Radio-frequency heating to recover oil from Utah tar sands

The IITRI RF Process for tar sands consists of two steps: first, the deposit is volumetrically heated with radio frequency energy to lower the viscosity of the bitumen; and the second, the bitumen is produced by one of several petroleum recovery methods. The RF (radio frequency) heating step is accomplished by inserting tubular electrodes into boreholes, and energizing them with an RF power source. The pattern of electrodes is designed so that the deposit between the electrodes is uniformly heated, with a minimum of energy loss. The RF is selected on the basis of the electromagnetic characteristics of the deposit. Electrical properties of Utah tar sands have been measured and found to behave as heterogeneous dielectrics, with parameters varying with moisture content. To demonstrate the RF heating method, 250 Kg samples of Utah tar sands have been heated to 150° C. At 100° to 150° C, the viscosity of the bitumen is reduced to 100 cp, depending on the specific deposit. This viscosity permits production by various means, using the tubular electrodes as recovery paths. One production method is by fluid replacement. Small laboratory experiments using 1 wt. percent sodium orthosilicate solution gave recoveries of 80 to 85 percent. Based on computer simulation, a gravity-drive method also appears promising. A high recovery rate is possible due to the relatively close spacing of the tubular conductors. Electrodes may be emplaced in boreholes drilled from the surface, but preferably for the Utah deposits from premined drifts. Mining and drilling costs are estimated to be $1 per barrel of recovered bitumen, and total costs in the order of $6 per barrel of bitumen.