Consolidation analysis of oil sand masses under applied temperature changes

Abstract

Stress and temperature changes in oil sand masses associated with in situ oil recovery schemes can give rise to stability and deformation problems. An analytical method is derived to analyze such problems and is incorporated in a finite-element formulation. A step-temperature 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 here, 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 fluctuations predicted by the step-temperature approach and leads to more realistic results. The finite-element formulation involves nonlinear variations of stress–strain response, compressibility, and flow and is performed in an incremental manner. The developed formulation has been verified by comparing the finite-element program results with both closed-form solutions and laboratory data. The program has been applied to predict the responses associated with an oil recovery scheme. Such analyses are important in the rational design of oil recovery schemes in oil sands. Key words: oil sand, thermal consolidation, thermal analysis, nonlinearity, finite element, oil recovery scheme.