四川盆地东南缘清虚洞组层序-岩相古地理特征及其油气地质意义

摘要

Qingxudong Formation.During the development of HST in sq2,the sedimentary pattern is evolved into the tidal flat environment of the restricted platform.In sq3 parasequence set,only HST sedimentary records have remained,belonging to the frequently exposed tidal flat environments. There,the gypsum rocks have most developed.sq3 parasequence set is one of the most important sets of the dense cap rock for the gas reservoirs of Dengying Formation and Qingxudong Formation.%通过对钻井岩屑描述、测井资料解释、野外露头观察、岩石薄片鉴定和样品测试数据的综合分析，将四川盆地东南缘下寒武统清虚洞组划分为1个Ⅲ级层序和3个准层序组，在准层序组内又划分出体系域，在此基础上对清虚洞组层序地层学特征进行了分析，编制了各准层序组沉积体系域的层序-岩相古地理图。sq1-TST 期，受持续海侵影响，主要为开阔台地沉积，浅滩规模较小；sq1-HST 期局限台地潮坪-湖相沉积较发育。sq2-TST 期台内滩沉积最为发育，也是清虚洞组颗粒滩相储层最发育的层位；sq2-HST 期沉积格局演变为局限台地潮坪环境。sq3准层序组仅残留高位体系域沉积记录，属于频繁暴露的潮坪环境，以膏岩类沉积为主要特征，为灯影组和清虚洞组天然气藏重要的区域性致密盖层发育层位。