The Shahejie Formation is a fundamental rock unit for hydrocarbon exploration and production in the Nanpu Sag, Bohai Bay Basin. Methodology including thin sectioning, core observations, fluorescence, scanning electron microscopy, cathodoluminescence, fluid inclusion, laser scanning confocal microscopy and geochemical analysis (C, O isotopes) were all utilized to investigate the reservoir characteristics and origin of the Es₁ Sandstone. Thin section study showed that the reservoir rock consisted of feldspathic litharenite and lithic arkose. The reservoir pores are categorized as intergranular pores, fracture pores, dissolution pores and intergranular cement dissolution pores. The studied sandstone had good porosity (0.05%–35%) and permeability (0.006–7000 mD). The Es₁ reservoir is classified as a fractured reservoir, a primary intergranular pore-associated reservoir and a dissolution reservoir. Deposition, diagenesis and tectogenesis are the main factors that played important roles in the development of the reservoir. Sedimentation is the foundation and assumption for reservoir development, but the effective reservoir is primarily controlled by primary pores, fractures, lithofacies, tectonic elements and dissolution pores. Moreover, compaction, fracture filling and cementation were the primary sources of reservoir densification. The reservoir was progressively formed through the influence of different geological and diagenetic events. The present study provides significant information and references for hydrocarbon exploration and development in the Nanpu Sag.

中文翻译：

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华东南堡凹陷沙一产砂岩储层（古近系）特征及成因

沙河街组是渤海湾盆地南堡凹陷油气勘探开发的基础性岩石单元。包括薄切片、岩心观察、荧光、扫描电子显微镜、阴极发光、流体包裹体、激光扫描共聚焦显微镜和地球化学分析（C、O 同位素）在内的方法都被用来研究 Es ₁砂岩的储层特征和成因。薄片研究表明，储集岩由长石岩屑岩和岩屑长石岩组成。储集层孔隙分为粒间孔、裂缝孔、溶蚀孔和粒间胶结物溶蚀孔。研究的砂岩具有良好的孔隙度（0.05%~35%）和渗透率（0.006~7000 mD）。Es ₁储层分为裂缝性储层、原生粒间孔隙伴生储层和溶蚀性储层。沉积作用、成岩作用和构造作用是在储层发育中起重要作用的主要因素。沉积作用是储层发育的基础和假设，但有效储层主要受原生孔隙、裂缝、岩相、构造要素和溶蚀孔隙的控制。此外，压实、裂缝充填和胶结是储层致密化的主要来源。储层是在不同地质和成岩事件的影响下逐步形成的。本研究为南堡凹陷油气勘探开发提供了重要信息和参考。