Abstract:
Primary and Secondary Recovery techniques together are able to recover only about
5-40% of oil from the reservoir. This leaves a significant amount of oil remaining in
the reservoir. The residual oil left after the water flooding is either from water swept
part or area by-passed by the water flooding. The by-passed residual oil has a high
interfacial tension with the water. One way of recovering this capillary trapped oil is
by flooding the reservoir with chemicals (surfactant, alkali-surfactant (AS),
surfactant-polymer (SP), or alkaline-surfactant-polymer (ASP)).
The Neem field which is the case for this study having approximately current
recovery factor of 8.2%. The oil production has peaked in 2006 and is now declining.
The pockets of residual oil saturation are still trapped in the reservoir especially in
Abu Gabra formations. The water flooding alone cannot recover capillary trapped oil
pockets efficiently, thus requires enhanced oil recovery techniques. The EOR
screening criteria suggested by Taber et.al was applied to Neem field Abu Gabra -6
reservoir in order to come up with the right EOR method that would reduce residual
oil saturation to the minimum. Four EOR cases such as base case, water flooding
case, water alternative gas case and surfactant /polymer flooding case, were simulated
for the AbuGabra-6(AG-6).
The main objective of this study was to perform a comparative simulation study to
evaluate the effectiveness of these chemical methods compared to conventional water
flooding method in terms of recovery factor. One of the flooding methods will be
chosen to for AG-6 based on the recovery factor.
Three cases were run using Eclipse 100, black oil simulator, and a correlation data for
EOR PVT Model. From simulation results, base case gives 8.2%, WI 51%, WAG
52% and SP flooding was found to be better than other cases in terms of recovery
factor it gives 57% for AG-6.It is recommended that right surfactant and polymer
structure that would be compatible with fluid and rock properties of AG-6to be
developed in the laboratory. It is also important that up-scaling the appropriate
laboratory identified chemicals to a field-scale usage be done correctly. The timing of
SP injection into AG-6 is also recommended to be early in the life of the field because
injection of SP at a later time might not lead to best possible oil recovery.
