川西北部地区中二叠统茅口组岩溶储层特征研究

Study of Karst Reservoir of the Middle Permian Maokou Formation in the North of West Sichuan

川西地区中二叠统茅口组在多个构造获得突破,但前期受勘探程度及资料限制,对茅口组储层研究相对较少,这制约了下一步勘探工作,因此开展川西北部茅口组储层特征研究是有必要的。基于此,本文根据钻井、化验分析、地震等资料,结合动静态资料重新评价茅口组储集类型,取得了以下三点认识:①川西北部地区中二叠统茅口组储集岩类主要为亮晶生物(屑)灰岩、粒屑灰岩、含生屑泥晶灰岩、白云岩、白云质(豹斑)灰岩。具有孔、洞、缝等多种储集空间,它们在空间上相互有机搭配形成了孔洞缝相结合的储渗空间。②川西北部茅口组气藏并不只是单一的裂缝性气藏,应以裂缝—孔洞型气藏为主,只有找准缝洞系统发育区,才能获得较好储量规模及勘探开发效果。③有利滩相是储层发育的基础,受岩溶作用改造后的有利地貌区是控制储层分布的主要因素。

From existing drilling data,chemical analyses and seismic exploration it is concluded that:karst reservoir of the Middle Permian Maokou Formation in the north of west Sichuan is conmposed of sparite(bioclastic limestone),grainstone,micritic bioclastic limestone,dolomitite and dolomitic limestone with good reservoir porocity;the karst reservoir is a reservoir dominated by fracture-hole type gas reservoir;the development of the reservoir is dependent on favorable beach facies and reservoir distribution is mainly controlled by landform.