Hydrocarbon accumulation characteristics and model of deep-seated glutenite on steep slope zone of fault basin: a case study of the E2s4 Member in Yanjia area, Dongying Sag

Abstract

Deep-seated oil and gas have become the focus of hydrocarbon exploration at home and abroad. Strengthening the research on the deep-seated hydrocarbon accumulation is the key to efficient exploration of oil and gas. Based on the analysis of light component and organic matter types of crude oil, the results show that there are two sets of source rocks in the E2s42 sub-member in Yanjia area, which are self-derived reservoirs. The reservoir types of the deep-seated glutenite in E2s4 member are mainly lithologic and lithologic-tectonic reservoirs. The distribution sequence is characterized by oil reservoirs in the high part of the structure, oil cracking gas reservoirs in the deep part, and condensate oil and gas reservoirs in the middle part. Further analysis shows that there are three layer pressure zones: overpressure zones (PCOE >1.4), the pressure transition zone (1.1 <PCOE<1.4) and the normal pressure zone (0.9 <PCOE<1.1), and the part near the upper fan area is dominated by the crude oil from the E2s42 sub-member, the middle fan area is dominated by the mixed source oil, and the lower fan area is dominated by the crude oil from the E2s41 sub-member. Compared with the characteristics of hydrocarbon migration and accumulation in middle and shallow strata, hydrocarbon accumulation in deep-seated glutenite is more controlled by hydrocarbon migration power and reservoir physical property. The secondary pore development zones are the key reservoir spaces for hydrocarbon in deep layer. On the basis of the above analyses, the hydrocarbon accumulation model of “source-reservoir-pressure” is constructed, which further reveals the hydrocarbon differential enrichment law of deep-seated glutenite, and guides the efficient exploration of oil and gas in Yanjia area, Dongying Sag.