Abstract The Ordos Basin is rich in tight oil resources, and the Upper Triassic Yanchang Formation tight oil reservoir is one of the most important exploration targets. In the study area, the Chang 63 tight sandstone reservoir exhibits lacustrine deep-water lobe-shaped delta deposits with low porosity, low permeability and a complex diagenetic alteration history. The reservoir quality is extremely heterogeneous because of the heterogeneity of the depositional lithofacies and diagenetic alterations. This research integrates multiple techniques to investigate the depositional lithofacies, the characteristics and distributions of various diagenetic alterations, and their controls on reservoir quality. Four lithofacies are identified, and the various lithofacies have different diagenetic characteristics and diverse reservoir qualities. The Chang 63 tight sandstone reservoir has experienced significant diagenetic alteration. Mechanical compaction and authigenic illite are the most important causes of the decrease in reservoir quality. Carbonate cementation preferentially occurs in sandstones of lithofacies “i“ and “ii” near the mudstone-sandstone contact surfaces. Sandstones within 1 m of adjacent mudstone-sandstone contact surfaces are usually tightly cemented by carbonate cement. Illite can be divided into two types according to its morphology. Both types of illite lead to a decrease in reservoir quality. Ultimately, by combining the relationship between depositional facies and lithofacies with the distribution of different diagenetic processes, five evolutionary patterns are identified for reservoir quality in the lacustrine deep-water lobe-shaped delta deposits can be summarized by ratings of best, moderate, relatively poor, poor and worst.

中文翻译：

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鄂尔多斯盆地三叠系延长组致密砂岩储层储层质量成岩蚀变控制

摘要 鄂尔多斯盆地致密油资源丰富，上三叠统延长组致密油藏是最重要的勘探目标之一。研究区长63致密砂岩储层发育低孔低渗湖相深水叶状三角洲沉积，成岩蚀变历史复杂。由于沉积岩相和成岩蚀变的非均质性，储层质量极其非均质。本研究综合多种技术，研究沉积岩相、各种成岩蚀变的特征和分布及其对储层质量的控制。识别出四种岩相，不同岩相具有不同的成岩特征和不同的储层性质。长63致密砂岩储层发生显着的成岩改造。机械压实和自生伊利石是储层质量下​​降的最重要原因。碳酸盐胶结作用优先发生在泥岩-砂岩接触面附近岩相“i”和“ii”的砂岩中。相邻泥岩-砂岩接触面 1 m 范围内的砂岩通常被碳酸盐胶结物紧密胶结。伊利石按其形态可分为两类。两种类型的伊利石都会导致储层质量下​​降。最终，结合沉积相和岩相的关系以及不同成岩过程的分布，