Non-planar wave identification method and system for controllable source audio magnetotelluric sounding

Abstract

The invention provides a non-planar wave identification method and system for controllable source audio magnetotelluric sounding. The method comprises the following steps: performing forward modeling on a two-layer model and a four-layer model in a uniform half-space model to obtain CSAMT observation data; comparing the data curve observed by the CSAMT corresponding to each model with the data curve corresponding to the MT; determining the reaction of the CSAMT observed data curve corresponding to each model to the shallow stratum, and further determining the change form of the observed data along with the frequency; and identifying the non-plane wave according to the relationship between the change form of the observed data corresponding to each model along with the frequency and the response of the non-plane wave. According to the method, the transition region and the near region of the non-plane wave can be correctly identified and divided, and a correct inversion result is obtained.

Description

technical field [0001] The invention relates to the field of geophysical electromagnetic detection, in particular to a non-plane wave identification method and system for controllable source audio frequency magnetotelluric sounding. Background technique [0002] Controlled source audio frequency magnetotelluric method (CSAMT) is an artificial source frequency domain electromagnetic sounding method, which is characterized by artificial field sources to increase the strength of electromagnetic signals, which in turn make up for the shortcomings of natural field sources such as weak signals and difficult observations. It is widely used in mineral census, oil and gas exploration, hydrological environment and other fields. Since the field construction of the CSAMT method is limited by the power of the transmitter, the output current of the transmitter is not enough, and the field strength observed in the far zone must be affected by the plane wave. Therefore, the transition zone ...

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Problems solved by technology

Since the field construction of the CSAMT method is limited by the power of the transmitter, the output current of the transmitter is not enough, and the field strength observed in the far zone must be affected by the plane wave. Therefore, the transition zone and near zone data of non-plane waves are often observed in the CSAMT measurement. If the data of the transition zone and the near zone are not clearly understood, the inversion results using 2D or 3D software of magnetotelluric sounding will lead to a large area of ​​high resistance in the deep part of the inversion result, and it will be wrongly interpreted that the deep part is a high resistive rock mass

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