Oil bearing shale and sand
Unlike conventional oil, the oil in shales and tar sands is solid, or nearly solid, rather than liquid and cannot migrate into oil reservoirs. Oil shales are abundant and widespread in the industrial world but are not, at present, regarded as a commercially viable source of oil. ‘SYNTHETIC’ FUELS, OIL SHALE AND TAR SANDS 183 hot enough for the kerogen to turn into oil underground. In situ retorting eliminates the mining cost, many of the costs for above-ground retorts and liquid handling equipment, and addresses the problem of disposing of the shale after the oil has been ‘cooked’ out of it.