基于非结构三角网格的海洋CSEM和MT二维联合反演研究

采用非结构三角形网格结合快速Occam算法对海洋可控源电磁(CSEM)与大地电磁(MT)数据进行二维联合反演试验研究.非结构三角形网格能够准确地模拟起伏地形和复杂地质构造,对反演目标区域采用精细网格剖分,其他区域采用粗网格剖分,在满足精度的前提下减少了不必要的计算量.将CSEM与MT数据加入到同一反演数据集中,通过对联合反演数据权重公式进行推导,构建CSEM及MT数据相关权重因子,控制不同数据的拟合权重来实现联合反演.最后对不同模型进行了反演计算,结果表明联合反演比单一反演对海底构造与异常体的还原度更高,验证了联合反演算法的可靠性.

A test study of 2D joint inversion of marine CSEM and MT based on unstructured triangular grid

In this paper,an unstructured triangular grid combined with a fast Occam algorithm is used to carry out a two-dimensional joint inversion study of marine controlled source electromagnetic(CSEM)and magnetotelluric(MT)data.The unstructured triangular grid can accurately simulate undulating terrain and complex geological structures.Fine meshing is used for the inversion target area,and the other area is divided by coarse meshing,which reduces unnecessary calculations under the premise of meeting accuracy.For the purpose of realizing the joint inversion,the CSEM and MT data are assembled to the same inversion data set,and the relevant weight factors of the CSEM and MT data are constructed from the joint inversion data weight formula,which controls the fitting weights of different data.Finally,inversion calculations are performed on different models,and the results show that the joint inversion has a higher degree of recovery of seafloor structures and anomalous bodies than a single inversion,which verifies the reliability of the joint inversion algorithm.