鄂尔多斯盆地宜君地区长3油层组沉积体系及砂体展布

Depositional system and sand body distribution in the third member of the Yanchang Formation in the Yijun area in the southern Ordos Basin

鄂尔多斯盆地南部是重要的石油产出区域,盆地南部宜君地区上三叠统延长组长3段为主要含油气目标勘探层位。基于对该区内大量钻井、测井及三维地震资料的研究,通过阴极发光、地震前积体倾向及倾角换算等方法,并结合前人的研究成果,对该地区的物源体系进行了系统地分析,认为该区晚三叠世主要受南部渭北隆起物源的影响。长3沉积时期该区的沉积体系发育,砂体展布受物源控制,主要发育辫状河三角洲前缘沉积,其中水下分流河道和河口坝砂体为良好的储集岩类型。在此基础上,对长33—长31各沉积期砂体分散体系及沉积相的平面展布特征进行研究,为储层有利区带预测提供良好的沉积学理论依据。

The southern Ordos Basin is an important oil-producing area in China and the third member of the Upper Triassic Yanchang Formation in the Yijun area in the southern Ordos Basin is a major hydrocarbon exploration target. Based on well logs and 3D seismic data,the provenance of the study area was studied using cathode luminescence,seismic progradation tendency and angle conversion methods. The Yijun area was influenced by the Weibei uplift in the south during the Late Triassic. The deposition system in the study area developed when the third member of the Yanchang Formation was deposited,and this provenance controlled the distribution of sand bodies. Braided river delta-front sediments were widespread in the study area,and subsea river channels and mouth bar sand bodies were favorable reservoirs for hydrocarbons. The distribution of sand bodies and features of the sedimentary facies from the third section to the first section of the third member of the Yanchang Formation were studied to determine its potential for hydrocarbon reservoirs.