Influence of high permeability subdomains on steam injection performance in heavy-oil reservoirs

Steam injection (or steam-flooding) can be considered the most frequent thermal recovery method used in the oil industry due to its added value in terms of heat concentration, availability, and moderate cost. Given the large extent of heavy oil reservoirs worldwide, many of them endowed with high permeability subdomains (HPSs), the numerical evaluation of steam-flooding efficiency has become relevant for understanding flow aspects in this type of formation. In view of the scant literature dealing with this issue, this paper is intended to evaluate the heavy-oil recovery factor in a model composed by HPSs subjected to steam injection over a period of 16 years. We investigated the impact of steam injection rate, the influence of multiple embedded subdomains, and the effect of injection well's flow directionality and HPS skewness. To this end, we resorted to numerical triphasic pseudo-compositional flow simulations carried out with CMG STARS(C) software over a model with rock-fluid properties similar to the Alto do Rodrigues Field's (Brazil's northeastern region). The outcomes indicate that, depending on the layout, number, and position of the HPSs, the ultimate oil recovery may increase or decrease. In particular, one observes that with equal increments of gas injection rates, the recovery factor can improve by up to 10%. Moreover, we emphasize that the growth or decay of the recovery factor has no apparent linear relationship with the testing parameters. Such findings are helpful for guiding steam-flooding strategies in revitalization projects of mature fields.