鄂尔多斯盆地南部延长组层序地层学研究

Research on Yanchang Formation Sequence Stratigraphy in Southern Ordos Basin

应用层序地层学理论,通过对测井和地震资料的综合研究,将鄂尔多斯盆地三叠系延长组地层划分为1个二级层序,4个三级层序。在T3y SQ4层序内为河流相-半深湖相沉积;在T3y SQ3层序内为半深湖-河流三角洲相-深湖相沉积;在T3y SQ2层序内为深湖-河流三角洲-泥沼相沉积;在T3y SQ1层序内为沼泽相-河流三角洲相沉积。根据地震大剖面上的前积反射特征,可以看出整个盆地分为西南物源体系域和东北物源体系域,2个体系域在湖盆中心八珠-坪庄相汇。在T3y SQ3和T3y SQ22个层序内部横向上有效储层发育的位置为三角洲前缘的水下分流河道砂和前三角洲的滑塌浊积砂体。

Through the sequence stratigraphy theory and the comprehensive study of well logs and seismic data, the Yanchang formation in the Ordos basin is divided into a second-order sequence and four third-order sequences. It is fluvial facies-semi-deep lake facies in T3 y SQ4sequence,semi-deep lake facies- river delta-deep lake facies in T3 y SQ3sequence,deep lake facies-river delta-slough phase in T3 y SQ2sequence,swamp facies-river delta in T3 y SQ1sequence. According to the progradation reflection characteristics on the big seismic section,the whole basin is divided into southwest provenance system and the northeast provenance system,the center of the lake basin is Bazhu-Pingzhuang.Effective location for reservoir of delta front underwater distributary channel sand and prodelta the creeping turbidite sandbodies in T3 y SQ3and T3 y SQ2sequences.