A coal and rock quality near-drill-bit while-drilling evaluation device suitable for mining directional drilling rigs

Abstract

The present invention discloses a coal-rock quality near-drill-bit while-drilling evaluation device adapted for a mining directional drill, the device comprises a PDC drill bit, a near-drill-bit while-drilling measurement pup joint, a screw drill tool, a while-drilling sonic wave detector, a trajectory measurement probe and a center cable drill rod connected in sequence, the near-drill-bit while-drilling measurement pup joint comprises a barrel, a first internal thread connection part and a first external thread connection part, and a detection module arranged on the barrel, the detection module comprises a rotation speed sensor, a positive pressure strain gauge, and a rotation torque strain gauge; the method comprises the following steps: 1. installation of the coal-rock quality near-drill-bit while-drilling evaluation device; 2. drilling and data collection of the coal seam to be detected; 3. acquisition of coal-rock quality evaluation indicators of the coal seam to be detected. The present invention has a reasonable design, processes the near-drill-bit while-drilling data to obtain the corrected basic rock mass quality indicators, and performs near-drill-bit while-drilling quantitative judgment of the coal-rock mass quality grade according to the corrected basic rock mass quality indicators.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine drilling measurement, and in particular relates to a coal and rock quality near-drill-bit drilling evaluation device adapted for a mining directional drill. Background Art

[0002] With the improvement of the modernization level of coal mines, coal mining is increasingly dependent on geological conditions. Coal mine safety production is one of the main factors restricting coal production capacity. In recent years, although the safety production situation of coal mines has been greatly improved, accidents such as tunnel roof collapse, rock burst and gas outburst occur from time to time, seriously threatening the safety production of coal mines. Among them, insufficient understanding of geological conditions and inaccurate advance geological predictions are the key causes of the above accidents. Therefore, it is a prerequisite for the safety production of underground coal mines to complete the correct evaluation of the properties of coal and rock mass while drilling and the quantitative characterization of coal and rock mass quality without affecting the directional drilling process. In addition, the advance quantitative prediction of coal and rock strength grade can effectively improve the efficiency of coal and rock mining and optimize hydraulic fracturing parameters.

[0003] At present, the existing coal rock quality evaluation method is mainly obtained through drilling and coring combined with indoor strength tests. The coal rock samples obtained by this method are out of the engineering geological environment, and the standard coal rock samples will inevitably affect the coal lithology during the processing process; the drilling and coring method is time-consuming and labor-intensive, and it is not easy to implement on a large scale on site. In addition, the existing rock mass quality analysis system mostly stays on the surface of the rock mass in terms of surrounding rock strength perception, and does not go deep into the rock mass to predict the coal rock grade.

[0004] Therefore, it is necessary to design a coal and rock quality near-drill-bit while-drilling evaluation device suitable for mining directional drilling rigs, to obtain while-drilling data in the process of directional drilling into the coal seam to be detected, and to process the while-drilling data to obtain the corrected basic rock quality indicators. According to the corrected basic rock quality indicators, the coal and rock quality grade can be quantitatively judged, which provides a basis for ensuring the subsequent safe and efficient production of coal mines, improving the efficiency of coal and rock excavation and optimizing hydraulic fracturing parameters. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a coal and rock quality near-drill-bit while-drilling evaluation device adapted to a mining directional drilling rig in view of the deficiencies in the above-mentioned prior art. The device has a reasonable design and obtains while-drilling data in the process of directional drilling into the interior of the coal seam to be detected, and processes the while-drilling data to obtain corrected basic rock quality indicators. The coal and rock quality grade is quantitatively judged based on the corrected basic rock quality indicators, thereby providing a basis for ensuring the subsequent safe and efficient production of coal mines, improving the efficiency of coal and rock excavation, and optimizing hydraulic fracturing parameters.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a coal and rock quality near-drill-bit while-drilling evaluation device adapted for a mining directional drill, characterized in that: it comprises a PDC drill bit, a near-drill-bit while-drilling measurement pup joint, a screw drill tool, a while-drilling sonic detector, a trajectory measurement probe and a center cable drill rod, which are detachably connected in sequence;

[0007] The near-bit measurement while drilling sub comprises a barrel, a first internal thread connection portion arranged at one end of the barrel near the PDC drill bit and a first external thread connection portion arranged at the other end of the barrel, and a detection module arranged on the barrel, wherein the first internal thread connection portion is connected to the PDC drill bit, and the first external thread connection portion is connected to the screw drill tool;

[0008] The detection module includes a rotation speed sensor, a normal pressure strain gauge, and a rotation torque strain gauge.

[0009] The above-mentioned coal and rock quality near-drill-bit while-drilling evaluation device adapted for a mining directional drill is characterized in that: a receiving groove is opened on the outer wall of the cylinder, and the speed sensor, positive pressure strain gauge and rotational torque strain gauge are mounted on the bottom of the receiving groove; a control box is arranged at the bottom of the receiving groove, and an electronic circuit board is arranged in the control box; a controller and a data transmission module connected to the controller are integrated on the electronic circuit board, and the speed sensor, positive pressure strain gauge and rotational torque strain gauge are all connected to the controller.

[0010] The above-mentioned coal and rock quality near-drill bit drilling evaluation device adapted for a mining directional drilling rig is characterized in that: the drilling acoustic wave detector comprises a left connecting tube, a left-end non-magnetic short section, an acoustic wave transmitting short section, a middle non-magnetic short section, an acoustic wave receiving short section, a right-end non-magnetic short section and a right connecting tube which are threadedly connected in sequence, the outer side wall of the left connecting tube is provided with a left connecting external threaded head connected to the other end of the screw drill tool, the inner side of the right connecting tube is provided with a right connecting internal threaded head, the left connecting tube, the left-end non-magnetic short section, the acoustic wave transmitting short section, the middle non-magnetic short section, the acoustic wave receiving short section, the right-end non-magnetic short section and the right connecting tube are all provided with an intermediate channel, and the right connecting internal threaded head is threadedly connected to one end of the trajectory measurement probe tube;

[0011] A sound wave transmitter is embedded in the outer wall of the sound wave transmitting short section, and a sound wave receiver and an intermediate transmitter are embedded in the outer wall of the sound wave receiving short section. The sound wave transmitter and the sound wave receiver are connected to the intermediate transmitter, and the intermediate transmitter wirelessly communicates with the data transmission module. The intermediate transmitter is electrically connected to one end of the communication cable in the center cable drill rod, and the other end of the communication cable in the center cable drill rod is connected to the computer on the directional drilling rig.

[0012] At the same time, a method for using a coal and rock quality near-drill-bit drilling evaluation device adapted to a mining directional drill with a simple method and reasonable design is provided, characterized in that the method comprises the following steps:

[0013] Step 1: Installation of coal and rock quality near-drill bit while-drilling evaluation device:

[0014] Step 101, sequentially connect the PDC drill bit, the near-bit while-drilling measurement pup joint, the screw drill tool, the while-drilling sonic detector, the trajectory measurement probe tube, and the center cable drill pipe;

[0015] Step 102, connecting the center cable drill rod to the mining directional drilling rig;

[0016] Step 2: Drilling and data collection of coal seams to be detected:

[0017] Step 201, the directional drilling rig drives the PDC drill bit to drill and break rock along the coal seam to be detected, and in the process of the PDC drill bit drilling and breaking rock along the coal seam to be detected, the near-drill bit measurement while drilling pup joint, screw drill tool, while drilling sonic detector, trajectory measurement probe and center cable drill rod are synchronously extended into the coal seam to be detected along with the PDC drill bit;

[0018] Step 202: During the process of the PDC drill bit breaking rock along the coal seam to be detected, the speed sensor, the normal pressure strain gauge and the rotation torque strain gauge are respectively detected, and the speed, normal pressure and torque detected at each sampling moment are transmitted to the controller, the controller wirelessly sends the speed, normal pressure and torque data through the data transmission module, the intermediate transmitter receives the speed, normal pressure and torque data and sends them to the computer on the directional drilling rig through the communication cable in the central cable drill pipe;

[0019] At the same time, the intermediate transmitter controls the acoustic transmitter to transmit an acoustic signal, and the acoustic signal is reflected by the coal seam to be detected to the acoustic receiver, and the acoustic receiver receives the transmitted acoustic signal and sends it to the intermediate transmitter;

[0020] Step 3: Obtaining coal rock quality evaluation indicators of the coal seam to be detected:

[0021] Step A: The intermediate transmitter records the distance between the sound wave transmitter and the sound wave receiver as ΔL, records the time difference between the time when the sound wave receiver transmits and the time when the sound wave receiver receives as Δt, and sends them to the computer; the computer calculates the time difference according to the time difference. Get the elastic longitudinal wave velocity V of the rock mass of the coal seam to be detected pm ;

[0022] Step B: Use computer to Get drillability index I d ; Where D is the diameter of the hole, F i represents the positive pressure at the i-th sampling moment in the drilling process, Mi represents the torque at the i-th sampling moment in the drilling process, v i represents the drilling speed at the i-th sampling moment in the drilling process, ω i represents the angular velocity of the drill bit, and ω i =2π×N i , N i represents the rotation speed at the i-th sampling moment in the drilling process, λ represents the first coefficient, α represents the second coefficient, and β represents the third coefficient;

[0023] Step C: Using a computer Get the rock saturated uniaxial compressive strength R at the i-th sampling moment during the drilling process c (i); where π represents the ratio of a circle to its circumference, N i represents the speed at the i-th sampling moment of the drilling process, M i represents the torque at the i-th sampling moment in the drilling process, R represents the radius of the PDC drill bit, and μ represents the friction coefficient between the drill bit cutting teeth and the bottom of the hole;

[0024] Step D: Use a computer to calculate the Get the rock mass integrity coefficient K v ; Among them, V pm represents the elastic longitudinal wave velocity of rock mass, V pr It represents the elastic longitudinal wave velocity of rock;

[0025] Step E: Use a computer to calculate the Get the measured index d at the borehole mouth c0 ; where v0 represents the drilling speed at the borehole mouth; N0 represents the rotation speed at the borehole mouth; W0 represents the positive pressure at the borehole mouth, ρ n represents water density; ρ m Indicates the density of the drilling fluid used;

[0026] Step F: Use a computer to calculate the Get the measured while drilling index d at the i-th sampling time in the drilling process c (i); where v i represents the drilling speed at the i-th sampling moment in the drilling process; N i represents the speed at the i-th sampling moment in the drilling process; W i represents the drilling pressure at the i-th sampling moment in the drilling process, that is, W i =F i ;

[0027] Step G: Use a computer to calculate the Get the corrected formation pressure influence coefficient K d ;

[0028] Step H: Use a computer to calculate the value according to the formula BQ = 100K d +3R c (i)+250K v , and obtain the corrected basic rock quality index BQ.

[0029] The above-mentioned method of use is characterized in that: Step H, the specific process is as follows:

[0030] When R c (i)>90K v +30, let R c (i)=90K v +30 Substitute into the formula in step H to calculate the corrected basic rock mass quality index BQ;

[0031] When K v >0.04R c (i) +0.4, let K v =0.04R c Substitute (i) + 0.4 into the formula in step H to calculate the corrected basic rock mass quality index BQ.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. The present invention has a simple structure, reasonable design and overall compactness. The PDC drill bit, near-bit measurement while drilling pup joint, screw drill, while drilling sonic detector, trajectory measurement probe and center cable drill pipe are coaxially arranged, which improves the drilling adaptability; and without interfering with the directional drilling process, while drilling data is obtained, and there is no need to wait until the drilling is completed before testing, which not only significantly improves the work efficiency, but also realizes the function of the directional drill to identify coal and rock information while drilling.

[0034] 2. The present invention is mounted on an existing underground directional drilling rig in a coal mine and adopts an integrated operation. The coal and rock parameter determination and the quality grade evaluation parameter acquisition are combined with the drilling process. There is no need for separate testing operations, thus saving time and labor costs.

[0035] 3. The present invention sets a near-drill-bit while-drilling measurement pup section in order to install a rotation speed sensor, a positive pressure strain gauge, and a rotational torque strain gauge on the near-drill-bit while-drilling measurement pup section, and obtain while-drilling data during directional drilling into the interior of the coal seam to be detected, thereby obtaining the coal and rock mass characteristic parameters of the coal seam to be detected, which is convenient for subsequent analysis.

[0036] 4. The purpose of the present invention is to provide a drilling acoustic wave detector to emit acoustic waves and receive reflected acoustic waves during the process of the PDC drill bit drilling along the coal seam to be detected. Since the propagation speed of acoustic waves inside the rock mass is different, the elastic longitudinal wave velocity of the rock mass of the coal seam to be detected is obtained, which reflects the physical and mechanical properties that are reduced due to the incompleteness of the rock mass, and then the rock mass integrity coefficient is obtained.

[0037] 5. The present invention provides a central cable drill rod, which can not only realize the wired transmission of the detected data by the communication cable, but also realize the water flow in the annulus inside the drill rod, thereby realizing wall protection, cooling and reducing wear during drilling.

[0038] 6. The method for using the coal and rock quality near-drill-bit while-drilling evaluation device adapted for a mining directional drill of the present invention is simple in steps, easy to implement and simple to operate, and can achieve the acquisition of corrected basic rock quality indicators.

[0039] 7. The present invention adopts the ratio of the measured index while drilling at the sampling moment of the drilling process to the measured index at the borehole mouth as the corrected formation pressure influence coefficient. The measured index while drilling at the borehole mouth is considered as the calculation scale because the formation pressure at the borehole mouth is zero and is representative. At the same time, the influence of the coal rock strength on the measured index can be filtered out, and only the influence of the formation pressure on the measured index is considered, thereby improving the accuracy of the corrected basic rock quality indicators.

[0040] In summary, the present invention has a simple structure and a reasonable design. It obtains downhole data during directional drilling into the coal seam to be detected, and processes the downhole data to obtain corrected basic rock quality indicators. The coal and rock quality grades are quantitatively judged based on the corrected basic rock quality indicators, providing a basis for ensuring the subsequent safe and efficient production of coal mines, improving coal and rock excavation efficiency, and optimizing hydraulic fracturing parameters.

[0041] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the structure of the present invention.

[0043] Figure 2 It is a structural schematic diagram of the near-drill-bit measurement while drilling short section of the present invention.

[0044] Figure 3 It is a schematic diagram of the structure of the drilling acoustic wave detector of the present invention.

[0045] Figure 4 The figure is a flowchart of the method of the present invention.

[0046] Figure 5 This is a schematic diagram of the principle of the BQ classification graphic method for basic rock quality indicators modified by the present invention.

[0047] Description of reference numerals:

[0048] 1—PDC drill bit; 2—MWD sub near the drill bit; 21—barrel;

[0049] 211—accommodation groove; 22—normal pressure strain gauge; 23—rotational torque strain gauge;

[0050] 24—rotation speed sensor; 25—first internal thread connection portion; 26—first external thread connection portion;

[0051] 27—control box; 271—controller; 272—data transmission module;

[0052] 3—screw drilling tool; 4—drilling acoustic wave detector; 41—left connecting tube;

[0053] 411—Left connecting external thread head; 42—Left end non-magnetic short section; 43—Acoustic wave emission short section;

[0054] 431—acoustic wave transmitter; 44—intermediate non-magnetic short section; 45—acoustic wave receiving short section;

[0055] 451—sound wave receiver; 46—right end non-magnetic short section; 47—right connecting tube;

[0056] 471—right connecting internal thread head; 48—middle channel;

[0057] 49—intermediate transmitter; 5—track measurement probe; 6—center cable drill rod. DETAILED DESCRIPTION

[0058] like Figures 1 to 3 The device for evaluating coal and rock quality near the drill bit while drilling, which is suitable for a mining directional drill, comprises a PDC drill bit 1, a near-drill bit while drilling measurement pup joint 2, a screw drill tool 3, a while drilling sonic detector 4, a trajectory measurement probe 5 and a center cable drill rod 6, which are detachably connected in sequence;

[0059] The near-bit measurement while drilling sub 2 comprises a barrel 21, a first internal thread connection portion 25 arranged at one end of the barrel 21 close to the PDC drill bit 1, a first external thread connection portion 26 arranged at the other end of the barrel 21, and a detection module arranged on the barrel 21, wherein the first internal thread connection portion 25 is connected to the PDC drill bit 1, and the first external thread connection portion 26 is connected to the screw drill tool 3;

[0060] The detection module includes a rotation speed sensor 24 , a normal pressure strain gauge 22 , and a rotation torque strain gauge 23 .

[0061] In this embodiment, a receiving groove 211 is opened on the outer wall of the cylinder 21, and the speed sensor 24, the positive pressure strain gauge 22 and the rotational torque strain gauge 23 are mounted on the bottom of the receiving groove 211. A control box 27 is set at the bottom of the receiving groove 211, and an electronic circuit board is set in the control box 27. The electronic circuit board integrates a controller 271 and a data transmission module 272 connected to the controller 271. The speed sensor 24, the positive pressure strain gauge 22 and the rotational torque strain gauge 23 are all connected to the controller 271.

[0062] In this embodiment, the drilling acoustic wave detector 4 includes a left connecting tube 41, a left non-magnetic short section 42, an acoustic wave transmitting short section 43, a middle non-magnetic short section 44, an acoustic wave receiving short section 45, a right non-magnetic short section 46 and a right connecting tube 47 which are threadedly connected in sequence. The outer side wall of the left connecting tube 41 is provided with a left connecting external thread head 411 connected to the other end of the screw drill 3, and the inner side of the right connecting tube 47 is provided with a right connecting internal thread head 471. The left connecting tube 41, the left non-magnetic short section 42, the acoustic wave transmitting short section 43, the middle non-magnetic short section 44, the acoustic wave receiving short section 45, the right non-magnetic short section 46 and the right connecting tube 47 are all provided with an intermediate channel 48, and the right connecting internal thread head 471 is threadedly connected to one end of the trajectory measurement probe 5;

[0063] The outer wall of the sonic wave transmitting pup section 43 is embedded with a sonic wave transmitter 431, and the outer wall of the sonic wave receiving pup section 45 is embedded with a sonic wave receiver 451 and an intermediate transmitter 49, the sonic wave transmitter 431 and the sonic wave receiver 451 are connected to the intermediate transmitter 49, the intermediate transmitter 49 wirelessly communicates with the data transmission module 272, the intermediate transmitter 49 is electrically connected to one end of the communication cable in the center cable drill rod 6, and the other end of the communication cable in the center cable drill rod 6 is connected to the computer on the directional drilling rig.

[0064] In this embodiment, during actual use, a card block is embedded in the receiving groove 211 to protect the detection module.

[0065] In this embodiment, in actual use, the PDC drill bit 1 is a directional drilling PDC drill bit with a diameter of 89 mm, good wear resistance and reliability, and a water outlet is arranged on the drill bit. During the drilling process, the water flow can effectively flush the drill bit, cool it, improve the drilling efficiency, and increase the life of the drill bit.

[0066] In this embodiment, in actual use, the screw drill 3 is a volumetric downhole power drill that uses drilling fluid as power to convert liquid pressure energy into mechanical energy, and can adopt a conventional structure in the art.

[0067] In this embodiment, during actual use, the center cable drill rod 6 can refer to the conventional structure in the field. The center cable drill rod is a signal transmission device used in directional drilling, and is also an important component to ensure the smooth implementation of directional drilling. It can not only realize water flow inside the center cable drill rod 6, but also realize data transmission of the communication cable.

[0068] like Figure 4 The method for using the device for evaluating the quality of coal and rock near the drill bit while drilling, which is suitable for a mining directional drill, is shown in the figure. Step 1: Installation of the device for evaluating the quality of coal and rock near the drill bit while drilling:

[0069] Step 101, sequentially connect the PDC drill bit 1, the near-bit while-drilling measurement sub 2, the screw drill tool 3, the while-drilling sonic detector 4, the trajectory measurement probe 5, and the center cable drill rod 6;

[0070] Step 102, connecting the center cable drill rod 6 to the mining directional drilling rig;

[0071] Step 2: Drilling and data collection of coal seams to be detected:

[0072] Step 201, the directional drilling rig drives the PDC drill bit 1 to drill and break the rock along the coal seam to be detected, and in the process of the PDC drill bit 1 breaking the rock along the coal seam to be detected, the near-drill bit measurement while drilling pup joint 2, the screw drill tool 3, the while drilling sonic detector 4, the trajectory measurement probe 5 and the center cable drill rod 6 are synchronously extended into the coal seam to be detected along with the PDC drill bit 1;

[0073] Step 202: During the process of the PDC drill bit 1 drilling along the coal seam to be detected, the speed sensor 24, the positive pressure strain gauge 22 and the rotation torque strain gauge 23 are respectively detected, and the speed, positive pressure and torque detected at each sampling moment are transmitted to the controller 271. The controller 271 wirelessly transmits the speed, positive pressure and torque data through the data transmission module 272. The intermediate transmitter 49 receives the speed, positive pressure and torque data and sends them to the computer on the directional drilling rig through the communication cable in the central cable drill pipe 6.

[0074] At the same time, the intermediate transmitter 49 controls the acoustic wave transmitter 431 to transmit an acoustic wave signal, and the acoustic wave signal is reflected by the coal seam to be detected to the acoustic wave receiver 451, and the acoustic wave receiver 451 receives the transmitted acoustic wave signal and sends it to the intermediate transmitter 49;

[0075] Step 3: Obtaining coal rock quality evaluation indicators of the coal seam to be detected:

[0076] Step A, the intermediate transmitter 49 records the distance between the sound wave transmitter 431 and the sound wave receiver 451 as ΔL, records the time difference between the time when the sound wave receiver 451 transmits and the time when the sound wave receiver 451 receives as Δt, and sends them to the computer; the computer calculates the time difference according to the time difference. Get the elastic longitudinal wave velocity V of the rock mass of the coal seam to be detected pm ;

[0077] Step B: Use computer to Get drillability index I d ; Where D is the diameter of the hole, F i represents the positive pressure at the i-th sampling moment in the drilling process, M i represents the torque at the i-th sampling moment in the drilling process, v i represents the drilling speed at the i-th sampling moment in the drilling process, ω i represents the angular velocity of the drill bit, and ω i =2π×N i , N i represents the rotation speed at the i-th sampling moment in the drilling process, λ represents the first coefficient, α represents the second coefficient, and β represents the third coefficient;

[0078] Step C: Using a computer Get the rock saturated uniaxial compressive strength R at the i-th sampling moment during the drilling process c (i); where π represents the ratio of a circle to its circumference, N i represents the speed at the i-th sampling moment in the drilling process, M i represents the torque at the i-th sampling moment in the drilling process, R represents the radius of the PDC drill bit, and μ represents the friction coefficient between the drill bit cutting teeth and the bottom of the hole;

[0079] Step D: Use a computer to calculate the Get the rock mass integrity coefficient K v ; Among them, V pm represents the elastic longitudinal wave velocity of rock mass, V pr It represents the elastic longitudinal wave velocity of rock;

[0080] Step E: Use a computer to calculate the Get the measured index d at the borehole mouth c0 ; where v0 represents the drilling speed at the borehole mouth; N0 represents the rotation speed at the borehole mouth; W0 represents the positive pressure at the borehole mouth, ρ n represents water density; ρ m Indicates the density of the drilling fluid used;

[0081] Step F: Use a computer to calculate the Get the measured while drilling index d at the i-th sampling moment in the drilling process c (i); where v i represents the drilling speed at the i-th sampling moment in the drilling process; N i represents the speed at the i-th sampling moment in the drilling process; W i represents the drilling pressure at the i-th sampling moment in the drilling process, that is, Wi =F i ;

[0082] Step G: Use a computer to calculate the Get the corrected formation pressure influence coefficient K d ;

[0083] Step H: Use a computer to calculate the value according to the formula BQ = 100K d +3R c (i)+250K v , and obtain the corrected basic rock quality index BQ.

[0084] In this embodiment, the specific process of step H is as follows:

[0085] When R c (i)>90K v +30, let R c (i)=90K v +30 Substitute into the formula in step H to calculate the corrected basic rock mass quality index BQ;

[0086] When K v >0.04R c (i) +0.4, let K v =0.04R c Substitute (i) + 0.4 into the formula in step H to calculate the corrected basic rock mass quality index BQ.

[0087] In this embodiment, in actual use, the collection frequency in step 202 is 1s / time.

[0088] In this embodiment, in actual use, λ represents the first coefficient, and the value of λ is 1, α represents the second coefficient, and the value of α is 1, and β represents the third coefficient, and the value of β is 0.4.

[0089] In this embodiment, in actual use, the friction coefficient μ between the drill cutting teeth and the bottom of the hole is 0.21.

[0090] In this embodiment, the drillability index I d To distinguish the lithology of the formation, the specific criteria are as follows:

[0091]

[0092] In this embodiment, the coal seam to be detected is coal rock, and the rock elastic longitudinal wave velocity V pr The value is 2000km / s.

[0093] In this embodiment, in actual use, the trajectory measurement probe 5 can adopt a conventional structure in the art.

[0094] In this embodiment, when actually used, Figure 5 The schematic diagram of the modified rock mass basic quality index BQ classification diagram method is shown in the figure, and the horizontal axis is the rock mass integrity coefficient K v The vertical axis is the modified rock mass basic quality index BQ under the saturated uniaxial compressive strength of rock.

[0095] In this embodiment, in actual use, the drilling trajectory can be obtained through the trajectory measurement probe 5, and the drilling trajectory and the corrected basic rock quality index can be linked according to the sampling time, so as to obtain the corrected basic rock quality index at each location on the drilling trajectory.

[0096] In summary, the present invention has a simple structure and a reasonable design. It obtains downhole data during directional drilling into the coal seam to be detected, and processes the downhole data to obtain corrected basic rock quality indicators. The coal and rock quality grades are quantitatively judged based on the corrected basic rock quality indicators, providing a basis for ensuring the subsequent safe and efficient production of coal mines, improving coal and rock excavation efficiency, and optimizing hydraulic fracturing parameters.

[0097] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for using a coal and rock quality near-drill-bit while-drilling evaluation device adapted for a mining directional drill, the device comprising a PDC drill bit (1), a near-drill-bit while-drilling measurement pup joint (2), a screw drill tool (3), a while-drilling sonic detector (4), a trajectory measurement probe (5), and a center-cable drill rod (6) that are detachably connected in sequence; The near-bit measurement while drilling sub (2) comprises a barrel (21), a first internal thread connection portion (25) arranged at one end of the barrel (21) close to the PDC drill bit (1), a first external thread connection portion (26) arranged at the other end of the barrel (21), and a detection module arranged on the barrel (21), wherein the first internal thread connection portion (25) is connected to the PDC drill bit (1), and the first external thread connection portion (26) is connected to the screw drill tool (3); The detection module comprises a rotation speed sensor (24), a normal pressure strain gauge (22), and a rotation torque strain gauge (23), and is characterized in that: The method comprises the following steps: Step 1: Installation of coal and rock quality near-drill bit while-drilling evaluation device: Step 101, sequentially connect the PDC drill bit (1), the near-bit while-drilling measurement sub (2), the screw drill tool (3), the while-drilling sonic detector (4), the trajectory measurement probe (5) and the center cable drill rod (6); Step 102, connecting the central cable drill rod (6) to the mining directional drilling rig; Step 2: Drilling and data collection of coal seams to be detected: Step 201: The directional drilling rig drives the PDC drill bit (1) to drill and break the rock along the coal seam to be detected. In the process of the PDC drill bit (1) breaking the rock along the coal seam to be detected, the near-drill bit measurement while drilling pup joint (2), the screw drill tool (3), the drilling sonic detector (4), the trajectory measurement probe (5) and the center cable drill rod (6) are synchronously extended into the coal seam to be detected along with the PDC drill bit (1); Step 202: During the process of the PDC drill bit (1) breaking rock along the coal seam to be detected, the speed sensor (24), the positive pressure strain gauge (22) and the rotation torque strain gauge (23) are respectively detected, and the speed, positive pressure and torque detected at each sampling moment are transmitted to the controller (271); the controller (271) wirelessly transmits the speed, positive pressure and torque data through the data transmission module (272); the intermediate transmitter (49) receives the speed, positive pressure and torque data and transmits them to the computer on the directional drilling rig through the communication cable in the central cable drill rod (6); At the same time, the intermediate transmitter (49) controls the acoustic wave transmitter (431) to transmit an acoustic wave signal, and the acoustic wave signal is reflected by the coal seam to be detected to the acoustic wave receiver (451), and the acoustic wave receiver (451) receives the transmitted acoustic wave signal and sends it to the intermediate transmitter (49); Step 3: Obtaining coal rock quality evaluation indicators of the coal seam to be detected: Step A: The intermediate transmitter (49) records the distance between the sound wave transmitter (431) and the sound wave receiver (451) as ΔL, records the time difference between the time when the sound wave receiver (451) transmits and the time when the sound wave receiver (451) receives as Δt, and sends the data to the computer; the computer calculates the time difference according to the time difference. Get the elastic longitudinal wave velocity V of the rock mass of the coal seam to be detected pm ; Step B: Use computer to Get drillability index I d ; Where D is the diameter of the hole, F i represents the positive pressure at the i-th sampling moment in the drilling process, M i represents the torque at the i-th sampling moment in the drilling process, v i represents the drilling speed at the i-th sampling moment in the drilling process, ω i represents the angular velocity of the drill bit, and ω i =2π×N i , N i represents the rotation speed at the i-th sampling moment in the drilling process, λ represents the first coefficient, α represents the second coefficient, and β represents the third coefficient; Step C: Using a computer Get the rock saturated uniaxial compressive strength R at the i-th sampling moment during the drilling process c (i); where π represents the ratio of a circle to its circumference, N i represents the speed at the i-th sampling moment in the drilling process, M i represents the torque at the i-th sampling moment in the drilling process, R represents the radius of the PDC drill bit, and μ represents the friction coefficient between the drill bit cutting teeth and the bottom of the hole; Step D: Use a computer to calculate the Get the rock mass integrity coefficient K v ; Among them, V pm represents the elastic longitudinal wave velocity of rock mass, V pr It represents the elastic longitudinal wave velocity of rock; Step E: Use a computer to calculate the Get the measured index d at the borehole mouth c0 ; where v0 represents the drilling speed at the borehole mouth; N0 represents the rotation speed at the borehole mouth; W0 represents the positive pressure at the borehole mouth, ρ n represents water density; ρ m Indicates the density of the drilling fluid used; Step F: Use a computer to calculate the Get the measured while drilling index d at the i-th sampling moment in the drilling process c (i); where v i represents the drilling speed at the i-th sampling moment in the drilling process; N i represents the speed at the i-th sampling moment in the drilling process; W i represents the drilling pressure at the i-th sampling moment during the drilling process, and W i =F i ; Step G: Use a computer to calculate the Get the corrected formation pressure influence coefficient K d ; Step H: Use a computer to calculate the value according to the formula BQ = 100K d +3R c (i)+250K v , and obtain the corrected basic rock quality index BQ.

2. A method for using a device for evaluating coal and rock quality near the drill bit while drilling adapted for a mining directional drill according to claim 1, characterized in that: The outer wall of the cylinder (21) is provided with a receiving groove (211); the rotation speed sensor (24), the positive pressure strain gauge (22) and the rotation torque strain gauge (23) are mounted on the bottom of the receiving groove (211); a control box (27) is provided at the bottom of the receiving groove (211); an electronic circuit board is provided in the control box (27); a controller (271) and a data transmission module (272) connected to the controller (271) are integrated on the electronic circuit board; the rotation speed sensor (24), the positive pressure strain gauge (22) and the rotation torque strain gauge (23) are all connected to the controller (271).

3. A method for using a device for evaluating coal and rock quality near the drill bit while drilling adapted for a mining directional drill according to claim 1, characterized in that: The drilling acoustic wave detector (4) comprises a left connecting tube (41), a left non-magnetic short section (42), an acoustic wave transmitting short section (43), an intermediate non-magnetic short section (44), an acoustic wave receiving short section (45), a right non-magnetic short section (46) and a right connecting tube (47) which are threadedly connected in sequence. The outer wall of the left connecting tube (41) is provided with a left connecting external thread head (411) connected to the other end of the screw drill (3). The inner side of the right connecting tube (47) is provided with a right connecting internal thread head (471). The left connecting tube (41), the left non-magnetic short section (42), the acoustic wave transmitting short section (43), the intermediate non-magnetic short section (44), the acoustic wave receiving short section (45), the right non-magnetic short section (46) and the right connecting tube (47) are all provided with an intermediate channel (48). The right connecting internal thread head (471) is threadedly connected to one end of the trajectory measurement probe (5). The outer wall of the sound wave transmitting short section (43) is embedded with a sound wave transmitter (431), and the outer wall of the sound wave receiving short section (45) is embedded with a sound wave receiver (451) and an intermediate transmitter (49). The sound wave transmitter (431) and the sound wave receiver (451) are connected to the intermediate transmitter (49), and the intermediate transmitter (49) communicates wirelessly with the data transmission module (272). The intermediate transmitter (49) is electrically connected to one end of the communication cable in the center cable drill rod (6), and the other end of the communication cable in the center cable drill rod (6) is connected to a computer on the directional drilling rig.

4. A method for using a device for evaluating coal and rock quality near the drill bit while drilling adapted for a mining directional drill according to claim 1, characterized in that: Step H, the specific process is as follows: When R c (i)>90K v +30, let R c (i)=90K v +30 Substitute into the formula in step H to calculate the corrected basic rock mass quality index BQ; When K v >0.04R c (i) +0.4, let K v =0.04R c Substitute (i) + 0.4 into the formula in step H to calculate the corrected basic rock mass quality index BQ.

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