Abstract

Absolute permeability plays an important role in reservoir engineering. Reservoirs like oil sands are shallow unconsolidated formations and stress dependent. During steam-assisted drainage (SAGD) the effective stress increases as results of either increasing in temperature or pore pressure. Rock properties for instance permeability will be induced by this change to influence therefore reservoir calculations.

To understand the behavior of stress-strain in unconsolidated reservoir during a SAGD, a series of drained triaxial compression tests were performed to study the shear-induced changes in absolute permeability at low stress conditions. The experimental program included stress-strain tests under two different paths: isotropic unloading and increasing of mean stress was followed by permeability tests at each levels of strain and at different confining effective stresses.

Results from this study showed a substantial increase of absolute permeability in the lower case of 50 kPa of effective confining stress. This gain was up to 88%. In the higher level of effective confining stress, however, there was a decrease of absolute permeability.

The aim of this project was to provide an empirical correlation linking the absolute permeability to effective confining stress and volumetric stain so that the behavior of absolute permeability at different overburden depths will be understood.

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