Structure-constrained two-dimensional gravity gradient and magnetotelluric joint inversion method

Abstract

The invention relates to a structure-constrained two-dimensional gravity gradient and magnetotelluric joint inversion method. The method includes the steps of establishing a multi-component gravity gradient and magnetotelluric joint inversion objective function, calculating forward responses and Jacobian matrixes of a gravity gradient method and a magnetotelluric method, and obtaining a fitting difference value between forward response values and observed data. The multi-component gravity gradient method is introduced into joint inversion to replace a conventional gravity exploration method. The magnetotelluric method provides abundant frequency information and large exploration depth. The introduction of the method into the joint inversion effectively overcomes defects of poor gravity gradient and poor gravity vertical resolution and better enables a density inversion model to be recovered. The method of the invention is a joint inversion method based on cross gradient structure coupling. Compared with single inversion and other conventional physical coupling inversion methods, the method of the invention does not depend on rock physical relationships and can better recover a realmodel structure, whether in physical property numerical value or in geometric space shape.

Description

Technical field: [0001] The invention relates to simultaneous inversion of two geophysical methods of multi-component gravity gradient and magnetotelluric (MT), in particular a two-dimensional multi-component gravity gradient and magnetotelluric joint inversion method utilizing cross-gradient structure constraints. Background technique: [0002] Gravity prospecting is a method of geological prospecting that uses changes in the surface gravitational acceleration value caused by the density difference between various rock masses and ore bodies that make up the crust. It has the advantages of lightness, speed, and low investment. , Exploring the distribution of solid minerals and oil and gas resources, etc. With the improvement of the accuracy of gravity surveying instruments and the progress of GPS technology, high-precision gravity gradient measurement technology has been developed rapidly. Gravity gradient measurement can observe the second derivative of gravity potential. ...

AI Technical Summary

Problems solved by technology

The first is the coupling method based on the petrophysical relationship, but this method needs to rely on the petrophysical relationship, and it is difficult to determine the accurate petrophysical relationship in complex areas, which has certain limitations; the second method is based on the spatial distribution of structural coupling. method, this method does not depend on the relationship of petrophysical properties, but only emphasizes the similarity in rock structure, and has universal adaptability

At present, the joint inversion research of the traditional gravity method and other geophysical methods has been studied at home and abroad, but the joint inversion research of the gravity gradient method and other geophysical methods with multiple components and more information has not been proposed and studied

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