Recovery of oil from Utah's tar sands

This project is designed to develop necessary engineering data and technology for recovery of oil from Utah's tar sands. Progress reports for four major aspects of this project, namely Hot Water Recovery, Energy Recovery in Thermal Processing, Effect of Variables in Thermal Processing and Bitumen Processing and Utilization are covered. Efforts have progressed to the point where collaboration with engineering companies for pilot plant development in preparation for commercialization has commenced. Hot water recovery technology has been shown to be technically feasible for application to high and medium grade Utah tar sands. Utah tar sands are generally believed to be oil-wet and the conditions for efficient separation differ appreciably from those practiced in commercial operation with Athabasca, Canada tar sands. The occurrence of high silica, low clay content tar sands in Utah may dramatically reduce water requirements and may eliminate the need for tailings ponds as required for Athabasca tar sands. Further work is required to prove this point. In recent work, a factorial design study of the major operating variables in the flotation step of the two step hot water process using Asphalt Ridge material has been carried out. Preliminary results are presented in this report. Considerations of energy balance and recovery in thermal processing show that there is sufficient energy available from combustion of coked sand above about 8 weight percent bitumen grade. Below 8 weight percent external energy must be input, preferably through the introduction of coal in the combustion zone. An energy efficient process concept, using heat pipes for energy transfer has been tested and shown to be attractive from a conservation standpoint. Further efforts must be made to prove out economic viability ii and operability relative to other thermal process configurations. A fluidized bed recovery process employing an arrangement of steps similar to that used widely in catalytic cracking has been studied in this laboratory. The principal variables effecting recovery and product quality are temperature, solids retention time, particle size, and particle size distribution. For a specified solids retention time, an optimum temperature for production of liquid products exists, below which insufficient production occurs, and above which raw crude oil is cracked to form more gases. Yields of greater than 80% raw crude oil are anticipated at residence times of less than 20 minutes. Detailed studies of energy recovery methods in thermal processing have been initiated for a two stage fluidized bed system just described. Characterization studies on extracted bitumen and the synthetic crude liquids obtained during pyrolysis were initiated to determine molecular composition of these tar sand oils and to develop concepts of reactions occurring during the pyrolysis. Some results of this work are presented. Virgin bitumen can be converted to raw crude oil by a variety of primary upgrading processes including visbreaking, coking, catalytic cracking and hydropyrolysis. Compared to coking, direct catalytic cracking provides higher quality products in greater yields; however, optimum conditions for catalytic cracking have not been identified and comparative economic analyses have not been made. Bitumen can be converted in virtually 100% yields to hydrocarbon gases and liquids by hydropyrolysis with the addition of 1 to 3 wt. percent hydrogen. Hydropyrolysis products show good promise as a catalytic cracking or a steam pyrolysis feedstock. Steam pyrolysis of bitumen to produce chemical intermediates is now underway.