陆相页岩岩性非均质性及其对油气滞留的影响

Lacustrine shale, which distributes in most area of the world, is a very important source rock type. The lacustrine shale has strong lithologic heterogeneity, however, the microscopic characters of lithologic heterogeneity as well as its impact on hydrocarbon retention has not been revealed, resulting in the poor understanding of hosting mechanisms about shale hydrocarbon. Using Yanchang Formation shale developed in Ordos Basin, this project conducts the researches such as mineral composition, organic carbon content, pore characteristics, oil-gas-water distribution to reveal the lithologic heterogeneity. Quantitative extraction and liquid components analysis are employed to characterize the distribution of liquid hydrocarbon. Desorption and gas components analysis are employed to characterize the distribution of gas hydrocarbon. Based on the analysis of geological factors influencing hydrocarbon retention, this project can reveal the hydrocarbon retention effects caused by lithologic heterogeneity and its micro geological factors, by means of cluster analysis and correlation analysis. The results are helpful to enrich the research content of primary migration, and have theoretical and practical significance for identifying the distribution of shale hydrocarbon.

陆相页岩是重要的烃源岩类型，其在全世界范围内广泛分布。陆相页岩的岩性非均质性强，而岩性非均质性的微观表现未被有效揭示，其对油气滞留能力的影响缺乏探索，由此限制了对页岩油气赋存规律的全面认识。本课题拟以鄂尔多斯盆地延长组页岩为研究对象，通过矿物组成、有机质含量、孔隙特征、油气水分布等微观地质要素的变化，深入揭示陆相页岩的岩性非均质性。针对液态烃开展低温抽提及定量分析，确定液态烃的分布特征；结合族组分分析，综合识别液态烃及其组分的残留特征。针对气态烃开展解析实验，确定气态烃的分布特征；结合气体组分分析，综合识别气态烃及其组分的残留特征。以油气滞留作用及其影响因素的地质分析为基础，以聚类分析与相关性分析作为约束手段，综合阐述岩性非均质性及其微观地质要素对油气滞留的影响。本成果有助于丰富和完善初次运移的研究内容，对指明页岩油气的富集与分布规律具有理论与现实意义。

陆相页岩的岩性非均质性强，而岩性非均质性的微观表现未被有效揭示，其对油气滞留能力的影响缺乏探索，由此限制了对页岩油气赋存规律的全面认识。本研究以鄂尔多斯盆地延长组长7页岩为研究对象，通过矿物组成、有机质含量、孔隙特征、油气水分布等微观地质要素的变化，深入揭示陆相页岩的岩性非均质性。针对液态烃开展低温抽提及定量分析，确定液态烃的分布特征；结合族组分分析，综合识别液态烃及其组分的残留特征。针对气态烃开展解析实验，确定气态烃的分布特征；结合气体组分分析，综合识别气态烃及其组分的残留特征。以油气滞留作用及其影响因素的地质分析为基础，阐述岩性非均质性及其微观地质要素对油气滞留的影响。.研究表明，延长组长7页岩岩性非均质性强，长7页岩内部包含纯页岩、含砂质纹层页岩、砂质薄层三种类型。上述不同岩性对油气运聚成藏的控制表现在：孔缝类型相似，但整体连通性存在差异，纯页岩的孔隙连通性差；厚层纯页岩的油气难以排出；在靠近岩性变化的部位，烃类的排出程度逐渐增强；由于非烃和NSO组分的极性强且分子大，它们在排运过程中出现分异现象，导致大量赋存于厚层纯页岩内部；由于排运过程中的分异现象，部分生物标志物在不同岩性中的含量也具有差异。不同的气态烃，排运能力亦存在差异，氮气十分容易运移，二氧化碳非常难以运移；烃类气体组分中，不同组分在排运过程中具有小分子组分优先运移的趋势。