Geophysical Alterations and Groundwater Flow Implications of In Situ and Ex Situ Conversion of Oil Shale in the Piceance Basin, Colorado, with Applications for Other Oil Shale Basins via Groundwater and 3D Geologic Computer Models

摘要

Piceance Basin oil-shale deposits have been identified as the richest in the world. In situ and ex situ conversion of the underground shale is one potential option to recover the billions of barrels of oil located across the Piceance Basin in Colorado. Though the U.S. Department of Energy considers it a "promising" technology, its subsurface environmental impacts are not yet fully explored. The in situ and ex situ pyrolysis of oil shale will, by nature of its releasing long-stored kerogen from the shale rock, change the porosity of the remaining subsurface materials (both of extracted shale and surrounding sandstone). A series of shale samples were subjected to pyrolysis at a variety of temperatures, pressures, and reaction times to simulate in situ and ex situ conversion. The resulting surface areas and porosities were measured using nitrogen adsorption isotherms, possible crystallization and materials structure changes monitored using x-ray diffractometry, and morphological changes observed via scanning electron microscopy. Preliminary lab results show development of micro- and mesopores, which are correlated with temperature, pressure, and extraction time. To explore the impact of these morphological changes on environmental fate and transport, geophysical investigations and groundwater flow and 3D geologic computer models were created, analysed, and were correlated with potential oil migration with respect to the Eocene aged shale and associated formations.