and the resistance coefficient in the channel. The drilling pressure loss includes the along-the-hole loss inside and outside the drill pipe and the local loss of the joint, drill bit, and core barrel. The along-the-hole loss inside and outside the drill pipe is calculated based on the hydraulic loss of the fluid when flowing in the pipe as follows:

[0024]

[0025] Where λ is the dimensionless resistance coefficient, L is the drill pipe length, d is the inner diameter of the drill pipe, v is the average flow velocity in the pipe, g is the acceleration due to gravity, and γ is the density of the mud;

[0026] When calculating the joint loss in the drill pipe, replace λ in the above formula with the local resistance coefficient ξ:

[0027]

[0028] Where a is the empirical coefficient, the lock joint is 1.5, the lock collar is 2, d is the inner diameter of the drill pipe, d1 is the inner diameter of the drill pipe joint, and the hydraulic loss of the drill bit and core tube is determined by actual measurement;

[0029] The total hydraulic loss is the sum of the hydraulic losses of the above parts. Taking into account the accumulation of rock debris and mud balls, the pump pressure is the total loss multiplied by a coefficient of 1.1 to 1.4.

[0030] Step S6: The amount of mud pumped is determined by factors such as the drilling method, drilling speed, rock properties, borehole structure, and drilling tools. The amount of flushing fluid is determined primarily by the return speed required to carry rock dust, while ensuring bottom hole flushing and drill bit cooling.

[0031] The return velocity v of the flushing fluid is the sum of the settling velocity w of the cuttings and the required upward movement velocity u:

[0032] v=w+u

[0033] If u is 0.1 to 0.3 times w, then v is equal to 1.1 to 1.3 times w;

[0034] The sedimentation velocity w is calculated according to the Littinger formula;

[0035]

[0036] Where d is the diameter of the spherical cuttings, ρ1 is the density of the cuttings, ρ2 is the density of the mud, and k is the coefficient g is the acceleration of gravity, c is the shape coefficient of the rock debris particles, which is 0.5 for spheres, 0.64-0.82 for discs, and 2.1 for irregular or flat particles;

[0037] The formula for calculating the flushing fluid volume in the positive cycle is:

[0038]

[0039] Where m is a coefficient, which is set between 1.05 and 1.1, considering the uneven return velocity caused by the irregular hole diameter and the leakage at the drill pipe joint, D is the borehole diameter, and d is the outer diameter of the drill pipe.

[0040] Substituting dm, ρ1, ρ2, c, and m, we can obtain the pumping capacity required for wireline coring drilling with the drill pipe;

[0041] Step S7, setting drilling data according to the data in steps S3-S6, and starting drilling after completing the drilling data setting;

[0042] In step S8, the mud is transported downward from the ground through the drill pipe, and continues downward through the annular gap between the outer tube and the inner tube assembly to approach the bottom of the drill bit. Part of the mud is ejected from the water hole, and the other part flows downward from the gap between the drill bit and the core to the bottom of the hole. The two parts of mud finally merge and return to the ground through the annular gap between the outer tube of the hole wall, the drill collar and the drill pipe.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] 1. The present invention is provided with an inner cutting part, a middle cutting part, and an outer cutting part. The diameter of each cutting part is successively enlarged in a stepped shape, which serves as a guide for advanced slotting. The number of composite sheets in each cutting part is small, so that the composite sheets have a high specific pressure, which is conducive to the composite sheets cutting rocks and improving drilling efficiency. The staggered coordination of the inner, middle, and outer cutting parts forms a smooth mud return channel, improving drilling efficiency and preventing coal dust from sticking to the drill. The number of blades outside the inner, middle, and outer cutting parts is small, and the blades are high and narrow, so that the mud cross-sectional area of ​​the mud return channel is large, which is conducive to the discharge of rock and coal dust, further improving drilling efficiency, and preventing coal dust from sticking to the drill.

[0045] 2. The drill bit of the present invention adopts a composite drill bit. Compared with diamond drill bits that crush rocks by grinding, the composite drill bit crushes rocks by both cutting and grinding, which is more suitable for drilling in coal-bearing formations and further improves drilling efficiency.

[0046] 3. The present invention adds a drill collar. After the annular gap between the hole wall and the drill rod is increased, the drill collar plays a role in reducing the hole inclination. The diameters of the drill rod, outer tube and drill collar are larger than the diameter of the drill bit, so that there is a larger annular gap between the hole wall and the drill tool, ensuring that the coal powder is discharged smoothly with the mud and preventing the coal powder from sticking to the drill. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the overall configuration of the present invention;

[0048] Figure 2 This is a schematic diagram of the three-dimensional structure of the drill bit of the present invention;

[0049] Figure 3 Schematic diagram of the mud flow direction of the present invention.

[0050] The numbers in the figure represent:

[0051] 1. Drill bit; 11. Drill bit body; 12. Cutting section mounting area; 13. Outer cutting section; 14. Inner cutting section; 15. Middle cutting section; 2. Lower reamer; 3. Outer tube; 4. Upper reamer; 5. Inner tube assembly; 6. Drill collar; 7. Drill pipe. DETAILED DESCRIPTION

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments, with respect to the above and other technical features and advantages of the present invention. However, the following embodiments are merely preferred embodiments of the present invention and are not exhaustive.

[0053] Example:

[0054] like Figure 1-Figure 3 As shown, the present invention provides a high-efficiency wireline coring drill assembly device for preventing coal dust from holding the drill, comprising a drill bit 1, a lower reamer 2, an outer tube 3, an upper reamer 4, an inner tube assembly 5, a drill collar 6 and a drill rod 7;

[0055] The bottom end of the lower reamer 2 is connected to the drill bit 1, the bottom of the outer tube 3 is threadedly connected to the top of the lower reamer 2, the bottom end of the upper reamer 4 is threadedly connected to the top of the outer tube 3, the bottom end of the drill collar 6 is connected to the top of the upper reamer 4, and the bottom end of the drill rod 7 is threadedly connected to the top of the drill collar 6. The lower reamer 2, the outer tube 3, the upper reamer 4, the drill collar 6 and the drill rod 7 cooperate to form the inner cavity of the drill tool. The tube-in-tube assembly 5 is arranged in the inner cavity of the drill tool, and a core tube is installed at the lower part of the inner tube assembly 5. During the drilling and coring operation, when the core of the core tube is full, the inner tube assembly is salvaged to the ground with a wire rope. After the core in the core tube is taken out, the inner tube assembly is dropped from the drill rod to the bottom of the hole.

[0056] In the rope coring operation in the coalfield, the annular gap between the borehole wall and the drill rod formed by the conventional rope coring drill tools S75 and S95 is small, and the frequency of coal dust sticking to the drill during drilling is high. In the two common drilling processes, the outer diameters of the drill rod are 42 mm and 50 mm, respectively, and the corresponding outer diameters of the drill bit are 75 mm and 91 mm, respectively. The difference between the outer diameters of the drill bit and the drill rod is 33 mm and 41 mm, respectively. Under this configuration, coal dust sticking to the drill rod has never occurred. It can be seen that when the difference between the borehole diameter and the drill rod diameter is greater than 33 mm, coal dust will not stick to the drill rod. Therefore, in this application, the diameter of the drill bit 1 is greater than the outer diameter of the drill rod 7, and the difference between the diameter of the drill bit 1 and the outer diameter of the drill rod 7 is greater than 33 mm, so that there is a larger annular gap between the hole wall and the drill tool, ensuring that the coal dust is smoothly discharged with the mud.

[0057] The outer diameter of the lower reamer 2 and the upper reamer 4 is larger than the diameter of the drill bit. The outer surfaces of the lower reamer and the upper reamer are formed with continuous reaming teeth, which play a role in protecting the drilling tool and trimming the hole wall. The lower reamer 2 and the upper reamer 4 are both tooth-shaped. Through the continuous teeth, the borehole can be further expanded and a backflow channel can be provided for mud circulation.

[0058] The inner wall of the outer tube 3 is machined to have a groove chamber, which serves to fix and suspend the inner tube assembly 5;

[0059] The drill body includes a drill body 11, and the end of the drill body is formed with three groups of cutting part installation areas 12. The outer cutting part 13 and the inner cutting part 14 are each provided with three groups. The upper part of each group of cutting part installation areas is provided with a group of inner cutting parts 14, and the lower part of each group of cutting part installation areas is provided with a group of outer cutting parts 13. The middle cutting part 15 is formed between two adjacent groups of cutting part installation areas 12. The operating diameters of the inner cutting part 14, the middle cutting part 15 and the outer cutting part 3 are gradually increased. The cutting part 14, the middle cutting part 15 and the outer cutting part 13 are staggered, and a mud reflux channel is formed between the staggered inner cutting part 14, the middle cutting part 15 and the outer cutting part 13. The surfaces of the inner cutting part 14, the middle cutting part 15 and the outer cutting part 13 are inlaid with a number of composite pieces for cutting and crushing. When the cutting operation is carried out, the inner cutting part 14, the middle cutting part 15 and the outer cutting part 13 crush the coal seam step by step, and the crushed coal powder flows back upward with the mud through the mud reflux channel.

[0060] Two groups of water holes are provided in each cutting part installation area 12. The aperture of the water holes is 14 mm and the external inclination angle of the water holes is 10°. During the cutting process, the mud enters the borehole through the water holes. Under the action of pressure, the mud is flushed out at 10° under the guidance of the water holes. At this angle, the mud can better flush the bottom of the hole while avoiding affecting the normal upward backflow of the mud. During the backflow process, the crushed coal powder is mixed in the mud and flows back upward synchronously, thereby bringing the coal powder upward.

[0061] The inner cutting part 14, the middle cutting part 15 and the outer cutting part 13 are all provided with outer diameter-keeping grooves on the surface, and each group of outer diameter-keeping grooves is inlaid with strip polycrystalline diamonds. The strip polycrystalline diamonds arranged on the inner cutting part 14, the middle cutting part 15 and the outer cutting part 13 can further expand the drill hole to prevent coal powder from being mixed between the drill hole and the outer wall of the drill bit 1 to form a stuck drill. Several groups of inner diameter-keeping grooves are provided on the inner wall surface of the drill bit body, and each group of inner diameter-keeping grooves is inlaid with strip polycrystalline diamonds. The strip polycrystalline diamonds arranged in the inner diameter-keeping grooves can grind the drill core to expand the space between the drill core and the inner wall of the drill bit 1 to prevent coal powder from being mixed between the drill hole and the inner wall of the drill bit 1 to form a stuck drill.

[0062] The method for using the anti-hold drill high-efficiency drilling tool includes the following steps:

[0063] Step S1, assembling and connecting the drill bit, the lower reamer, the outer tube, the upper reamer, the drill collar and the drill pipe;

[0064] Step S2, after the inner tube assembly is assembled on the ground, the inner tube assembly is dropped from the inner cavity of the drill tool to the bottom of the inner cavity of the drill tool;

[0065] Step S3: Determine the drilling pressure based on the ultimate compressive strength of the rock, the compressive strength of the composite sheets, and the total number of composite sheets. The calculation formula for determining the bottom hole drill pressure P based on the ultimate compressive strength of the rock is:

[0066] P=qm

[0067] Where q is the ultimate pressure that a single effective composite sheet can withstand, and m is the number of effective composite sheets;

[0068] Step S4, determine the speed n, the calculation formula of the speed n is:

[0069]

[0070] Where n is the drill bit speed, V is the drill bit linear speed, and D is the drill bit outer diameter;

[0071] Step S5: Determine the pumping pressure of the mud before drilling and flushing. The pressure loss during the circulation of the flushing fluid depends on the total length of the circulation channel, the flow velocity in the channel, the specific gravity of the fluid, the rheological parameters, and the resistance coefficient in the channel. The drilling pressure loss includes the along-the-hole loss inside and outside the drill pipe and the local loss of the joint, drill bit, and core barrel. The along-the-hole loss inside and outside the drill pipe is calculated based on the hydraulic loss of the fluid when flowing in the pipe as follows:

[0072]

[0073] Where λ is the dimensionless resistance coefficient, L is the drill pipe length, d is the inner diameter of the drill pipe, v is the average flow velocity in the pipe, g is the acceleration due to gravity, and γ is the density of the mud;

[0074] When calculating the joint loss in the drill pipe, replace λ in the above formula with the local resistance coefficient ξ:

[0075]

[0076] Where a is the empirical coefficient, the lock joint is 1.5, the lock collar is 2, d is the inner diameter of the drill pipe, d1 is the inner diameter of the drill pipe joint, and the hydraulic loss of the drill bit and core tube is determined by actual measurement;

[0077] The total hydraulic loss is the sum of the hydraulic losses of the above parts. Taking into account the accumulation of rock debris and mud balls, the pump pressure is the total loss multiplied by a coefficient of 1.1 to 1.4.

[0078] Step S6: The amount of mud pumped is determined by factors such as the drilling method, drilling speed, rock properties, borehole structure, and drilling tools. The amount of flushing fluid is determined primarily by the return speed required to carry rock dust, while ensuring bottom hole flushing and drill bit cooling.

[0079] The return velocity v of the flushing fluid is the sum of the settling velocity w of the cuttings and the required upward movement velocity u:

[0080] v=w+u

[0081] If u is 0.1 to 0.3 times w, then v is equal to 1.1 to 1.3 times w;

[0082] The sedimentation velocity w is calculated according to the Littinger formula;

[0083]

[0084] Where d is the diameter of the spherical cuttings, ρ1 is the density of the cuttings, ρ2 is the density of the mud, and k is the coefficient g is the acceleration of gravity, c is the shape coefficient of the rock debris particles, which is 0.5 for spheres, 0.64-0.82 for discs, and 2.1 for irregular or flat particles;

[0085] The formula for calculating the flushing fluid volume in the positive cycle is:

[0086]

[0087] Where m is a coefficient, which is set between 1.05 and 1.1, considering the uneven return velocity caused by the irregular hole diameter and the leakage at the drill pipe joint, D is the borehole diameter, and d is the outer diameter of the drill pipe.

[0088] Substituting dm, ρ1, ρ2, c, and m, we can obtain the pumping capacity required for wireline coring drilling with the drill pipe;

[0089] Step S7, setting drilling data according to the data in steps S3-S6, and starting drilling after completing the drilling data setting.

[0090] In step S8, the mud is transported downward from the ground through the drill pipe, and continues downward through the annular gap between the outer tube and the inner tube assembly to approach the bottom of the drill bit. Part of the mud is ejected from the water hole, and the other part flows downward from the gap between the drill bit and the core to the bottom of the hole. The two parts of mud finally merge and return to the ground through the annular gap between the outer tube of the hole wall, the drill collar and the drill pipe.

[0091] The above description is merely a preferred embodiment of the present invention and is intended to be illustrative rather than restrictive of the present invention. Those skilled in the art will appreciate that many changes, modifications, and even equivalents may be made to the present invention within the spirit and scope of the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A high-efficiency wireline coring drill assembly device that prevents coal dust from holding the drill, characterized in that: Includes drill bit, lower reamer, outer tube, upper reamer, inner tube assembly, drill collar and drill pipe; The bottom end of the lower reamer is connected to the drill bit, the bottom of the outer tube is threadedly connected to the top of the lower reamer, the bottom end of the upper reamer is threadedly connected to the top of the outer tube, the bottom end of the drill collar is connected to the top of the upper reamer, and the bottom end of the drill rod is threadedly connected to the top of the drill collar. The lower reamer, outer tube, upper reamer, drill collar and drill rod cooperate to form the inner cavity of the drill tool, and the inner tube assembly is arranged in the inner cavity of the drill tool.

2. The high-efficiency wireline coring drill assembly with anti-coal dust holding function according to claim 1, characterized in that: The drill bit includes a drill bit body, and three groups of cutting part installation areas are formed at the end of the drill bit body. The external cutting parts and internal cutting parts are each provided with three groups. A group of internal cutting parts is provided in the upper part of each group of cutting part installation areas, and a group of external cutting parts is installed in the lower part of each group of cutting part installation areas. A middle cutting part is formed between two adjacent groups of cutting part installation areas.

3. The high-efficiency wireline coring drill assembly with anti-coal dust holding function as claimed in claim 2, characterized in that: The operating diameters of the inner cutting part, the middle cutting part and the outer cutting part increase step by step. The inner cutting part, the middle cutting part and the outer cutting part are staggered, and a mud reflux channel is formed between the staggered inner cutting part, the middle cutting part and the outer cutting part. The surfaces of the inner cutting part, the middle cutting part and the outer cutting part are inlaid with a number of composite pieces for cutting and crushing rocks.

4. The high-efficiency wireline coring drill assembly with anti-coal dust holding function as claimed in claim 3, characterized in that: A plurality of water holes with different diameters are provided in each group of the cutting part installation areas, and the outer bevel angles of the water holes are all 10°.

5. The high-efficiency wireline coring drill assembly for preventing coal dust from encroaching on the drill according to claim 3, characterized in that: The surfaces of the inner cutting part, the middle cutting part and the outer cutting part are all provided with outer diameter-maintaining grooves, and each group of outer diameter-maintaining grooves is inlaid with strip-shaped polycrystalline diamonds.

6. The high-efficiency wireline coring drill assembly for preventing coal dust from encroaching on the drill according to claim 2, characterized in that: The inner wall surface of the end of the drill body is provided with a plurality of groups of inner diameter-keeping grooves, and each group of inner diameter-keeping grooves is inlaid with strip-shaped polycrystalline diamonds.

7. The high-efficiency wireline coring drill assembly with anti-coal dust holding function as claimed in claim 2, characterized in that: The diameters of the lower reamer and the upper reamer are larger than the diameter of the drill bit, and continuous reaming teeth are formed on the exteriors of the lower reamer and the upper reamer.

8. The high-efficiency wireline coring drill assembly for preventing coal dust from encroaching on the drill according to claim 1, characterized in that: The diameter of the drill bit is larger than the outer diameter of the drill rod, and the difference between the diameter of the drill bit and the outer diameter of the drill rod is larger than 33 mm.

9. A method for using the high-efficiency wireline coring drill assembly for preventing coal dust from encroaching on the drill according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1, assembling and connecting the drill bit, lower reamer, outer tube, upper reamer, drill collar and drill pipe; Step S2, after the inner tube assembly is assembled on the ground, the inner tube assembly is dropped from the inner cavity of the drill tool to the bottom of the inner cavity of the drill tool; Step S3: Determine the drilling pressure based on the ultimate compressive strength of the rock, the compressive strength of the composite sheets, and the total number of composite sheets. The calculation formula for determining the bottom hole drill pressure P based on the ultimate compressive strength of the rock is: P=qm Where q is the ultimate pressure that a single effective composite sheet can withstand, and m is the number of effective composite sheets; Step S4, determine the speed n, the calculation formula of the speed n is: Where n is the drill bit speed, V is the drill bit linear speed, and D is the drill bit outer diameter; Step S5: Determine the pumping pressure of the mud before drilling and flushing. The pressure loss during the circulation of the flushing fluid depends on the total length of the circulation channel, the flow velocity in the channel, the specific gravity of the fluid, the rheological parameters, and the resistance coefficient in the channel. The drilling pressure loss includes the along-the-hole loss inside and outside the drill pipe and the local loss of the joint, drill bit, and core barrel. The along-the-hole loss inside and outside the drill pipe is calculated based on the hydraulic loss of the fluid when flowing in the pipe as follows: Where λ is the dimensionless resistance coefficient, L is the drill pipe length, d is the inner diameter of the drill pipe, v is the average flow velocity in the pipe, g is the acceleration of gravity, and γ is the density of the mud; When calculating the joint loss in the drill pipe, replace λ in the above formula with the local resistance coefficient ξ: Where a is the empirical coefficient, the lock joint is 1.5, the lock collar is 2, d is the inner diameter of the drill pipe, d1 is the inner diameter of the drill pipe joint, and the hydraulic loss of the drill bit and core tube is determined by actual measurement; The total hydraulic loss is the sum of the hydraulic losses of the above parts. Taking into account the accumulation of rock debris and mud balls, the pump pressure is the total loss multiplied by a coefficient of 1.1 to 1.

4. Step S6: The amount of mud pumped is determined by factors such as the drilling method, drilling speed, rock properties, borehole structure, and drilling tools. The amount of flushing fluid is determined primarily by the return speed required to carry rock dust, while ensuring bottom hole flushing and drill bit cooling. The return velocity v of the flushing fluid is the sum of the settling velocity w of the cuttings and the required upward velocity u: v=w+u If u is 0.1 to 0.3 times w, then v is equal to 1.1 to 1.3 times w; The sedimentation velocity w is calculated according to the Littinger formula; Where d is the diameter of the spherical cuttings, ρ1 is the density of the cuttings, ρ2 is the density of the mud, and k is the coefficient g is the acceleration of gravity, c is the shape coefficient of the rock debris particles, which is 0.5 for spheres, 0.64-0.82 for discs, and 2.1 for irregular or flat particles; The formula for calculating the flushing fluid volume in the positive cycle is: Where m is a coefficient, which is set between 1.05 and 1.1, considering the uneven return velocity caused by the irregular hole diameter and the leakage at the drill pipe joint, D is the borehole diameter, and d is the outer diameter of the drill pipe. Substituting dm, ρ1, ρ2, c, and m, we can obtain the pumping capacity required for wireline coring drilling with the drill pipe; Step S7, setting drilling data according to the data in steps S3-S6, and starting drilling after completing the drilling data setting.

10. The method for using the high-efficiency wireline coring drill assembly with anti-coal dust holding function as claimed in claim 9, characterized in that: The process also includes step S8, in which the mud is transported downward from the ground through the drill pipe, and continues downward through the annular gap between the outer tube and the inner tube assembly to approach the bottom of the drill bit. Part of the mud is ejected from the water eye, and the other part flows downward from the gap between the drill bit and the core to the bottom of the hole. The two parts of mud finally merge and return to the ground through the annular gap between the outer tube of the hole wall, the drill collar and the drill pipe.

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