An experimental investigation on effects of saturation levels and fluid types on elastic properties of bitumen-saturated sands at elevated temperatures

The change of saturation levels and fluid types during steam-assisted gravity drainage (SAGD) production significantly influences elastic properties of oil sands. However, experimentally establishing petrophysical-elastic parameters relationships of oil sands that govern the SAGD process remains a challenge. Here, with modified low impedance transducers and an optimized measurement workflow, oil sands sample with varying saturation levels and fluid types are successfully investigated at varying temperatures and pressures. This is the first time that oil sands are measured at controlled bitumen-saturated levels at elevated temperatures. The results demonstrate that elastic properties of the tested sample are somewhat dependent on the pressure but strongly dependent on the temperature at varying saturation levels and fluid types. Specifically, both P- and S-wave velocities at dry conditions increase with increasing pressure but insensitive to the temperature change. However, both P- and S-wave velocities at fluid-saturated conditions are much higher than that at dry conditions mainly due to part of bitumen transforming to solid frame in low temperatures (<Liquid point) or fluid effects in high temperatures (>Liquid point). These experimental investigations qualitatively capture the elastic behaviors of bitumen-bearing sands at varying petrophysical conditions, thereby helping us in understanding the underlying processes of heavy oil production using the SAGD technique.