东海西湖凹陷西斜坡断层—岩性油气藏富集评价体系与勘探方向

近年来，东海陆架盆地西湖凹陷西斜坡随着勘探程度的不断提高，勘探思路逐步由构造油气藏转向构造—岩性复合油气藏。通过系统地开展煤系烃源岩生烃潜力评价，明确煤层及暗色泥岩是斜坡带主力烃源岩。通过“源—渠—汇”系统的沉积体系精细研究，明确了西斜坡共发育8种构造—岩性复合圈闭类型；通过油气成藏条件及油气分布规律研究，弄清了始新统平湖组中—上段圈闭有效性是油气成藏主控因素，平湖组下段供烃能力及储层物性为主控因素，并建立了西斜坡油气藏综合评价体系。研究认为，西湖凹陷西斜坡北段迎翠轩地区始新统—古新统三角洲和平南、初阳—宝石地区始新统潮坪—三角洲及平湖斜坡内带为构造—岩性规模储量发育区，是下步有利的勘探方向。

Evaluation system and exploration optimization for fault-lithologic reservoir on the western slope of Xihu Sag,East China Sea Shelf Basin

With continued progress of exploration degree on the western slope of Xihu Sag of East China Sea Shelf Basin, exploration strategy has gradually changed from structural reservoirs to structural-lithological composite ones. Through the systematic evaluation of the hydrocarbon-generating potential of coal-measure source rocks, it was concluded that coal seams and carbonaceous mudstone are the main source rocks in this area. According to the study of sedimentary system based on the “Source-to-Sink” system, 8 types of structural-lithological composite trap were proposed. Furthermore, the accumulation conditions and distribution characteristics of oil and gas were studied, it is then confirmed that effectiveness of trap is the main controlling factor for oil-and-gas accumulation in the upper and middle members of Pinghu Formation, while the hydrocarbon-supplying capacity and physical properties of reservoir are the main controlling factor in the lower member of Pinghu Formation. Consequently, a comprehensive evaluation system was established. By the means of the comprehensive evaluation of structural-lithological composite reservoirs, the Eocene-Paleocene delta in Yingcuixuan area of the northern segment of the western slope belt, the Eocene tidal flat-delta in Pingnan, Chuyang and Baoshi areas, and the inner zone of Pinghu slope are large-scale reserve areas, which is valuable and favorable for further exploration.