On 3D Inversion For Gravity And Gravity Gradient Data Using Correlation Imaging Method

Gravity exploration has the characteristics of large exploration depth and cheap exploration costs.It is an important part of geophysical exploration.The inversion of gravity and gravity gradient data is an important part of gravity interpretation.The gravity gradient data is the second derivative of the gravitational field.During the derivation process,low-frequency information is suppressed and high-frequency signals are enhanced.Therefore,gravity gradient data contains more high-frequency signals,while gravity data contains more low-frequency signals.The joint inversion of gravity and gravity gradient data can make the information contained in the two achieve complementary effects.With the development of gravity gradient instrument,the physical property inversion and application of gravity gradient data has also become an important hot spot in the field of gravity exploration.Correlation imaging is a fast imaging method.Because it does not need to solve optimization problems of large equations,it can quickly obtain the distribution of underground structures.The method has the advantages of high efficiency and has been favored by domestic and foreign researchers.In this paper,the 3D correlation imaging method of gravity and gravity gradient is studied,and the joint inversion equation of original gravity data and gravity gradient data is constructed and solved,which improves the resolution and precision of single gravity anomaly data inversion.In order to further improve the depth resolution of physical property inversion,the correlation imaging results are constrained to inversion calculation as a prior information,and a more accurate distribution of physical property parameters is obtained.The article first gives the basic principles of correlation imaging of gravity and gravity gradient data,and gives the results of correlation imaging through model tests.The correlation imaging method is applied to the measured gravity and gravitygradient data of mcfaulds Lake area in Canada,and the results are consistent with the measured regional abnormal distribution.In this paper,the reweighted smooth inversion method is selected to participate in joint inversion of gravity and gravity gradient data,combined inversion of single component inversion and gravity gradient data.The above inversion results are compared and analyzed by two different density cuboid models and step models,and the combined results are obtained.The inversion resolution is better than that of single component inversion,and the results of combined inversion and joint inversion are roughly similar.Then compare the results of the reweighted inversion method based on correlation imaging constraints with the results of conventional reweighted smooth inversion.Through two cuboid model experiments,it is concluded that the resolution of the inversion results based on correlation imaging constraints proposed in this paper is better than that of conventional smooth inversion.Finally,the method was applied to the measured data of the Vinton Salt Dome in Louisiana,USA,and achieved good inversion results.