Evaluating shale oil in the Dongying Depression, Bohai Bay Basin, China, using the oversaturation zone method

Increasing energy demands resulting in the need for unconventional shale oil-gas resources are attracting ever more attention. However, although some studies have been conducted on unconventional shale oil resources, little work to date has been carried out on the potential of lacustrine mudstones and shale. In the Dongying Depression of the Bohai Bay Basin, China, significant amounts of oil have been recorded from more than one hundred wells, and flow has been verified in more than ten during conventional petroleum exploration. Because three boreholes aimed at exploring for shale oil have recently been drilled in this depression, we describe here the characteristics of lacustrine mudstones and shale and provide a preliminary assessment of the three wells using the oil sorption index and the oversaturation zone. The results of this study show that the three wells exhibit good potential for shale oil and further suggestions for exploration are presented. We also discuss a number of unusual phenomena discovered in these shale borehole profiles as well as future predictions for the potential distribution of shale oil.