微动探测技术在华北平原中深层地热资源勘查中的应用研究OA

In areas with strong electromagnetic interference,conventional electromagnetic methods often face challenges of insufficient detection accuracy and depth in mid-deep geothermal exploration.This study selected the Fanjiazhuang area in North China Plain as a typical research site,aiming to establish an optimized scheme suitable for mid-deep geothermal exploration(depth～4 000 m)in this region by comparing the performance of two microtremor array configurations.High-precision distributed seismometers(A10S-3C)were employed for data acquisition.Apparent S-wave velocity(Vx)profiles were obtained by extracting dispersion curves based on the Spatial Autocorrelation(SPAC)method and subsequent calculation,with calibration and validation provided by data from the JK01 borehole.The results indicate that the linear array(with a station spacing of 150 m)is superior to the nested circular array in terms of lateral resolution and the accuracy of stratigraphic interface identification.Regarding the identification of deep fault structures,the nested circular array exhibits greater advantages;however,the linear array can also effectively reveal fault features.Based on an integrated interpretation of the Vx profiles from both arrays,a previously unidentified buried fault was detected.Consequently,a combined geothermal migration model,characterized by"high-angle tensional faults(dip angles 65°-70°)+a weathering crust of the Jixianian System dolomite,"was proposed.The study demonstrates that the microtremor detection scheme centered on a linear array with a 150-m station spacing offers the integrated advantages of strong anti-interference capability,deep detection depth,and high resolution.It provides an efficient technical means for mid-deep geothermal resource exploration in the North China Plain and similar regions.