Method for calculating three-dimensional magnetotelluric sounding main impedance

Abstract

The invention provides a method for calculating the three-dimensional magnetotelluric sounding main impedance, and belongs to the field of electromagnetic exploration of geological exploration and underground mineral resource exploration such as petroleum, natural gas, and shale gas etc. The method includes: (1) acquiring time domain recording data obtained via field acquisition, wherein the data comprising an electric field and a magnetic field in the mutual vertical direction, namely ex (t), ey (t), hx (t), and hy (t), and t referring to time; (2) performing conversion of the time domain recording data in step (1) from time domain to frequency domain; (3) calculating the tensor impedance original value and performing editing processing of the original value; (4) calculating a correct coordinate rotation angle theta0; (5) calculating the main impedances a and b in the three-dimensional construction condition; (6) calculating three-dimensional scattering tensor factors e, lambda1, and lambda2; and (7) giving a calculating result of the coordinate rotation angle theta0, a three-dimensional scattering tensor factor C, and the main impedance Z0.

Description

technical field [0001] The invention belongs to the field of electromagnetic exploration for geological exploration of petroleum, natural gas, shale gas, etc., and underground mineral deposit exploration, and specifically relates to a method for calculating the main impedance of three-dimensional magnetotelluric sounding. Background technique [0002] Magnetotelluric sounding (MT) is to observe the changes of the natural alternating electromagnetic field in the underground rock formation on the ground, so as to study its electromagnetic characteristics, so as to solve geological problems related to mineral deposits, oil and gas reservoirs, and geological structures. Physical Prospecting Methods. The basic principle is: take the natural alternating electromagnetic field as the field source (incident plane wave), when the alternating electromagnetic field propagates in the underground medium in the form of waves, due to the effect of electromagnetic induction, the observed val...

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Problems solved by technology

[0006] Aiming at the problems existing in MT data of complex terrain and underground structures and the application of inversion results, the present invention provides a method for calculating the main impedance of three-dimensional magnetotelluric sounding, and a method for eliminating the influence of three-dimensional terrain and superficial structures by the three-dimensional scattering tensor factor (referring to elimination), and then perform coordinate rotation on the data after eliminating the influence to calculate the apparent resistivity and phase corresponding to the main impedance (under TE and TM polarization)

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