雪峰山西侧秭归—五峰段海相层系油气地质条件研究

雪峰山西侧地区秭归—五峰段海相层系发育4套优质烃源岩,包括下震旦统陡山沱组、下寒武统水井沱组、上奥陶统五峰组—下志留统龙马溪组和下二叠统栖霞组—茅口组,烃源岩有机碳丰度介于0.21%～9.77%之间,其中水井沱组烃源岩有机碳丰度大于等于1.99%,最大为9.77%,是研究区最好的烃源岩.震旦系灯影组蛤蟆井段储层的孔隙度和渗透率均相对较高,平均值分别为8.23%和3.66×10-3μm2,是研究区内最好的储集层.根据研究区震旦系—中三叠统海相层系生、储、盖层的发育情况,可将其划分为3个海相层系成藏组合类型(下组合2个,上组合1个).震旦系—下寒武统石牌组油气组合在研究区内保存完整,并可形成下生上储型和上生下储型2个次级生储组合类型;震旦系灯影组白云岩储集层具有一定的油气勘探前景. 

The oil and gas geological condition of marine strata in the Zigui-Wufeng, the western Xuefeng Mountains area

There are four sets of high-quality hydrocarbon source rocks in the Zigui-Wufeng,the western Xuefeng Mountain area,including Doushantuo Formation of Lower Sinian,Shuijingtuo Formation of Lower Cambrian,Wufeng Formation of Upper Ordovician-Longmaxi Formation of Lower Silurian,and Qixia and Maokou formations of Lower Permian.The Content of organic carbon usually being 0.21%～9.77%.But organic carbon of Shuijingtuo Formation of Lower Cambrian is more than 1.99%,the max is 9.77%,which is the best hydrocarbon source rocks.Porosity and permeability of the reservoir rocks,the Hamajing Member of Dengying Formation of Sinian,are relatively higher,average is 8.23%,and 3.66×10-3μm2.Hence the Hamajing Member is the best reservoir in the studied area.Based on the development of the source-reservoir-cap rocks in the Sinian-Middle Triassic marine strata,three assemblages can be divided,of which the lower two assemblages belong to the Lower Marine Assemblage,the other belongs to the Upper Marine Assemblage.The assemblage of Sinian-Shipai Formation of Lower Cambrian is well preserved,and can be divided into two secondary assemblages,i.e.,the combination of lower source rocks with upper reservoir rocks and the combination of lower reservoir rocks with upper source rocks.It is concluded that the dolomite reservoir of Sinian Dengying Formation in assemblageⅠis of certain oil and gas exploration prospects.