Research On Gravity Forward Modelling Of 3D Random Density Construct

Gravity exploration,as one of the important branches of applied geophysics,is widely used to explore the distribution of solid minerals and oil and gas resources,and to find out the stability of large-scale construction engineering basement.With the development of modern science and technology and observation technology,a large amount of data has been accumulated in gravity exploration.With the support of a large number of data,how to realize fast and precise inversion imaging becomes an important issue.Because forward modeling is the basis of inversion,it is necessary to develop fast and accurate forward algorithms.At present,the main way to solve this problem in our country is to divide the geological body into homogeneous bodies by fine dissection and put forward an efficient forward calculation method.In fact,the formation has complex heterogeneity,which will affect the accuracy of calculation and interfere with the interpretation of gravity exploration data.This paper proposes three-dimensional random density modeling based on formation heterogeneity for in-depth study.The main research work and achievements include:(1)Three-dimensional stochastic density modeling is a new modeling method based on the theory of geostatistics.An autocorrelation stochastic density model is established by using correlation function.The model fully considers the heterogeneity of geological bodies.By comparing the effects of different correlation lengths on the model,it can be seen that the larger the correlation lengths,the better the continuity of density in the model,and the better the simulation of actual formation density distribution.(2)Comparing the forward calculation results of different typical terrain by nonrandom density model,observation error and random density model,the image and result obtained by random density model are better than the other two models,and the anti-jamming ability is strong,and the interpretation of gravity data is more convincing.A group of forward results with different depth random density are compared,and it is concluded that shallow random density has a greater impact on the results.The results show that the three-dimensional stochastic density model is universal.Only the shallow density has an effect on forward calculation,which greatly reduces the amount of forward and backward calculation,and can improve the efficiency and accuracy of calculation.Because the stochastic density model simulates the actual distribution of formation density,its forward interpretation of gravity data is more reasonable.The research work and preliminary results of this paper provide strong support for solving the three-dimensional forward problem of complex geological bodies and for fast and precise inversion imaging problem.