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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。
Based on the theory of sequence stratigraphy, through the comprehensive study of logging and seismic data, the Triassic Yanchang Formation in the Ordos Basin is divided into one second-order sequence and four third-order sequences. In the T3y SQ4 sequence, it is fluvial facies-semi-deep lacustrine facies deposition; in the T3y SQ3 sequence, it is semi-deep lacustrine-fluvial facies-deep lacustrine facies sedimentation; in the T3y SQ2 sequence, deep lacustrine-fluvial delta- Facies deposition; marsh-delta deposition in the T3y SQ1 sequence. According to the pre-product reflection features on the large seismic section, we can see that the whole basin is divided into the southwest source system tract and the northeast provenance system tract, and the two system domains are in the center of the lake basin. Laterally-validate reservoir development within the T3y SQ3 and T3y SQ sequences is the delta front subaqueous distributary channel sand and the delta front slump-turbidite sand body.