Abstract: The consolidated drained triaxial compression tests on oil sand, which is from a heavy oil reservoir of Fengcheng oil field in Kelamayi, Xinjiang, are conducted at both room and high temperatures to study its mechanical and thermal properties. Experimental results show that the deviatoric stress-strain behaviour of oil sand at room temperature is divided into three stages: elastic, plastic and softening stages. At high temperature the compaction stage occurs before the elastic stage, however the variations of volumetric strain are significantly different at different confining pressures. Elastic modulus and Poisson's ratio of oil sand show a good linear relationship with the consolidation pressure. There is less effect of high temperature on the peak strength, residual strength, elastic modulus and Poisson's ratio. The values of internal friction angle and cohesion of oil sand are 34°and 0.47 MPa respectively, which are close to those of coarse grained soils. The coefficient of thermal expansion increases with increasing confining pressure, and the circumferential expansion coefficient is sufficiently larger than the axial one. A critical temperature occurs at the confining pressure of 5 MPa. The deformation of oil sand presents varied characteristics as the temperature below or above the critical temperature. The axial, circumferential and volumetric deformations expand linearly with the increase of temperature when temperature is below the critical value, but the deformations reduce linearly when temperature is above it. Finally, comparing the properties of Fengcheng oil sand with Athabasca oil sand and Cold Lake oil sand, it is found that the strength and deformation characteristics of oil sand are similar to great extent. Thus this study is particularly significant in the exploitation of heavy oil from the Fengcheng area.

Key words: Fengcheng oil field, oil sand, rock mechanics, thermal properties, experimental research