Recovery and upgrading of oil from Utah tar sands

Research has progressed in four principal areas: A) Bitumen Upgrading; B) Thermal Recovery by Fluidized Bed Pyroiysis; C) Water Assisted Recovery; and D) Two-Stage Thermal Recovery using Heat Pipes. Hydropyrolysis continues to show promise for upgrading of bitumen with high liquid yields. Valuable experience has been gained in the operation of the 2 £/hr PDU. The semiquantitive effects of the important process variables have been ascertained. High conversions to liquids and low coke production can be achieved with good atomization quality in the PDU. The product distribution obtained when processing the TS-IIC liquid product at 505°C, 1800 psig H2, and 2.8 sec. residence time was 4.7% gas, 84.5% liquid (24.9° API), 10.6% residual liquid and 0.2% coke. The investigation of the fluidized bed pyroiysis of the bitumenimpregnated sandstone from the PR Spring Tar Sand deposit has been completed, and the results have been incorporated into the correlation used to predict pyroiysis product distributions and yields. The differences in the nature of the three native PR Spring bitumens, Rainbow I, Rainbow II, and South, were reflected in the product distributions and yields as a function of reactor temperature and sand retention time and in the product qualities. The Conradson Carbon Residue, the atomic hydrogen-to-carbon ratio, and the asphaltene content of the native bitumens were excellent correlating parameters for the product distributions and yields. The kinetics of the pyrolysis reactions are currently being studied in an attempt to refine the pyrolysis model for the fluidized bed process. In water-assisted recovery, shear forces are known to be important to bitumen disengagement. Both cohesive and adhesive forces must be overcome in order to attain high recovery of the bitumen. This phenomena has been studied using a high speed video system to elucidate the separation of the bitumen from the sand substrate. Results indicate that cohesive forces which can be controlled through viscosity-reducing diluents contribute significantly to the stability of the bitumen-sand interface. A residual amount of bitumen remains in contact with the sand grains, depending upon the level of shear achieved due to adhesive forces between the bitumen and the sand surface. Results are to be used in improving the design of water-assisted recovery processes. Preliminary design and economic evaluation for a two-stage thermal recovery process was conducted. The process design study, using heat pipes to transfer heat from the exothermic combustion zone to the endothermic pyrolysis zone, included two cases: 15,000 and 50,000 bbl/day. Projected capital investments were $137M and $468M, and operating costs were $13.30 and $14.48/bbl, respectively. The design basis assumed a purchase cost of $5/ton of raw ore. Product oil was a raw pyrolysis oil. The design is accompanied by a second-law thermodynamic analysis. Results show that the process is stable and easily controlled, and represents an economically attractive method for hydrocarbon recovery from tar sands.