Tar sand research and development at the University of Utah

The recovery of hydrocarbon values from the extensive tar sand deposits of North America has generally been approached by one of two methods: in situ thermal production of the bitumen or of a bitumen-derived liquid or surface mining of the deposit followed by processing of the mined ore. In either approach the produced hydrocarbon liquid must be upgraded to give a suitable feedstock for subsequent processing in a conventional petroleum refinery. The in situ thermal methods that have been applied to tar sands include steam soak, steam drive, and in situ combustion, all of which have been extensively used in enhanced oil recovery of heavy oils (^20 °AP1). The selection of the appropriate thermal method for a specific reservoir or deposit is based on established reservoir screening parameters, including viscosity and gravity of the reservoir fluid at the reservoir temperature and pressure, permeability and depth of the reservoir, geology and mineralogy of the reservoir, and the reservoir temperature and pressure. Surface mining-bitumen recovery methods all involve mining of the tar sand deposit, transportation of the mined ore from the deposit to the processing facility, separation of the bitumen from the sand substrate, disposal of the spent sand, and upgrading of the bitumen or bitumen-derived hydrocarbon liquid. The bitumen may be recovered by one of the following methods:water-assisted separation, solvent extraction, solvent-assisted aqueous separation, or thermal processing of the tar sand. The aqueous and solvent-assisted aqueous separation methods recover the native bitumen, whereas the product liquids from the pyrolysis processes are partially upgraded because the thermal recovery methods operate at temperatures high enough to induce thermal cracking of the bitumen. The success of any surface mining-bitumen recovery technology depends on the ability to carry out each of the steps economically. The mineability of a prospective deposit is the primary factor in the decision to recover the bitumen by a surface method, although the disposal of spent sand poses a significant environmental problem that must be considered.