Drilling transient electromagnetic tunnel advanced forecasting system and detection method

Abstract

The invention provides a drilling transient electromagnetic tunnel advanced forecasting system and detection method, and the system comprises a transient electromagnetic detection assembly which is provided with a plurality of transmitting-receiving coil units which are connected in sequence; one part of the receiving and transmitting coil units are coaxial receiving and transmitting coils, and the other part of the receiving and transmitting coil units are coplanar receiving and transmitting coils; the attitude sensing device detects the attitude of the transient electromagnetic detection assembly in a drill hole, and the transmitting control unit is connected with the transmitting coils and used for controlling the transmitting coils to transmit pulse electromagnetic fields in sequence and controlling transmitting parameters. The receiving control unit is connected with each receiving coil, acquires the received detection data and preprocesses the detection data of each measuring point, and the processing system corrects the three-dimensional space coordinates of the measuring points according to the information of the attitude sensing device and constructs a three-dimensional geological imaging model in combination with the corresponding detection data. According to the borehole transient electromagnetic probe provided by the invention, borehole transient electromagnetism can be well applied to advanced tunnel prediction.

Description

Technical Field

[0001] The present invention belongs to the field of tunnel advanced prediction, and particularly relates to a borehole transient electromagnetic tunnel advanced prediction system and a detection method. Background Technique

[0002] The statements in this part merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] For tunnel advanced geological prediction, generally 3 - 5 boreholes are arranged in a triangular pattern at the tunnel face. This method has high costs and strict requirements for the drilling positions. Meanwhile, the rock formation conditions obtained from only a few boreholes are likely to overlook the possible disaster risks at the un - drilled positions.

[0004] The borehole transient electromagnetic method (or transient electromagnetic logging) is an electromagnetic exploration method. In this method, a square wave is input into the transmitting coil, and during the turn - off period, the secondary - field induced voltage signal of the underground medium is collected by the receiving coil to identify the underground electrical information. In the traditional method, the mutual inductance between the coaxial transmitting and receiving coils is relatively large. When the secondary - field signal is generated, due to the "transient process" in the coil, the primary field has not completely dissipated and is still much stronger than the secondary - field signal. Therefore, the early signals generated by shallow geological bodies (about 10 meters deep) are covered, which cannot meet the requirements of tunnel advanced prediction and makes it difficult to apply the borehole transient electromagnetic method in tunnel advanced prediction. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a borehole transient electromagnetic tunnel advanced prediction system and a detection method, which can enable the better application of the borehole transient electromagnetic method in tunnel advanced prediction.

[0006] According to some embodiments, the present invention adopts the following technical solutions:

[0007] A borehole transient electromagnetic tunnel advanced prediction system includes a transient electromagnetic detection component, an attitude sensing device, a transmitting control unit, a receiving control unit, and a processing system. Among them, the transient electromagnetic detection component is used to be arranged in a borehole and includes a plurality of sequentially connected transmitting - receiving coil units;

[0008] The transmitting - receiving coil unit includes two relatively arranged unit skeletons, which are detachably connected. On the two unit skeletons, there are first slots for arranging the transmitting - coil skeleton and second slots for arranging the receiving - coil skeleton;

[0009] A plurality of turns of transmitting coils are wound on the transmitting - coil skeleton, and a plurality of turns of receiving coils are wound on the receiving - coil skeleton;

[0010] Some of the transmitting - receiving coil units are coaxial transmitting - receiving coils, and some of the transmitting - receiving coil units are coplanar transmitting - receiving coils;

[0011] The attitude sensing device is arranged beside the transient electromagnetic detection component and is used to detect the attitude of the transient electromagnetic detection component in the borehole. The emission control unit is connected to each emission coil and is used to control each emission coil to emit pulsed electromagnetic fields in sequence and control the emission parameters;

[0012] The receiving control unit is connected to each receiving coil and is used to acquire the detected data received, preprocess the detected data of each measurement point, and transmit the preprocessed detected data to the processing system;

[0013] The processing system is used to correct the three-dimensional space coordinates of the measurement points according to the information of the attitude sensing device, and combine the corresponding detected data to construct a three-dimensional geological imaging model.

[0014] As an alternative implementation manner, the receiving coil skeleton and the two transmitting coil skeletons are eccentrically arranged so that the magnetic fluxes received by the inner and outer parts of the receiving coil in the transmitting coil are mutually compensated, that is, the mutual inductance of the transmitting and receiving coil unit is zero.

[0015] As an alternative implementation manner, the two unit skeletons are spliced to form a cylindrical structure; the unit skeleton is made of an insulating material, and each transmitting and receiving coil unit is connected by a metal connecting piece.

[0016] As an alternative implementation manner, each transmitting and receiving coil unit is arranged at a circumferential angle difference of 360° / N, where N is the total number of transmitting and receiving coil units, so as to realize full coverage detection in the circumferential direction of the borehole.

[0017] As an alternative implementation manner, a wire routing hole is arranged in the unit skeleton, and the interiors of the unit skeletons of different transmitting and receiving coil units are connected.

[0018] As an alternative implementation manner, there are multiple groups of slots on the outer side of the unit skeleton. Each group of slots includes two slots arranged at intervals, and an elastic piece is arranged between each group of slots. The arrangement positions of each group of slots are different to form a centering device.

[0019] As an alternative implementation manner, for the transmitting and receiving coil units of the coplanar transmitting and receiving coils, the first slot positions are arranged on the outer surface of the unit skeleton, the two first slot positions are arranged oppositely, and the positions of the two first slot positions are staggered along the extending direction of the unit skeleton;

[0020] The extending direction of the long side of the receiving coil skeleton is collinear with the extending direction of the unit skeleton;

[0021] The extending direction of the long side of the transmitting coil skeleton is collinear with the extending direction of the unit skeleton;

[0022] The planes where the transmitting coil and the receiving coil are located are parallel to each other.

[0023] As an alternative embodiment, the transceiver coil unit of the coaxial transceiver coil adopts the mutual inductance formula of circular coils, and the transceiver coil unit of the coplanar transceiver coil adopts the mutual inductance formula of square coils to achieve geometric compensation.

[0024] As an alternative embodiment, the emission control unit includes two relatively arranged unit skeletons, which are detachably connected between the unit skeletons. An emission circuit and a power supply unit are arranged in the unit skeletons. The power supply unit provides electrical energy for the emission circuit. The emission circuit is connected to the emission coils of each transceiver coil unit and controls the emission parameters. At the same time, it controls the emission coils of multiple transceiver coil units to emit a pulsed electromagnetic field once. The emission parameters include waveform, current magnitude, and turn-off time.

[0025] As an alternative embodiment, the reception control unit includes two relatively arranged unit skeletons, which are detachably connected between the unit skeletons. A collection device, a storage device, and a power supply unit are arranged in the unit skeletons. The collection device and the storage device are connected and are used to control each receiving coil unit to collect through each receiving coil during the gap when its emission coil emits a field once. The collection device performs gain processing on the transient electromagnetic signal, converts the analog signal into a digital signal, and transmits it to the storage device for storage.

[0026] As an alternative embodiment, the attitude sensing device includes two relatively arranged unit skeletons, which are detachably connected between the unit skeletons. A three-axis accelerometer, a three-axis gyroscope sensor, and a temperature sensor are arranged inside or on the unit skeletons. The three-axis accelerometer and the three-axis gyroscope sensor are used to record attitude information, and the temperature sensor is used to obtain the temperature in the borehole for temperature compensation of the three-dimensional attitude.

[0027] The detection method of the above borehole transient electromagnetic tunnel advanced prediction system includes the following steps:

[0028] Set the transient electromagnetic detection component and the attitude sensing device of the borehole transient electromagnetic tunnel advanced prediction system in the borehole, and move the front end of the borehole transient electromagnetic tunnel advanced prediction system to the bottom of the borehole;

[0029] Control each receiving coil unit to perform detections in multiple directions around the borehole, and record the attitude information of the transient electromagnetic detection component. Control the receiving coil unit to perform detections at each detection point one by one until reaching the hole mouth;

[0030] Record the detection data and preprocess the detection data;

[0031] According to the attitude information, establish a coordinate system, establish an Euler angle relationship in the coordinate system, and form a rotation matrix. Calculate the spatial position coordinates of the receiving coil unit at each detection point according to the rotation matrix, and calculate the normal vector direction of the receiving coil;

[0032] According to the calculated spatial position coordinates and the direction of the receiving coil normal vector, correct the three-dimensional spatial coordinates of each detection point, and combine the detection data of each detection point to construct a three-dimensional geological imaging model.

[0033] As an alternative implementation, the process of correcting the three-dimensional spatial coordinates of each detection point according to the calculated spatial position coordinates and the direction of the receiving coil normal vector, and combining the detection data of each detection point to construct a three-dimensional geological imaging model includes:

[0034] According to the receiving coil normal vector of the corresponding receiving coil unit, correct the Green's function in the forward model to a direction-sensitive form;

[0035] Using the spatial coordinates of the receiving coil unit, construct an inversion grid model to ensure the correspondence between the detection data and the voxels of the model, and map the detection data of each detection point into the grid through the electromagnetic response weights corresponding to each voxel;

[0036] Using the receiving coil direction information of the receiving coil unit to constrain the conductivity anisotropy, construct an inversion objective function, constrain the conductivity gradient through the directional derivative, use the conjugate gradient method to iteratively solve the inversion objective function, and update the conductivity distribution each time.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] The present invention creatively adopts a combination form of a coaxial coil and a coplanar square coil. By eccentrically arranging, the magnetic fluxes of the receiving coil inside and outside the transmitting coil are mutually cancelled, realizing the zero mutual inductance of the transmitting and receiving coils; the coaxial coil adopts the circular coil mutual inductance formula, and the coplanar coil adopts the square coil mutual inductance formula to achieve geometric compensation; through the zero mutual inductance design, the secondary field signal is effectively separated, solving the problem of the shallow blind area of the traditional transient electromagnetic method.

[0039] The present invention creatively provides an omnidirectional detection system. A plurality of transmitting and receiving coil units (also called probes) are arranged at a circumferential angle difference of 360° / N, where N is the number of units, to achieve full circumferential coverage detection of the borehole. The transmitting and receiving coil units adopt a modular design. The transmitting coil and the receiving coil therein adopt different parameters to optimize the signal-to-noise ratio, and the receiving coil and the transmitting coil respectively adopt intelligent control units to achieve efficient transmission and reception control and real-time signal processing.

[0040] The present invention uses an attitude sensing device to obtain attitude and temperature information, establishes a mapping relationship between the probe coordinate system and the gravity coordinate system through quaternion-Euler angle conversion, derives the probe pose and the direction of the receiving coil normal vector based on the rotation matrix, corrects the three-dimensional spatial coordinates of each detection point, synchronously processes the transient electromagnetic decay curve with the attitude data and depth information, and constructs a three-dimensional geological imaging model, improving the accuracy of imaging.

[0041] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides preferred embodiments in conjunction with the accompanying drawings and detailed descriptions are as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The schematic drawings forming a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments and descriptions thereof are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0043] Figure 1 It is a schematic diagram of the calculation process of the mutual inductance coefficient of coaxial coils in an embodiment;

[0044] Figure 2 It is a schematic diagram of the calculation process of the mutual inductance coefficient of coplanar coils in another embodiment;

[0045] Figure 3 It is a schematic diagram of the process of predicting the advance of a tunnel by borehole transient electromagnetic method in an embodiment;

[0046] Figure 4 It is a schematic diagram of a borehole transient electromagnetic tunnel advance prediction system in an embodiment;

[0047] Figure 5 It is an exploded view of the structure of the transmitting and receiving coil unit of coplanar coils in an embodiment;

[0048] Figure 6 It is a schematic diagram of the coordinate system of the probe device in an embodiment;

[0049] Figure 7 It is a schematic diagram of the structure of the transmitting and receiving coil unit of coaxial coils in an embodiment;

[0050] Figure 8 It is a detection schematic diagram of three coplanar transmitting and receiving coil units in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The present invention will be further described below in conjunction with the drawings and embodiments.

[0052] It should be noted that the following detailed descriptions are all illustrative and are intended to provide a further description of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0053] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0054] In the case of no conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0055] Embodiment 1

[0056] First, a borehole transient electromagnetic probe (i.e., a transceiver coil unit) capable of realizing shallow detection is provided. The probe includes two forms: a coplanar transceiver coil and a coaxial transceiver coil. By selecting the relative vertical distance and relative horizontal distance between the transceiver coils, the magnetic fluxes received by the receiving coil inside and outside the transmitting coil are mutually compensated, so that the mutual inductance of the transceiver coils can be 0. Thus, the coverage of the primary field is eliminated, and the secondary field of shallow geological bodies can be collected.

[0057] To achieve zero mutual inductance of the transceiver coils, the following method can be used to select the relative spatial position of the transceiver coils. According to the borehole diameter size, select the largest possible relative vertical distance between the transceiver coils and set this distance as h.

[0058] Determine the transceiver distance according to the mutual inductance coefficient of the transceiver coils. The coaxial coils usually use circular coils. As Figure 1 shown, the calculation formula of its mutual inductance coefficient is as follows:

[0059]

[0060] Where:

[0061] N R 、N T - The number of layers of the receiving coil (RX) and the transmitting coil (TX);

[0062] μ 0 Is the vacuum permeability;

[0063] l 1 Is the path of the transmitting coil;

[0064] l 2 Is the path of the receiving coil;

[0065] dl 1 Is the transmitting coil element;

[0066] dl 2 Is the receiving coil element;

[0067] r is the distance between a source point Q1 on the transmitting coil and any point Q2 on the receiving coil;

[0068]

[0069] where r 1 and r 2 are the radii of the two coils, d is the distance between the transmitter and the receiver, θ and φ are the angles between the lines connecting dl 1 and dl 2 and the x-axis in the cylindrical coordinate system with the centers of coil 1 and coil 2 as the origin and the normal as the z-axis.

[0070] Coplanar coils usually use square coils. As Figure 2 shown, the calculation formula for the mutual inductance coefficient is as follows:

[0071]

[0072] where μ 0 is the magnetic permeability of vacuum; l 1 is the path of the transmitting coil; l 2 is the path of the receiving coil; dl 1 is the differential element of the transmitting coil; dl 2 is the differential element of the receiving coil; r is the distance between a source point Q1 on the transmitting coil and any point Q2 on the receiving coil; N R is the number of turns of the receiving coil; N T is the number of turns of the transmitting coil.

[0073] A borehole transient electromagnetic advanced prediction system, as Figure 3 shown, includes multiple transmitting and receiving coil units. The transmitting and receiving coil units use the above-mentioned probe, that is, part of them are coplanar coils and part of them are coaxial coils. However, it should be noted that the two types of transmitting and receiving coil units / probes can be arranged at intervals, the coplanar coils or coaxial coils are arranged continuously. The coaxial coils are suitable for forward detection and circumferential shallow detection, and the coplanar coils are suitable for circumferential deep detection, enriching data information and improving the detection accuracy.

[0074] For multiple transmitting and receiving coil units, in this embodiment, a coaxial transmitting and receiving coil unit and three coplanar transmitting and receiving coil units with a detection direction angle of 120° form a transient electromagnetic detection component, which is also connected to a transmitting control unit 7, a receiving control unit 6 and an attitude sensing device 2. The above structure can be called a probe device and is arranged in the borehole 1.

[0075] The borehole transient electromagnetic advanced prediction system also includes a winch device. The connection of the winch device can be realized by using the existing logging winch technology. The movement distance L of the probe device can be controlled through the depth recording system of the winch device.

[0076] The transmitting and receiving coil parameters of multiple transmitting and receiving coil units are exactly the same, but the normal directions of the planes where the transmitting and receiving coils are located are assembled front and back with a certain angular difference; the angle is determined by dividing 360 degrees by the number of transmitting and receiving coil units.

[0077] As Figure 5 shown, the coplanar transmitting and receiving coil units include unit skeletons 1-1 and 1-2, and the unit skeletons 1-1 and 1-2 are combined into a cylindrical integral skeleton. Slots for the receiving coil skeleton are dug inside it, and slots for the transmitting coil skeleton are dug on the opposite sides of the front and back ends of its surface; it also includes transmitting coil skeletons 1-3, 1-4 and a receiving coil skeleton 1-5. The long side extension directions of the transmitting coil skeletons 1-3 and 1-4 are the same as the axis of the unit skeletons 1-1 and 1-2, and the axis of the long side extension direction of the receiving coil skeleton 1-5 is collinear with the axis of the unit skeleton; the transmitting coil and the receiving coil are respectively wound around the transmitting coil skeletons 1-3, 1-4 and the receiving coil skeleton 1-5, and the planes where the transmitting coil and the receiving coil are located are parallel to each other and point to the circumferential direction of the axis.

[0078] In this embodiment, the transmitting coil is wound with enameled wire with a wire diameter of 1 mm, the receiving coil is wound with enameled wire with a wire diameter of 0.3 mm, the transmitting coil is wound 20 turns, the receiving coil is wound 200 turns, the size of the transmitting coil skeleton is 4 cm × 40 cm × 2 cm, the size of the receiving coil is 4 cm × 50 cm × 2 cm, and the transmitting and receiving coils are wound on their skeletons; the unit skeleton is 1.5 m long, the cross-section is circular, the radius is 5 cm, made of insulating material, and wire holes are arranged inside.

[0079] Of course, in other embodiments, the above parameters can be adjusted.

[0080] Another type of transmitting and receiving coil unit uses a coaxial coil combination. After the transmitting and receiving coils are fixed by the zero-flux method, ferrite is installed inside the coils. In some embodiments, there is a certain eccentricity between the transmitting coil and the receiving coil, as Figure 7 shown.

[0081] In this embodiment, the transmitting coil is wound with enameled wire with a wire diameter of 1 mm, the receiving coil is wound with enameled wire with a wire diameter of 0.3 mm, the transmitting coil is wound 20 turns, the receiving coil is wound 700 turns, the size of the transmitting coil skeleton is a cylinder with a radius of 4 cm and a length of 10 cm, the size of the receiving coil is a cylinder with a radius of 4 cm and a length of 20 cm, and the transmitting and receiving coils are wound on their skeletons; the unit skeleton is 40 cm long, the cross-section is circular, the radius is 6 cm, made of insulating material, and wire holes are arranged inside.

[0082] Of course, in other embodiments, the above parameters can be adjusted.

[0083] The emission control unit is equipped with an emission circuit and a battery. The emission circuit is connected to the emission coil through enameled wire and controls the emission parameters, and at the same time controls the emission coils in multiple transceiver coils to emit a pulsed electromagnetic field one by one respectively; the emission parameters include waveform, current magnitude and turn-off time. The emission circuit controls the emission parameters of the emission coil. The frequency of the emission square wave current can be set to 25 Hz (not limited to), and the emission current intensity can be set to 1 - 5 A (not limited to). The battery outputs power to supply the emission current after being processed by a step-down and current-limiting protection circuit.

[0084] The reception control unit is equipped with a collection device, a storage device and a battery. The collection device is connected to the reception coil and the storage device through enameled wire and controls each reception coil unit to collect through the reception coil during the interval when its emission coil emits a field once. The amplifier inside the receiver can perform gain processing on the transient electromagnetic signal, convert the analog signal into a digital signal through an A / D converter and transmit it to the collection card in real time for processing and storage. The amplifier is mainly a low-noise amplifier, and the noise frequency used is different from the detection signal frequency. The collection device is a collection card, and its core is an A / D chip, and the analog signal is converted into a digital signal through the collection card. The sampling accuracy of the data collection card limits the accuracy of the collected data. By using a high-precision A / D converter, after the signal is converted, it is transmitted to an embedded computer for processing.

[0085] The embedded computer refers to a dedicated computer system designed for processing borehole transient electromagnetic data. It is directly embedded inside the receiver component, and its core is composed of several microprocessors designed in advance to execute data processing tasks, and can receive the digital signal sent by the A / D converter to achieve storage and processing.

[0086] The storage device stores all detection-related parameters and the measured induced electromotive force values, including: The operation process is as follows: The data reception system receives the transient electromagnetic signal of the reception coil, converts the analog signal into a digital signal through the data collection card, and then transmits the signal to the memory card. After the data collection at one point is completed, the embedded computer can read the stored data and process the stored data. The battery outputs power to supply the emission current after being processed by a step-down and current-limiting protection circuit.

[0087] The attitude sensing device includes a collection recorder, and the core component is a high-precision attitude sensor. The high-precision attitude sensor needs to include at least motion sensors such as a three-axis accelerometer, a three-axis gyroscope sensor, and a thermometer. The three-axis accelerometer and the three-axis gyroscope sensor are used to record attitude information, and the thermometer is used for temperature compensation of the three-dimensional attitude.

[0088] The attitude sensing device obtains temperature-compensated three-dimensional attitude and azimuth data through a built-in processor, and outputs zero-drift three-dimensional attitude and azimuth data represented by quaternions and Euler angles in real time.

[0089] Using the attitude data of each detection point recorded by the attitude sensing device carried in the borehole transient electromagnetic tunnel advanced prediction system for calculation, obtaining the attitude information of the device system at each detection point and correcting the detection azimuth of each coplanar transceiver coil unit.

[0090] The specific process includes:

[0091] Adopt the described borehole transient electromagnetic tunnel advanced prediction system to penetrate into the advanced borehole of the tunnel face, and conduct detection in the circumferential direction of the borehole to obtain geological information within dozens of meters around the borehole in front of the tunnel face; in the method, n detection points are set from the bottom of the hole to the hole mouth, the detection point n is the bottom detection point of the hole, and the detection point 0 is the hole mouth detection point. The distance between each point can be set to be different from 1m to 10m. Move the probe device to the bottom of the borehole. At this time, the probe is located at the detection point n. When the probe is stable and hardly shakes, control the three transceiver coil units a, b, c (or more) to conduct detections in multiple directions in the circumferential direction of the borehole, and record the attitude information of the probe at this time. The probe device moves out of the borehole along the borehole, and conducts detections at each detection point one by one until it reaches the hole mouth, that is, the detection point 0. The transceiver coil units a, b, c collect detection data, depth information and attitude information of a total of 3×(n + 1) detection points. The data collected by the transceiver coil units a, b, c are stored in a storage device as a group. The specific process of completing the borehole transient electromagnetic advanced prediction at each point is as follows:

[0092] Transmission process: After the probe is stable, the transmission control unit inputs a pulsed current into the transmission coil of the transceiver coil unit. The step current waveform includes step wave, square wave, triangular wave, trapezoidal wave, etc. The transmission coil is generally a circular or square hollow coil, which is controlled by the input current. The current in the coil drops from a certain value to 0 in a very short time. During this period, the transmission coil emits a pulsed electromagnetic field outward under the action of electromagnetic induction. The electromagnetic field propagates continuously in the surrounding rock and induces an electromagnetic induction in the surrounding rock to generate a secondary induction field in the opposite direction to the primary field. The secondary induction field propagates back to the receiving coil of the transceiver coil unit and induces electromagnetic induction in the receiving coil, causing the receiving coil to generate an induced voltage value that changes with time, which is the detection data.

[0093] Receiving process: The induced voltage value generated in the receiving coil is acquired by the acquisition circuit in the receiving control system. The acquisition circuit generally uses an acquisition card, such as an A / D chip. The common sampling rate is 256ksps (not limited to), and the minimum detection time is in the order of μs. At 10 -6 s~10 -3Collect hundreds of (not limited to) induced voltage values and their corresponding time points between s (not limited to) to form an induced voltage value curve that changes with time, i.e., an attenuation curve. The attenuation curve is amplified and processed by an amplifier in the acquisition circuit, and the amplification factor ranges from 1 to 1000 times, so that the acquired induced voltage value is increased to above the μV level, and the induced voltage signal is transmitted into the embedded computer for processing.

[0094] Attitude processing flow: The probe attitude information is also imported into the embedded computer at the same time. The attitude information is the Euler angles reflecting the probe device at each point represented by quaternions. The specific method is as follows:

[0095] Through the depth information and the attitude information, the attitude information and the moving distance L in the x, y, and z directions of the probe are obtained on the same time axis t. The method for obtaining the attitude information is as follows: A gravity coordinate system is established at the portal of the drift face, and the portal is the zero point. According to the settings of the attitude sensor itself, a gravity coordinate system is established, which is called the probe device coordinate system. In this embodiment, the x and y axis orientations are determined according to the north-south direction; the probe points into the hole, with the center of the probe attitude sensor as the origin and the probe pointing direction as the z axis; the coil normal points to the hole wall, and the pointing direction is the y axis; In the probe device coordinate system, the Euler angle relationship is established. The Euler angles respectively correspond to the attitude roll, yaw, and pitch, and respectively correspond to the internal rotation of the z, y, and x axes. These three rotation angles are named γ, β, and α, as Figure 6 shown.

[0096] Furthermore, according to the Euler angles, the quaternion q 0 , q 1 , q 2 , q 3 Establish a rotation matrix according to the internal rotation in the order of z-y-x as follows:

[0097]

[0098] g represents the gravity coordinate system, n represents the device coordinate system of the nth node (n = 0, 1, 2, 3...), represents the rotation matrix from the gravity coordinate system to the device coordinate system. The direction unit vector of the probe in the gravity coordinate system at the nth detection point is Solved by the following equation:

[0099]

[0100] In the formula represents the direction unit vector of the probe in the probe device coordinate system.

[0101] Furthermore, the spatial position coordinates of the probe at each detection point are:

[0102]

[0103] The distance between each detection point is a fixed value d, and the coordinates at the orifice position are set as a 0 (0, 0, 0).

[0104] Furthermore, at the nth node position, the unit direction vector of the receiving coil direction in the gravity coordinate system is j n , which can be obtained through the following equation:

[0105]

[0106] The f=(0, 1, 0) is the unit direction vector of the receiving coil normal direction in the detection device coordinate system.

[0107] Furthermore, obtain the spatial position coordinates of the probe at each node The unit direction vector of the receiving coil direction of the three coplanar transceiver single coil elements at the nth node position in the gravity coordinate system Obtain multiple circumferential direction detection data of an observation point, such as Figure 8 shown.

[0108] Based on the rotation matrix above, the pose (Roll / Pitch / Yaw) of the probe and the direction of the receiving coil normal vector are derived, and the spatial position coordinates a of the detection points at each position are obtained n (the orifice origin (0, 0, 0) and the unit direction vector of the receiving coil normal direction in the gravity coordinate system Correct the detection azimuth in the forward and inverse inversions.

[0109] In the forward model, the direction of the normal vector of the receiving coil directly affects the measured component of the transient electromagnetic response, and the calculation of the Green's function needs to be adjusted according to the coil direction. The receiving coil normal vector is j n , and its measured signal is the magnetic field vector B of the nth detection point n The projection in the normal direction:

[0110]

[0111] In the forward model, the Green's function G(r, r′) needs to be corrected to a direction-sensitive form:

[0112]

[0113] Among them, G 0 is the Green's function tensor of the isotropic medium, represents the curl operation.

[0114] In the parameter correction of the inversion, the probe spatial coordinate an =(x n , y n , z n ) is used to construct the inversion grid to ensure the exact correspondence between the measured data and the model voxels. For voxel assignment, let the detection point a n be located inside the voxel V p (i.e., a n ∈V p ), then the electromagnetic response weight ω np of this voxel is:

[0115]

[0116] where v p is the voxel center coordinate and Δ is the voxel side length.

[0117] Define the mapping matrix W, whose element maps the discrete detection data D n to the three-dimensional grid:

[0118] Dg rid = WD meas

[0119] where D meas is the transient electromagnetic response actually measured by the probe at each detection point (such as the induced voltage or the magnetic field decay curve), usually time-series data; D grid is the data matrix obtained by interpolating the measured data D meas at the discrete detection points onto the three-dimensional inversion grid.

[0120] Utilize the receiving coil direction information to constrain the conductivity anisotropy, and define the inversion objective function as:

[0121]

[0122] where

[0123] σ is the conductivity distribution to be inverted (values on the three-dimensional grid);

[0124] is the forward model, simulating the electromagnetic response under the given conductivity;

[0125] λ 1 , λ 2 are regularization parameters, balancing data fitting and model smoothness / prior constraints;

[0126] is the gradient of the conductivity, constraining the model smoothness;

[0127] σ n is the value of the conductivity distribution to be solved in the inversion problem at the nth voxel;

[0128] is the value of the prior conductivity (such as known geological information) distribution in the nth voxel;

[0129] According to the coil direction j n Define the data covariance matrix C:

[0130] C nm = δ nm ·(∈ iso + ∈ aniso ·|j n ·j m |)

[0131] where ∈ iso is the isotropic noise, v aniso is the directional correlation noise, δ nm function is 1 when n = m, otherwise 0.

[0132] If the known geological structure is anisotropic (such as layered strata), the conductivity gradient is constrained by the directional derivative:

[0133]

[0134] Use the conjugate gradient method to iteratively solve the objective function, and update the conductivity distribution σ each time:

[0135]

[0136] where the Jacobian matrix J needs to be calculated according to the direction-sensitive Green's function:

[0137]

[0138] J np : the element in the nth row and pth column of the matrix, representing the partial derivative of the nth observed data with respect to the pth model parameter (conductivity unit). is the nth data point calculated by the forward model. σ p is the conductivity value of the pth grid cell.

[0139] Through residual analysis Evaluate the inversion convergence.

[0140] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0141] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0142] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0143] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are performed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0144] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art without creative efforts within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A drilling transient electromagnetic tunnel advance prediction system, characterized in that: It includes a transient electromagnetic detection component, a posture sensing device, a transmitting control unit, a receiving control unit and a processing system, wherein the transient electromagnetic detection component is used to be arranged in a borehole, and includes a plurality of sequentially connected transmitting and receiving coil units; The transceiver coil unit comprises two unit frames arranged opposite to each other, the unit frames are detachably connected, and the two unit frames are provided with a first slot for arranging the transmitting coil frame and a second slot for arranging the receiving coil frame; The transmitting coil skeleton is wound with a plurality of turns of the transmitting coil, and the receiving coil skeleton is wound with a plurality of turns of the receiving coil; Some of the transceiver coil units are coaxial transceiver coils, and other transceiver coil units are coplanar transceiver coils; The attitude sensing device is arranged beside the transient electromagnetic detection component, and is used to detect the attitude of the transient electromagnetic detection component in the borehole. The transmitting control unit is connected to each transmitting coil, and is used to control each transmitting coil to transmit a pulse electromagnetic field in sequence, and control the transmitting parameters; The receiving control unit is connected to each receiving coil, and is used to obtain the received detection data, pre-process the detection data of each measuring point, and transmit the pre-processed detection data to the processing system; The processing system is used to correct the three-dimensional spatial coordinates of the measuring point according to the information of the attitude sensing device, and to construct a three-dimensional geological imaging model in combination with the corresponding detection data.

2. A drilling transient electromagnetic tunnel advance prediction system as claimed in claim 1, characterized in that: The receiving coil frame and the two transmitting coil frames are eccentrically arranged so that the magnetic fluxes received by the receiving coil at the inner and outer parts of the transmitting coil compensate each other, that is, the mutual inductance of the transmitting and receiving coil units is zero; Alternatively, two unit frames are spliced ​​together to form a cylindrical structure; the unit frame is made of insulating material, and each transceiver coil unit is connected by a metal connector.

3. A borehole transient electromagnetic tunnel advance prediction system as claimed in claim 1, characterized in that: Each transceiver coil unit is arranged with a circumferential angle difference of 360° / N, where N is the total number of transceiver coil units, so as to achieve full circumferential coverage detection of the borehole.

4. A drilling transient electromagnetic tunnel advance prediction system as claimed in claim 1, characterized in that: The unit frame is provided with wiring holes, and the unit frames of different transceiver coil units are internally connected; Alternatively, there are multiple groups of grooves on the outer side of the unit frame, each group of grooves includes two grooves arranged at intervals, an elastic sheet is arranged between each group of grooves, and the arrangement positions of the grooves in each group are different to form a centering device.

5. The drilling transient electromagnetic tunnel advance prediction system according to claim 1, characterized in that: The transceiver coil unit of the coplanar transceiver coil has a first slot disposed on the outer surface of the unit frame, two first slots are disposed opposite to each other, and the positions of the two first slots are staggered along the extension direction of the unit frame; The long side extension direction of the receiving coil frame is collinear with the extension direction of the unit frame; The long side extension direction of the transmitting coil frame is collinear with the extension direction of the unit frame; The planes where the transmitting coil and the receiving coil are located are parallel to each other; The transceiver coil unit of the coaxial transceiver coil adopts the circular coil mutual inductance formula, and the transceiver coil unit of the coplanar transceiver coil adopts the square coil mutual inductance formula to achieve geometric compensation.

6. A drilling transient electromagnetic tunnel advance prediction system as claimed in claim 1, characterized in that: The transmitting control unit includes two unit frames arranged opposite to each other, which are detachably connected to each other. A transmitting circuit and a power supply unit are arranged inside the unit frames. The power supply unit provides electrical energy for the transmitting circuit. The transmitting circuit is connected to the transmitting coil of each transceiver coil unit and controls the transmitting parameters, and at the same time controls the transmitting coils of multiple transceiver coil units to transmit a pulsed electromagnetic field. The transmitting parameters include waveform, current size and shutdown time.

7. A drilling transient electromagnetic tunnel advance prediction system as claimed in claim 1, characterized in that: The receiving control unit includes two unit frames arranged opposite to each other, which are detachably connected to each other. A collection device, a storage device and a power supply unit are arranged in the unit frames. The collection device and the storage device are connected to control each receiving coil unit to collect data through each receiving coil during the interval when its transmitting coil transmits a primary field. The collection device performs gain processing on the transient electromagnetic signal, converts the analog signal into a digital signal and transmits it to the storage device for storage.

8. The drilling transient electromagnetic tunnel advance prediction system according to claim 1, characterized in that: The posture sensing device includes two relatively arranged unit frames, which are detachably connected to each other. A three-axis accelerometer, a three-axis gyroscope sensor and a temperature sensor are arranged inside or on the unit frames. The three-axis accelerometer and the three-axis gyroscope sensor are used to record posture information, and the temperature sensor is used to obtain the temperature in the borehole to perform temperature compensation for three-dimensional posture.

9. The detection method of the drilling transient electromagnetic tunnel advance prediction system according to any one of claims 1 to 8, characterized in that: The following steps are involved: The transient electromagnetic detection component and the attitude sensing device of the drilling transient electromagnetic tunnel advance prediction system are arranged in the borehole, and the front end of the drilling transient electromagnetic tunnel advance prediction system is moved to the bottom of the borehole; Control each receiving coil unit to detect the borehole in multiple directions, record the attitude information of the transient electromagnetic detection assembly, and control the receiving coil unit to detect each detection point one by one until reaching the hole mouth; Record detection data and pre-process the detection data; According to the posture information, a coordinate system is established, an Euler angle relationship is established in the coordinate system, and a rotation matrix is ​​formed, and the spatial position coordinates of the receiving coil unit of each detection point are calculated according to the rotation matrix, and the direction of the normal vector of the receiving coil is calculated; According to the calculated spatial position coordinates and the direction of the normal vector of the receiving coil, the three-dimensional spatial coordinates of each detection point are corrected, and the three-dimensional geological imaging model is constructed by combining the detection data of each detection point.

10. The detection method according to claim 9, characterized in that: According to the calculated spatial position coordinates and the direction of the normal vector of the receiving coil, the three-dimensional spatial coordinates of each detection point are corrected, and the process of constructing a three-dimensional geological imaging model by combining the detection data of each detection point includes: According to the receiving coil normal vector of the corresponding receiving coil unit, the Green's function in the forward model is corrected into a direction-sensitive form; The spatial coordinates of the receiving coil unit are used to construct an inversion grid model to ensure that the detection data corresponds to the voxels of the model. The detection data of each detection point is mapped to the grid through the electromagnetic response weight corresponding to each voxel. The receiving coil direction information of the receiving coil unit is used to constrain the conductivity anisotropy, and the inversion objective function is constructed. The conductivity gradient is constrained by the directional derivative. The conjugate gradient is used to iteratively solve the inversion objective function, and the conductivity distribution is updated in each iteration.

Images