基于非结构有限元的带地形海洋可控源电磁法二维Occam反演

基于非结构三角形网格的自适应有限元正演模拟,对带地形海洋可控源电磁法(MCSEM)二维Occam反演算法进行了研究。该算法正演采用基于非结构网格的自适应有限元法,能用较少的单元剖分精确地模拟复杂起伏地形和构造模型。反演运用基于高斯牛顿法改进的快速Occam算法,能快速地搜索拉格朗日乘子、减少模型的搜索量。对二维海洋油气藏模型进行了反演计算,结果表明,该算法能稳定收敛到真实模型附近,具有较高的计算精度和计算效率。通过对带地形模型的反演,讨论了起伏地形下海洋可控源电磁场二维反演效果,为准确解释MCSEM数据提供了参考。

Two-dimensional Occam Inversion of Marine Controlled-source Electromagnetic Method in Terrain Based on Unstructured Finite Element Method

Based on the adaptive finite element forward simulation with unstructured triangular meshes,the two-dimensional Occam inversion algorithm of marine controlled-source electromagnetic method(MCSEM)in terrain is studied in this paper.The adaptive finite element method based on unstructured mesh is used in the forward modeling,which can accurately simulate rough topography and complex structures with fewer element subdivisions than with structured mesh.Fast Occam algorithm based on Gauss-Newton method is used in the inversion,which can search Lagrange multiplier quickly and reduce the search amount of models.The inversion of two-dimensional offshore oil and gas reservoir model shows that the inversion can converge steadily to the real model with greater precision and efficiency.The effectiveness of MCSEM data inversionwithrugged terrain is tested,which provides a reference for accurate interpretation of MCSEM data.