渤海湾盆地东营凹陷湖相富有机质页岩纹层特征和储集性能

Lamina characteristics and their influence on reservoir property of lacustrine organic-rich shale in the Dongying Sag， Bohai Bay Basin

陈扬 胡钦红 赵建华 蒙冕模 尹娜 张晓贝 许格非 刘惠民

Yang Chen Qinhong Hu Jianhua Zhao Mianmo Meng Na Yin Xiaobei Zhang Gefei Xu Huimin Liu

以渤海湾盆地东营凹陷沙河街组四段上亚段（沙四上亚段）页岩为研究对象，通过有机质分析、薄片观察、扫描电镜、高压压汞和低压氮气吸附等技术，明确页岩纹层特征及其对储层物性的影响，为页岩油勘探开发提供理论依据。沙四上亚段页岩按照成分可划分出4种在孔隙发育特征上具有差异性的纹层单元，总结出7种纹层组合类型。粒状方解石纹层+混合纹层+有机质纹层组合是沙四上亚段储集能力最好的纹层组合类型，同时发育较多的纳米孔和微米孔，纳米孔主要由混合纹层的粘土矿物晶间孔和粒状方解石纹层中的有机质收缩缝构成，微米孔主要由混合纹层内微裂缝和粒状方解石纹层边界处的微裂缝提供。泥晶方解石纹层+有机质纹层组合储集能力次之，纳米孔主要由泥晶方解石纹层中的脆性矿物粒间孔构成，微米孔主要由纹层间薄弱面形成的微裂缝提供。页岩的储层物性受到埋藏压实作用、粘土矿物转化作用、方解石重结晶作用和有机酸溶蚀作用等多重因素影响，不同纹层组合的页岩储层物性影响因素有所不同。

The shale of the upper 4 member of Shahejie Formation in the Dongying Sag， Bohai Bay Basin （E） is studied to clarify the characteristics of shale laminae and their influence on reservoir properties through organic matter analysis， thin section observation， scanning electron microscopy （SEM） observation， high pressure mercury intrusion experiment and low-temperature nitrogen adsorption （LTNA）. The results will be of a theoretical basis to shale oil exploration and development. This shale interval （E） can be divided into four lamina units different in composition and pore feature， and consequently seven types of lamina assemblages are concluded. The assemblage of granular calcite lamina， mixed lamina and organic lamina is of the best reservoir capacity in this interval with well-developed nano- and micro- pores. Its nano-pores are mainly composed of clay-mineral intergranular pores in the mixed lamina and constricted fissures of organic matters in the granular calcite lamina； while the micro-pores are mainly composed of micro-cracks in the mixed lamina and at the boundary of the granular calcite lamina. The assemblage of micrite calcite lamina and organic lamina ranks second in terms of reservoir property. Its nano-pores are dominated by rigid mineral intergranular pores in the micrite calcite lamina， and the micro-pores by the micro-cracks formed on inter-lamina weak surfaces. Under the effect of burial compaction， clay mineral transformation， calcite recrystallization and organic acid dissolution， the lamina assemblages are different in reservoir properties.

10.11743/ogg20220206