PDE-based magnetic measurement data equivalent source reduction-to-the-pole and type conversion method

Abstract

The invention provides a PDE-based magnetic measurement data equivalent source reduction-to-the-pole and type conversion method, which comprises the steps: S1, obtaining magnetic field data d0, and establishing a topographic relief curved surface according to topographic height information of an area where the magnetic field data are located; S2, determining a spatial range of mesh generation, andperforming non-uniform multilayer mesh generation; S3, according to the magnetic inclination angle, the magnetic declination angle and the magnetic induction intensity of the geomagnetic field, carrying out PDE three-dimensional inversion calculation with a depth regularization factor, a positive value constraint term and a regularization term on the magnetic field data d0 to obtain a multi-layerequivalent source model of a magnetic anomalous body; and S4, giving different geomagnetic pole parameters, and performing non-linear PDE magnetic field three-dimensional forward modeling calculationby using a multi-layer equivalent source model to obtain one or more of reduction-to-the-pole data, magnetic anomaly total field data, magnetic anomaly component data and magnetic gradient tensor data. The method has the beneficial effects that the underground magnetic anomaly data in a complex environment can be subjected to self-adaptive and high-precision reduction-to-the-pole and data type conversion calculation.

Description

Technical field [0001] The invention relates to the technical field of geophysical surveys, in particular to a PDE-based magnetic survey data equivalent source polarization and type conversion method. Background technique [0002] In geomagnetic detection, people usually detect the total field anomaly of the magnetic field, but in actual data interpretation, it is often necessary to convert these data into the required parameters and types, such as the conversion of different magnetization directions (polarization data) , The conversion of magnetic field components, tensor data, etc. The main challenge of magnetic field data type conversion lies in the undulating measurement surface of aeromagnetic (terrestrial magnetic survey) and the irregular measurement position of the data (non-grid measurement), traditional data type conversion And chemical polarization calculations cannot process these data, and the traditional single-layer, double-layer, and three-layer data conversion me...

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Problems solved by technology

[0002] In geomagnetic detection, people usually detect the total field anomaly of the magnetic field, but in actual data interpretation, it is often necessary to convert these data into required parameters and types, such as the conversion of different magnetization directions (polarized data) , magnetic field components, conversion of tensor data, etc. The main challenge of magnetic field data type conversion lies in the undulating measurement surface of aeromagnetic (terrestrial magnetic survey) and the irregular measurement position of data (non-grid measurement), the traditional data type conversion And chemical pole computing cannot process these data, and the data conversion method of traditional single-layer, double-layer, and three-layer equivalent sources has low precision of the processing results and cannot meet the application requirements

[0003] Existing literature 1 "Dampney, C.N.G. THE EQUIVALENT SOURCE TECHNIQUE [J]. geophysics, 1969, 34(1): 39." proposed the equivalent source method for the first time, using virtual field sources to simulate measured anomalies, which can be used for potential field data Space continuation (including surface continuation), gradient calculation, and component conversion, etc.; selecting a single-layer equivalent source and arranging it near the surface is the main feature of the equivalent source method, for example, literature 2 "Li Y.Reduction to the poleusing equivalent sources[J].SEG Technical Program Expanded Abstracts,1999,19(1):2484. "Achieved the Polarization Method of Low Latitude Magnetic Anomaly by Setting a Single Layer Equivalent Source in a Limited Depth, Literature 3" Huang Yijian, Wang Wanyin, Yu Changchun. Data processing and conversion of 3D random point potential field using equivalent source method[J]. Advances in Geophysics, 2009(01):101-107." Using a single-layer equivalent source to realize the magnetic field data However, due to the limitations of observational data, the near-surface single-layer equivalent source model cannot completely simulate the deep field source information, so that the potential field reconstructed by the equivalent source will be distorted during continuation; in order to ensure the calculation Efficiency and high-precision reconstruction of the potential field, the multi-layer equivalent source method is a relatively reasonable choice, literature 4 "Li D., Q.Liang, J.Du, S. Sun, Y. Zhang, C. Chen, 2019, Transforming total-field magnetic anomalies into three components using dual-layer equivalent sources, Geophysical Research Letter, 47(3), e2019GL084607." Divide underground equivalent sources into two layers, Literature 5 "Li Duan, Chen Chao, Duan Jinsong et al. Multi-layer equivalent source surface magnetic anomaly conversion method[J]. Geophysical Journal, 2018, 061(007): 3055-3073.” proposed a method of dividing the underground equivalent source into three layers to realize the magnetic field data conversion

[0004] The application of these technologies enables people to use the equivalent source technology to perform polarization and data type conversion calculations for ground magnetic data, but there are the following problems: 1) The equivalent source grid has only three layers at most, and the grid section In the existing technology, due to the limited number of layers of equivalent sources and the unreasonable grid division of underground space, the accuracy and speed of magnetic field data type conversion and polarization are affected; 2) each equivalent source needs to be separately estimating the depth position of the layer, and then placing it separately; 3) Using the linear forward modeling method and the linear model inversion method to calculate the equivalent source, the anti-interference ability and calculation accuracy are poor

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