Classification and potential of continental shale oil resources in China and resource evaluation methods and criteria

Continental shale oil resource is an important alternative source for increasing and stabilizing China's crude oil production. China has abundant continental shale oil resources. The opinions of researchers are divided over the classification of shale oil resources in China, resource evaluation methods and criteria, and resource potential prediction. Considering this fact, the authors of this article first summarized and analyzed the exploration progresses made in the typical shale oil exploration areas in China and the geological insights gained through exploration activities. Then, based on the current shale oil research status and actual oil production conditions in China, shale oil resources were classified into three types: interlayer shale oil, pure shale oil, and in-situ converted shale oil. Furthermore, the corresponding resource evaluation methods and quantitative models were proposed, the key parameters and their lower limits were determined and the resources of the three major types of shale oil in the shale formations in China's major basins were evaluated using a set of unified evaluation criteria. The in-place resources of pure shale oil, interlayer shale oil and in-situ converted shale oil are 145.4 x 108 t, 95.1 x 108 t and 708.2 x 108 t, respectively, and the recoverable resources are respectively 9.4 x 108 t, 7.1 x 108 t and 460.3 x 108 t. The research results can provide guidance for the evaluation of shale oil resources in China and the exploration planning for such resources and serve as valuable references for international peers to understand China's current status of research and development potential of shale oil.