延安地区山西组泥页岩岩相及沉积相特征

目前世界能源发展由化石能源向新能源转化,天然气作为清洁的化石能源是两者过渡最好的选择。鄂尔多斯盆地延安地区山西组地层是中国陆相页岩气勘探潜力较大的层系,近年来已经获得了巨大的勘探开发成果。为进一步加深对该地区的地质认识,以鄂尔多斯盆地延安地区山西组泥页岩为研究对象,综合应用野外露头、岩心、测井等资料,开展山西组岩石类型、岩相类型、沉积相展布研究。结果表明：延安地区山西组泥页岩主要发育泥质硅质页岩（S-3）、黏土岩（CM）、含钙/硅质黏土页岩(CM-1)、含钙/黏土质硅质混合页岩(M-2)四种岩相类型。页岩、粉砂质泥岩、碳质泥岩、细粒砂岩4种岩石类型。发育滨浅湖亚相、三角洲前缘亚相和前三角洲亚相,研究区水下分流河道砂体呈南北条带状发育。通过有机质成熟度（Ro）、有机碳含量（TOC）、暗色泥岩厚度将岩相进一步划分为3种类型,其中Ⅰ型岩相为油气勘探有利岩相,在山1段主要分布在延长东部地区、北部地区,山2段主要分布在甘泉下寺湾地区。

Characteristics of shale lithofacies and sedimentary facies of Shanxi Formation in Yan ''an area

At present, the world''s energy development is transforming from fossil energy to new energy, and natural gas as a clean fossil energy is the best choice for the transition. The Shanxi formation in Yan ''an area of Ordos Basin is a layer with great exploration potential of continental shale gas in China, and great exploration and development achievements have been made in recent years. To further deepen the geological understanding of the area, Taking the mud shale of Shanxi Formation in Yan ''an area of Ordos Basin as the research object, the rock types, lithofacies types and sedimentary facies distribution of Shanxi Formation are studied by using outcrop, core and well logging data. The results show that the shale of Shanxi Formation in Yan ''an area mainly develops four lithofacies types, namely, argillaceous siliceous shale (S-3), claystone (CM), calc/siliceous clay shale (CM-1) and calc/clayey siliceous mixed shale (M-2). There are four rock types: shale, silty mudstone, carbonaceous mudstone and fine grained sandstone. Shore-shallow lake subfacies, delta front subfacies and pre-delta subfacies are developed, and the sand bodies of underwater distributary channels in the study area are developed in a north-south belt. According to the maturity of organic matter (Ro), organic carbon content (TOC) and thickness of dark mudstone, the lithofacies can be further divided into three types. Among them, type I lithofacies is favorable for oil and gas exploration, mainly distributed in the eastern and northern Yanchang area of Shan-1 member, and Shan-2 member is mainly distributed in Xiasiwan area of Ganquan.