The He 8 sandstone unit in the Western Sulige field is one of the most prolific gas‐producing intervals in the Ordos Basin. Sedimentologic and reservoir characteristics analysis were conducted to investigate the reservoir's petrological, diagenetic, petrophysical properties, and production characteristics. Three sandstone types and four lithofacies were identified. The two most commonly observed lithofacies are labelled lithofacies C and D. Lithofacies C is composed of fine‐ to medium‐grained litharenites (Sandstone I); lithofacies D includes coarse‐grained sublitharenites (Sandstone II) and coarse‐grained/gravelly litharenites (Sandstone III). Compared with Lithofacies C, Lithofacies D was deposited as a series of laminated sand sheets in a higher energy fluvial system. The tightness of Sandstone I is a result of an episode of intense compaction of the rock framework causing early‐diagenetic dissolution of grains and deformation of ductile rock fragments. The processes that led to the low permeability of Sandstone II and Sandstone III are more complex. In addition to intense compaction, the growth and emplacement of quartz and clay cements are a critical factor. Diagenesis and porosity evolution analysis show that the petrophysical properties of these sandstones were better at the gas charging time. The porosity and permeability values of Sandstones II and III are similar at surface, but significantly different at formation pressure. This leads to differences in gas production rates. Sandstone II has higher gas production rates and cumulative gas production than Sandstone III. The presence or absence of Sandstone II controls the distribution of sweet spots within less productive tight gas reservoirs.

中文翻译：

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鄂尔多斯盆地西苏里格油田二叠系He 8致密砂岩的沉积相和储层特征

苏里格西部油田的He 8砂岩单元是鄂尔多斯盆地中产气最多的层段之一。进行了沉积学和储层特征分析，以研究储层的岩石学，成岩作用，岩石物理性质和生产特征。确定了三种砂岩类型和四种岩相。两种最常见的岩相分别被标记为岩相C和D。岩相C由细粒至中等粒度的锂辉石组成（砂岩I）。岩相D包括粗粒次石质岩（砂岩II）和粗粒/砾石质锂钙石（砂岩III）。与岩相C相比，岩相D在一系列较高能量的河流系统中沉积为一系列层压砂岩片。砂岩I的致密性是岩石框架强烈压实的结果，导致早期成岩作用的颗粒溶解和韧性岩石碎片的变形。导致砂岩II和砂岩III低渗透性的过程更为复杂。除强烈压实外，石英和粘土水泥的生长和定位也是一个关键因素。成岩作用和孔隙演化分析表明，这些砂岩的岩石物性在充气时较好。砂岩II和III的孔隙率和渗透率值在表面相似，但在地层压力下显着不同。这导致气体生产率的差异。砂岩II比砂岩III具有更高的天然气生产率和累计天然气产量。