Transient electromagnetic three-dimensional finite difference forward modeling method and system thereof

Abstract

The invention relates to a transient electromagnetic three-dimensional finite difference forward modeling method and a system thereof, the time step iterations of preset times are carried out on the initial time step, and the time steps at the other moments are controlled and determined by the apparent conductivity of the underground medium in the geoelectric model at the current moment, so that the proper time step can be obtained by self-adaptive adjustment, for a geoelectric model with high conductivity comparison, the total time iteration step number can be obviously reduced, better adaptability is achieved, the volume effect of a transient field is fully utilized, and the calculation efficiency of forward modeling is effectively improved.

Description

technical field [0001] The invention relates to the technical field of geophysical exploration, in particular to a transient electromagnetic three-dimensional finite difference forward modeling method and system. Background technique [0002] Transient electromagnetic method uses grounded electrodes or ungrounded return lines to transmit bipolar pulse currents underground, and the induced eddy current in the underground medium under its excitation produces a secondary field that changes with time. During the intermittent period of the primary field, the receiving coil is used to measure The magnetic field signal, through the extraction and analysis of the secondary field signal, achieves the purpose of detecting underground geological bodies. Currently, as one of the main non-seismic methods, it is widely used in near-surface resources, environment, and engineering exploration. [0003] Forward modeling is of key significance for the analysis of response characteristics of ...

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Problems solved by technology

However, for some cases where there are low-conductivity anomalies such as cavities in the ground, since the conductivity of the low-conductivity anomaly is close to 0, even if it is approximated as a finite resistance conductor, its conductivity is extremely small, and the time iteration step is limited by the low Compared with the case of no abnormal body, the number of time iteration steps and calculation time required for forward modeling will be greatly increased, which greatly reduces the efficiency of forward modeling

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