The feasibility of in-situ steam injection technology for oil shale underground retorting

Abstract

The basic principles of in-situ steam injection technology (MTI) for oil shale underground retorting were presented and related technical processes were analyzed. The convection heat transfer of steam enhanced the efficiency of heating the oil shale layer, which shortened the time to achieve a complete pyrolysis of organic matter. Under the influence of steam the migration capacity of oil and gas improved and the oil and gas products were carried out of the production well more quickly. Moreover, by using superheated steam (up to 570 °C) to pyrolyze oil shale, the oil recovery rate exceeded 95%, and the gas production per unit mass was 0.041 m3/kg, at the same time, the quality of oil and gas products greatly improved. The proportion of light oils accounted for 75.38%, and the yield of H2 and CO in pyrolysis gases was increased. The numerical simulation of steam injection indicated that the MTI technology was a rapid and efficient method for oil shale underground retorting to extract oil and gas by using the injection and production wells alternately for injecting steam. It demonstrated that the development period of the MTI technology was only about 300 days for an oil shale reservoir with a well spacing of 50 m, and the roof and floor of the oil shale layer served as thermal and steam insulation. The successful industrial implementation of the MTI technology in the future should alleviate the increasing energy crisis in China and reduce the country’s dependence on imported petroleum.