大地电磁测深在桂北地区页岩气调查评价中的应用

Application of magnetotelluric sounding method in the survey and evaluation of shale gas resources in North Guangxi

桂北地区页岩气资源潜力大,但是地形起伏大,灰岩出露范围广,深部探测方法开展条件较差,因此该区深部研究程度较低。本次采用大地电磁法在桂北地区车河—侧岭一带为页岩气调查评价进行深部探测技术服务,克服了恶劣自然条件影响,取得较好的探测效果。根据研究区岩石的电性特征,通过对探测数据资料的处理与解释,得到综合地质推断成果图。结果显示:研究区地层整体较平缓,向斜形态较稳定,目标层位下石炭统鹿寨组一段炭质页岩顶界面最大埋深约2000 m,底界面最大埋深约2500m,厚200~500m,该层连续性比较好,受断层影响不大。综上所述,大地电磁测深法在炭质泥页岩层探测中应用效果较好,为页岩气资源调查评价提供可靠的地球物理依据。

There is a great potential for the shale gas resources in North Guangxi.But the area terrain is undulating,the limestone outcrops are wide,and the condition for deep detection methods is poor,so the degree of deep research in this area is relatively lower.In the study,the magnetotelluric sounding method is used to provide deep detection technology service for shale gas survey and evaluation in the Chehe-Sianling area of North Guangxi.In the process the influence of harsh natural conditions is overcome and a good detection result is achieved.According to the electrical characteristics of the rocks in the study area,through the processing and reasonable interpretation of the detection data,the comprehensive geological inference result map is obtained.The result shows that the stratum is ordinarily gentle and the syncline is relatively stable in the study area.The target stratum,carbonaceous shale of the first section in the Lower Carboniferous Luzhai Formation is about 2000mdeep at the top interfere,about 2500mdeep at the bottom boundary,and is 200-500mthick.The continuity of this layer is relatively good,and it is not greatly affected by the fault.To sum up,the magnetotelluric sounding method has a good application effect in the detection of carbonaceous shale layer,and it provides a reliable geophysical basis for the investigation and evaluation of shale gas resources.