Weibei sag is a typical strike-slip pull-apart basin in Tanlu fault zone. The volcanic rocks mainly distributed at Ek3 of Eogene. Based on the analysis of the reservoir-forming factors of volcanic reservoirs in this area, oil shale and lime mudstone of middle-upper submember of Ek2 were considered to be the chief source rocks. The upper overflow subfacies subjected intense weathering were the main reservoir, and fractured-pore was the main reservoir space. Reverse fault blocks with greater displacement exposed directly to two groups of source rocks and formed a favorable trap-source configuration. Grooming network formed by fault and weathering crust provided favorable migration conditions. Dark mudstone of middle-lower submember of Ek2 provided a favorable cap rock condition. Three kinds of accumulation modes were summarized: Near-source lithofacies controlled accumulation model in northern subsag belt,middle-source fault-lithofacies controlled accumulation model in Zaohu fault zone and far-source faults controlled accumulation model in southern slope zone. Zaohu fault zone and southern slope zone were favorable area of hydrocarbon accumulation.
Sun Yaoting Xu Shouyu Zhang Shiqi Liu Jinhua . Compared research of reservoir-forming condition of Ek3 volcanic rocks in sub-structural belt of Weibei sag[J]. Chinese Journal of Geology, 2017, 52(3): 818-836.