Study On Delineation Of Coal - Bearing Strata In Gaoyuan - Qiubei Area Of ​​Yunnan Province By High - Frequency Magnetotelluric Method

Coal is pillar industry of China’s energy, is the important energy for people’s production and life, is the important force to promote China’s fast economic growth, and therefore coal geological exploration is important. Wenshan Zhuang and Miao Autonomous Prefecture in Southeastern Yunnan Province distribute coal-bearing strata of Permian and Triassic and the coal quality is good, is national shortage kind of coking coal, fat coal, etc. China Geological Survey Bureau release coal resources investigation and assessment mission statement of Wenshan Basin in 2013. Based on this program, Kunming University carry out the research of delineation of the Wenshan Basin coal seams, to provide scientific basis for further exploration of coal resources.Currently relatively mature coal geological exploration method is seismic method, logging exploration and trenching, but according to Regional geological data, a wide range of study area is covered by Limestone, in areas covered by limestone, seismic exploration is ineffective, logging exploration and trenching are too expensive, and the study area has very complex topography, most of the survey lines are disposed in the mountains, traffic is inconvenience. High-frequency magnetotelluric method (EH4) has characteristics of Using portable equipment deep detection depth (up to 1000m)、responsive to the low resistivity body and not shielding from high resistivity layer, And abroad there is few reports about coal geological exploration conducted by EH4, so we use EH4 to conduct delineation Research of containing coal seams.The research is the delineation of containing coal seams, determining the thickness and depth of containing coal seams, Therefore, in order to carry on EH4 work quickly and efficiently, do the research of dot pitch, in order to select the appropriate dot pitch to carry out EH4 work, Qiubei surveyed area selected dot pitch 500m、200m、100m, pick up four typical cross-section to study, Kaiyuan surveyed area selected dot pitch 50m, pick up two typical cross-sections to study, and collected 123 samples of Rocks and minerals.Physical properties of rock and ore samples were analyzed to summarize electrical parameters of the rock and ore specimens and the electrical characteristics of target stratum and the vertical overburden. During this time research of delineation of the Wenshan Basin coal seams, the data obtained fields seriously affected by the static effect. Analysis correction effect by different correction methods at study area, and select the data corrected by the phase method to draw the resistivity section to delineate containing coal seams. According to geological and geophysical characteristics of the survey area, establish EH4 exception model of the survey area. After the analysis of EH4 depth-cross-sectional view of the apparent resistivity, combined with the corresponding geological characteristics and established models like the delineate containing coal seams determine containing coal seams thickness, depth changes.Conduct the drilling verification of Qiubei study area, the geophysical exploration result coincides with drilling result, it demonstrate the effectiveness of geophysical exploration methods, provide the direction for further coal resources exploration.