Abstract

There are many processes the oil industry used to recover more oil from the reservoir after the natural energy is depleted. In this research work, ultrasound energy has been tested as a method of improving oil recovery after waterflooding. The method used in this research work was a numerical simulation using MATLAB Reservoir Simulation Toolbox (MRST-2017a). Ultrasound energy source equation was incorporated into the residual energy equation in the MRST. Acoustic attenuation pressure equation was modelled as part of the residual pressure equation in the MRST. Effect of ultrasound waves on pore wall deformation was also modelled from waves stress equation. Two-phase (oil/water) black oil model was used to simulate fluid flow. Results obtained from the simulation runs show that the ultrasound energy has an impact on reservoir performance i.e. increase in fluid flowrates and pore pressure and temperature rise which led to oil viscosity reduction and consequently improve mobility ratio. However, attenuation of ultrasound energy increases with propagation distance, but this effect was compensated by increasing the intensity of the ultrasound power. Though, high power intensity induced stress on the reservoir pore throat. Results obtained also show that high porosity and permeability values affect the performance of the acoustic energy basically due to an increase in the rate of waves absorption.

Key words: Ultrasound energy, improved oil recovery, reservoir simulation toolbox, MATLAB.