川东南清虚洞组沉积特征及其对储层的控制

摘要

The palaeogeomorphology of southeast Sichuan is high in northwest and low in southeast during the late period of the Early Cambrian.The Qingxudong Formation develops a set of carbonate rocks;its thickness is about 200 meters;it can be divided into the first member and second member from bottom to top.Combining the evidences from sedimentology,palaeostructure,sea level fluctuations,etc.,we found that the sedimentation model of Qingxudong Formation is one with carbonate gentle slope;it develops inner and shallow gentle slope and we can further identify some subfacies such as tidal flat,lagoon,shallows and interbank sea from northeast to southwest.On the basis of those above-mentioned,we studied how deposition controls on the evolution of reservoir and concluded that the most favorable reservoir is the inner gentle slope,the second favorable ones are the lagoon of gentle slope and the shallows of shallow slope,and the interbank sea is the worst.The physical property of dolarenite and crystal powder dolomite rock is better and that of cryptite is the worst.%早寒武世晚期,川东南呈现西北高东南低的古地理面貌,清虚洞组普遍发育一套碳酸盐岩沉积,厚约200m,自下而上划分为清一段、清二段。综合沉积学、古构造及海平面变化等方面的证据认为,清虚洞组为碳酸盐缓坡沉积模式,发育内缓坡相和浅缓坡相,进一步识别出潮坪、湖、浅滩及滩间海亚相,沉积相带大致呈北东-南西向展布。在此基础上,探讨了沉积作用对储层演化的控制,最有利于储层形成的沉积相带是内缓坡浅滩亚相,其次是内缓坡湖亚相和浅缓坡浅滩亚相,浅缓坡滩间海亚相最差。砂屑白云岩和粉晶白云岩的储集性能较好,泥晶灰岩最差。