大民屯凹陷沙四段层序地层学研究

以层序地层学理论为指导,对岩性、钻测井、地震及露头资料进行了分析,表明大民屯凹陷沙四段存在H型、TH型、LT型及LTH型4种基本层序叠置样式,不同的层序样式沉积环境不同,成藏条件各异:烃源岩有利部位在LT型及LTH型层序的湖侵体系域及低位体系域,储集条件有利的部位在TH型中的TST、LT型样式中的LST和TST、LTH型样式中的LST和TST中的深水重力流沉积.良好盖层为LT型、LTH型层序样式的TST以及LTH型层序样式的HST.古近系划分为3个3级构造层序,通过体系域界面的识别,划分了体系域.沙四段低位体系域由砂砾岩夹红色泥岩构成多套反旋回沉积,水进体系域主要为大套暗色泥岩夹粉砂岩,深湖区可见砂砾混杂的重力流沉积.高位体系域近物源区砂砾岩含量较高,向湖区泥质岩类大量增加.

Research in the sequence stratigraphy of Sha-4 Formation in Damintun sag

The lithology data,well drilling data,well testing data,seismic data and outcrop data are analyzed based on the theory of sequence straitigraphy,and the results show that there are four basic sequence overlay styles in the Sha-4 fomation.They are H,TH,LT,and LTH styles.They have different depositional environment and reservoir conditions.The favorable positions for source rock locate in the TST and LST of LT and LTH styles;the favorable accumulation positions locate in the LST of TH style,the LST and TST of LT style,the LST and TST of LTH style;the transgressire system tracts(TST) of LT and LTH styles and high stand system(HST)of LTH style have nice cap rocks.The stratigraphy of the Paleogene is divided into 3 three-grade structural sequences,there are three kinds of system tract .The main system tract is LST,which is made up of several sets of glutenite negative circle deposition and red mudrock.It becomes thinner step by step from resourse to lake center.TST is made up of thick black mudrock and silty mudrock,pelitic siltstone,the content of sand is very little.There is gravity flow deposition in deep lake area.A majority of the HST belongs to sha-3 member,the content of glutenite is higher in close source area,and mudrock gradually increases towards lake center.