Cold production of heavy oil: An experimental investigation of foamy oil flow in porous media

he heavy oil reservoirs in which production during the primary phase involve generation of foam are classfied as "Foamy Oil Reservoirs". These reservoirs exhibit unexpectedly high primary recovery with slower than expected pressure decline and lower than expected gas oil ratios. The anomalous production behaviour of these reservoirs remains unexplained. The overall objective of this study was to improve the understanding of foamy oil flow using experimental techniques.;A series of experiments was conducted, using a cone and plate viscometer, to assess the rheological properties of foamy oil at simulated reservoir pressures and temperatures. The viscosity of a gas-oil dispersion was found to be slightly higher than the continuous live oil viscosity. The results from simulated distillation showed that the removal of the asphaltenes altered the oil composition. The equilibrium phase behaviour of foamy oils was found to be similar to that of conventional light oils.;A series of flow visualization studies was carried out using an etched glass micromodel of homogeneous pore pattern. A substantial insight of the pore scale phenomena during pressure depletion of solution gas drive reservoir was acquired. Experimental investigations using micromodel was further pursued using a more realistic heterogeneous pore network. A measurement section was also added to monitor fluid expansion. The experimental results explicated that the rate of pressure drawdown was the most important parameter that altered the flow behaviour in the pore scale level and induced "foaminess" during solution gas drive process. Mathematical expressions for nucleation rate were derived for various oil samples. The growth of gas bubbles under different operating conditions was also studied and was found to follow a power law model. The internal displacement exhibited some similarity with an immiscible, external displacement process. Scrutiny of fluid production behaviour suggested that some microbubbles (bubbles of the order of 1...