Abstract: A great number of hydrocarbon exploration targets exist in the fourth member of the Shahejie Formation, in the Shaojia area of the Jiyang depression. However, hydrocarbon exploration activities in Shaojia are limited due to hydrocarbon distribution heterogeneity and the lacking understanding of hydrocarbon accumulation. In this paper, a quantitative evaluation on hydrocarbon accumulation disparity was conducted to intuitively study the characteristics of hydrocarbon accumulation and provide guidance for exploration decision making fast and conveniently. Based on current exploration achievements, differences in hydrocarbon accumulation at different levels, including petroleum system, play and trap, were analyzed systematically and evaluated quantitatively in the study case, by improved geological evaluation methods of play and trap and mathematics approaches such as statistical mining. The results showed that there is a significant disparity in hydrocarbon accumulation in the study area, which is mainly controlled by the geological factors including source, reservoir, migration and accumulation. In general, the northern fault terrace zone, which possesses favorable accumulation conditions, could still be the main progressive exploration area; and the evaluated first class traps would be the optimized targets in further exploration. The southern gentle slope zone shows a large variation in accumulation conditions, which is of the potential to be the replacement tract by exploration enhancement. In contrast, the western fault zone possesses poor accumulation conditions of high exploration risks, but could be treated as potential areas of oil and gas regionally. The quantitative disparity evaluation conducted in this study can contribute to reducing exploration costs as well as deepening our understanding of hydrocarbon accumulation, and serve as a reference for efficient explorations in similar cases.

Key words: difference in hydrocarbon accumulation, quantitative evaluation, Shaojia area, fourth member of the Shahejie Formation