Time shift magnetotelluric signal acquisition and inversion method

Abstract

The invention provides a time shift magnetotelluric signal acquisition and inversion method. The method comprises the following steps: arranging a plurality of signal receiving devices along a specified testing line in a testing region to acquire a plurality of groups of magnetotelluric signals in a time-sharing way; performing standard inversion on magnetotelluric original data obtained at an initial moment to obtain an initial moment underground electrical structure; forwarding the electrical structure to obtain a group of forwarding analog data, and subtracting original data from the analog data to obtain a data residual; subtracting the data residual from observed data at each moment to obtain a group of new time shift data sets; performing standard inversion by using a new time shift data set; during inversion, restraining the model updating direction to obtain an inversion result which is closer to a real situation. The method has the advantages that system errors in time shift data and calculation errors in a forwarding process are eliminated, the influences of system errors on the difference among different moment models can be lowered through a differential inversion result, and model change realized through inversion is closer to a real situation.

Description

technical field [0001] The invention relates to a time-shifted magnetotelluric signal acquisition and inversion method, which is used for dynamic oil and gas storage monitoring and exploration of reservoir physical properties, especially resistivity characteristic changes, and belongs to the field of geographic information. Background technique [0002] The time-lapse geophysical method is mainly used to monitor the change of underground media over time. The exploitation process of oil and gas reservoirs is to replace the oil and gas in the pores with a fluid, such as water, hydrothermal liquid, liquid gas, etc.; Sex varies widely. Time-lapse electromagnetic method is very sensitive to the change of pore fluid, which is an important factor for the rapid development of time-lapse electromagnetic method. At present, the time-lapse electromagnetic method is mainly used to monitor the dynamic change process of interwell oil and gas reservoirs over time. In this regard, time-la...

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Problems solved by technology

Since the inversion itself is a numerical approximation, and the inversion result is related to many factors, such as the noise contained in the data, the numerical error caused by the discretization of the forward modeling grid, etc., it is difficult for this independent inversion method to guarantee the accuracy of the inversion. The differences in the derived models are due to changes in the properties of the subsurface medium

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