米仓山前缘长兴—飞仙关组油气成藏特征分析

Analysis on hydrocarbon accumulation characteristics of Changxing-Feixianguan Formation in Micang Montain leading edge

米仓山前缘油气勘探潜力大,构造变形强,油气成藏复杂,勘探程度低。为此,从米仓山前缘露头、实钻资料入手,开展山前带油气成藏特征分析。资料显示:地层水为典型的海源沉积型气田水,未有地表水渗入;天然气组分、同位素具有PG,YB气藏类似的原油裂解气特征,与浅层陆相存在较大差异,表明该区油气保存条件好;二叠系烃源条件较PG、YB气藏差,并且研究区礁滩岩性圈闭规模大,造成早期油气充注不足。沥青分布统计、生烃高峰时期古构造分析认为,东北部构造高部位可能发育有规模性油气藏。

The oil and gas exploration potential in Micang Montain leading edge is great.Because tectonic deformation is strong and hydrocarbon accumulation is complex,the exploration degree is low.For this reason,from the outcrop and the real drilling data,this paper analyzes the reservoir characteristics of piedmont zone.Formation water data show as the typical gas field water with sea sedimentary type and without infiltration of surface water.Gas composition and isotopes have the similar characteristics to PG and YB gas oil cracking,but there is a big difference with the shallow continental facies.Comprehensive analysis shows there is a good preservation condition in this area.Compared with PG and YB,Permian hydrocarbon source condition is poor.In work area,the scale of reef lithologic trap is large,resulting in insufficient hydrocarbon charging at early stage.Through the distribution statistics of asphalt and the palaeostructure analysis in the peak time of hydrocarbon generation,it is considered that there is a scale reservoir in the high position of northeast structure.