Heavy oil reserves accounts for more than 8 trillion barrels of the total reserve. Thermal methods such as steam flooding (SF) and its variants have been applied extensively to develop the reserves. Complex heavy oil reservoirs possess certain properties that make the steam flooding ineffective. The properties include low thickness, deeper depth and formation nature (naturally fractured carbonates). Heat losses, gravity override and channeling are the common problems associated with it. Polymer flooding (PF) is one of the major non-thermal methods employed to recover heavy oil. Higher Salinity and divalency in carbonate reservoirs restricts polymer flooding applications. Higher oil viscosity also limits its application.
In this work, we investigated the potential of viscoelastic surfactant (VES) in recovering heavy oil in complex reservoirs where steam-flooding and polymer flooding fail. VES exhibits certain unique properties which are ascertained individually. The properties include IFT reduction, viscosity, elasticity, emulsification, salinity resistance, compatibility, and thermal stability. The properties of VES extend its applicability in complex reservoirs and hybrid technique that combined the synergism of VES, P, and hot water has been investigated.
Reservoir simulation studies with 5-spot pattern have been conducted to compare the performance of Steam flood, polymer flood, and hybrid VES flooding in thin heavy oil reservoirs. Results indicated that VES could be an ideal hybrid option along with hot water to recover high viscous heavy oil in thin reservoirs.