Classification evaluation criteria and exploration potential of tight oil resources in key basins of China

Abstract

In general, the migration distance of continental tight oil in China is relatively short, and the formation and distribution are mainly controlled by the tectonic setting, source rock, reservoir, and source-reservoir matching relationship. It is characterized by continuous or quasi-continuous distribution and local enrichment in the development area of high-quality source rocks. The matching relationship between source rock and reservoir in vertical and horizontal directions controls the formation, distribution, and scale of tight oil reservoirs. Based on the source-reservoir matching relationship, tight oil resources are classified between in-source type and out-source type. These two types of tight oil are widely distributed in China's major petroliferous basins. The distribution and enrichment of in-source tight oil resources are controlled by the distribution of source rocks and favorable reservoirs. Out-source tight oil resources are controlled by the transport system and the distribution of favorable reservoirs, but the effectiveness of the transport system is controlled by the distribution of source rocks. The two important parameters of source rocks and reservoirs should be taken into account in the classification evaluation of tight oil resources. The classification evaluation of source rocks and reservoir conditions are both bases for the evaluation of the exploration potential of tight oil. The total amount of tight oil resources is 9.051 × 109 t in six major basins, (e.g., Songliao, Bohai Bay, Ordos, Sichuan, Santanghu, Qaidam, and Junggar basins), which are primary areas for tight oil exploration.