鄂尔多斯盆地西峰油田长8沉积相研究

Study on the sedimentary facies of Chang 8 oil-bearing bed in Xifeng oilfield, Eerduosi Basin

西峰油田位于鄂尔多斯盆地陕北斜坡中段的庆阳鼻褶带上,其主力油层为三叠系延长组长8油层.以岩心资料为主,结合测井资料,综合分析了储层岩性、沉积构造及粒度分布等特征,认为长8期发育河控三角洲沉积体系.且以水下三角洲亚相为主,可进一步细分为水下分流河道、河口砂坝、远砂坝、席状砂等.建立了三角洲的垂向相序,文中还探讨了沉积相与含油性的关系,为储集相带的预测及下一步的勘探奠定基础,为大规模开发提供技术支持.

Xifeng oilfield is located in Qingyang nose fold belt in Shanbei slope, Eerduosi Basin. The main oil bearing formation is Chang 8 reservoir of Yanchang Formation, Triassic. The lithological character, sedimentary structure and grain size distribution of the reservoir are analyzed based on core data and logging data, and it is held that river dominated delta system develops in Chang 8. The main microfacies include submerged distributary channel, mouth bars, distal bar and sheet sand. The vertical facies sequence of the delta subfacies is established. The relationship is studied between sedimentary facies and oil bearing characteristics of the reservoir. It is pointed that the sedimentary facies belts control the physical property and oil bearing property of the reservoir, and that submerged distrobutary channel and mouth bar are main favorable microfacies. The result of the study provides the support for prediction of favorable facies belts of the reservoir and next exploration.