oa Accessibility and mobility of hydrocarbons in lacustrine shale: Solvent flow-through extraction experiments on Eocene oil shales from Bohai Bay Basin

In order to examine the mobility of hydrocarbons in a lacustrine shale oil system, three cylindrical core plugs from the Eocene Shahejie Formation lacustrine shale oil system in the Jiyang Depression were sequentially extracted with dichloromethane (DCM) in flow-through experiments under controlled stress conditions in a tri-axial flow cell ( Fig.1 ). Orientations of the three sample plugs were perpendicular to bedding (#1) and parallel to bedding (#2 and #3) ( Fig.2 ). Post-experiment Micro-CT analysis confirmed three different flow patterns: Cross bedding flow (#1), minor bedding-parallel flow (#2), and extensive bedding-parallel flow along open fractures (#3) (Fig. 3). Extraction times were 28 days, 7 days and 3 days, for samples #1, #2 and #3, respectively. Sequential series of extracts from the samples were analyzed using gas chromatography. For comparison, hydrocarbon compositions also were determined on bulk extracts of powdered original sister-sample material and the residues after flow-through experiments.