Transcripción del resumen del autor. Immiscible CO2 injection is a potentially viable method of enhanced oil recovery (EOR) for medium oil reservoirs in south-western Saskatchewan. The relatively high reservoir pressures could result in a large extent of CO2 dissolution, significant oil viscosity reduction and oil swelling. Laboratory corefloods were used to compare the performance of different modes of CO2 injection into a medium-gravity oil system. The following methods were compared: injection of a single CO2 slug chased by water, simultaneous injection of water/CO2, and different water-alternating-gas (WAG) cycles. The results indicate that both a single CO2 slug and the first WAG cycle in a series produced oil very efficiently, possibly owing to good gas/oil contact at the relatively high residual oil saturation at this stage. The simultaneous injection of water/ CO2 was not as effective as a single CO2 slug, possibly because the co-injected water shielded the oil from being contacted by the gas. Among the four runs, a coreflood with four WAG cycles recovered the most incremental oil—20.58% initial oil in place (IOIP)-while the co-injection process produced the least (8.91% IOIP). This experimental study suggests that the immiscible CO2 EOR process is viable for medium oil reservoirs with relatively high pressures, and that proper process application is important for maximizing additional oil production.

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