UBC Theses and Dissertations
Stress, deformation and flow analysis of oil sand masses under applied load and temperature changes Srithar, Thillaikanagasabai
Stress and temperature changes in oil sand masses associated with oil recovery can give rise to stability and deformation problems. An analytical formulation is developed to analyze such kind of problems and incorporated in the finite element program 'CONOIL II’. Oil sand is a multiphase material, which can be analyzed as an equivalent two phase material; solid grains saturated with a single fluid phase, having an equivalent compressibility. The equivalent compressibility is obtained by combining the concepts of unsaturated soils with the gas laws and the gas-liquid interaction effects. Classical approach, as used in thermal elasticity is not appropriate to analyze the temperature induced effects, unless the time steps are made very small. A better formulation is presented, which involves introducing additional terms in the stress-strain relation and in the flow continuity equation, to account for temperature induced effects. The new approach reduces the oscillations predicted by the classical approach and leads to more realistic results. The analytical equations for the coupled stress, deformation and flow problems have been solved by finite element analysis. The finite element formulation involves nonlinear variations of stress-strain response, compressibility and flow, and is performed in an incremental manner. The developed finite element program has been verified by comparing its results with the closed form solutions and laboratory data. Then, the program has been applied to predict the responses associated with an oil recovery scheme. Such kind of analyses are important in the rational design of oil recovery schemes in oil sands.
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