鄂尔多斯盆地湖相页岩油富集区评价研究

The shale oil and gas remained in argilaceous source rock of sedimengtary basin amount to quite large volumes,and are most likely turned into resources when they possess particular shale oil and gas' accumulation conditions and high degree of enrichment. Therefore the resource evaluation and selection of shale oil and gas enrichment zones have significant in fluences on exploratory decision and has important theoretical and practical value.Black shale, oil shale, and interlayered sandstone samples were collected from drillcore slabs in Chang 7 member of hydrocarbon source rocks of Yanchang Formation in Ordos Basin, and the samples were either stored in freezing conditions or sealed in airtight conditions. Via ion beam polishing, samples were prepared for field emission electron microscopic observation (on cooling stage), nuclear resonance analysis, absorbed gas desorption testing, isothermal sorption testing, core displacement testing as well as a variety of organic geochemical testing. Based on the analytical results, the black shale, oil shale and interlayered sandstone of Chang 7 member were studied and assessed for hydrocarbon bearing, hydrocarbon composition, hydrocarbon occurrence, and microscopic structures of rocks, and factors affecting concentration of oil and gas in lacustrine source rock, i.e., shale, were analyzed. On the basis of these studies, a method for assessing the possibility of exploration of hydrocarbon resources in lacustrine shale was explored and established, and the method was preliminarily applied to assessment of hydrocarbon potential in lacustrine high grade hydrocarbon source rock, i.e., shale, of Chang 7 member, for preferential targeting of zones enriched in shale oil and gas resources.

沉积盆地泥质烃源岩中滞留烃（页岩油气）总量巨大，其中，具备页岩油聚集条件、且富集程度较高的部分页岩油最有可能转化为资源，因此，页岩油富集区的评价优选和资源评价研究具有重要的理论和实际意义。本项研究拟采用冷冻法和密闭法采集长7黑色泥页岩、油页岩、砂岩夹层岩心样品，运用离子束抛光制备－场发射电子显微镜观测（冷台）、显微荧光检测、核磁共振分析、吸附气解吸试验、等温吸附试验、岩心驱替试验、及各项有机地球化学分析测试等实验技术，检测并研究评价长7黑色泥页岩、富有机质页岩和夹层砂岩的含油气性、烃类组成性质、烃类赋存状态、岩石显微组构特征等，剖析湖相烃源岩页岩油气富集因素，探索建立湖相页岩油气可采性评价方法，评价长7湖相优质烃源层页岩油气潜力，优选页岩油气富集区。

沉积盆地泥质烃源岩中滞留烃总量巨大，其中，能够满足页岩油成藏地质条件、且富集程度较高的部分最有可能转化为页岩油资源，因此，开展湖相页岩油实验方法、富集区评价优选和资源评价研究是十分必要的。开展了湖相页岩油地质评价实验方法试验，开展了长7段湖相黑色泥页岩、富有机质页岩含油气性及富集因素、薄夹层致密砂岩的含油性及富集因素、岩石显微组构特征与页岩油气组成性质、赋存状态研究。湖相页岩油资源量评价方法、湖相页岩油富集因素与有利区优选方法研究。取得的重要成果认识有：（1）通过方法试验，建立了泥页岩中游离烃有机溶剂快速分离提取与定量的实验方法；试验建立了现场泥页岩冷冻岩芯中理论可动烃的三段式热解测试方法，并应用于鄂尔多斯盆地长7段油页岩、黑色泥页岩的理论可动烃测定，取得了良好的应用效果；试验建立了测定泥页岩孔隙度的核磁共振方法；试验建立了泥页岩保真预处理－氩离子抛光－场发射电子显微镜观察方法；建立了泥页岩全岩组份x射线衍射分析与脆性指数评价方法。（2）长7富有机质页岩中游离烃以偏轻的烃类组份为主，具有较好的可动性，而吸附烃主要赋存于干酪根结构中，且以沥青质等极性组份为主，高有机质丰度与强烈的排烃作用是造成游离烃与吸附烃组份显著差异的主要原因。（3）页岩层中薄夹层砂岩含有一定数量的Ⅱ1型有机质，自身具有一定的生烃能力，具有良好的含油性。（4）长7段发育油页岩、黑色泥页岩与砂泥互层三种类型的页岩油层；（5）综合实验研究认为鄂尔多斯盆地延长组长7段湖相页岩层分布面积大、厚度中等、脆性矿物含量较高、微－纳米级微孔裂隙较发育、处于成熟－高成熟阶段、可动烃含量较高，具备良好的湖相页岩油成藏地质条件。湖盆中部多期次大面积分布的震浊积岩有利于页岩油的富集，偏轻的油质与良好的含气性有利于页岩油的开发。初步形成了湖相页岩油成藏地质理论与实验评价方法。鄂尔多斯盆地延长组长7湖相页岩油资源潜力巨大，勘探开发前景良好。