重磁电综合解释在下扬子无为地区页岩气勘探中的应用

The Application of Integrated Interpretation Gravity,Magnetic and Electric Methods in Shale Gas Exploration in Yangtze Wuwei Area

下扬子无为地区古生界富有机质页岩分布范围广泛,其作为下扬子地区页岩气勘探的重点研究区,具有良好的油气勘探前景。为尽快查明该区页岩气的分布特征,建立地下不同层位构造体系,提出油气有利目标区,本文基于区内重力和航磁数据,结合已知地质和物性资料,对区内典型剖面进行了重磁联合反演和综合地质解释推断,基本查明了研究区的断裂分布情况,推断了8条断裂,划分出三个次级构造单元,即“两凹加一隆”的构造格局,初步确定了油气主要目标层位的分布特征,并对油气有利区进行了评价。结果表明,无为地区古生界构造较为平缓,上部三叠系周冲村组膏岩盖层发育且分布稳定,是页岩油气成藏的有利单元,从而证明重、磁、电综合物探方法在解决该地区油气构造问题方面具有良好的应用效果。

The rich organic shale in Palaeozoic group is widely distributed in Wuwei area of lower Yangtze.As the key research area of shale gas exploration in Wuwei area of lower Yangtze,it has a good prospect of oil and gas exploration.In order to find out the distribution characteristics of shale gas in this area as soon as possible,this paper established a different underground tectonic system,and put forward favorable target area of oil and gas.Based on the gravity and aeromagnetic data,combined with the known geological and physical data,this paper makes gravity-magnetic joint inversion and comprehensive geological interpretation for the typical profile in the area.It identifies the basic fracture distribution in the study area,judges the eight fractures,classifying into three secondary tectonic units,namely,“two concave plus a grand” tectonic framework,which preliminarily determines the oil and gas distribution characteristics of main target strata.The results show that the Palaeozoic group structure is relatively flat,the cream rock cover in upper Triassic Zhouchongcun group has a stable growth and distribution,which is the favorable unit of shale oil and gas accumulation.The study proves that the gravity,magnetic and electric comprehensive geophysical exploration method has a good application effect in solving the problem of oil and gas structure in this area.