三维地质体对AMT二维反演的影响研究

摘要

In order to explore the influence of three-dimensional geological bodies on two-dimensional inversion results and the choice of polarization modes in two-dimensional inversion, a series of two-dimensional and three-dimensional geoelectric model are designed in forward calculation in this paper. Two-dimensional inversion calculation is performed on the forward modeling results. The results show that the phase is less affected by the three dimensional distortion, and the apparent resistivity is greatly affected. When the three-dimensional abnormal body model extends small, the error of the inversion result of TE mode is large, while the inversion of TM mode is relatively good. The inversion is obtained by the false bottom covering structure, inversion of TE+TM that combines the advantages of the TM model and TE inversion can reflect the position and value of the conductor resistivity. When the three-dimensional geological body increases extend length, the inversion results of the two-dimensional inversion of three-dimensional data are reliable by using TM and TE+TM model inversion.%为探究三维地质体对二维反演结果地影响以及二维反演中极化模式的选择问题, 设计了一系列二维、三维地电模型进行正演计算, 并对正演结果进行二维反演计算.研究结果表明:相位受到三维畸变的影响较小, 视电阻率较大;当三维异常体模型走向延伸较小时, TE模式的反演结果误差较大, TM模式的反演结果相对较好, 但是反演得到了虚假的下覆构造, TE+TM联合反演结合了TE和TM模式反演的优点, 可以较好地反映异常体的赋存位置及电阻率值;当三维异常体模型走向延伸长度增大时, 三维数据的二维反演结果是可靠的, 用TM和TE+TM模式反演都比较合理.