An in-line drill pipe type drilling geological state while drilling detection device and detection method

Abstract

The present application relates to a kind of embedded drill pipe type drilling geological state while drilling detection device and detection method, belong to drilling geological detection technical field.To solve the problem that geological state identification accuracy is not high in prior art, easily disturbed and cannot be detected in real time continuously, provide a kind of detection device includes the hole bottom detection mechanism embedded in first drill pipe and the orifice processing terminal installed outside hole.The hole bottom detection mechanism collects the hole bottom vibration signal when drilling, and the amplitude and frequency of vibration signal are calculated by its built-in data processing unit.When signal characteristics change meet the preset condition, determine that geological state changes, and immediately transmit the signal carrying time information to orifice processing terminal by VLF transmitting unit, finally calculate the position of geological change and display in real time.The present application embeds detection mechanism, protects the device and prolongs its service life;Low frequency communication is combined with high-precision time service, which significantly improves the accuracy and real-time of detection.

Description

Technical Field

[0001] This invention belongs to the field of borehole geological exploration technology, and relates to a borehole geological condition detection device and method with an embedded drill rod. Background Technology

[0002] Coal and gas outbursts often occur in areas with complex geological structures and abrupt changes in coal seam occurrence conditions. Therefore, accurately identifying the geological conditions and their changing patterns within the underground mining face area is a crucial technical guarantee for effective outburst prevention. Current industry standards require that when using boreholes to pre-drain coal seam gas for outburst prevention, the coal and rock encounters during the drilling process must be recorded, and the geological structure and coal seam occurrence conditions must be comprehensively analyzed. When abrupt changes are detected, appropriate measures must be taken promptly to ensure safety.

[0003] Currently, the mainstream method for determining geological conditions is through borehole exploration combined with information from multiple boreholes, and its detection cost is relatively low. This method typically relies on manual observation of the coal and rock cuttings discharged at the borehole opening to identify the geological conditions. However, this manual observation method has significant limitations. It not only interrupts the drilling process and requires a high level of experience from the workers, but the samples discharged at the borehole opening may also contain residues generated by the friction between the drill pipe and the borehole wall, making it impossible to guarantee that their original location is from the bottom of the borehole, thus seriously affecting the accuracy of geological condition identification.

[0004] Because coal seams and rock strata differ fundamentally in their physical properties, the vibration signals generated at the bottom of the borehole, such as maximum amplitude and frequency, will vary significantly when the drill bit is drilling in different media. Utilizing this principle to collect borehole bottom vibration signals can effectively identify geological conditions. However, existing borehole bottom signal acquisition devices are typically installed between the drill rod and the drill bit, which directly rubs against the borehole wall during drilling. This not only introduces a large amount of interference signals but also severely affects the sensor's lifespan and increases production costs. Therefore, there is an urgent need for a technical solution that can address the low accuracy of geological condition identification, improve the level of automation in detection, and enhance drilling efficiency. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an embedded drill rod type borehole geological condition detection device and detection method.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An embedded drill rod type borehole geological condition detection device includes:

[0008] Bottom hole detection mechanism 1, adapted to be embedded within the first drill rod connected to the drill bit, the bottom hole detection mechanism 1 comprising:

[0009] Bullet-shaped casing 11;

[0010] The signal acquisition module 12, installed inside the bullet-shaped housing 11, is used to acquire the bottom vibration signal during the drilling process.

[0011] The data transmission module 13, installed inside the bullet-shaped outer shell 11, is used to transmit the bottom vibration signal and geological condition change information.

[0012] A time reference calibration module 14 is disposed within the bullet-shaped casing 11; and

[0013] A first power supply mechanism 15 is disposed inside the bullet-shaped outer casing 11;

[0014] as well as,

[0015] Orifice processing terminal 2, adapted to be installed outside an orifice, the orifice processing terminal 2 comprising:

[0016] Terminal housing 21;

[0017] Data receiving module 22 is used to receive signals from the data transmitting module 13;

[0018] The timer installed inside the terminal housing 21 is used to provide a time reference for the time reference calibration module 14.

[0019] A central processing unit housed within the terminal housing 21 is used to process received signals and determine the geological conditions of the borehole; and

[0020] The second power supply mechanism is installed inside the terminal housing 21.

[0021] Furthermore, the bullet-shaped housing 11 of the bottom hole detection mechanism 1 also includes a connecting screw 1211 and a positioning plate 1212. During installation, the connecting screw connects to the threaded groove 1121 provided on the bullet-shaped housing 11, and cooperates with the drill rod through the positioning plate at its rear end to position the bottom hole detection mechanism 1, so as to align the screw 1114 used for fixing and the opening on the drill rod wall. The bottom hole detection mechanism 1 is fixed inside the drill rod by the screw 1114, and the screw is not exposed on the outer surface of the drill rod. A gap is left between the cross section of the bottom hole detection mechanism 1 and the inner wall of the drill rod, which serves as an air or water supply channel.

[0022] Furthermore, the signal acquisition module 12 includes a vibration sensor 121, an acquisition board 122, and a data processing unit 123; the vibration sensor 121 is used to acquire the vibration signal at the bottom of the hole; the data processing unit 123 is electrically connected to the vibration sensor 121 and is used to process and calculate the acquired vibration signal in real time to obtain the maximum amplitude and vibration frequency of the vibration signal.

[0023] Furthermore, the data transmission module 13 includes a vibration signal wireless transmission unit 131 and a very low frequency (VLF) electromagnetic wave transmission unit;

[0024] The vibration signal wireless transmission unit 131 is used to transmit the bottom vibration signal of the hole to the data receiving module 22;

[0025] The VLF transmitting unit 132 is used to transmit an ultra-low frequency electromagnetic wave signal carrying time information when it is determined that the drilling medium has changed.

[0026] Furthermore, the borehole processing terminal 2 also includes a display screen 211 and a function button area 212 disposed on the terminal housing 21; the display screen 211 is used to display geological status information inside the borehole in real time; the central processing unit processes, judges, and stores the received data in real time, and sends the results to the display screen 211 for presentation.

[0027] A method for detecting geological conditions in a borehole using an embedded drill rod, the method being applied to the aforementioned device, includes the following steps:

[0028] S1: Installation and initialization: Install and fix the bottom hole detection mechanism 1 inside the drill rod, and time it through the hole opening processing terminal 2;

[0029] S2: Acquisition and calculation: After drilling begins, the signal acquisition module 12 synchronously acquires the vibration signal at the bottom of the hole, and the data processing unit 123 calculates the maximum amplitude and vibration frequency of the vibration signal.

[0030] S3: Identification and positioning: Based on the calculated changes in maximum amplitude and vibration frequency, determine whether the drilling medium has changed; when a change in the drilling medium is determined, record the current time and trigger the data transmission module 13 to transmit a signal containing the time information to the borehole processing terminal 2. The borehole processing terminal 2 records the time when the signal is received and calculates the location of the geological change based on the time difference between the transmission and reception times; and

[0031] S4: Display and storage: The results of the borehole geological condition determination are displayed and stored in real time on the borehole processing terminal 2.

[0032] Furthermore, in step S3, the step of determining whether the drilling medium has changed specifically includes:

[0033] For the i-th and (i-1)-th vibration signals acquired consecutively, their maximum amplitude values ​​are denoted as A. i and A i-1 The vibration frequencies are denoted as F. i and F i-1;

[0034] When the condition is met and When the drilling medium changes, it is determined that i is an integer greater than 1, and α and β are preset threshold values ​​for amplitude change rate and frequency change rate, respectively.

[0035] Furthermore, the value of α is 30%, and the value of β is 70%, which are determined based on the characteristics of coal and rock strata underground in the coal mine.

[0036] Furthermore, in step S3, when a change in the drilling medium is detected, the VLF transmission unit within the data transmission module 13 is triggered, transmitting data carrying the geological change time t to the outside of the borehole. j The information is an ultra-low frequency electromagnetic wave signal, where j is the number of times the drilling medium changes.

[0037] Furthermore, in step S3, the step of calculating the location where the geological state changes specifically involves:

[0038] When the aperture processing terminal 2 receives the ultra-low frequency electromagnetic wave signal, it records the reception time as t'. j ;

[0039] Let the wave velocity of the ultra-low frequency electromagnetic wave be v, then the distance L from the opening to the location where the geological state changes for the jth time is... j For: L j =v×(t' j -t j ).

[0040] The beneficial effects of this invention are as follows:

[0041] (1) The present invention installs and fixes the bottom hole detection mechanism inside the drill rod in an embedded manner, so that it is not affected by the rotation and forward pushing of the drill rod and the friction with the hole wall during the drilling process. This ensures that the device will not be damaged by external forces such as friction and pressure when working in the hole, effectively extending its service life. At the same time, the detection device can be taken out after the drill is withdrawn and reused in other drill holes, which significantly reduces the detection cost.

[0042] (2) This invention utilizes ultra-low frequency electromagnetic waves for signal transmission. These waves have a long wavelength, strong penetration, and are not easily affected by the complex electromagnetic environment in coal mines, thus ensuring the stability of signal transmission. Combined with a high-precision timer, it can accurately record the acquisition time of abrupt signal changes inside the borehole and the reception time outside the borehole, thereby greatly improving the accuracy and timeliness of borehole geological condition detection and realizing real-time acquisition of drilling detection and results.

[0043] (3) The detection device and method proposed in this invention can perform continuous detection while drilling and display the geological condition distribution of the entire borehole section in real time outside the borehole. This helps the mine to more accurately control the drilling construction quality, provides a reliable basis for the effective implementation and verification of disaster prevention and control measures, and improves the overall safety assurance level.

[0044] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0046] Figure 1 This is a schematic diagram of the external structure of the bottom hole detection mechanism in the drilling detection device of the present invention;

[0047] Figure 2 This is a cross-sectional view of the bottom hole detection mechanism in the drilling detection device of the present invention;

[0048] Figure 3 This is a cross-sectional view of the drill rod installation within the bottom hole detection mechanism of the drilling detection device in this invention;

[0049] Figure 4 This is a schematic diagram of the installation and positioning structure of the hole bottom detection mechanism in this invention;

[0050] Figure 5 This is a schematic diagram of the appearance of the borehole treatment terminal in the drilling detection device of the present invention.

[0051] Reference numerals: 1. Bottom hole detection mechanism; 11. Bullet-shaped outer shell; 111. Cylindrical shell; 112. Top conical cover; 113. Bottom conical cover; 1111. Shell disassembly surface; 1112. Screw fixing surface; 1113. Groove; 1114. Screw; 1121. Threaded groove; 1122. Conical cover disassembly surface; 12. Signal acquisition module; 12. Vibration sensor; 121. Connecting screw; 1211. Positioning piece; 1212. Acquisition board; 122. Data processing unit; 123. Data transmission module; 13. Vibration signal... The system includes a wireless transmission unit 131, a VLF transmitting unit 132, a time reference calibration module 14, a first power supply mechanism 15, a battery pack 151, a charging port 152, an aperture processing terminal 2, a terminal housing 21, a data receiving module 22, a display screen 211, a function button area 212, a data transmission port 213, a time synchronization button 2121, a detection button 2122, a query button 2123, a power on / off button 2124, a vibration signal receiving unit 221, and a VLF receiving unit 222. Detailed Implementation

[0052] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0053] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0054] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0055] Reference Figures 1 to 5 The drilling detection device of the present invention comprises two core parts: one is a bottom detection mechanism 1 installed inside the borehole, and the other is a borehole processing terminal 2 installed outside the borehole.

[0056] Reference Figure 1 , Figure 2 and Figure 3 The bottom hole detection mechanism 1 is designed to be embedded within the first drill rod directly connected to the drill bit. The mechanism 1 is externally a bullet-shaped housing 11, whose streamlined design facilitates its insertion and fixation within the drill rod. The bullet-shaped housing 11 consists of a central cylindrical housing 111 and two identically structured top and bottom conical caps 112 and 113. The cylindrical housing 111 is threaded to the two conical caps and is equipped with sealing rings to ensure the airtightness of the entire housing, preventing water or dust intrusion during drilling. For ease of installation and removal, threaded grooves 1121 are provided at the tips of the top and bottom conical caps 112 and 113, respectively, allowing the connection of screws to push or pull them into or out of the drill rod. Simultaneously, a conical cap removal surface 1122 and a housing removal surface 1111 are provided on the outer surface of the conical caps and in the middle of the cylindrical housing, respectively, to facilitate tightening or loosening using tools.

[0057] The bottom hole detection mechanism 1 is clamped and fixed inside the drill rod by three screws 1114 at each end. The corresponding screw fixing surface 1112 is a planar structure located on the outer surface of the cylindrical housing 111 for contact with the screws 1114. These screws are installed through pre-drilled holes in the drill rod wall, and the screw ends are confined within the thickness of the drill rod wall, not exposed on the outer surface of the drill rod, thus avoiding scratching with the hole wall during drilling. After installation, an annular gap is maintained between the outer shell of the detection mechanism and the inner wall of the drill rod. This gap can serve as a channel for air or water supply during drilling, without affecting the original function of the drilling rig.

[0058] Inside the bullet-shaped outer casing 11, a data acquisition board 122 is arranged along the central axis. This board extends through the entire internal space and is fixed in a groove 1113 on the inner wall of the cylindrical casing 111. All internal electronic modules are mounted on this data acquisition board 122.

[0059] The internal modules include a signal acquisition module 12, a data transmission module 13, a time reference calibration module 14, and a first power supply mechanism 15.

[0060] The signal acquisition module 12 includes a vibration sensor 121 and a data processing unit 123. The vibration sensor 121 is installed on the acquisition board 122 near the top cone cover 112, i.e., the end closest to the drill bit, so as to directly sense the vibration generated when the drill bit breaks rock or coal. The data processing unit 123 is installed adjacent to the vibration sensor 121 and is used to process the acquired raw vibration signal in real time and calculate its characteristic parameters such as maximum amplitude and dominant frequency.

[0061] The data transmission module 13 is installed at one end of the acquisition board 122 near the bottom conical cover 113. It includes a vibration signal wireless transmission unit 131 and a VLF transmission unit, namely the VLF transmission unit 132. The vibration signal wireless transmission unit 131 has a built-in LoRa module, which is responsible for transmitting continuous vibration signal data to the terminal at the borehole opening over long distances with low power consumption. The VLF transmission unit 132 is used to transmit a single signal wave with strong penetrating power at critical moments when geological changes are detected, for precise timing.

[0062] The time reference calibration module 14 is installed in the middle of the acquisition board 122. It is used to receive the time signal sent by the port terminal and provide a unified and synchronized time reference for the signal acquisition module 12 and the data transmission module 13.

[0063] The first power supply unit 15 includes a battery pack 151 and a charging port 152, providing power to all internal modules.

[0064] Reference Figure 5 The borehole processing terminal 2 has a terminal housing 21, resembling a handheld terminal device. Its front surface features a display screen 211 and a function button area 212. The display screen 211 displays real-time geological and construction information such as borehole geological conditions and drilling depth. The function button area 212 includes a timing button 2121, a detection button 2122, a query button 2123, and a power on / off button 2124. A data receiving module 22 is located on the side of the terminal, containing a vibration signal receiving unit 221 and a VLF receiving unit 222. A data transmission port 213 is located at the bottom of the terminal, which can also be used as a charging port. The core components inside the terminal are a timer with nanosecond-level accuracy, a central processing unit, and a secondary power supply mechanism.

[0065] Furthermore, after installation, the cross-section of the bottom hole detection mechanism has a gap with the inner wall of the drill rod, which serves as a channel for air or water supply during drilling. The bottom hole detection mechanism is fixed inside the drill rod by clamping with three screws at each end. The screws are installed through holes in the drill rod wall and are not exposed on the outer surface of the drill rod.

[0066] Furthermore, the bullet-shaped outer casing includes a cylindrical shell, a top conical cap, and a bottom conical cap with identical structures. The cylindrical shell and the conical cap are connected by threads and sealed with a sealing ring. The bullet-shaped outer casing is also equipped with a connecting screw 1211 and a positioning plate 1212. During installation, the connecting screw 1211 engages with the threaded groove 1121 at the tip of the conical cap, and the positioning plate 1212 at its rear end assists in aligning and positioning the bottom hole detection mechanism within the drill pipe. The outer surface of the conical cap has a conical cap disassembly surface for installing and disassembling the cap from the cylindrical shell. The inner wall of the cylindrical shell has a groove, and each end of the outer surface has three screw fixing surfaces for limiting the installation of the detection device within the drill pipe. The middle of the outer surface has a shell disassembly surface.

[0067] Furthermore, the signal acquisition module includes a vibration sensor, an acquisition board, and a data processing unit. The acquisition board is installed and fixed within a recess in the cylindrical housing and extends through the internal space of the cylindrical housing; the vibration sensor is installed on the end of the acquisition board, near the top conical cover; the data processing unit is installed on the acquisition board, adjacent to the vibration sensor. The data processing unit performs real-time processing and calculation on the acquired vibration signals.

[0068] Furthermore, the data transmission module includes a vibration signal wireless transmission unit and a VLF transmission unit; the data transmission module is installed below the end of the acquisition board and near the bottom conical cover; the vibration signal wireless transmission unit has a built-in LoRa module to enable the transmission of vibration signals from inside the hole to outside the hole.

[0069] Furthermore, the time reference calibration module is installed in the middle of the acquisition board and synchronizes the time information between the signal acquisition module and the data transmission module through the acquisition board; the first power supply mechanism includes a battery pack and a charging port; the charging port is installed above the end of the acquisition board and near the bottom conical cover.

[0070] Furthermore, the terminal housing has a display screen and a function button area on its front surface, and a data transmission port on its bottom side. The display screen is used to display real-time geological condition information and borehole foundation information; the function button area includes a time synchronization button, a detection button, a query button, and a power on / off button; the data transmission port can also be used as a charging port.

[0071] Furthermore, the data receiving module includes a vibration signal receiving unit and an ultra-low frequency electromagnetic wave receiving unit. The timer has a precision of nanoseconds and is used to send precise time to the time reference calibration module and unify the time between the bottom hole detector and the external processing terminal. The central processing unit processes, judges, stores, and sends the results to the display screen for presentation in real time.

[0072] A detection method for a borehole geological condition detection device with an embedded drill rod as described above includes the following steps:

[0073] S1: After verifying that the drilling detection device is functioning normally, install and fix the bottom hole detection mechanism inside the drill pipe, and complete the time synchronization through the wellhead processing terminal. After entering the drilling information and coal (rock) stratum properties at the opening into the wellhead processing terminal, install and fix the wellhead processing terminal at the wellhead, and ensure that its position does not change during drilling.

[0074] S2: Drilling begins. The bottom-of-hole detection mechanism synchronously collects vibration signals and calculates the maximum amplitude and frequency of the vibration signals through the data processing unit. This calculation determines whether to trigger the VLF transmitting unit to emit a signal, ultimately achieving real-time identification of the borehole geological conditions. Simultaneously, the vibration signals are transmitted to the borehole-head processing terminal for storage and analysis and verification of the bottom-of-hole vibration signals.

[0075] S3: The method for identifying borehole geological conditions while drilling is as follows:

[0076] S31: For the continuously acquired vibration signals at the bottom of the hole, the calculated maximum amplitude, vibration frequency, and signal acquisition time are respectively denoted as array A. i F i and T i (i = 1, 2, 3, ...), where i represents the number of times the vibration signal is collected, and T1 is the time corresponding to the first collection of the vibration signal.

[0077] S32: Let the change in amplitude be ΔA. i+1 =|A i+1 -A i | / A i The frequency change is ΔF i+1 =|F i+1 -F i | / F i When ΔA is satisfied i+1 ≥A 临界 And ΔF i+1 ≥F 临界 When it is determined that the drilling medium has changed, A 临界 F 临界 The value is generally taken as 30% or 70%, or determined based on the characteristics of the coal and rock strata underground in the coal mine.

[0078] S33: When the drilling medium change judgment condition in S32 is triggered, immediately extract the corresponding vibration signal acquisition time T. i+1 Assign values ​​to array Tsend j =T i+1 (j = 1, 2, 3, ...), where j represents the number of times the drilling medium changes. When the array Tsend...j Upon receiving a new data value, the VLF transmitting unit is immediately activated to transmit a Tsend signal to the external receiving unit. j When the ultra-low frequency electromagnetic wave that provides time information is received by the external ultra-low frequency electromagnetic wave receiving unit, the reception time is recorded as TS. j .

[0079] S34: The ultra-low frequency electromagnetic wave signal is a single signal wave with a known wave velocity. Let its wave velocity be V. Then the borehole geological condition identification result during drilling is:

[0080] Within the range of (TS1-Tsend1)·V meters along the drilling path, the geological conditions of the borehole are the same as those at the borehole opening.

[0081] Within a range of (TS1-Tsend1)·V to (TS2-Tsend2)·V meters along the drilling path, the geological conditions of the borehole change;

[0082] Within the range of (TS2-Tsend2)·V to (Tsend3-Tsend3)·V meters along the drilling path, the geological conditions change again and become the same as at the borehole opening;

[0083] And so on.

[0084] S4: The results of the borehole geological condition assessment are displayed in real time on the borehole processing terminal screen and stored at the same time to complete the drilling exploration.

[0085] Example 1: The process of drilling from a coal seam to a rock stratum

[0086] This embodiment describes the workflow for probing the roof strata by drilling through the coal seam during gas drainage drilling operations.

[0087] Step 1: Preparation and Initialization.

[0088] Before drilling begins, the operators first check the working status of the bottom hole detection mechanism 1 and the wellhead processing terminal 2 to ensure sufficient power. Then, using a push rod, they connect the connecting screw inside the bottom hole detection mechanism 1 and insert it into the first drill pipe. Precise positioning is achieved using the positioning plate 1212 at the rear end of the connecting screw to align with the hole position. Finally, the drill pipe is securely fixed inside using screws 1114 through an opening in the drill pipe wall. The power to the wellhead processing terminal 2 is then turned on. The operator inputs basic information such as the current borehole number and initial depth on the terminal and records the medium property at the opening as "coal". Afterwards, the time synchronization button 2121 in the function button area is pressed. The nanosecond-level timer inside the terminal sends a precise time signal to the time reference calibration module 14 of the bottom hole detection mechanism 1, completing the time synchronization of the two devices. Finally, the wellhead processing terminal 2 is fixed in a stable position near the wellhead.

[0089] Step 2: Drilling and continuous monitoring.

[0090] Press the detection button 2122 to begin drilling. As the drill bit penetrates the coal seam, the vibration sensor 121 at the bottom of the hole continuously collects vibration signals. Due to the relatively uniform coal quality, the data processing unit 123 calculates the maximum vibration amplitude Ai and the vibration frequency F. i The vibrations will fluctuate within a relatively stable range. These continuous vibration signals are transmitted to the aperture processing terminal 2 via the LoRa wireless transmission unit 131 for storage, serving as the basis for data analysis and verification.

[0091] Step 3: Mutation identification and signal emission.

[0092] When the drill bit emerges from the coal seam and contacts the overlying hard rock strata, the drilling medium undergoes a fundamental change. The rock is much harder than coal, leading to a significant increase in drilling vibration, particularly a sharp rise in vibration frequency. The data processing unit 123 within the bottom hole detection mechanism 1 compares the continuously acquired vibration signal parameters in real time, and detects changes in amplitude. and frequency change Simultaneously, if preset judgment conditions are met, such as exceeding 30%, the system immediately records the precise moment t1 when the medium change occurs and assigns it to the array T. At the same time, the VLF transmitting unit 132 is immediately activated to transmit an ultra-low frequency electromagnetic wave signal carrying the moment information t1 out of the aperture.

[0093] Step 4: Location calculation and result display.

[0094] The ultra-low frequency electromagnetic wave signal penetrates the strata at a known wave velocity v and is received by the VLF receiving unit 222 at the borehole opening. The borehole processing terminal 2 records the reception time as t1'. The central processing unit in the terminal immediately calculates that the distance L1 from the location where the borehole geological state changes to the opening is v×(t1'-t1).

[0095] Once the calculation is complete, the results are immediately updated and displayed on screen 211. For example, the screen will display: "Within the range of the borehole opening to L1 meters along the drilling path, the geological conditions of the borehole are the same as at the borehole opening, which is a coal seam; at L1 meters, the geological conditions change, and the borehole enters a rock stratum." At the same time, the results are stored in the terminal, and construction personnel can view them at any time through the query button 2123.

[0096] Example 2: The process of drilling into interbedded rock and returning to the coal seam

[0097] This embodiment describes the exploration process in which a drill bit briefly passes through a thin layer of rock interlayer (commonly known as rock interlayer) and then returns to the coal seam.

[0098] The first part of the process is the same as in Example 1. The system first detects a change from coal to rock and calculates its position L1. As the drilling rig continues to drill, passes through this interbedded rock and re-contacts the coal seam below, the drilling vibration will change from the previous intense "rock mode" back to the relatively gentle "coal seam mode".

[0099] The data processing unit 123 of the borehole bottom detection mechanism 1 will again capture the vibration signal change that meets the conditions and determine it as a second medium change. The system records the time t2 at this moment and triggers the VLF transmitting unit 132 to transmit a signal carrying the time information t2 again. After receiving the signal at time t'2, the borehole terminal calculates the distance between the second change point and the opening as L2 = v × (t'2 - t2).

[0100] Finally, the entire geological profile will be displayed on screen 211: "The area from the borehole opening to L1 meters along the drilling path is a coal seam; the area from L1 meters to L2 meters is a rock stratum (interbedded with gangue); starting from L2 meters, the geological conditions change again and become the same as at the borehole opening, returning to the coal seam." This cycle repeats continuously, enabling continuous and real-time detection of the geological conditions along the entire drilling path.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A drilling geological condition detection device with an embedded drill rod, characterized in that, The system includes a bottom hole detection mechanism (1) and a borehole processing terminal (2). The bottom hole detection mechanism (1) is adapted to be embedded in the first drill rod connected to the drill bit. The bottom hole detection mechanism (1) includes a bullet-shaped housing (11), a signal acquisition module (12), a data transmission module (13), a time reference calibration module (14), and a first power supply mechanism (15). The bullet-shaped housing (11) includes a cylindrical shell (111), a top conical cover (112), and a bottom conical cover (113). The cylindrical shell (111) and the top conical cover (113) are connected together. 112) and the bottom conical cap (113) are threaded together and equipped with a sealing ring. The top conical cap (112) and the bottom conical cap (113) are provided with threaded grooves (1121) at their tips. The threaded grooves (1121) are used to cooperate with the connecting screw (1211) to push the bottom hole detection mechanism (1) into or pull out of the drill rod. The rear end of the connecting screw (1211) is provided with a positioning piece (1212). The positioning piece (1212) is used to assist in aligning and positioning the bottom hole detection mechanism (1) in the drill rod. The bottom hole The detection mechanism (1) is clamped and fixed inside the drill rod by three screws (1114) at each end. The screws (1114) are installed through holes in the drill rod wall and their ends are confined within the thickness of the drill rod wall and do not protrude from the outer surface of the drill rod. An annular gap is maintained between the outer shell of the bottom hole detection mechanism (1) and the inner wall of the drill rod. The annular gap is used as a channel for air or water supply during the drilling process. A data acquisition plate (122) is arranged along the central axis inside the bullet-shaped outer shell (11). The data acquisition plate (122) penetrates the inner part of the bullet-shaped outer shell (11). The space is fixed in the groove (1113) on the inner wall of the columnar shell (111). The signal acquisition module (12) includes a vibration sensor (121) and a data processing unit (123). The vibration sensor (121) is installed on the acquisition board (122) near the top cone cover (112) to acquire the bottom hole vibration signal generated when the drill bit breaks rock or coal. The data processing unit (123) is arranged adjacent to the vibration sensor (121). The data processing unit (123) is also configured to process the continuously acquired data. i Second and third i Calculation of the maximum amplitude of the first hole bottom vibration signal A i , A i 1 and vibration frequency F i , F i 1, and in and When it is determined that the drilling medium has changed, among which, The preset threshold for the rate of change of amplitude. The preset frequency change rate threshold is used; the data transmission module (13) is installed on one end of the acquisition board (122) near the bottom cone cover (113). The data transmission module (13) includes a vibration signal wireless transmission unit (131) and a VLF transmission unit (132). The vibration signal wireless transmission unit (131) has a built-in LoRa module and is used to transmit continuous bottom hole vibration signals to the borehole processing terminal (2). The VLF transmission unit (132) is used to transmit ultra-low frequency electromagnetic wave signals carrying geological change time information when it is determined that the drilling medium has changed. The time reference calibration module (14) is installed in the middle of the acquisition board (122) and is used to provide a time reference for the signal acquisition module (113). 2) The data transmission module (13) provides a unified and synchronized time reference. The borehole processing terminal (2) is suitable for installation outside the borehole and includes a terminal housing (21), a data receiving module (22), a timer, a central processing unit, and a second power supply mechanism. The data receiving module (22) includes a vibration signal receiving unit (221) and a VLF receiving unit (222). The timer is a nanosecond-level timer and is used to send a precise time signal to the time reference calibration module (14) to unify the time of the bottom hole detection mechanism (1) and the borehole processing terminal (2). The central processing unit is used to process the received signals and determine the geological state of the borehole. When it is determined that the drilling medium has changed, the acquisition time of the corresponding bottom hole vibration signal is extracted. t j And immediately trigger the VLF transmitting unit to emit a message carrying the moment of geological change out of the borehole. t j The information is a very low frequency electromagnetic wave signal; the VLF receiving unit records the reception time when it receives the very low frequency electromagnetic wave signal. The central processing unit operates according to a unified and synchronized time base, following... Calculate the first j The distance from the location where the sub-geological state changes to the opening point And according to the location where geological conditions changed in each period The geological conditions of the borehole along the drilling path are determined by segmenting the coal seam or rock strata properties at the borehole opening. v The known wave velocity of the ultra-low frequency electromagnetic wave signal is given.

2. The embedded drill rod type borehole geological condition detection device according to claim 1, characterized in that: The borehole processing terminal (2) also includes a display screen (211) and a function button area (212) disposed on the terminal housing (21); the display screen (211) is used to display geological status information inside the borehole in real time; the central processing unit processes, judges and stores the received data in real time, and sends the results to the display screen (211) for presentation.

3. A method for detecting geological conditions in a borehole using an embedded drill rod, comprising using the embedded drill rod type borehole geological condition detection device as described in claim 2, characterized in that... Includes the following steps: S1: After checking that the device is working properly, install and fix the bottom hole detection mechanism (1) inside the first drill rod connected to the drill bit. Send a precise time signal to the time reference calibration module (14) through the nanosecond-level timer of the hole opening processing terminal (2) to complete the time synchronization between the bottom hole detection mechanism (1) and the hole opening processing terminal (2). After recording the drilling information and the coal seam or rock stratum properties at the opening in the hole opening processing terminal (2), fix the hole opening processing terminal (2) at the hole opening and ensure that the position of the hole opening processing terminal (2) does not change during the drilling process. S2: After drilling begins, the vibration signal at the bottom of the hole is synchronously collected by the vibration sensor (121), and the data processing unit (123) calculates the number of consecutively collected signals. i Second and third i Maximum amplitude of the first hole bottom vibration signal A i , A i 1 and vibration frequency F i , F i 1. The continuous bottom vibration signal is transmitted to the orifice processing terminal (2) through the vibration signal wireless transmission unit (131) for storage and for analysis and verification of the bottom vibration signal. S3: Determine if the drilling medium has changed, for the first continuously acquired data... i Second and third i The maximum amplitude of the first-order bottom hole vibration signal is denoted as follows: A i and A i 1. The vibration frequencies are denoted as follows: F i and F i 1. When the conditions are met and When it is determined that the drilling medium has changed, among which, i It is an integer greater than 1. The preset threshold for the rate of change of amplitude. The preset frequency change rate threshold; The value is 30%. The value is 70%; S4: When a change in the drilling medium is detected, extract the acquisition time of the corresponding bottom hole vibration signal. t j And immediately trigger the VLF transmitting unit (132) to emit a message carrying the moment of geological change out of the borehole. t j The information is a very low frequency electromagnetic wave signal, among which, j The number of times the drilling medium changes; S5: The ultra-low frequency electromagnetic wave signal is a single signal wave with a known wave velocity. When the VLF receiving unit (222) of the aperture processing terminal (2) receives the ultra-low frequency electromagnetic wave signal, it records the receiving time as... Let the wave velocity of the ultra-low frequency electromagnetic wave signal be... v Then the first j The distance from the location where the sub-geological state changes to the opening point L j for .

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