The Study Of Wide Field Electromagnetic Method In The Deep Geothermal Investigation

Along with our country economy from rapid development into the new normal,"transfer mode,adjusting structure,promoting balance" has been the subject of economic development。In the economic transformation,the reduce of fossil energy,increase the development of new energy is of great significance for the sustainable and healthy development of national economy.Geothermal energy as a collection of thermal energy,mineral and water resources,one of the new green energy,has large reserves,wide distribution,great potential and broad prospect,it will be more and more important in the development of new energy.In the past few years,deep geothermal resource exploration is mainly limited by geophysical methods which is poor efficiency and low resolution in deep exploration,coupled with limited ground information,it is so difficult to determine target block and locate drill position.With the development of exploration technology,especially the eheory of the wide field electromagnetic method which is presented by academician He Ji-shan,Geophysical prospecting will Provide more and more information for access to new sources of deep geothermal resources.Based on the basic characteristics and related characteristics of geothermal field、geothermal energy and geothermal system,several frequency domain sounding methods commonly used in geothermal resource exploration,including Magnetotelluric method(MT),Controlled Source Audio-Frequency Magnetotellurics(CSAMT)and Wide Field Electromagnetic method(WFEM),the main characteristics of each method are analyzed and compared.Main achievements of the paper include:The geologic stratification of ten section is carried out by using the wide field apprarent resistivity and eight faults are divided,which provide a scientific basis for the comprehensive study and drilling design in the study area.②According to the results of the wide field apprarent resistivity inversion,two major hot water reservoirs in the study area are obtained:the first hot water reservoir is the Jurassic strata,which shows low resistance zone,the lithology is mainly composed of mudstone and gritstone and the thickness is about 2000m;the second hot water reservoir is the Ordovician and Jurassic unconformity contact,the limestone outcropped was denudated,which shows low resistance to high resistance transition zone.③Integrated information about geology and geophysical,it is believed that the geothermal belongs to medium temperature geothermal system of convective type.④Wide field electromagnetic method in the deep geothermal resources exploration,access to good quality data,high credibility,exploration depth of more than 3000m,is an efficient deep geothermal resources exploration geophysical method.