Exploration of tight oil resources based on stratigraphic paleo-tectonics during hydrocarbon generation in the Ordos Basin, China

摘要

For many years, oil resource exploration has emphasized the current structural characteristics of potential oil-bearing formations. The traditional view of the Ordos Basin has been that the slope in northern Shaanxi is a gentle westward-dipping monocline that lacks structural traps, such as anticlines. Therefore, it was assumed that structural factors could exert no control over the formation and distribution of the oil reservoirs in the Yanchang Formation. By modeling the evolution and structure of a target layer in the Chang-8 reservoir during its hydrocarbon accumulation period, combined with a comprehensive analysis of the distributional characteristics of the Chang-8 oil reservoir, we found a strong link between paleo-slopes and paleo-highs in the target layer and the modern distribution of tight oils. The paleo-structural characteristics of the target layer clearly exhibit control over the Chang-8 reservoir. We have proposed a new understanding and method for tight oil exploration, which is based on the recovery of the paleo-geomorphology of the target layer during the hydrocarbon generation period. It incorporates a number of key controls over tight oil accumulation and represents an evolution in the mindset suggested for tight oil exploration in the Ordos Basin.