Transient electromagnetic multi-parameter constraint inversion imaging method for sedimentary strata

Abstract

The invention relates to a transient electromagnetic multi-parameter constraint inversion imaging method for sedimentary strata. According to known drilling data, a geological prospecting profile map, geological or regional geological data and other geophysical prospecting data conforming to geological laws, an inversion initial model suitable for sedimentary stratum ground transient electromagnetic prospecting is constructed; transverse space constraint conditions such as formation resistivity, formation thickness and formation interface and prior information constraint conditions such as formation resistivity and formation thickness are added, under the constraint conditions, the data inversion fitting difference and the mean square error of known prior information are extremely small at the same time, and it can be guaranteed that the inversion result is close to the actual situation as much as possible. According to the method, the stratigraphic interface constraint condition is added, the stratigraphic thickness corresponding to each measuring point is adjusted according to the actual situation, then inversion imaging is carried out by adopting the transverse constraint stratigraphic resistivity, the inversion result can well conform to the actual geoelectric model for the inclined strata, and jumping of local measuring points can be suppressed.

Description

technical field [0001] The invention relates to an inversion imaging method, belonging to the field of geophysical exploration, in particular to a transient electromagnetic multi-parameter constrained inversion imaging method of sedimentary strata. Background technique [0002] Ground transient electromagnetics are widely used in coal fields, metal mines, engineering surveys and other fields due to their high construction efficiency and convenient construction. In this method, a rectangular transmission loop is arranged on the ground and a step pulse signal is sent to the underground. At the moment when the current is turned off, a time-varying induced secondary field will be generated in the underground rock formation. Because the induced secondary field includes the underground formation With abundant geoelectric information, the purpose of detecting underground geological anomalies can be achieved by observing the change of the induced secondary field (often observing the...

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Problems solved by technology

[0006] In summary, the existing transient electromagnetic inversion imaging technology is generally divided into two categories, one is quasi-seismic imaging or approximate inversion imaging technology, which needs to meet certain assumptions before it can be applied; the other is single-point One-dimensional inversion, when performing single-point one-dimensional inversion, the inversion calculation is performed independently for adjacent measurement points, without considering the geological information of the actual stratum, and there is no mutual constraint between the measurement points, resulting in the inversion results prone to error Distortion point, the inversion stratum level does not match the actual stratum

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