鄂尔多斯盆地富县探区三叠系延长组沉积特征

Depositional feature of tertiary Yanchang Formation of Fuxianexploratory area in Ordos Basin

针对鄂尔多斯盆地富县探区三叠系延长组砂岩成分成熟度较低,长石、岩屑含量高,石英含量相对低的特点,以及对岩心和露头资料进行了研究。结果表明:该区沉积相类型有湖相沉积,有较大规模的三角洲砂体发育,三角洲砂体存在着明显的东、西分异性。对每一种沉积体系进行了相、亚相及微相划分和详细的描述,阐述了长8、长6、长2三个重点储集层段的沉积相构成、垂向演化及平面展布规律,为勘探部署提供了理论依据。

Yanchang Formation,being 1 120～1 450 m thick,consists of light grey and dark grey mediumfine sandstone,dark grey siltstone,blackish grey mudstone with black carbonaceous mudstone,shale and oil shale.The sandstone has a low maturity,which is peculiar to its high content of feldspar and detritus and also low content of quartz.After further studying of cores and outcrops,we think in this area lacustrine deposition has existed,so has the development of large scale of delta sand body.Classification and detailed description have been done for facies,subfacies and microfacies.Depositional facies construction,vertical evolution and plane spreading have also been presented of 3 important reservoir intervals,Chang 8,Chang 6 and Chang 2,which is basic for exploration deployment.