32 results about "Magnetotellurics" patented technology

An embodiment of the invention provides a magnetotelluric data acquisition system comprising a data acquisition station and a broadband magnetic field sensor. The data acquisition station is capable of acquiring magnetotelluric data and high-frequency or audio magnetotelluric data in the same time; the broadband magnetic field sensor is capable of switching high and low frequencies. According to the magnetotelluric data acquisition system and method, three acquisition modes for different exploration purposes are provided. In the acquisition mode 1, high-frequency or audio magnetotelluric data is acquired; in the acquisition mode 2, at any observation point, low-frequency magnetotelluric data and high-frequency or audio magnetotelluric data are acquired in sequence, the low-frequency magnetotelluric data and the high-frequency or audio magnetotelluric data can be integrated in a broadband magnetotelluric data file; in the acquisition mode 3, the low-frequency magnetotelluric data is acquired. The magnetotelluric data acquisition system has such advantages that production cost is low, data acquisition efficiency is high, field production operations are simple and reliable, and few instruments or devices are used.

The invention belongs to the field of geophysical exploration and particularly relates to a field?audio magnetotelluric (AMT) data acquisition method. The method specifically comprises the following steps: (1) measuring lines?and?measuring point coordinates for area AMT acquisition are designed indoors; (2) measuring equipment is used for carrying out on-site positioning on the designed measuring lines?and?the measuring point coordinates and obstacles on the north-south measuring line are removed; (3) electrodes are laid; (4) a north-south horizontal magnetic?sensor Hx and an east-west horizontal magnetic?sensor Hy are laid in a central measuring point L4M4; (5) the potential ULiMj of each measuring point and the magnetic field in the center of a measuring net are measured; (6) the measuring net is moved and work in the whole measuring area is finished; (7) measured potentials of four points around the measuring point are used to calculate the electric field intensity; (8) tensor impedance, apparent resistivity, and phase data of each measuring point are calculated; and (9) tensor impedance and apparent resistivity of each measuring point are calculated to obtain homogenized high-density impedance, apparent resistivity and phase data.

The invention discloses a magnetotelluric signal denoising method based on noise discrimination, which comprises the following steps: calculating approximate entropy and LZ complexity of each electromagnetic signal sample; using the approximate entropy, LZ complexity and class value of each electromagnetic signal sample to train the preset classification model to get the noise discrimination classification model; acquiring magnetotelluric signals to be processed, and performing noise screening on the magnetotelluric signals to be processed according to the noise screening classification modelto obtain electromagnetic signal segments with non-strong interference and electromagnetic signal segments with strong interference; combining the empirical mode decomposition of complementary set andwavelet threshold method, the strong disturbance electromagnetic signal being suppressed; the reconstructed magnetotelluric signal being obtained by combining the de-noising suppressed electromagnetic signal with the non-strong disturbance electromagnetic signal. The method of the invention can more accurately discriminate the data segments with strong interference and non-strong noise interference, retain the real magnetotelluric signal, and improve the denoising effect of the magnetotelluric signal.

The invention brings forward a method and apparatus for obtaining controllable source audio magnetotelluric (CSAMT) apparent phase information, and relates to the field of coalfield hydrogeology and geophysics. The method comprises the following steps: obtaining CSAMT electric field component potential difference data; through the potential difference data, obtaining apparent resistivity data; and according to the apparent resistivity data, calculating apparent phase data by use of a ratio. According to the invention, restrictions of a "remote area" are removed, under the condition of lack of magnetic field data, the apparent phase information is obtained by use of electric field single component data, and thus an important reference basis is provided for CSAMT data interpretation.

The invention, which belongs to the field of electromagnetic method data processing of the artificial field source frequency domain for geophysical exploration, discloses a near-field correction method of the apparent resistivity of a controlled source audio-frequency magnetotelluric method. The method comprises: step A, transforming current data, electric field data, and magnetic field data in atime domain into frequency domain data by using Fourier transformation; step B, according to electric field data and magnetic field data in the frequency domain data, carrying out calculation to obtain a Cagniard apparent resistivity and a phase; and step C, determining whether a near-field effect exists based on the Cagniard apparent resistivity and phase features; and if so, acquiring a correction parameter based on ratio of normalized theoretical electric field data to electric field data after current normalization. Therefore, morphological distortion of an apparent resistivity curve is corrected and a low-frequency data form is restored; and thus the data of the source-detectable audio-frequency magnetotelluric method can be applied to the data inversion to the great extent, so that more underground electrical structure information is obtained.

The present invention proposes a magnetotelluric meshless numerical simulation method for a random conductive medium model. The method is for heterogeneity of underground space, and according to the method, a shape function is constructed based on discrete nodes, and dependence on a mesh no longer exists. The method provided by the present invention comprises: using the spectral decomposition theory and the hybrid autocorrelation function theory of the stochastic modeling process to construct a random conductive medium model of underground space; establishing a function of the magnetotelluric corresponding boundary value problem; establishing a shape function of a meshless method by using a least squares method; using the Lagrange multipliers method to load essential boundary conditions; resolving linear equations by using the biconjugate gradient stabilized (BICGSTAB) algorithm of incomplete LU decomposition preprocessing, to obtain a field value of each node in the region; and using the field values to calculate the apparent resistivity and phase of each point, thereby completing the whole numerical simulation calculation process. The section calculated according to values of the random conductive medium model better complies with the actual situation, and is more advantageous for the interpretation and processing work of the magnetotelluric data.

The invention provides a controlled source audio-frequency magnetotellurics one-dimensional inversion method using an improved genetic algorithm. By applying the genetic algorithm to CSAMT one-dimensional data inversion, a target function based on the combination of frequency weighting and phase weighting is proposed, a selection operator based on the combination of fitness value ranking selection and the simulated annealing method is proposed, segmented crossover probability upper and lower limits are proposed, and a crossover operator based on the combination of the self-adaptive crossover probability based on fitness values and a mutation operator based on the combination of fitness and gene weighting are proposed; by using the probability-based optimal individual preservation strategy, the individual with the smallest fitness value is replaced by the individual with the largest fitness value with a certain probability. Compared with the conventional CSAMT data inversion method, the method prevents inversion failure caused by the emergence of ill-conditioned matrixes, can avoid the problems of prematurity and the condition of being liable to be caught in a local extremum in the standard genetic algorithm, and enables chromosomes to move in the optimal solution direction rapidly to find the optimal solution.

The invention provides a high-precision magnetotelluric forward modeling method, which comprises the following steps of establishing a geophysical model, and dividing a geoelectric model by adopting Chebyshev points; establishing a Chebyshev derivation matrix; utilizing the Chebyshev derivation matrix to convert a partial differential equation of the magnetotelluric forward modeling calculation into an algebraic equation; carrying out the boundary condition processing; solving a large asymmetric dense complex coefficient linear equation set; carrying out the magnetotelluric response calculation. In order to improve the forward modeling calculation precision of the magnetotelluric response, the invention provides the magnetotelluric forward modeling method with high precision, high adaptability and high efficiency. According to the method, the magnetotelluric high-precision forward modeling can be performed, so that the magnetotelluric inversion calculation efficiency can be greatly improved, and the method has the important practical significance for promoting the popularization and application of the magnetotelluric method in the deep resource exploration field.

The invention discloses a controllable-source high-frequency magnetotelluric instrument system. The controllable-source high-frequency magnetotelluric instrument system comprises an emitting terminaland a receiving terminal, the receiving terminal is arranged in the emitting-electrode midperpendicular electromagnetic field measuring range of the emitting terminal and in a region with the receiving-emitting distance of 1.5 Km to 3 Km; the emitting-electrode midperpendicular electromagnetic field measuring range is a 60-degree sector range with the emitting-electrode midperpendicular as the central horizontal line; the invention also discloses a controllable-source high-frequency magnetotelluric instrument method. By means of the controllable-source high-frequency magnetotelluric instrumentsystem, earth's surface constructions within 500 m can be efficiently and accurately measured, and a detecting dead zone is reduced.

The invention relates to a time-shift controlled source audio-frequency magnetotellurics detection method applied to a coalbed methane development process. According to the method, a plurality of actual measurement point apparent resistivity curves are repeatedly acquired a plurality of times for the same target region or test region according to a certain time interval and a "six-identical requirement" with the same observation method adopted before and during the coalbed methane development of the target region, wherein the six-identical requirement is explained in the descriptions of the invention; and the above data are processed, so that an along-coalbed differential apparent resistivity data body is obtained, and coal reservoir water system dynamic change during a coalbed methane well draining and mining process and a range influenced by the coalbed methane development process can be obtained, and coalbed methane development can be quantitatively monitored. The method has been applied to the coalbed methane development of some regions in the Zhijin County of the Guizhou Province and the southern region of the Yanchuan County with successful experience achieved.

The embodiment of the invention provides an advanced geological forecasting method and device and a storage medium. The method comprises the following steps: detecting the geology to be detected by using an audio magnetotelluric method (AMT), and determining a first area in which crack water is suspected to exist in the geology to be detected; detecting the first area with a seismic reflection method (TSP) to obtain a first detection result, wherein the first detection result represents the state of the crack water in a first distance segment in the first area; when the first detection resultis determined to satisfy a first condition, detecting the first area by using a detection strategy including a three-dimensional sector transient electromagnetic method (3D-STEM) to obtain a second detection result; and implementing geological forecasting according to the second detection result.

The invention provides a low-frequency geomagnetic signal denoising method based on shift-invariant sparse coding. The method comprises the following steps: firstly, decomposing a noise-containing magnetotelluric time sequence into a low-frequency effective signal and a noise-containing high-frequency signal by using mathematical morphology filtering; and then dividing the high-frequency signal containing noise into a plurality of segments, autonomously learning a feature structure of human noise from the high-frequency signal containing noise by using shift invariant sparse coding to construct a learning type redundant dictionary, and performing signal-noise separation on the high-frequency effective signal containing noise by using the learned redundant dictionary to obtain a denoised high-frequency effective signal; and adding the low-frequency effective signal and the high-frequency effective signal to obtain a full-band magnetotelluric effective signal. Strong human noise in low-frequency magnetotelluric data can be effectively removed, the quality of the magnetotelluric data is remarkably improved, and the deep detection effect of a magnetotelluric method is improved.

The invention discloses a magnetotelluric three-dimensional forward modeling method based on a spherical coordinate system, and belongs to the technical field of geophysical exploration. The method comprises the following steps: a, establishing a magnetotelluric control equation; b, dividing the spherical coordinate system into a plurality of small inverted quadrangular prism grid units; c, setting spherical coordinate model parameters, and constructing a spherical coordinate staggered grid unit with a discrete magnetic field; d, cycling a single frequency, and performing numerical dispersionon the magnetotelluric control equation in the spherical coordinate staggered grid unit; e, solving a system of linear equations; and f, calculating impedance via a spherical coordinate tensor impedance formula, and then substituting the impedance into a Kania apparent resistivity calculation formula to figure out the apparent resistivity and phase at a measuring point. By adoption of the magnetotelluric three-dimensional forward modeling method disclosed by the invention, the interference of the earth curvature on the magnetotelluric three-dimensional deep detection can be effectively overcome, calculation errors caused by the earth curvature are avoided, the magnetotelluric three-dimensional forward modeling method is suitable for the numerical simulation of magnetotelluric three-dimensional forward modeling, and can be better matched with an earth model, and the accuracy is high.

The invention discloses an intelligent broadband long-period magnetotelluric measurement system comprising a data recorder. The data recorder is connected with an electrode, a three-axis inductive magnetic sensor and a three-axis flux gate sensor through cables. The electrode is a non-polarizable electrode, and is used for observing electric field signals. The three-axis inductive magnetic sensor is composed of three magnetic sensors which are arranged in the due north, due east and vertically-down directions respectively and are used for observing three-component high-frequency magnetic field signals. The flux gate sensor is integrated with a three-axis coil and is used for observing three-component low-frequency magnetic field signals. The data recorder collects and stores the voltage output signals of the electrode, the three-axis inductive magnetic sensor and the three-axis flux gate sensor at high precision. The data recorder is equipped with multiple groups of lead-acid batteries and is connected with a solar panel. The multiple groups of lead-acid batteries are connected in parallel to power the data recorder. The solar panel charges the multiple groups of lead-acid batteries. The system is built to satisfy the demand for building a long-period magnetotelluric observation station, and has the characteristics of wide frequency, low noise, low power consumption, and intelligence.

The present invention discloses a determination system containing magnetosphere-shaped dielectric electromagnetic response. The system comprises an electromagnetic response analyzing module and an electromagnetic response numerical value calculation module, and has the positive theoretical and practical significance for identifying a magnetic anomaly effect in the field actual measurement controlled source audiofrequency magnetotelluric (CASMT) data and improving the data explanation precision.

The invention belongs to the technical field of applied geophysics of the field of geological mineral exploration, and particularly relates to a method of quickly contouring a multi-metal mineralization position. The method comprises the following steps of laying a geophysical induced polarization intermediate gradient surface scanning survey network in an exploration area, carrying out induced polarization intermediate gradient survey on the laid geophysical induced polarization intermediate gradient surface scanning survey network, laying an audio magnetotelluric survey network to find out underground electric difference at the abnormal induced polarization position according to the abnormal induced polarization form, carrying out survey on each survey line of the audio magnetotelluric survey network, carrying out inversion on data of the audio magnetotelluric survey and ensuring the inversion result to be consistent, drawing a geoelectric section diagram of the corresponding survey line, determining geoelectric characteristics at the abnormal induced polarization position according to the geoelectric section diagram of each survey line of the audio magnetotelluric survey network, and determining the electric transition zone and the electric change zone below the abnormal induced polarization position to be the possible mineralization position according to the geoelectric characteristics acquired by the audio magnetotelluric engineering.