Application of Magnetotellurics in Geothermal Reservoir Characterization

Abstract

In this paper we examine Magnetotelluric (MT) data and analysis from a few different styles of geothermal resource. The geothermal resources examined include both shallow (<1000m depth) and deep (>2000m) scenarios. The implications with respect to survey and limitations imposed by survey design on the interpretation of the results are discussed. The results of 1-D, 2-D and 3-D inversions are compared and discussed in terms of their vertical and spatial resolutions and the reliability of the results in conjunction with the geology of the study areas. The continued improvement in the power and affordability in multi-core PC-platform computing allows for the relatively rapid inversion of MT data in 3-D. In the past it had been necessary to invert in 3-D with only a subset of the original dataset and with a limited number of frequencies (often <10 frequencies) in order to reduce the computational time and cost; this is no longer necessarily the case. The effect of number of frequencies used in the 3-D inversion process is discussed in terms of the choice of the acquisition data density and data distribution for a given dataset.