镇原地区长8油层组层序-岩相古地理特征及砂体展布规律

Sequence-based lithofacies paleogeography and sand body distribution of Chang 8 oil reservoir set in Zhenyuan area, Ordos Basin

延长组长8油层组是鄂尔多斯盆地镇原地区重要的储集层之一。通过岩心观察以及测井和分析测试资料的研究,结合前人研究成果,对长8油层组进行了精细的沉积相分析,确定长8油层组属于辫状河浅水三角洲沉积体系,并从中识别出主河道、分流河道、决口扇、水下分流河道、分流间湾、分流间洼地、河口坝及远砂坝等沉积微相。在精细高分辨率层序地层分析和建立等时地层格架的基础上,以相当于小层砂体的短期旋回层序为等时地层单元编制层序-岩相古地理图,并分析各类成因砂体的发育、组合和演化特征及展布规律。研究结果可为该区长8油层组的储层预测和岩性油藏的高效勘探开发提供精细的沉积、层序资料。

The Chang 8 oil reservoir set is one of the important reservoirs in Zhenyuan area, Ordos Basin. Based on core observation, well logging and analytical data and previous research results, this paper studied the sedimentary facies of Chang 8 oil reservoir set. The Chang 8 oil reservoir set was deposited by shallow-water braided river delta. Microfacies such as main channels, distributary channel, crevasse splay, underwater distributary channel, interdistributary estuary, depression, mouth bar and distal bar were identified. According to the fine high resolution sequence and stratigraphic framework, we compiled the sequence-based lithofacies palaeogeography maps on the basis of the short-term base cyclic units which were equal to a sublayer sand body, and analyzed the causes, assemblage, distribution and evolution of various types of sand bodies. The resuhs can provide fine depositional and sequence data for the reservoir prediction and efficient exploration and development of the lithologic reservoirs of Chang 8 oilreservoir set in the study area.