Abstract
A peripheral waterflood is planned in the Minagish Oolite Reservoir, Burgan Field. This is a large carbonate reservoir which has been under limited primary production since 1965. There is considerable uncertainty in the waterflood oil forecast because of the minimal amount of data with which to characterize the reservoir. This study identifies key subsurface uncertainties impacting waterflood performance and quantifies uncertainty with P10/P50/P90 oil forecasts.
Experimental design (ED) techniques were used to establish the minimum number of reservoir simulation runs needed to quantify uncertainty. Both traditional and ED techniques were used to preserve history matches for all simulations. Analysis of variance and multiple linear regressions were used to identify the most significant uncertainties and to create a proxy for the simulator. The proxy was used in Monte Carlo simulation to develop P10/P50/P90 oil forecasts.
Uncertainty analyses have not often been conducted on producing reservoirs. In this report a new technique combining ED with history matching has been successfully demonstrated. The technique can be applied to other producing reservoirs. Despite the need to restrict simulator inputs for history matching, it was shown that considerable uncertainty exists in the waterflood oil forecast. The results are valuable for: a) identifying actions to reduce uncertainty and b) input to additional development evaluations.
