CN117092704A - geological detection system - Google Patents
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- CN117092704A CN117092704A CN202210520057.9A CN202210520057A CN117092704A CN 117092704 A CN117092704 A CN 117092704A CN 202210520057 A CN202210520057 A CN 202210520057A CN 117092704 A CN117092704 A CN 117092704A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/081—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices the magnetic field is produced by the objects or geological structures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
- G01R33/0327—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect with application of magnetostriction
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
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- Y02A90/30—Assessment of water resources
Abstract
The embodiment of the application discloses a geological detection system which comprises detection equipment and a magnetic field sensor. The magnetic field sensor is used for detecting a magnetic field signal emitted by the geological body and emitting a detection signal corresponding to the magnetic field intensity of the magnetic field signal to the detection equipment under the action of the magnetic field signal. The detection device is used for determining the magnetic field intensity of the magnetic field signal based on the detection signal and determining whether the geologic body is a geologic body of a target type based on the magnetic field intensity of the magnetic field signal. In the scheme, the special geologic body is determined by using the magnetic field intensity, and the magnetic field intensity is not detected by using a coil, so that the problem that the equivalent inductance interferes with the detection result is solved, and the accuracy of the detection result can be improved. In addition, the sensor for detecting the magnetic field intensity can be generally made smaller, so that the normal use in drilling can be ensured.
Description
Technical Field
The application relates to the technical field of geological detection, in particular to a geological detection system.
Background
In the coal mining process, various special geologic bodies such as water bodies, oil gas and the like can be encountered. When some special geologic bodies are mined, serious safety accidents can be caused. Therefore, prior to coal mining, the mine must be subjected to geological exploration.
Currently, a relatively effective method for geological exploration is a transient electromagnetic method, in which a transient magnetic field signal is generated to excite a secondary electromagnetic field at a low-resistance abnormal body, and the geological conditions at different depths in the earth can be inversely interpreted by detecting the magnetic flux of the secondary field signal. Because the secondary field signal is smaller, a large coil with the length of meter is generally adopted in a tunnel of a tunneling surface for signal detection. However, due to the problems of more underground interference signals, complex geological structure conditions, strong measurement polyneurality and the like, the detection accuracy is low. In order to reduce the influence of various interference factors in a roadway on signal detection to the greatest extent, a scheme of transient electromagnetic in a hole is developed, namely a coil is placed in a drill hole for detection.
Because of the limited size of the drill hole, the detection capability of the electromagnetic sensor can be improved only by increasing the number of turns of the coil. However, although the number of turns of the coil can increase magnetic flux, additional problems such as equivalent inductance and the like are difficult to eliminate, signal reception is affected, the detection capability is limited, the detection accuracy and the detection distance are affected, and finally the detection of the geologic body is inaccurate.
Disclosure of Invention
The embodiment of the application provides a geological detection system, which can solve the problem of inaccurate geological detection results in the prior art. The technical scheme is as follows:
in a first aspect, the present application provides a geological detection system comprising a detection device and a magnetic field sensor. After the magnetic field sensor detects the magnetic field signal emitted by the geological body, a detection signal corresponding to the magnetic field intensity of the magnetic field signal is emitted to the detection equipment under the action of the magnetic field signal.
The magnetic field sensor can be an optical fiber sensor, and the optical fiber sensor can be different in spectrum of reflected signals under the action of magnetic field signals with different magnetic field intensities. The magnetic field sensor can also be a giant magnetoresistance sensor, and the giant magnetoresistance sensor changes the resistance of the giant magnetoresistance sensor under the action of magnetic field signals with different magnetic field intensities, so that the magnitude of detection current is changed. The magnetic field sensor can also be a magnetic field sensor with higher sensitivity and based on quantum technology, the quantum magnetic field sensor generates energy level transition under the action of a magnetic field signal and can radiate electromagnetic signals, and the magnetic field sensing can be realized by detecting the electromagnetic signals.
The detection device receives the detection signal emitted by the magnetic field sensor, determines the magnetic field strength of the magnetic field signal based on the detection signal, and then determines whether the geologic body is a geologic body of a target type (i.e., a geologic body with low resistivity), such as a water body, based on the magnetic field strength of the magnetic field signal. A simple way to determine the presence of a target geologic volume may be: judging whether the intensity of the magnetic field is larger than an intensity threshold value, and if so, indicating that the target geologic body exists within a certain distance. By adopting the scheme, the special geologic body is determined through the detected magnetic field intensity, the magnetic field intensity is not required to be detected by using the detection coil, so that the problem that the equivalent inductance interferes with the detection result is avoided, and the accuracy of the detection result can be improved. In addition, the sensor for detecting the magnetic field intensity can be generally made smaller, so that the normal use in drilling can be ensured.
In one possible implementation, the geological exploration system further comprises a magnetic field generator. The transient magnetic field signal can be formed by switching the magnetic field generator from an on state to an off state or from the off state to the on state. And after the magnetic field sensor detects the secondary field echo signal emitted by the geological body, the magnetic field sensor emits a corresponding detection signal to the detection equipment. The detection equipment determines the corresponding magnetic field intensity according to the detection signal, so as to determine whether the geologic body is the geologic body of the target type.
By adopting the scheme, the geologic body can generate a secondary field under the excitation of an external magnetic field signal, the magnetic field signal of the secondary field echo signal of the magnetic field signal emitted by the secondary field is stronger than the magnetic field signal actively emitted by the geologic body, the geologic body is easier to detect by a magnetic field sensor, and the obtained detection result is more accurate.
In one possible implementation, after determining that the geological volume is of the target type, the detection device may determine the position information of the geological volume using a geological volume inversion model based on the magnetic field strength of the magnetic field signal of the geological volume and the position information of the magnetic field sensor. The geologic volume inversion model may employ, among other things, magnetotelluric linear or nonlinear inversion algorithms, such as fast relaxation inversion, nonlinear conjugate gradient inversion, occam inversion, and the like. The detection equipment determines the medium characteristic distribution in the detection area through the geologic body inversion model, and further identifies the position information of the low-resistance geologic body (such as a water body) according to the medium characteristic distribution.
Alternatively, the detection device may determine the position information of the geologic body based on the reception time of the magnetic field signal of the geologic body and the position information of the magnetic field sensor.
The technician may pre-establish an algorithm model (which may be a machine learning model or a mathematical formula derived based on theory) for calculating the magnetic field strength of the secondary field echo signal from the receiving time of the secondary field echo signal and the position information of the magnetic field sensor based on a distance formula, where the propagation speed of the magnetic field (i.e., electromagnetic wave) in the formation may be approximately considered to be a uniform value. Thus, the detection device can determine the position information of the geologic body under a preset coordinate system.
Optionally, after the detection device determines the detected geologic body of the target type, the position information of the geologic body may be sent to a specified computer device, where the computer device may display the position information of the geologic body, and may also send an alarm, such as a signal lamp alarm, an audible alarm, etc., to a technician.
By adopting the scheme, whether the geologic body is of a target type or not can be determined, the position information of the geologic body can be detected, and meanwhile, an alarm can be sent to a technician, and the mining plan can be timely adjusted so as to ensure the safety of coal mining operation.
In one possible implementation, the magnetic field sensor is an optical fiber sensor, and the detection device is connected to the optical fiber sensor through an optical fiber. The signal detector of the detection device comprises a light emitter and a light receiver, and the optical fiber sensor is connected with the signal detector of the detection device through an optical fiber. The signal detector of the detection device continuously transmits optical signals to the optical fiber sensor, and simultaneously continuously receives reflected optical signals transmitted by the optical fiber sensor.
The optical fiber sensor can detect magnetic field signals emitted by the geological body and has different optical signal reflection characteristics under the action of the magnetic field signals with different magnetic field intensities, for example, the reflectivity of optical signal components with the same frequency is changed. The detection device determines, based on the reflected light signal received from the optical fiber sensor, a frequency corresponding to a peak in the reflected light spectrum according to a spectral feature (may also be referred to as a reflection spectrum) of the reflected light signal, the frequency being a reflection frequency, and then determines, based on the reflection frequency when the magnetic field signal is not detected, the reflection frequency when the magnetic field signal is detected, and a correlation algorithm model of the optical fiber sensor, a magnetic field strength of the magnetic field signal emitted by the geological body, thereby determining whether the geological body is a geological body of a target type.
By adopting the scheme, the optical fiber sensor is small in size, can meet the detection requirement in the hole, is sensitive to the detection of the magnetic field intensity, and is favorable for improving the accuracy of geological detection.
In one possible implementation, the optical fiber sensor includes an optical fiber grating and a magneto-sensitive component, the optical fiber grating is in contact with the magneto-sensitive component, and the optical fiber grating is connected with the detection device through an optical fiber. The magneto-sensitive component is used for detecting magnetic field signals emitted by the geological body, the reflection characteristics of the fiber bragg grating are adjusted under the action of the magnetic field signals with different magnetic field intensities, and the fiber bragg grating is used for reflecting the received optical signals according to the adjusted reflection characteristics under the action of the magneto-sensitive component.
By adopting the scheme, the magnetic-sensitive component is very sensitive to the detection of the secondary field echo, namely the magnetic field intensity of the secondary field echo can be accurately detected, and the reflection frequency of the optical fiber grating to the optical signal can be timely adjusted, so that the accuracy of the detection result can be improved.
In one possible implementation, the magnetostriction component is a magnetostrictive material, and the fiber grating is fixed on the magnetostrictive material in the following manner: the magnetostrictive material has an arc-shaped groove structure, and the side surface of the fiber grating parallel to the main optical axis (which can be called an axial direction) is stuck or clamped on the arc-shaped groove of the magnetostrictive material. When the magnetostrictive material deforms under the action of the secondary field echo signal, an external force is applied to the fiber grating, so that the fiber grating is deformed.
In one possible implementation, the magnetostrictive material covers at least half of the perimeter of the radial cross section of the fiber grating.
In general, the larger the contact area between the magnetostrictive material and the fiber grating, the more obvious the deformation of the fiber grating under the action of the magnetostrictive material, and the more obvious the change of the reflection frequency of the optical signal. In order to better enable the magnetostrictive material to detect the secondary field echo signals in all directions, the contact area of the side surface of the fiber grating parallel to the main optical axis and the magnetostrictive material can be more than or equal to half of the side surface area.
When the magnetostrictive material detects a secondary field echo signal in any direction, deformation can occur, and the fiber bragg grating is driven to deform. After the fiber bragg grating is deformed, the reflection spectrum of the optical signal changes when the fiber bragg grating is not deformed, and after the signal detector of the detection equipment receives the reflection optical signal emitted by the optical fiber sensor, the frequency corresponding to the peak in the reflection spectrum is determined according to the reflection spectrum of the reflection optical signal, and the frequency is the reflection frequency. Then, the detection device can determine the magnetic field intensity of the secondary field echo signal corresponding to the reflected light signal by using a related algorithm model of the optical fiber sensor according to the reflected frequency, thereby determining whether the object is a geological body of a target type.
By adopting the scheme, the fiber bragg grating can obviously deform under the action of the magnetostrictive material, so that the change of the reflection frequency becomes obvious, the analysis of the detection result is facilitated, and the accuracy of the detection result is improved.
In one possible implementation, the geological exploration system includes at least two fiber optic sensors. In this case, the detection device determines a first deformation of each optical fiber sensor in a radial direction of the optical fiber grating and a second deformation of each optical fiber sensor in a main optical axis direction of the optical fiber grating based on the reflected light signals received from the at least two optical fiber sensors, and then determines a magnetic field strength of the magnetic field signal emitted from the geological body using a related mathematical model of the magnetic field strength based on the first deformation of each optical fiber sensor and the second deformation of each optical fiber sensor.
The main optical axes of at least two optical fiber sensors are parallel or collinear, the perpendicular line from the equivalent center of the magnetostrictive material in any one optical fiber sensor to the main optical axis of the optical fiber grating is not parallel or collinear with the perpendicular line from the equivalent center of the magnetostrictive material in other optical fiber sensors to the main optical axis of the optical fiber grating, and the first deformation is the deformation of the optical fiber sensor along the perpendicular line direction.
Optionally, after the detecting device determines the first deformation and the second deformation of each optical fiber sensor, a vector sum of the first deformation and an average value of the second deformation may be determined, so that a related mathematical model of the magnetic field strength is used to determine the magnetic field strength of the magnetic field signal emitted by the geological body.
Optionally, when determining the magnetic field strength of the magnetic field signal emitted by the geological body, the detection device may further determine the direction of the total deformation of each optical fiber sensor according to the direction of the first deformation and the direction of the second deformation of each optical fiber sensor, thereby determining the magnetic field direction at each optical fiber sensor. Then, the position information of the geologic body is determined according to the magnitude and direction of the magnetic field intensity of each optical fiber sensor and the geologic body inversion model.
By adopting the scheme, at least two optical fiber sensors are used as a group of optical fiber sensors, and the magnetic field intensity of the secondary field echo signal is calculated more accurately by calculating the average value of the axial deformation and the vector sum of the radial deformation of the at least two optical fiber sensors, so that the size of the magnetic field generated by the geologic body is calculated accurately. Further, by comparing the time points when the reflection frequencies of at least two optical fiber sensors are changed or the detected magnetic field strengths, the distances of the geologic body to each optical fiber sensor can be ordered, thereby determining the approximate orientation of the geologic body.
In one possible implementation, the optical fiber sensor includes at least two optical fiber gratings, which are respectively connected to the detection device by optical fibers.
In this case, the detection device determines the third deformation of each fiber grating in the radial direction of the fiber grating and/or the fourth deformation in the axial direction of the fiber grating based on the optical signal received from each fiber grating. Then, the detection equipment determines the magnetic field intensity corresponding to the secondary field echo signal by using a related mathematical model of the magnetic field intensity based on the third deformation and/or the fourth deformation of the at least two fiber gratings.
The side surfaces of the at least two fiber gratings, which are parallel to the main optical axis, are fixed at different positions of the outer surface of the magnetostrictive material, the main optical axes of the at least two fiber gratings are parallel to each other, the equivalent center of the magnetostrictive material is not collinear with the perpendicular line of the main optical axis of each fiber grating, and the third deformation of the fiber gratings is the deformation of the fiber gratings along the perpendicular line direction.
Optionally, after the detecting device determines the third deformation and the fourth deformation of each optical fiber sensor, a vector sum of the third deformation and an average value of the fourth deformation may be determined, so that a related mathematical model of the magnetic field strength is used to determine the magnetic field strength of the magnetic field signal emitted by the geological body.
Optionally, when determining the magnetic field strength of the magnetic field signal emitted by the geological body, the detection device may determine the direction of the total deformation of the optical fiber sensor according to the direction of the third deformation and the direction of the fourth deformation of each optical fiber grating, so as to determine the direction of the magnetic field strength at the optical fiber sensor. And then, determining the position information of the geologic body according to the magnitude and direction of the magnetic field intensity detected by the optical fiber sensor and the geologic body inversion model.
By adopting the scheme, at least two fiber gratings share the same magnetostrictive material, so that the detection of the same secondary field echo signal by the at least two fiber gratings can be ensured, the actual condition of the secondary field echo signal can be reflected more accurately by calculating the detection result of the at least two fiber gratings, and the detection accuracy is improved.
In one possible implementation, the magneto-sensitive component is a magnetic fluid in which the fiber grating is immersed. When the optical fiber sensor detects a secondary field echo signal emitted by the geologic body, the molecules of the magnetic fluid rotate towards the magnetic field direction. The distribution mode of the molecules of the magnetic fluid changes, so that the dielectric property of the magnetic fluid changes, and the reflection spectrum of the fiber bragg grating changes.
The detection device determines a corresponding reflection spectrum (i.e. a spectral feature) from the received reflected light signal, thereby determining a reflection frequency corresponding to a peak in the reflection spectrum and further determining a dielectric property of the magnetic fluid. And finally, the detection equipment can determine the magnetic field intensity of the secondary field echo signal corresponding to the reflected light signal by using a related algorithm model of the optical fiber sensor according to the dielectric property of the magnetic fluid.
In one possible implementation, the fiber optic sensor comprises at least three fiber gratings, wherein the main optical axes of the at least three fiber gratings may be parallel to each other. The detection device may determine the deformation of each fiber grating based on the frequency of the reflected light signal received from each fiber grating before the transient magnetic field signal is emitted by the magnetic field generator. Then, based on the deformation of each fiber grating, attitude information of the fiber sensor is determined. In addition to determining the attitude information of the optical fiber sensor at the detection position, in the process of sending the optical fiber sensor to the detection position, the detection device monitors the deformation of the optical fiber sensor to acquire the motion trail of the optical fiber sensor, determines the final position information (namely the actual position information) when the optical fiber sensor reaches the detection position through geometric operation according to the reference position information, the attitude information and the motion trail of the optical fiber sensor, and finally determines the position information of the geologic body by adopting a geologic body inversion model (which can be a machine learning model) based on the detected magnetic field intensity information from the geologic body, the attitude information and the actual position information of the optical fiber sensor.
Before detection, a technician drills a horizontal hole along the tunneling direction of the roadway. Then, an optical fiber sensor connected to the detecting device through an optical fiber is inserted into the hole so that the optical fiber sensor is in a horizontal state when entering the hole, and this position is recorded as a reference position, that is, reference position information of the optical fiber sensor.
The detection device continuously transmits an optical signal to the optical fiber sensor before the magnetic field generator transmits the transient magnetic field signal, and the optical fiber sensor continuously reflects the optical signal. In the process of inserting the optical fiber sensor into the hole, the position of the optical fiber sensor can deviate under the action of external force, and meanwhile, the external force can enable each optical fiber grating to deform differently, so that the reflection frequency of each optical fiber grating for optical signals is changed. For example, when the optical fiber sensor is bent upward, the optical fiber grating located above is compressed, and the optical fiber grating located below is stretched.
In this case, for each fiber grating, after the detection device receives the optical signal reflected by the fiber grating, the axial deformation and the radial deformation of the fiber grating are determined by the reflection frequency of the optical signal and the reference reflection frequency. Then, the detection device can determine the attitude information of the optical fiber sensor based on the axial deformation and the radial deformation of each optical fiber grating through a virtual work equation and a Newton iteration method, wherein the optical fiber sensor can be approximately considered to be not deformed but to be offset integrally, and the attitude information can be considered to be an included angle between a connecting line of two ends of the optical fiber sensor and the horizontal direction.
By adopting the scheme, the actual position and the attitude information of the optical fiber sensor can be accurately determined before detection, so that the position information of the geologic body is determined according to parameters such as the actual position and the attitude information of the optical fiber sensor and a geologic body inversion model, and the accuracy of geologic body detection is ensured.
In one possible implementation, the optical fiber sensor includes three optical fiber gratings distributed in a regular triangle, where the three optical fiber gratings are fixed on the same magnetostrictive material or the three optical fiber gratings are immersed in the same magnetic fluid.
In one possible implementation, the optical fiber is a polarization maintaining fiber. The detection device transmits a first optical signal and a second optical signal to the optical fiber sensor, wherein the first optical signal and the second optical signal are optical signals with different polarization directions. The magneto-sensitive component is used for detecting magnetic field signals emitted by the geological body, and under the action of the magnetic field signals with different magnetic field intensities, the first reflection characteristic of the fiber bragg grating on the first optical signal is adjusted, and the second reflection characteristic of the fiber bragg grating on the second optical signal is adjusted. The fiber grating is a grating etched on the polarization maintaining fiber, and is used for reflecting the first optical signal and the second optical signal. The detection device determines the magnetic field strength of the magnetic field signal emitted by the geologic volume based on the frequencies of the reflected light signals received from the fiber optic sensor in different polarization directions.
By adopting the scheme, the estimation of the magnetic field intensity on the radial plane can be realized by utilizing the reflection spectrum change of the fiber bragg grating to the light with different polarization directions, and at the moment, when the magnetic field intensity is determined, the detection equipment calculates by combining the reflection frequencies of the light with two polarization directions, so that the mutual verification can be realized, the result is more accurate, and the accuracy of the detection result is ensured.
In one possible implementation, the geological exploration system includes a plurality of fiber optic sensors connected in series by optical fibers, and the fiber optic sensor at one end is connected to the exploration device by optical fibers.
By adopting the scheme, the detection equipment can combine the detection results of a plurality of optical fiber sensors to more accurately determine the position information of the geologic body, improve the accuracy of the detection results, be favorable for providing accurate data reference for mine operation and ensure the safety of mine operation.
In one possible implementation, the geological exploration system includes a plurality of optical fiber sensors, the plurality of optical fiber sensors are divided into at least three groups, each group of optical fiber sensors is connected in series through an optical fiber, and the optical fiber sensor at one end of each group of optical fiber sensors is connected with the exploration equipment through an optical fiber.
By adopting the scheme, the detection equipment can be provided with a plurality of groups of optical fiber sensors in different directions, so that on one hand, the accuracy in determining the position of the geologic body can be improved, on the other hand, the detection direction can be enlarged, more accurate and richer reference data can be provided for mine operation, and the safety of the mine operation is ensured.
In a second aspect, the application provides an optical fiber sensor comprising an optical fiber grating and a magnetostrictive material, the optical fiber grating being fixed to the magnetostrictive material, the optical fiber grating being a grating etched on a polarization maintaining fiber. Taking the geological detection system of the first aspect as an example, when the optical fiber sensor is adopted, the optical fiber sensor can be connected with the detection equipment through the polarization-maintaining optical fiber, so that the polarization direction of an optical signal can not be changed when the optical signal propagates in the optical fiber, and the accuracy of a detection result when the optical fiber sensor is used for detection is effectively ensured.
In a third aspect, the present application provides an optical fiber sensor comprising a magneto-sensitive component and at least three fiber gratings, the at least three fiber gratings being in contact with the magneto-sensitive component. By adopting the optical fiber sensor, the optical signal reflected by the optical fiber sensor can be continuously detected, and the current position information and the current posture information of the optical fiber sensor are determined through analysis of the reflected optical signal, so that the actual posture information and the actual position information when the optical fiber sensor reaches the designated detection position can be determined, and the accuracy of the detection result is reasonably improved.
The technical scheme provided by the embodiment of the application has the beneficial effects that:
in an embodiment of the application, a geological detection system comprises a detection device and a magnetic field sensor. The magnetic field sensor detects a magnetic field signal emitted by the geological body and emits a corresponding detection signal to the detection equipment. The detection device determines the magnetic field intensity of the corresponding magnetic field signal according to the detection signal, thereby determining whether the geologic body is a geologic body of the target type through the magnetic field intensity of the magnetic field signal. In the scheme, the special geologic body is determined by using the magnetic field intensity, and the magnetic field intensity is not detected by using a detection coil, so that the problem that the equivalent inductance interferes with the detection result is solved, and the accuracy of the detection result can be improved. In addition, the sensor for detecting the magnetic field intensity can be generally made smaller, so that the normal use in drilling can be ensured.
Drawings
FIG. 1 is a schematic diagram of a geological exploration system according to an embodiment of the present application;
FIG. 2 is a schematic structural diagram of a detecting device according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a geological exploration system according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a geological exploration system according to an embodiment of the present application;
FIG. 5 is a schematic diagram of an optical fiber sensor according to an embodiment of the present application;
FIG. 6 is a schematic diagram of an optical fiber sensor according to an embodiment of the present application;
FIG. 7 is a schematic diagram of a geological exploration system according to an embodiment of the present application;
FIG. 8 is a schematic diagram of a geological exploration system according to an embodiment of the present application;
FIG. 9 is a schematic view of a radial cross-section of the fiber sensor of FIG. 6, provided by an embodiment of the present application;
FIG. 10 is a schematic diagram of an optical fiber sensor according to an embodiment of the present application;
FIG. 11 is a schematic diagram of an optical fiber sensor according to an embodiment of the present application;
FIG. 12 is a schematic illustration of a radial deformation provided by an embodiment of the present application;
FIG. 13 is a schematic diagram of an optical fiber sensor according to an embodiment of the present application;
FIG. 14 is a schematic illustration of a radial deformation provided by an embodiment of the present application;
FIG. 15 is a schematic diagram of an actual position and a reference position of an optical fiber sensor according to an embodiment of the present application;
fig. 16 is a schematic structural diagram of an optical fiber sensor according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.
Before explaining the embodiment of the present application in detail, an application scenario of the embodiment of the present application is described.
Various geologic bodies such as water, oil gas and the like are reserved in the stratum. In the coal mining process, the geologic bodies can increase the difficulty of coal mining more or less, even form disasters, and cause casualties and equipment damage. For example, if dangerous water is encountered in the exploitation process, the flood damage is very easy to cause casualties, and the like. Therefore, before the coal mine is mined, the detection of the geologic body must be carried out along the mining direction of the mine, and if dangerous geologic bodies are detected, the mining plan can be timely adjusted so as to ensure the safety of the coal mine mining operation.
In the stratum, the dangerous geologic body is generally a geologic body with low resistivity, and the geologic body with low resistivity (such as a water body and the like) can outwards emit a magnetic field signal, wherein the magnetic field strength of the magnetic field signal is obviously stronger than that of the geologic body with high resistivity such as soil, rock and the like. Thus, it is possible to determine whether or not a target geologic volume (i.e., a geologic volume of low resistivity) is present in the current detection direction by detecting the magnetic field strength of the magnetic field signal. The embodiment of the application is described by taking the detection of the water body as an example, and other conditions are similar, so that the embodiment of the application is not repeated.
The embodiment of the application provides a geological detection system, the corresponding structure of which is shown in figure 1, the geological detection system comprises detection equipment and a magnetic field sensor, and the detection equipment is connected with the magnetic field sensor.
The magnetic field sensor can detect a magnetic field signal emitted by the geological body and emit a corresponding detection signal to the detection equipment according to the detected magnetic field signal. The magnetic field sensor can be an optical fiber sensor, and the optical fiber sensor can reflect optical signals with different frequencies under the action of magnetic field signals with different magnetic field intensities and different spectrums of reflected signals. The magnetic field sensor can also be a giant magnetoresistance sensor, and the giant magnetoresistance sensor changes the resistance of the giant magnetoresistance sensor under the action of magnetic field signals with different magnetic field intensities, so that the magnitude of detection current is changed. The magnetic field sensor may also be a quantum technology based magnetic field sensor with a higher sensitivity. No limitation is made here as to the type of magnetic field sensor.
The detection device can determine the magnetic field intensity of the magnetic field signal corresponding to the detection signal according to the received detection signal, thereby determining whether the currently detected geologic body is a target geologic body according to the magnetic field intensity. A simple way to determine the presence of a target geologic volume may be: judging whether the intensity of the magnetic field is larger than an intensity threshold value, and if so, indicating that the target geologic body exists within a certain distance.
From a hardware composition point of view, the detection device may comprise a signal detector, a processor and a memory, the corresponding structure being shown in fig. 2.
The signal detector may be configured to receive a detection signal (which is an analog signal) emitted by the magnetic field sensor, and to convert the received detection signal into a digital signal. The type of signal detector is determined according to the type of magnetic field sensor, for example, when the magnetic field sensor is a fiber optic sensor, the signal detector is an optical receiver and an optical transmitter, and so on.
The processor may be a central processing unit (Central Processing Unit, CPU), a System on Chip (SoC), or the like. The processor may be configured to determine a magnetic field strength of the secondary field echo signal, may be configured to determine whether the body is a target type body, and so on.
The memory may be various volatile memories or nonvolatile memories, such as Solid State Disk (SSD), dynamic random access memory (Dynamic RandomAccess Memory, DRAM) memory, and the like. The memory may be used to store pre-stored data, intermediate data, and result data during execution of the operational instructions. Such as the magnetic field strength of the secondary field echo signal, the position information of the magnetic field sensor, etc.
The detection device may comprise communication means, display means, etc. in addition to the signal detector, the processor and the memory.
The communication component may be a wired network connector, a wireless fidelity (Wireless Fidelity, wiFi) module, a bluetooth module, a cellular network communication module, or the like. The communication means may be used for data transmission with other devices, which may be management devices, servers or other probe devices, etc.
The display unit may be a display panel integral with the probe device or may be a display device with a communication connection established separately from the probe device. When the display device is a display panel, it may be a twisted nematic (TwistedNematic, TN) panel, a vertically aligned (Vertical Alignment, VA) panel, an In-Plane Switching (IPS) panel, or the like. The display component can be used to display detection signals, can be used to display magnetic field signals, can be used to display position information of the geologic volume, and the like.
Because the low-resistance geologic body can generate a secondary field under the excitation of an external magnetic field signal, the magnetic field strength of the magnetic field signal (called a secondary field echo signal) emitted by the secondary field is stronger than that of the magnetic field signal actively emitted by the geologic body and is easier to detect by a magnetic field sensor, and the detection of the low-resistance geologic body can be realized by detecting the magnetic field strengths of the secondary field echo signals at different moments in a period of time after the excitation magnetic field signal is emitted. Accordingly, embodiments of the present application provide a geological detection system, as shown in FIG. 3, that includes a detection device, a magnetic field generator, and a magnetic field sensor. The magnetic field generator can emit transient magnetic field signals for exciting the geologic body to generate secondary field echo signals, wherein the transient magnetic field signals can be electromagnetic pulses which change instantaneously, and the transient magnetic field signals can be formed by switching the magnetic field generator from an on state to an off state or from the off state to the on state. The magnetic field sensor is used for detecting a secondary field echo signal emitted by the geological body and emitting a corresponding detection signal to the detection equipment.
The process of using the geological detection system to detect the geological body can be as follows:
first, a technician needs to perform a drilling operation in advance in a driving direction of a mine tunnel and insert a magnetic field sensor into the hole. If the diameter of the hole is too large, dangerous geologic bodies can possibly leak, and certain potential safety hazards exist, so the diameter of the hole is generally smaller, such as 3 cm.
Then, after the magnetic field sensors are inserted into the holes, the detecting device may determine positional information of each magnetic field sensor under a preset coordinate system. Meanwhile, a technician determines the transmitting position of the magnetic field generator in the roadway and records the position information (i.e., the space coordinates) of the magnetic field generator under a preset coordinate system in the detection device. Next, the technician uses the magnetic field generator to emit an electromagnetic pulse (i.e., a transient magnetic field signal) of a prescribed magnetic field strength that instantaneously changes in the direction of the heading of the mine tunnel, and the detection device can record the time at which the magnetic field generator emits the transient magnetic field signal and the magnetic field strength of the magnetic field signal.
The magnetic field generator may be connected to a detection device, in which case the detection device may also be used to supply power to the magnetic field generator, the technician changing the on-off state between the magnetic field generator and the detection device, e.g. changing the on-state to the off-state, etc., so that the magnetic field generator emits a transient magnetic field signal. The magnetic field generator may also be independent of the detection device, i.e. have an independent power supply, and the technician changes the on-off state between the magnetic field generator and the power supply, thereby causing the magnetic field generator to emit a transient magnetic field signal.
Then, in the process of expanding and spreading the magnetic field signal emitted by the magnetic field generator from the shallow layer to the deep layer in the stratum, and after encountering some geologic bodies with low resistivity (i.e. geologic bodies of a target type, such as water bodies and the like), vortex current can be generated in the geologic bodies, and the vortex current can further excite a secondary field in the geologic bodies and emit secondary field echo signals outwards.
And then, the secondary field echo signals emitted by the geologic body are spread outwards, and after the magnetic field sensor detects the secondary field echo signals, detection signals corresponding to the magnetic field intensity of the secondary field echo signals are emitted to the detection equipment under the action of the secondary field echo signals. For example, when the magnetic field sensor is an optical fiber sensor, the spectrum of the reflected signal is different under the action of the secondary field echo signals with different magnetic field intensities, that is, the optical signals with different frequencies can be reflected; when the magnetic field sensor is a giant magnetoresistance sensor, the resistance of the magnetic field sensor is changed under the action of secondary field echo signals with different magnetic field intensities, so that the magnitude of detection current is changed, and the like. Meanwhile, the detection device can record the receiving time of the secondary field echo signal. Specifically, the detection device continuously detects for a period of time, and records a group of received detection signals and corresponding moments of the detection signals.
Finally, the detection device, when determining the magnitude of the magnetic field strength at each fiber sensor, may also determine the direction of the magnetic field strength at each fiber sensor. Then, the position information of the geologic body is determined according to the magnitude and direction of the magnetic field intensity detected by each optical fiber sensor and the geologic body inversion model. Specifically, the detection device may determine the position information of the geological body under the preset coordinate system according to the magnetic field strength of the transient magnetic field signal transmitted by the magnetic field generator, the size and direction of the secondary field echo signal detected by each magnetic field sensor at different times within a period of time after the transient magnetic field is transmitted, the position information of the magnetic field generator, and the position information of each magnetic field sensor. Because a plurality of low-resistance dielectric bodies generally exist in the target area, the signal detected by the detection equipment may be a superimposed signal of a plurality of secondary field echoes in the target area, the detection equipment determines the dielectric characteristic distribution in the detection area by using a magnetotelluric linear or nonlinear inversion algorithm, such as fast relaxation inversion, nonlinear conjugate gradient inversion, occam inversion and the like, and further identifies the position information of the low-resistance dielectric bodies (such as water bodies) in the target area according to the dielectric characteristic distribution.
Optionally, the detection device determines the magnetic field strength of the secondary field echo signal corresponding to the detection signal according to the received detection signal. If the magnitude of the magnetic field strength is greater than the strength threshold, the detection device can further determine the information about the geologic volume. The technician may previously establish an algorithm model (which may be a machine learning model or a mathematical formula derived based on theory) for calculating the magnetic field strength of the secondary field echo signal from the transmission time of the magnetic field signal, the reception time of the secondary field echo signal, the position information of the magnetic field generator, the position information of the magnetic field sensor, and the like, based on the distance formula.
Optionally, after the detection device determines the detected geologic body of the target type, the position information of the geologic body may be sent to a specified computer device, where the computer device may display the position information of the geologic body, and may also send an alarm, such as a signal lamp alarm, an audible alarm, etc., to a technician.
Compared with other various sensors, the optical fiber sensor has smaller volume and is more suitable for detection operation in a narrow space. Furthermore, the optical fiber sensor uses light as a carrier of sensitive information, and the optical fiber as a medium for transmitting the sensitive information, so that the optical fiber sensor has higher sensitivity.
The embodiment of the application provides a geological detection system, a magnetic field sensor adopts an optical fiber sensor, the corresponding structure is shown in fig. 4, a signal detector of detection equipment comprises a light emitter and a light receiver, and the optical fiber sensor is connected with the signal detector of the detection equipment through an optical fiber. The signal detector of the detection device continuously transmits optical signals to the optical fiber sensor, and simultaneously continuously receives reflected optical signals transmitted by the optical fiber sensor.
Optionally, since the reflection frequencies of the fiber bragg gratings for the optical signals with different polarization directions are different, in order to ensure that the polarization directions of the optical signals cannot be changed when the optical signals propagate in the optical fibers, polarization-maintaining optical fibers can be used in the geological detection system to connect the detection device with the optical fiber sensor.
The optical fiber sensor may include an optical fiber grating (such as an optical fiber bragg grating, a weak grating with low reflectivity, etc.) and a magneto-sensitive component, where the optical fiber grating is in contact with the magneto-sensitive component.
The fiber grating is one kind of etched fiber with grating structure. The fiber bragg grating is connected with the detection device through an optical fiber and is used for reflecting an optical signal with a certain frequency (commonly called a reflection frequency) in the optical signals emitted by the detection device.
Magneto-sensitive parts refer to parts whose own properties change under the action of a magnetic field (i.e. when a magnetic field signal is detected), such as magnetostrictive materials, magnetic fluids, etc. The magneto-sensitive component is used for detecting the secondary field echo signals, and adjusting the reflection characteristics of the fiber bragg grating under the action of the secondary field echo signals with different magnetic field intensities, and the fiber bragg grating can strongly reflect optical signals with certain frequencies. Two common magnetically sensitive components are described below:
(1) The magneto-sensitive component can be magnetic fluid, and the fiber bragg grating is soaked in the magnetic fluid, and the corresponding structure is shown in fig. 5. The molecules of the magnetic fluid are distributed in the internal gaps of the fiber bragg grating. When no magnetic field signal is detected, the molecules of the magnetic fluid are randomly distributed, and the dielectric characteristics (such as dielectric constant, refractive index and the like) of the magnetic fluid are a certain fixed value. In general, when a magnetic fluid detects a magnetic field signal, molecules of the magnetic fluid are distributed along the magnetic field direction (i.e., rotate toward the magnetic field direction), the direction of rotation of the molecules is related to the magnetic field direction, and the rotation speed and the rotation amount of the molecules are related to the magnetic field intensity. The change of the distribution mode of the molecules in the magnetic fluid can change the dielectric property of the magnetic fluid, thereby leading to the corresponding change of the reflection property of the fiber bragg grating on the optical signal.
(2) The magnetostriction part can be a magnetostriction material, the side surface of the fiber bragg grating parallel to the main optical axis is fixed on the magnetostriction material, the corresponding structure is shown in fig. 6, and the magnetostriction material can deform differently under the action of magnetic field signals with different magnetic field intensities. Because the fiber grating is fixed on the magnetostrictive material, the deformation of the magnetostrictive material can generate corresponding force (such as pressure, tensile force and the like) on the fiber grating, so that the fiber grating is correspondingly deformed, and the reflection characteristic of the fiber grating on optical signals is changed.
When the geological detection system includes a fiber-optic sensor, it may be useful to determine whether the formation includes a body of water. When the geological detection system comprises a plurality of optical fiber sensors, the detection result of each optical fiber sensor can be jointly calculated, so that the position information of the water body in the stratum can be determined.
The geological exploration system may include a plurality of fiber optic sensors, and accordingly, there are a variety of possible connection configurations:
connection structure I
The plurality of sensors can be connected in series through optical fibers, and the magnetic field sensor at one end is connected with the detection equipment through the optical fibers, and the corresponding structure is shown in fig. 7.
Connection structure II
The plurality of optical fiber sensors can also be divided into a plurality of groups, each group of optical fiber sensors is connected in series through optical fibers, the optical fiber sensor positioned at one end of each group of optical fiber sensors is connected with the detection equipment through optical fibers, and the corresponding structure is shown in fig. 8.
For example, a technician may divide a plurality of fiber optic sensors into three groups, each group of fiber optic sensors being placed in a different aperture, the three groups of fiber optic sensors being located in a Kong Chengzheng triangular distribution. For each group of optical fiber sensors, each optical fiber sensor is connected in series through an optical fiber, and the optical fiber sensor at one end is connected with the detection equipment through an optical fiber. For the same secondary field echo signal, the three groups of optical fiber sensors can detect, and the detection equipment can perform joint calculation according to detection results of the three groups of optical fiber sensors, so that the accuracy of the detection results is improved, and the position information of the geologic body is accurately determined. The number of groups of the optical fiber sensors may be larger than three, and the number of groups is not limited here.
The geologic body generates a secondary field echo signal under the action of transient magnetic field signals emitted by the magnetic field generator. When the optical fiber sensor detects the secondary field echo signal, the reflection spectrum changes, and an optical signal having a frequency corresponding to the magnetic field intensity of the secondary field echo signal is reflected. After receiving the reflected light signal emitted by the optical fiber sensor, the signal detector of the detection device determines the frequency corresponding to the peak in the reflected light spectrum according to the reflected light spectrum of the reflected light signal, wherein the frequency is the reflected frequency. Then, the detection device can determine the magnetic field strength of the secondary field echo signal corresponding to the reflected light signal and the position information of the geologic body according to the reflected frequency by using a related algorithm model (the algorithm model can be a machine learning model or a mathematical formula derived based on theory) of the optical fiber sensor.
The embodiment of the application provides an optical fiber sensor, a magnetostrictive material is provided with an arc-shaped groove structure, and a side surface of an optical fiber grating parallel to a main optical axis (which can be called an axial direction) is stuck or clamped in the arc-shaped groove of the magnetostrictive material, and the corresponding structure is shown in figure 6.
In the optical fiber sensor, the optical fiber grating is fixed on the magnetostrictive material, and when the magnetostrictive material deforms under the action of a secondary field echo signal, an external force is applied to the optical fiber grating, so that the optical fiber grating is deformed. In general, the larger the contact area between the magnetostrictive material and the fiber grating, the more obvious the deformation of the fiber grating under the action of the magnetostrictive material, and the more obvious the change of the reflection frequency of the optical signal. In order to better enable the magnetostrictive material to detect the secondary field echo signals in all directions, the contact area of the magnetostrictive material and the fiber grating can be larger than or equal to half of the side surface area of the fiber grating, namely, the magnetostrictive material covers at least half of the perimeter of the radial section of the fiber grating. For example, the magnetostrictive material half wraps the fiber grating, that is, the arc-shaped groove of the magnetostrictive material is a semicircular groove, the corresponding structure is shown in fig. 9, and at this time, the contact area of the magnetostrictive material and the fiber grating is equal to half of the side surface area of the fiber grating; the magnetostrictive material completely wraps the fiber grating, and the corresponding structure is shown in fig. 10, where the contact area of the magnetostrictive material and the fiber grating is equal to the surface area of the fiber grating side, and so on.
By adopting the structure, when the magnetostrictive material detects the echo signal of the secondary field in any direction, the magnetostrictive material can deform and drive the fiber grating to deform. After the fiber bragg grating is deformed, the reflection characteristic of the fiber bragg grating is changed compared with that of the fiber bragg grating when the fiber bragg grating is not deformed, namely the reflection spectrum (also called spectrum characteristic) of the optical signal is changed, after the signal detector of the detection equipment receives the reflected optical signal emitted by the fiber optic sensor, the frequency corresponding to the peak in the reflection spectrum is determined according to the reflection spectrum of the reflected optical signal, and the frequency is the reflection frequency. Then, the detection device can determine the magnetic field intensity of the secondary field echo signal corresponding to the reflected light signal by using a related algorithm model of the optical fiber sensor according to the reflected frequency, thereby determining whether the water body exists or not.
Alternatively, other sensor structures may be used in embodiments of the present application, for example, a plurality of magnetostrictive materials fixed at different positions on the side of the fiber grating to realize sensing of the secondary field echo signals from different directions. There is no particular limitation herein.
In order to improve accuracy of the geological detection system, the geological detection system can adopt polarization-maintaining optical fibers, at this time, the fiber bragg grating can be an optical grating etched on the polarization-maintaining optical fibers, the detection equipment can emit two paths of optical signals (called a first optical signal and a second optical signal) with different polarization directions, and relevant information of the geological body is determined according to reflection conditions of the fiber bragg grating on the two paths of polarized light.
For the case of magnetostrictive materials for the magnetically sensitive member, several possible configurations of the fiber optic sensor are given below in connection with the use of polarization maintaining fibers, and the method of determining the magnetic field strength is described in connection with the configuration. The corresponding optical fiber sensor is combined with the polarization maintaining optical fiber, so that the detection accuracy of the magnetic field strength can be better improved.
Structure one
The embodiment of the application provides an optical fiber sensor, a magnetostrictive material is provided with an arc-shaped groove structure, and a side surface of an optical fiber grating parallel to a main optical axis (which can be called an axial direction) is stuck or clamped in the arc-shaped groove of the magnetostrictive material, and the corresponding structure is shown in figure 6. The specific structure is the same as the above-mentioned structure, and a detailed description thereof will be omitted.
By adopting the structure, when the magnetostrictive material detects the echo signal of the secondary field in any direction, obvious deformation can be generated, and the deformation has an axial component and a radial component (namely, the equivalent center of the magnetostrictive material and the vertical direction of the main optical axis of the fiber grating). The deformation component of the magnetostrictive material in the axial direction drives the fiber grating to generate the same deformation in the axial direction, for example, when the magnetostrictive material stretches in the axial direction, a tensile force is applied to the fiber grating in the axial direction, so that the fiber grating stretches in the axial direction, and the like. The deformation component of the magnetostrictive material in the radial direction drives the fiber grating to deform inversely in the radial direction, for example, when the magnetostrictive material expands in the radial direction, a pressure is applied to the fiber grating in the radial direction, so that the fiber grating contracts in the radial direction, and the like. After the fiber grating is deformed, the reflection frequency of the optical signal is changed compared with the reflection frequency of the optical signal when the fiber grating is not deformed.
The reflection characteristics (i.e., reflection frequency) of the fiber grating on the first optical signal and the second optical signal are different, and when the fiber sensor does not detect the secondary field echo signal, the fiber grating is not deformed, and at this time, the reflection frequency of the fiber grating on the first optical signal and the second optical signal is kept unchanged, which may be referred to as a reference reflection frequency, and the reference reflection frequency of the fiber grating on the first optical signal may be referred to as f 1 The reference reflection frequency of the fiber grating to the second optical signal is denoted as f 2 . When the optical fiber sensor detects the secondary field echo signal, the optical fiber grating deforms, at the moment, the reflection frequency of the optical fiber grating on the first optical signal and the second optical signal changes, and the reflection frequency of the optical fiber grating on the first optical signal at the moment can be recorded as f 1 ' the reflection frequency of the fiber grating to the second optical signal at this time is denoted as f 2 ’。
After the detection device receives the reflected light signals, the reflection frequencies of the first light signal and the second light signal can be respectively determined. Then, the axial deformation P of the fiber grating is calculated according to the reflection frequency of the first optical signal, the reference reflection frequency, the reflection frequency of the second optical signal and the reference reflection frequency ＝ And radial deformation P ⊥ 。
For axial deformation P ＝ It is necessary to determine the reference center reflection frequency (f) before the deformation of the fiber grating 2 +f 1 ) And/2, the center reflection frequency (f) of the fiber grating after deformation 2 ’+f 1 ')/2; then, the absolute value of the difference between the reference center reflection frequency and the center reflection frequency is calculated (f 2 ’+f 1 ’)/2-(f 2 +f 1 ) 2|; finally, the axial deformation P is determined from the absolute value of the difference ＝ Axial deformation P ＝ The positive correlation with the absolute value of the difference is denoted as p= ≡l (f 2 ’+f 1 ’)/2-(f 2 +f 1 )/2|。
For radial deformation P ⊥ It is necessary to determine the difference (f 2 ’-f 1 '), a first optical signal andthe difference (f) of the reference reflection frequencies of the second optical signal 2 -f 1 ) The method comprises the steps of carrying out a first treatment on the surface of the Then, a difference between the difference of the reflected frequency and the difference of the reference reflected frequency is determined, and an absolute value is taken, that is, | (f 2 ’-f 1 ’)-(f 2 -f 1 ) I (I); finally, the radial deformation P is determined from the absolute value ⊥ Radial deformation P ⊥ Positively correlated with the absolute value, denoted as P ⊥ ∞|(f 2 ’-f 1 ’)-(f 2 -f 1 )|。
Next, the detection device detects the axial deformation P of the fiber grating ＝ And radial deformation P ⊥ And determining the magnetic field intensity corresponding to the secondary field echo signal by using a related mathematical model of the magnetic field intensity.
Alternatively, for a fiber optic sensor, the detection device may also rely on the radial deformation P of the fiber optic sensor when determining the magnetic field strength at the fiber optic sensor ⊥ Is a direction and axial deformation P of ＝ And determining the direction of the total deformation of the fiber sensor, thereby determining the direction of the magnetic field at the fiber sensor. Then, position information of the geologic body is determined according to the magnitude and direction of the magnetic field intensity of the plurality of optical fiber sensors and the geologic body inversion model.
Structure II
The geological exploration system comprises at least two optical fiber sensors, each of which comprises a magnetostrictive material and a fiber grating, and is described below by taking two optical fiber sensors as an example.
The geological exploration system may include two fiber optic sensors, referred to as a first fiber optic sensor and a second fiber optic sensor, with the corresponding structure shown in fig. 11. The main optical axes of the first optical fiber sensor and the second optical fiber sensor are collinear, the first optical fiber sensor comprises a first magnetostrictive material and a first optical fiber grating, the second optical fiber sensor comprises a second magnetostrictive material and a second optical fiber grating, the first magnetostrictive material and the second magnetostrictive material can have a flat plate structure, a perpendicular line from the equivalent center of the first magnetostrictive material to the main optical axis of the first optical fiber grating is called a first perpendicular line, a perpendicular line from the equivalent center of the second magnetostrictive material to the main optical axis of the second optical fiber grating is called a second perpendicular line, the directions of the first perpendicular line and the second perpendicular line on the same radial plane are different, an included angle between the first perpendicular line and the second perpendicular line is 120 DEG, and the corresponding structure is shown in fig. 12.
When the first optical fiber sensor and the second optical fiber sensor detect the secondary field echo signals emitted by the same geologic body, the deformation of the whole optical fiber sensor is approximately regarded as the same. For the first optical fiber sensor, after the secondary field echo signal emitted by the geologic body is detected, the axial deformation corresponding to the first optical fiber grating and the deformation in the first vertical direction can be determined. For the first optical fiber sensor, after the secondary field echo signal emitted by the geologic body is detected, the axial deformation corresponding to the second optical fiber grating and the deformation in the second vertical direction can be determined. The calculation process of the deformation in each direction is the same as that in the first structure, and will not be described here.
Further, the detection device may calculate an average value of the axial deformation of the first fiber grating and the axial deformation of the second fiber grating, and a vector sum of the deformation in the first perpendicular direction and the deformation in the second perpendicular direction (as shown in fig. 12). And then, determining the magnetic field intensity of the secondary field echo signals emitted by the water body in the direction perpendicular to the main optical axis according to the average value and the vector sum.
By adopting the geological detection system, the first optical fiber sensor and the second optical fiber sensor are used as a group of optical fiber sensors, and the magnetic field intensity of the secondary field echo signal is calculated more accurately by calculating the vector sum of the average value of the axial deformation and the radial deformation of the optical fiber sensors, so that the size of the magnetic field generated by the water body is calculated accurately. In the geological detection system, a plurality of groups of optical fiber sensors are placed, the plurality of groups of optical fiber sensors are connected in series through optical fibers, and according to the detection results of the plurality of groups of optical fiber sensors, the position information of the water body can be determined.
Structure III
The optical fiber sensor can comprise a magnetostrictive material and at least two optical fiber gratings, wherein the at least two optical fiber gratings are respectively connected with the detection equipment through optical fibers, the side surfaces of the at least two optical fiber gratings, which are parallel to the main optical axis, are fixed at different positions on the outer surface of the magnetostrictive material, the main optical axes of the at least two optical fiber gratings are parallel to each other, and the equivalent center of the magnetostrictive material is not collinear with the perpendicular line of the main optical axis of each optical fiber grating, namely, the radial deformation direction of each optical fiber grating is different. The following description will take an example in which the optical fiber sensor includes three optical fiber gratings.
The optical fiber sensor comprises three optical fiber gratings which are distributed in a regular triangle, and the corresponding structure is shown in figure 13. When the optical fiber sensor detects a secondary field echo signal, the magnetostrictive material deforms to drive each optical fiber grating to deform axially and radially. The detection equipment can determine the axial deformation and the radial deformation of each fiber grating according to the optical signal of each fiber grating, and the deformation determination process is the same as the deformation determination process in the first structure, and the description is omitted here. Then, the detection device calculates the average value of the axial deformation (such as the fourth deformation of the first fiber grating, the fourth deformation of the second fiber grating, and the fourth deformation of the third fiber grating in fig. 14) of the three fiber gratings, and the vector sum of the radial deformation (such as the third deformation of the first fiber grating, the third deformation of the second fiber grating, and the third deformation of the third fiber grating in fig. 14) of the three fiber gratings, and determines the magnetic field strength corresponding to the secondary field echo signal using the relevant mathematical model of the magnetic field strength according to the vector sum of the average value of the axial deformation and the radial deformation.
In this embodiment, the magneto-sensitive component is taken as a magnetofluid material as an example, and the structure of the optical fiber sensor and the process of determining the relevant information of the water body are described.
When the magneto-sensitive component is magnetic fluid, the fiber bragg grating is soaked in the magnetic fluid, and the corresponding structure is shown in figure 5. When the optical fiber sensor detects a secondary field echo signal emitted by the water body, the molecules of the magnetic fluid rotate towards the magnetic field direction. The distribution mode of the molecules of the magnetic fluid changes, so that the dielectric property of the magnetic fluid changes, and the reflection spectrum of the fiber bragg grating changes, namely the frequency of an optical signal which can be reflected by the fiber bragg grating changes.
The detection device determines a corresponding reflection spectrum according to the received reflected light signal, thereby determining a reflection frequency corresponding to a wave peak in the reflection spectrum. Finally, the detection device can determine the magnetic field intensity of the secondary field echo signal corresponding to the reflected light signal by using a related algorithm model of the optical fiber sensor according to the reflection frequency of the reflected light signal.
Before detection, a technician can establish a space coordinate system and drill a horizontal hole along the tunneling direction of the roadway. Then, an optical fiber sensor connected to the detecting device through an optical fiber is inserted into the hole to ensure that the optical fiber sensor is in a horizontal state, which is called a reference position. However, the actual position of the optical fiber sensor is deviated from the reference position due to various reasons, such as that the hole is not secured in a horizontal state at the time of drilling, that the optical fiber sensor is deviated from the reference position by an external force at the time of insertion into the hole, and the like, as shown in fig. 15. For the optical fiber sensor, if the position information of the optical fiber sensor is not determined, the calculation result of the detection equipment is greatly deviated from the actual situation, and finally the water body position information is inaccurate. Therefore, the actual position of the fiber sensor needs to be determined before detection.
In view of the above needs, an embodiment of the present application provides an optical fiber sensor, which includes a magneto-sensitive component and at least three fiber gratings, and a process for determining an actual position of the optical fiber sensor will be described below by taking a magnetostrictive material and three fiber gratings as examples.
When the optical fiber sensor comprises a magnetostrictive material and three optical fiber gratings, the structure is the same as the structure III, the corresponding structure is shown in fig. 13, and the structure is not repeated here.
The detection device continuously transmits an optical signal to the optical fiber sensor before the magnetic field generator transmits the transient magnetic field signal, and the optical fiber sensor continuously reflects the optical signal. In the process of inserting the optical fiber sensor into the hole, the position of the optical fiber sensor can deviate under the action of external force, and meanwhile, the external force can enable each optical fiber grating to deform differently, so that the reflection frequency of each optical fiber grating for optical signals is changed. In general, the position and shape of the optical fiber sensor are changed as shown in fig. 15, the optical fiber sensor is bent upward, the optical fiber grating located above is compressed, the optical fiber grating located below is stretched, and so on.
For each fiber bragg grating, after the detection device receives the optical signal reflected by the fiber bragg grating, the axial deformation and the radial deformation of the fiber bragg grating are determined through the reflection frequency and the reference reflection frequency of the optical signal, and the deformation determination process is the same as the above, and details are omitted here. Then, the detection equipment can determine the attitude information of the optical fiber sensor through a virtual work equation and a Newton iteration method based on the axial deformation and the vertical line deformation of each optical fiber grating. In addition to determining attitude information of the optical fiber sensor at the detection position, in the process of sending the optical fiber sensor to the detection position, the detection device monitors deformation of the optical fiber sensor to acquire a motion trail of the optical fiber sensor, and determines final position information (i.e., actual position information) when the optical fiber sensor reaches the detection position through geometric operations according to reference position information, attitude information and motion trail of the optical fiber sensor. For each optical fiber sensor, after the secondary field echo signals are detected, the detection equipment can determine the position information of the water body by adopting a geologic body inversion model according to the detected magnetic field intensity information (such as the magnitude and the direction of the magnetic field intensity) from the geologic body, the secondary field echo signals emitted by the water body and detected by the optical fiber sensor at different moments in time after the magnetic field is emitted, the position information of the magnetic field generator, and the posture information and the actual position information of the optical fiber sensor.
Alternatively, the optical fiber sensor may be approximately regarded as deformed but entirely offset, and the posture information may be regarded as an angle between a line connecting both ends of the optical fiber sensor and a horizontal direction. Further, the detection device can determine the actual position information of the optical fiber sensor through geometric calculation according to the reference position information and the gesture information of the optical fiber sensor, wherein the reference position information can be the coordinate of the central point of the main optical axis under a preset space coordinate system when the optical fiber sensor does not deviate, and the actual position information can be the coordinate of the central point of the connecting line of the two ends of the optical fiber sensor after the optical fiber sensor deviates under the preset space coordinate system.
Alternatively, when the magneto-sensitive component is magnetic fluid, the structure may be adopted, that is, the optical fiber sensor includes a magnetic fluid and at least three optical fiber gratings, the corresponding structure is as shown in fig. 16, the at least three optical fiber gratings are immersed in the magnetic fluid, and the main optical axes of the at least three optical fiber gratings are parallel to each other. In this case, the process of determining the actual position information of the optical fiber sensor is the same as that described above, and a detailed description thereof will be omitted.
In an embodiment of the application, a geological detection system comprises a detection device and a magnetic field sensor. The magnetic field sensor detects a magnetic field signal emitted by the geological body and emits a corresponding detection signal to the detection equipment. The detection device determines the magnetic field intensity of the corresponding magnetic field signal according to the detection signal, thereby determining whether the geologic body is a geologic body of the target type through the magnetic field intensity of the magnetic field signal. In the scheme, the special geologic body is determined by using the magnetic field intensity, and the magnetic field intensity is not detected by using a detection coil, so that the problem that the equivalent inductance interferes with the detection result is solved, and the accuracy of the detection result can be improved. In addition, the sensor for detecting the magnetic field intensity can be generally made smaller, so that the normal use in drilling can be ensured.
The foregoing description of the embodiments of the application is not intended to limit the application, but rather, the application is to be construed as limited to the appended claims.
Claims (17)
1. A geological detection system, comprising a detection device and a magnetic field sensor;
the magnetic field sensor is used for detecting a magnetic field signal emitted by the geological body, and emitting a detection signal corresponding to the magnetic field intensity of the magnetic field signal to the detection equipment under the action of the magnetic field signal;
the detection device is used for receiving the detection signal, determining the magnetic field intensity of the magnetic field signal based on the detection signal, and determining whether the geologic body is a geologic body of a target type based on the magnetic field intensity of the magnetic field signal.
2. The geological exploration system of claim 1, further comprising a magnetic field generator;
the magnetic field generator is used for transmitting transient magnetic field signals;
the magnetic field signal emitted by the geologic body is a secondary field echo signal generated by the geologic body under the excitation of the transient magnetic field signal emitted by the magnetic field generator.
3. The geological exploration system of claim 1, wherein said exploration apparatus is further configured to:
after determining that the geologic body is a geologic body of a target type, determining position information of the geologic body based on a magnetic field strength of a magnetic field signal of the geologic body and position information of the magnetic field sensor.
4. A geological exploration system according to any of claims 1-3, wherein said magnetic field sensor is an optical fiber sensor, said exploration equipment being connected to said optical fiber sensor by an optical fiber;
the detection device is further used for transmitting optical signals to the optical fiber sensor;
the optical fiber sensor is used for detecting magnetic field signals emitted by the geologic body and has different optical signal reflection characteristics under the action of the magnetic field signals with different magnetic field intensities;
the detection device is used for determining the magnetic field intensity of a magnetic field signal emitted by the geologic body based on the spectral characteristics of the reflected light signal received from the optical fiber sensor.
5. The geological exploration system of claim 4, wherein said fiber optic sensor comprises a fiber optic grating and a magnetically sensitive member, said fiber optic grating in contact with said magnetically sensitive member, said fiber optic grating in fiber optic connection with said exploration apparatus;
The magneto-sensitive component is used for detecting magnetic field signals emitted by the geologic body and adjusting the reflection characteristics of the fiber bragg grating under the action of the magnetic field signals with different magnetic field intensities;
the fiber bragg grating is used for reflecting the received optical signals.
6. The geological exploration system of claim 5, wherein said magnetically sensitive member is a magnetostrictive material to which said fiber grating is secured.
7. The geological exploration system of claim 6, wherein said magnetostrictive material covers at least half of a radial cross-sectional perimeter of said fiber grating.
8. The geological exploration system of claim 6, wherein said geological exploration system comprises at least two fiber optic sensors;
the detection device is used for:
determining a first deformation of each optical fiber sensor along the radial direction of the optical fiber grating and a second deformation along the main optical axis direction of the optical fiber grating based on the reflected light signals received from the at least two optical fiber sensors;
and determining the magnetic field intensity of the magnetic field signal emitted by the geological body based on the first deformation and the second deformation of each optical fiber sensor.
9. The geological exploration system of claim 6, wherein said fiber optic sensor comprises at least two fiber optic gratings, said at least two fiber optic gratings being respectively connected to said exploration apparatus by optical fibers;
the detection device is used for:
determining third deformation of each fiber grating along the radial direction of the fiber grating and fourth deformation along the main optical axis direction of the fiber grating based on the optical signals received from each fiber grating;
and determining the magnetic field intensity of the magnetic field signal emitted by the geological body based on the third deformation and the fourth deformation of each fiber bragg grating.
10. The geological exploration system of claim 5, wherein said magnetically sensitive component is a magnetic fluid in which said fiber grating is immersed;
the detection equipment is used for determining the dielectric property of the magnetic fluid based on the frequency spectrum characteristics of the reflected light signals and determining the magnetic field intensity of the magnetic field signals emitted by the geologic body based on the dielectric property of the magnetic fluid.
11. The geological exploration system of claim 6 or 10, wherein said fiber optic sensor comprises at least three fiber optic gratings, said exploration apparatus further configured to:
Before the transient magnetic field signal is emitted by the magnetic field generator, determining deformation of each fiber grating based on frequency of a reflected light signal received from each fiber grating, determining attitude information of the fiber sensor based on the deformation of each fiber grating, and determining actual position information of the fiber sensor based on the attitude information and reference position information of the fiber sensor;
and determining the position information of the geologic body based on the magnetic field intensity of the magnetic field signal emitted by the geologic body, the attitude information and the actual position information of the optical fiber sensor.
12. The geological exploration system of claim 11, wherein said fiber optic sensor comprises three fiber optic gratings distributed in a regular triangle.
13. The geological exploration system of claims 5-12, wherein said optical fiber is a polarization maintaining fiber;
the detection device is used for transmitting a first optical signal and a second optical signal to the optical fiber sensor, wherein the first optical signal and the second optical signal are optical signals with different polarization directions;
the magneto-sensitive component is used for detecting magnetic field signals emitted by the geological body, and under the action of the magnetic field signals with different magnetic field intensities, adjusting the first reflection characteristic of the fiber bragg grating on the first optical signal and the second reflection characteristic of the fiber bragg grating on the second optical signal;
The fiber bragg grating is a grating etched on the polarization-maintaining fiber and is used for reflecting the first optical signal and the second optical signal;
the detection device is used for determining the magnetic field intensity of the magnetic field signal emitted by the geological body based on the frequency spectrum characteristics of the reflected light signals in different polarization directions received from the optical fiber sensor.
14. A geological exploration system according to any of claims 4 to 13, comprising a plurality of fibre optic sensors connected in series by optical fibres, and the fibre optic sensors at one end are connected to said exploration apparatus by optical fibres.
15. The geological exploration system of any of claims 4-13, comprising a plurality of fiber optic sensors, said plurality of fiber optic sensors being grouped into at least three groups, each group of fiber optic sensors being connected in series by optical fibers, and said fiber optic sensor at one end of each group of fiber optic sensors being connected to said exploration apparatus by optical fibers.
16. The optical fiber sensor is characterized by comprising an optical fiber grating and a magnetostrictive material, wherein the optical fiber grating is fixed on the magnetostrictive material, and the optical fiber grating is etched on a polarization-maintaining optical fiber.
17. An optical fiber sensor, characterized in that the optical fiber sensor comprises a magneto-sensitive component and at least three optical fiber gratings, wherein the at least three optical fiber gratings are contacted with the magneto-sensitive component.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210520057.9A CN117092704A (en) | 2022-05-12 | 2022-05-12 | geological detection system |
| PCT/CN2023/081457 WO2023216713A1 (en) | 2022-05-12 | 2023-03-14 | Geological detection system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210520057.9A CN117092704A (en) | 2022-05-12 | 2022-05-12 | geological detection system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101598773B (en) * | 2009-07-02 | 2011-09-14 | 西北工业大学 | Magnetic induction intensity sensing head and magnetic induction intensity measurement method and device thereof |
| CN102141602A (en) * | 2010-02-01 | 2011-08-03 | 陆樟献 | Magnetic field sensor and magnetic field tester |
| CN106125017B (en) * | 2016-08-31 | 2018-11-06 | 成都市和平科技有限责任公司 | A kind of magnetic field intensity measuring device based on fiber grating |
| CN108226819A (en) * | 2016-12-13 | 2018-06-29 | 中国移动通信集团上海有限公司 | A kind of ground magnetic field monitoring system and method based on fiber grating |
| CN107703552B (en) * | 2017-09-21 | 2019-04-02 | 武汉长盛煤安科技有限公司 | A kind of mining drilling three-dimensional orientation transient electromagnetic forward probe device and method |
| CN107703369A (en) * | 2017-09-29 | 2018-02-16 | 北京计算机技术及应用研究所 | One kind is based on magnetostrictive fiber optic weak magnetic field detecting system |
| CN209727848U (en) * | 2019-04-19 | 2019-12-03 | 中国计量大学 | A kind of leakage field lossless detection device based on fiber Bragg grating F-P chamber magnetic field sensor |
| CN111458668A (en) * | 2020-06-02 | 2020-07-28 | 黑龙江大学 | Vector magnetic field sensor and method for detecting magnetic field by using same |
| CN111983529A (en) * | 2020-09-02 | 2020-11-24 | 金华伏安光电科技有限公司 | Magnetic field sensor and system based on optical cavity |
| CN113009384B (en) * | 2020-12-28 | 2023-12-29 | 国网江西省电力有限公司信息通信分公司 | Vector magnetic field sensor, preparation method and detection system |
| CN114217354A (en) * | 2021-12-15 | 2022-03-22 | 成都理工大学 | Electromagnetic data acquisition system and method based on optical fiber electromagnetic sensor |
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