可控源电磁法2.5维自适应有限元各向异性正反演  

Modeling and inversion of the CSEM field in 2.5D anisotropic media with an adaptive finite element method

作　　者：粟琪 戴世坤[1,2] 赵东东[1,2] 

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410083 [2]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083

出　　处：《石油地球物理勘探》2018年第2期418-429,共12页Oil Geophysical Prospecting

基　　金：国家自然科学基金项目(41574127)资助

摘　　要：本文基于非结构化的三角单元网格的自适应有限元法进行各向异性介质的正演模拟,其优势在于对起伏地形和复杂地质构造的模拟,采用自适应策略的网格剖分在满足计算精度的前提下尽量减少了计算量;反演运用基于高斯牛顿法改进的Occam算法,在对初始条件要求不高的前提下能快速地搜索拉格朗日乘子、减少模型的搜索量。对一维VTI介质模型和经典二维各向异性海洋油气藏模型进行了正演计算,验证了程序的计算精度和效率;对海底起伏地形各向异性模型进行了反演计算,该算法能够比较准确地还原海底各向同性的围岩、基岩异常体的电阻率以及各向异性异常体的埋藏情况。最后对实测数据进行了反演,进一步验证了算法的可行性。We conduct a forward calculation of anisotropic media with the adaptive finite element method based on unstructured triangular meshes.In the simulation of tough topography and complex geological structures,the adaptive mesh strategy can ensure not only computational efficiency but also computational accuracy.The improved Occam algorithm based on Gauss Newton method can find quickly and appropriately the Lagrange multiplier under the condition of little dependence on the initial conditions.The forward modelings of a 1 DVTI model and a classical 2 Danisotropic ocean reservoir model prove the computational accuracy and efficiency.For a complex 2 Danisotropic seafloor model,the inversion algorithm shows resistivity and buried depth of surrounding rocks,bedrocks and anisotropic anomalous bodies.Finally,tests on measured data shows the feasibility of the proposed algorithm.

关 键 词：可控源电磁法 2.5维反演 自适应有限元法 各向异性 

分 类 号：P631[天文地球—地质矿产勘探]