广域电磁法在低阻覆盖区的应用与评价——以河南中牟为例

The application and evaluation of the wide field electromagnetic method in the low resistance coverage area-Exemplified by Zhongmu area of Henan Province

在分析和总结河南中牟含气页岩层电阻率等物理性征基础上,将广域电磁法勘探技术用于南华盆地低阻覆盖区页岩气探测,获得工作区地下5 km内地层电阻率分布规律和特征,查明了工作区的构造展布,同时揭示了以二叠系太原组、山西组以及上、下石盒子组为主要目的层的含气页岩发育特征。此次探测工作表明,在低阻覆盖区广域电磁法是获取南华盆地深部含气页岩埋深和分布范围的有效探测手段,可为后期有利区带评价、区块优选页岩气层提供地球物理参数。

Based on an analysis and summary of the physical properties of the gas-bearing shale layer in Zhongmu area of Henan Province,the authors used the wide-area electromagnetic exploration technology to detect shale gas in the low-resistance coverage area of the Nanhua Basin,obtained the distribution regularity and characteristics of the stratigraphic resistivity within 5 km under the work area,and ascertained the structural distribution of the work area.In addition,the development characteristics of gas-bearing shales were revealed,with the main target layers being the Permian Taiyuan Formation,Shanxi Formation,Upper Shihezi Formation and Lower Shihezi Formation.The results show that,in the low-resistance coverage area,the wide-field electromagnetic method is an effective detection method to obtain the buried depth and distribution range of deep gas-bearing shale in the Nanhua Basin,providing geophysical parameters for the evaluation of favorable zones in the later period and the optimization of shale gas layers in the block.