The Forward Theoretical Expressions Without Analytic Odd Points In Whole Spaces Of Gravity And Magnetic Anomaly Panel Method

The forward problem is to calculate the outliers of the observation point with the geologic body, of which the physical properties and morphology is known. and inversion problem is to calculate the property and abnormal body with the known outliers of the observation point. The purpose of studying the forward problem is to solve the problem of inversion, so forward modeling is the basis of the inversion.In recent years, many scholars have studied on the point element method, and solve the "singularity" problem in element method. With the continuous development of inversion method, the requirement for the time of forward calculation has been higher and higher. On the other hand, the surface element method has been seldom studied in recent years. this kind of method is similar to equivalent the quality or the magnetic distance of a certain range with a slice which has the same quality or the magnetic distance. Because the abnormal geologic body can be partitioned into multiple slices to calculate, so the result will have a high accuracy. Comparing with the point element method, the surface element method simple and can be very speed. Along with the rapid development of high precision magnetic anomaly interpretation, the problems needs to be solved will be more and more comprehensive. on some specific problems, such as Rugged topography or in the well, we need to calculate the abnormal value of the whole space of the abnormal body.In this paper, we analyzed the former gravity and magnetic formula of element method and found the reason why it will generate the "singularity" in surface element method. And we rederived the weight and magnetic anomaly theoretical expressions which has no parsing "singularity" of the whole space. In order to validation theoretical result, we designed different model with inerratic grid, one has flat surface and the other has curved surface, and then we calculating the forwarding result of the whole space. In the forward calculating, we used the abnormal body of different size different buried depth, and discretized it into different number of slices, and tested the precision of different results. In the end, we give the conditions of using the slice element method.