Thermal expansion and pore pressure generation in oil sands

Abstract

The prediction of stress changes and deformations arising from ground heating requires the coupled solution of the heat transfer and consolidation equations. Heat consolidation as a class of problems is distinct from other thermally induced consolidation problems involving processes such as frost heave and thaw consolidation in that it involves heating to elevated temperatures well above normal ground temperatures. Two of the important parameters required in analyses of heat consolidation problems are thermal expansion coefficients and a coefficient of thermal pore pressure generation.Relationships describing thermal expansion behaviour and thermal pore pressure generation in oil sands are presented. Both drained and undrained thermal expansion coefficients for Athabasca oil sand were determined by means of heating experiments in the temperature range 20–300 °C. The thermal pore pressure generation coefficient was evaluated in undrained heating experiments under constant total confining stresses and under constant effective confining stresses. The equipment and experimental methods developed during this study are appropriate for determination of thermal expansion and pore pressure generation properties of oil sands and other unconsolidated geologic materials. Key words: thermal expansion, oil sand, tar sand, thermal pore pressure generation, heat consolidation, thermal consolidation, coefficient of thermal expansion, thermal stresses, ground heating, thermally enhanced oil recovery, thermoelasticity, undrained heating.