可控源音频大地电磁测深在深部地热资源勘查中的应用效果

The application effect of controlled source audio-frequency magnetotellurics to exploration of deep geothermal resources

可控源音频大地电磁测深法(CSAMT)的电磁场表达式是基于水平电偶极子源在均匀半空间的假设条件下推导而来的,它要求地电结构是水平均匀介质或水平均匀层状介质。实际工作中,电性结构往往不是简单的一维结构,在复杂地质条件下,其应用会受到多种地质因素的约束。通过具有代表性的深部地热资源勘查实例,来说明这些具体的地质影响因素,对应用CSAMT法开展深部地热资源勘探取得良好的地质效果,具有一定的借鉴作用。

The derivation of the electromagnetic expressions of Controlled Source Audio-frequency Magnetotellurics （CSAMT） is based on the assumption of the horizontal electric dipole source and the 1-D homogeneous half space where the geoelectric property structure is horizontally uniform and vertically layered. In real applications, however, such assumption is not always satisfied and various factors need to be taken into account when the geological conditions are complex. In this article, we identify the key factors and illustrate their effects via examples of deep geothermal resource exploration using CSAMT method. Keywords： Controlled Source Audio-frequency Magnetotellurics, static effects and source effects, exploration of geothermal resources, the geoel- ectric property structure