Distribution and main controls for shale oil resources in USA

Systematic analyses of statistical data of shale oil resources and an integrated investigation of geological elements in major shale oil basins in USA were made. They characterize the distribution features of shale oil resources and document the controlling factors for shale oil endowment in USA. The results provide insights for shale oil exploration and production in China. Recoverable shale oil resources amount to 1 51×109 bbl in USA, of which 36.5×109 bbl have already been proven with a discovery rate of 24.2%. The shale oil resources are unevenly distributed. The Permian Basin has the lion's share of the total, followed by the Gulf and Williston basins. The enrichment of shale oil resources is largely governed by the volume of high quality source rocks, the extensive top and bottom seals of shale oil plays and the scale of "sweet spots" in shale oil reservoir intervals. The former two control the total endowment of shale oil resources and the latter controls the production volume of shale oils. It is suggested that China's shale oil exploration should focus on the selection of favorable plays and their fairways in large sedimentary basins. The delineation of new "sweet spots" and the expansion of the extent of known "sweet spots" are the keys for the new breakthroughs of shale oil exploration and the increase of both shale oil production and reserves.