Hoe Creek II Revisited: Boundaries of the Gasification Zone

Abstract

Lawrence Livermore Laboratory has completed an exploratory drilling program at the site of the Hoe Creek II Field Experiment on in situ coal gasification. We have used the results to further define the boundaries of the gasification zone. The gasification zone was 12 to 16 m wide and extended at least 7.6 m behind the injection well and 18 m toward the production well. All the coal within 2.9 m of the injection well was gasified despite an override condition that existed almost from the start of forward-combustion gasification. Cavity-spreading mechanisms that do not depend on the product flow paths being at the bottom of the seam are suggested. Natural convection may drive these mechanisms. For these mechanisms to function the injection point must be at the bottom of the coal seam