The buried-hill reservoir in Proterozoic bedrock is one of the important fields of oil and gas exploration in Mahaidong area,northern margin of Qaidam Basin,and the reservoir represents one of the main factors affecting oil and gas accumulation in bedrock. According to the data of the outcrop,core,thin section,scanning electron microscopy,imaging logging,etc.,the development and influencing factors of bedrock reservoirs were studied. The results demonstrate that the Proterozoic bedrock reservoirs in Mahaidong area developed 9 rock types in 4 categories,including schist,gneiss,eclogite,and amphibole,and 6 reservoir space types in 2 categories,including fractures and dissolution pores,and the reservoir petrophysical properties are dominated by low porosity and(extra-)low permeability. Moreover,the bedrock fracture is a key factor influencing the development of dissolution pores and dissolution fractures as well as the high yield of a reservoir. The development of fractures is mainly controlled by lithology and structure. Fractures of schist and gneiss with a high content of brittle minerals are highly developed,and more fractures are developed when they are closer to the fault at a higher grade and with a longer active time. In addition,the hanging wall and intersection of faults are the dominant development areas for reservoirs.
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LI Junliang. Characteristics and controlling factors of reservoirs in Proterozoic bedrock in Mahaidong area,northern margin of Qaidam Basin[J]. Petroleum Geology and Recovery Efficiency,2022,29(2):15~22