Predicting the migration pathways and depths of penetration of dense non-aqueous phase liquids (DNAPLs) is a formidable challenge, especially in the UK where the majro aquifers commonly possess significant degrees of fracturing. One of the most challenging field parameters to record is fracture aperture, due to inherent difficulties in measuring small aperture fractures. A new field techniques has been developed to measure oleoporic fracture aperture in situ by the injection of a harmless NAPL (sunflower oil) into a fracture isolated by a double packer array beneath the water table. Regulatory permission has been obtained for NAPL injection into a fractured Permian sandstone aquifer in Scotland. Here we present the experimental design, with single and dual phase injection experiment results. The technique provides a new dataset of in situ fracture aperture for a sandstone aquifer, including detailed evidence for constrictions and enlargements of fracture aperture at increasing radial distance from the borehole.
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