Analysis of the effectiveness of the alternating water and gas injection method (WAG)

Abstract

Being the main source of primary energy in the world, oil is an increasingly used resource, and at the same time more difficult to be explored and produced. Special recovery methods have been extensively studied to increase the oil recovery. The WAG method consists of the alternating injection of water and gas for the recovery of the residual oil in the reservoirs. The objective of the present work is to simulate the alternating injection process and to evaluate its recovery efficiency when compared to the water injection and CO2 injection method using the MRST software (Matlab Reservoir Toolbox Simulator). In general, an increase of about 4% in oil production was found, when the WAG methods and CO2 methods are compared.The results show that, for three scenarios analyzed, up to 12 years of production the water flooding has the same volumes of recovered oil as the WAG or CO2 mechanisms. After that period, the WAG mechanism resulted in greater volumes of oil produced.