Three-dimensional anisotropic forward modeling algorithm for borehole-to-surface electromagnetic method using non-conforming meshes and high-order finite element
Electrical anisotropy typically exhibited by subsurface media increases the complexity of borehole-to-surface electromagnetic(BSEM)responses.Therefore,forward modeling for anisotropic media models and summarizing their characteristics are crucial for accurately interpreting EM exploration data.Currently,precise modeling for complex three-dimensional geological structures is one of the challenges in forward modeling.We employ a high-precision modeling method based on octree grids.By subdividing hexahedral elements into eight smaller elements to locally refine the grids,this method ensures the accuracy of modeling with fewer cells,thereby reducing computational costs.Additionally,to improve the accuracy of numerical solutions,we use higher-order shape functions during calculations.The three-dimensional anisotropic forward modeling method for borehole-to-surface EM surveys is achieved by a combination of octree grids and higher-order shape func-tions.The comparison of numerical solutions with analytical solutions of anisotropic layered models validates the correctness of the algorithm.We utilize octree grids to achieve precise modeling of complex anisotropic oil and gas models and set different horizontal and vertical resistivities for anomalous bodies.The results indicate that vertical resistivity has a greater influence on the response than horizontal resistivity.These findings provide practical guidance for field applications and lay the groundwork for further three-dimensional inversion of anisotropic media.
anisotropyoctreefinite element methodhigh-order shape function
万方数据
维普
