WATER CONSUMPTION ANALYSIS FOR AN IN SITU OIL SHALE RETORT

Net water consumption for the generation and extraction of oil from oil shale is a central issue for both the producers and the external stakeholders in areas where the water resources are scarce. Published water consumption estimates ex-situ retorting of oil shale range from 1.6 to 6.2 barrels of water for every barrel of product. This uncertainty in water consumption may be even greater for in situ oil shale development technologies, due to both a paucity of data on which to base water consumption estimates, and a lack of a consistent approach to estimate water quantity needs. Based on surface retorting approaches, we have developed a system dynamics modeling approach to examine the temporal water use for an in-situ oil shale retort for the construction, production, and the reclamation phases. Although this model has been designed for in-situ retort, it has ignored the potential egress of ground water into the retort zone. Our objective in this study is to evaluate the impact of ground water leakage into a retort zone during production and reclamation on the total water consumption estimate of an in-situ oil shale retort. Leakage rates are determined with a Darcy model approach using a range of parameters derived from published literature. The hypothetical oil shale retorting facility used in the model is loosely based on the Shell In-Situ Conversion Process. The results illustrate the impact of leakage on net water usage and the potential need for engineering approaches for controlling ground water egress into retorts.