Shear strength and stress—strain behaviour of Athabasca oil sand at elevated temperatures and pressures

Abstract

The results of a series of triaxial compression tests on undisturbed samples of Athabasca oil sand at elevated temperatures ranging from 20 to 200 °C are summarized. The material tested had experienced gradual unloading and depressurization as a result of erosion in the Saline Creek valley near Fort McMurray. More deeply buried oil sands are known to contain much higher concentrations of dissolved hydrocarbon gases in the pore fluids. The measured shear strength of Athabasca oil sand did not change significantly as a result of the increased temperatures that were applied. The strength of Athabasca oil sand (at 20–200 °C) was found to be greater than comparable shear strengths reported for dense Ottawa sand (at 20 °C). Although heating to 200 °C had little effect on shear strength, it is recognized that pore pressure generation during undrained heating may cause substantial reduction of the available shearing resistance, particularly in gas-rich oil sands. The experimental data were used to investigate the influence of such factors as stress path dependency, microfabric disturbance, and heating to elevated temperatures on the shear strength and stress–strain behaviour of oil sand. Curve fitting of the test data suggests that the hyperbolic model is a useful empirical technique for stress—deformation analyses in oil sands. Hyperbolic stress—strain parameters derived from the experimental results for Athabasca oil sand are presented. Key words: oil sand, Athabasca oil sand, tar sand, shear strength, stress, strain, deformation, heating, high temperature, elevated temperatures, high pressure, elevated pressure, thermal properties, drained heating, undrained heating, triaxial compression testing.

Effects of temperature changes on soil hydraulic properties

“…3 reflect an increase in parameter c as temperature increases. The increase in parameter c indicates the expansion of soil particles, especially in heavy loam with high clay content (Plum and Esrig, 1969;Agar et al, 1987;Murata and Kukawa, 1992;Hueckel et al, 2011). From a macroscopic view, a reduction in the void ratio with temperature increases is a result of particle swelling.…”

Production froide des huiles visqueuses. Première partie : Observations sur champ

“…réalisés après réchauffement de la carotte à des températures allant de 4 °C (Dusseault et Morgenstern, 1978) à 200° ( Agar, Morgenstern et Scott, 1987). Les essais ont toujours été effectués sur des matériaux de faible teneur en huile (< 15 %) et les expérimentateurs se sont intéressés davantage au comportement du squelette sableux qu'au complexe sablehuile visqueuse.…”

“…Si la teneur en gaz est faible, la température n'a pas d'effet sur la résistance au cisaillement (Agar, Morgenstern et Scott, 1987). Essais triaxiaux sur des sables à huile visqueuse d'Athabasca (d'après Dusseault et Morgenstern, 1978).…”

Thermomechanical Behavior of Energy Pile Embedded in Sandy Soil

“…The circulation of fluid (usually water) in heat exchangers allows the energy pile to exchange heat and energy with the ground since the temperature below 4 m depth underground remains constant [3]. However, the temperature change of pile foundations during heating and cooling may lead to some irreversible volumetric strain for the surrounding soils [4,5]. It would also cause the changes in the toe resistance and shaft friction along the pile, which would affect the serviceability and stability of pile foundations [6][7][8].…”