不均質性を考慮した掃攻率改善のための効果的貯留層内ブロッキングの検討

Abstract

Most of the conventional EOR processes have already been established, and the development of a new innovative EOR process is quite difficult. Therefore, the sweep efficiency improvement (SEI) is more important for an efficient EOR. Several SEI methods have been applied actually in many fields. However, the injected EOR fluid tends to flow selectively in the already swept high permeable zones, and the sweep efficiency is poor as the result. In this case, in-depth profile modification by blocking such the already swept high permeable zones with a polymer gel would be a more effective than already existing SEI methods.In this study, numerical simulations to confirm the effect of the in-depth profile modification on SEI has been conducted to thirty-two heterogeneous reservoir models under the several blocking conditions. The relation between the blocking effect on SEI and the heterogeneity indexes, which are Dykstra-Parsons coefficient for vertical heterogeneity and correlation length for horizontal heterogeneity, is also investigated.From this study, following results have been obtained. First, the blocking effect increases with the increase in the volume of injected polymer gel and the decrease in the volume of chase water. That is to say, the blocking effect increases when the blocking is done more perfectly. Second, the blocking effect increases with the increase in the vertical heterogeneity, and horizontal heterogeneity is less correlated to the blocking effect compared to the vertical heterogeneity.