鄂尔多斯盆地东北部山西组高分辨层序地层学研究

High-Resolution Sequence Stratigraphy of Shanxi Formation(Permian) in Northwestern Portion of Ordos Basin

依据4个露头剖面、35口井的岩心和302口井的测井资料,按照基准面旋回的原理对鄂尔多斯盆地东北部山西组进行了高分辨率层序地层划分。作为晚古生代长期基准面下降旋回的组成部分,山西组构成一个中期基准面旋回(MSC2),自下而上划分为五个短期旋回(SSC1、SSC2、SSC3、SSC4、SSC5);探讨了各短期旋回的层序结构、叠加样式和空间变化;建立了研究区山西组高分辨率层序地层对比格架。通过对基准面旋回期间体积分配和相分异的分析,讨论了短期基准面旋回过程中有利储集砂体的沉积相类型和控制因素;指出中期基准面旋回的早期的短期基准面上升半旋回形成最有利储集砂体,沉积微相为三角洲平原分流河道和三角洲前缘水下分流河道。应用单因素综合作图法,研究了储集砂体的空间展布。

High-resolution sequence stratigraphy division of Shanxi Formation in northwestern part of Ordos basin has been put forward according to principle of base level cycle based on 4 outcrops and 35 core description and 305 well logs. As a component of long-term base-level decreasing cycle, Shanxi Formation constitutes a medium-term cycle, which can be subdivided into 5 short-term cycles in ascending order（SSC1 ,SSC2, SSC3 ,SSC4, SSCS）. Based on the sequence structure, and stack style and space variation, the high-resolution sequence stratigraphy correlation framework is established to discuss sedimentary facies styles and controlling factors and physical property. The most favorable reservoir bodies were formed during early stage of semi-ascending cycle of short - term base-level cycle. Reservoir bodies are mainly composed of delta plain distributary channel and delta front sub-aqueous channel. Here, the monofactor mapping method is adopted to study space distribution of the reservoir bed.