倾斜地形对TEM影响分析及其校正方法

Analysis of the influence of inclined terrain on TEM and its correction method

倾斜地形对瞬变电磁响应的影响,会直接造成探测结果不能真实反映沉积地层固有的电性规律。根据毕奥-萨伐尔定律,对倾斜地形影响下瞬变电磁回线源内测点产生的磁场进行计算,分析研究垂直分量一次场受地形影响后在地下不同深度的分布特征,该特征直接影响反演结果,造成反演电阻率偏离实际地层电性。为校正地形影响,总结瞬变电磁反演电阻率偏移归位算法,并将该算法用于存在地形影响的陕北侏罗系煤田采空区探测工程中,实现了倾斜地形影响校正及采空区的空间定位。

The influence of inclined terrain on transient electromagnetic response will directly cause that the detection results can not truly reflect the inherent electrical law of sedimentary strata.According to Biot Savart law,the magnetic field generated by the measuring points in the transient electromagnetic loop source under the influence of inclined terrain is calculated,and the distribution characteristics of the primary field of vertical component at different depths under the influence of terrain are analyzed and studied.This characteristic directly affects the inversion results and causes the inversion resistivity to deviate from the actual formation resistivity.In order to correct the topographic influence,the resistivity migration homing algorithm of transient electromagnetic inversion is summarized,and the algorithm is applied to the goaf detection of Jurassic Coalfield in Northern Shaanxi with terrain influence,so as to realize the correction of inclined terrain influence and the spatial positioning of goaf.