Gravity Gradient Tensor Forward Research And Boundary Extraction

Gravity gradient tensor is the second derivative of gravity potential.Compared to the vertical component of gravity field measurement in traditional gravity measurement,which more sensitive about the density abnormal. Gravity gradient tensor measurements have been carried out more than ten years, and had made certain achievements, but the technology of measurement and data interpretation is nearly blank in our country.The anomaly of gravity gradient tensor, which is related to the coordinate system, are complex.If a single tensor component is processing and interpretation individual, it is easy to lose useful information and result in misinterpretation. The combinations of different tensor components can not only create invariant,which are simple, easy to explain, more fixed,more related with the size and shape of source and independence of the coordinate, but also focus on information of various components, thus supporting data processing and interpretation.This paper introduces the concept of gravity gradient tensor and the current development at home and abroad. Basing on previous studies,we proposed a finite element algorithm,which is suitable for the forward of full gravity gradient tensor. The forward method is based on the boundary fitted of finite element method, and use Delaunay tetrahedral unstructured mesh subdivision for the geophysical model.complex model of the gravity tensor forward is come true.In this paper,we introduce several kinds of common algorithums for edge extraction of potential data at present,summs up their advantage and disadvantage respectively. The tensor anomalies of two dimensional body and three dimensional body, such as the limited extension at the bottom of the vertical plate, inclined plate, sphere, horizontal cylinder and prism were analysised, and the effect on tensor characteristics of different parameters to different models were also analysised.We select the appropriate algorithums for edge extraction, analysis the effect the boundary extraction algorithms to different modles, and get the relationship between the parameters of body and various boundary extraction algorithms, which lays the foundation for the initial model select of gravity tensor inversion, and the extraction of underground information in the actual data processing.