Application Of Magnetotelluric In Geothermal Resource Exploration

With the development of society,geothermal as a new type of green energy,compared with traditional petrochemical energy has a lot of advantages,geothermal application prospects are very wide.At present,the amount of shallow geothermal resources is very difficult to meet people’s needs.The deep geothermal resources generally have the characteristics of large burial depth and high mining risk.In order to reduce the mining risk,it is necessary to carry out the geological exploration work before exploiting the geothermal resources.Magnetotelluric method is one of the most common prospecting methods in geological prospecting.This research area is the Xianshuihe River fault Zone of Himalaya tectonic junction in west Sichuan.The topography of the research area is complex,the Alpine Canyon is all over,and the conventional geophysical prospecting method is difficult to work in this area.The 20 survey points along the Xianshuihe River,97 km in length,were applied to the geothermal resource exploration in the area by Magnetotelluric,and the following conclusions were obtained:1.The Magnetotelluric detection equipment has the advantages of simple operation,light equipment,high efficiency and deep detection depth.In addition,magnetotelluric exploration can effectively detect the location of underground fault zone related to geothermal,cover thickness,heat source location,and so on,so select Magnetotelluric method as the exploration method in this area.2.By analyzing the time series curve and spectrum curve of noise jamming data in this area,the main noise types in the study area are: periodic noise,step noise,impulse noise,etc.The jamming principle is studied,and the robust and artificial power spectrum selection method is used to denoise the data,and the apparent resistivity curve after robust processing and the artificial power spectrum is obviously smooth.By analyzing the cause of noise interference,the concrete measures to avoid noise interference are put forward.3.Through the analysis and comparison of different inversion methods,NLCG is chosen as the inversion algorithm,different polarization modes can produce different inversion results,and the TM mode is selected as the inversion model by analyzing and contrasting different polarization modes.In addition,the optimal parameter configuration is obtained by comparing the inversion results of different inversion parameters.4.Two-dimensional electrical structure diagram is obtained by two-dimensional inversion of the data of the past noise processing.The two-dimensional inversion diagram is analyzed to obtain three clear electrical interface,which provides guidance for the development of deep geothermal resources in the later stage.