The Role of Wettability in Gas-Assisted Gravity Drainage Process

This paper pertains to experimental study of wettability effect in oil recovery under Gas Assisted Gravity Drainage process. The experiments are performed on long unconsolidated porous media and sensitivity analyses are done for wettability and gas injection rate. Two set of experiments also are extended by subsequent water flooding after gas breakthrough time to decrease the oil recovery duration. The experiments are simulated and relative permeability curves are evaluated by history matching. Two flow regimes are observed during oil recovery. In the early stage oil produces under bulk flow which is affect by viscous force and injection rate while wettability has a weak influence. For the next stage film flow takes place through porous media leading to very slow rate. In this stage higher oil recovery is observed in water wet media due to flow of oil by spreading film, however it vanishes abruptly compared to oil wet media. In oil wet media, oil remains continuous through wetting film but it is subjected to strong capillary retention. Moreover only in water wet media subsequent water flooding by generation of oil bank and displacing of residual oil leads to considerable recovery.

Keywords:

Gravity Drainage , Subsequent water flooding , Wettability , Relative Permeability , Three Phase flow