Foamy oil behavior contributes significantly to the anomalously high primary recovery of heavy oils observed in the Orinoco Belt, Venezuela. Nowadays, disappearance of this phenomenon results in a rapid increase in the produced GOR and a fast decline in oil production when the reservoir pressure is below the pseudo-bubble pressure. This paper presents the results of a laboratory investigation, including pressure-volume-temperature (PVT) studies of foamy oil-natural gas mixtures and coreflood tests, for evaluating the feasibility of the natural gas injection process for enhanced heavy oil recovery with foamy oil characteristics. The study characterized the natural gas dissolution process in the foamy oil, and examined the effects on viscosity reduction and foamy oil swelling of the presence of natural gas. Coreflood tests were carried out to investigate the effects on oil recovery of injection mode (huff-n-puff, continous gas injection, and intermittent gas injection) and their different process parameters, such as reservoir pressure, injection timing, permeability and the size of the gas slug. The results indicate that significant amounts of natural gas could dissolve in the oil, which would cause oil swelling, viscosity reduction and artificial foamy oil formation. Core-flooding tests show that the natural gas huff-n-puff process could increase oil recovery 7.8% compared to the primary pressure depletion process, indicating a greater potential for recovering heavy oil. The continous and intermittent gas flood processes were not viable methods to enhance oil recovery from the heavy oil reservoirs in the Orinoco Belt, Venezuela.

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