Geomechanical Model and Acoustic Impedance Analysis on Heavy-Oil Project

This study presents an analysis of the changes that could be expected in geomechanics, fluid flow and seismic during steam injection in unconsolidated sandstone reservoirs. Variations of the rock, fluid properties and velocities due to steam injection in a heavy oil unconsolidated formation were predicted using laboratory testing, field data and logs. A 3D thermal, compositional and geomechanical reservoir model was built based on these data and a 2D synthetic seismogram was calculated for time lapse modeling. The synthetic seismogram results were used to calculate the variation in acoustic impedance and fluid substitution was evaluated using Gassmann's equation. Thermal-Fluid-Geomechanics simulations indicated a 6% increase of the pore pressure inside the chamber during the injection and a 45% increase of the water saturation. This resulted in rock dilation and shear strain around the steam chamber, thus reducing the overburden and acoustic impedance during the steam injection process used to increase heavy oil recovery.