东营凹陷北带西段王庄潜山油藏的发现,揭示了太古宙基岩储层极大的油气勘探潜力。本文基于露头、岩心、薄片、测井、成像测井、孔渗数据以及试油资料,对东营凹陷北带太古宙基岩风化壳储层发育特征进行了总结,对其主控因素进行了深入探索,取得了以下主要认识:(1)太古宙基岩主要为二长花岗岩和花岗闪长岩,局部发育花岗片麻岩,岩石脆性较强,容易产生裂缝,具备形成优质储层的岩性基础。(2)基岩风化壳储层纵向上可划分为崩解型储层、溶蚀-崩解型储层以及残积-崩解型储层三类。(3)崩解型储层主要以构造缝、溶蚀缝和节理缝为主,储层物性较差,平均孔隙度为2.2%,平均渗透率为0.25 mD,主要分布在构造高部位;溶蚀-崩解型储层表现为明显的双层结构,上覆溶蚀层发育厚度为50~150 m,储层物性好,平均孔隙度为4.7%,平均渗透率为1.3 mD,储集空间以溶蚀孔、溶蚀增强缝为主,下伏的崩解层物性差,储集空间以裂缝为主,主要分布在构造中低部位;残积-崩解型储层表现为上薄下厚特点,上覆残积层厚度分布在10~43 m,岩体松散破碎,储集空间以溶蚀孔为主,平均孔隙度为4.5%,平均渗透率为1.7 mD,下伏崩解层致密,块状结构明显,储集空间以各种成因的裂缝为主,主要分布在研究区临近构造高部位的缓坡带。(4)基岩风化壳储层物性及分布主要受控于4个因素:富含高脆性矿物含量的岩石影响裂缝的发育程度,构造应力控制裂缝的形成及产状分布,发达的断裂体系加速了基岩风化壳有效储层的形成,古海拔高程最终控制了基岩风化壳储层分布。研究成果对于东营凹陷以及其他断陷盆地基岩风化壳储层评价和油气勘探具有重要的借鉴意义。

The discovery of the Wangzhuang buried-hill reservoir in the western section of the northern belt of the Dongying sag highlights the significant oil and gas exploration potential of Archean bedrock reservoirs. Based on data from outcrops, cores, thin sections, logging, imaging logging, porosity, permeability, and oil testing, this paper summarizes the development characteristics of Archean bedrock weathering crust reservoirs in the Dongying sag. It also delves into the main controlling factors. The results indicate: (1) Archean bedrocks mainly consist of monzogranite and granodiorite, with locally developed granite gneiss. These rocks are brittle and prone to fracturing, providing a lithological basis for high-quality reservoir formation. (2) Vertically, the bedrock weathering crust reservoirs can be categorized into three types: disintegration reservoirs, dissolution-disintegration reservoirs, and eluvial-disintegration reservoirs. (3) Disintegration reservoirs are primarily composed of structural fractures, dissolution fractures, and joint fractures. They exhibit poor physical properties with an average porosity of 2.2% and permeability of 0.25 mD, mainly concentrated in the upper part of the structure. Dissolution-disintegration reservoirs display a distinct double-layer structure. The overlying dissolution layer is 50-150 m thick with good physical properties, including dissolution pores and enhancement fractures, resulting in an average porosity of 4.7% and permeability of 1.3 mD. The underlying disintegration reservoirs have poor physical properties and are dominated by fractures, primarily located in the middle and lower parts of the structure. Eluvial-disintegration reservoirs are characterized by a thin upper layer and a thick lower layer. The overlying eluvium is 10-43 m thick, loose, and fragmented. The reservoir spaces are mainly composed of dissolution cavities, with an average porosity of 4.5% and permeability of 1.7 mD. The underlying disintegration layer is dense with a massive structure, and the reservoir spaces are primarily fracture-dominated, mainly distributed in the gentle slope belt near the higher part of the structure. (4) The physical properties and distribution of bedrock weathering crust reservoirs are controlled by four main factors: the presence of high brittle minerals in rocks influences fracture development, tectonic stress affects fracture formation and distribution, a developed fault system accelerates the formation of effective reservoirs, and paleo-elevation determines the distribution of bedrock weathering crust reservoirs. These research findings are crucial for evaluating bedrock weathering crust reservoirs and guiding oil and gas exploration in the Dongying sag and other faulted basins.