Study of low-salinity waterflooding for single-and two-phase experiments in Berea sandstone cores

摘要

Single-phase experiments were carried out in Berea sandstone to understand the behavior of the water-rock system and establish a baseline to interpret multiphase experiments. The water-rock reactions at microscopic level are reflected in the macroscopic scale by alteration in permeability in the rock and pH in the effluent In our experiments we assume that the significant changes are solely a result of the alteration of the brine salinity since the composition of the brine and mineralogy of the core were held constant. Injection of brine with 1% salinity produced permanent permeability reduction due to fines release. Two-phase experiments were carried out on undamaged and damaged Berea sandstone cores. Comparison of single-phase and two-phase experiments results in undamaged Berea cores that showed the same pressure and pH behavior when low salinity waterflooding is performed. Incremental oil production was observed in both undamaged and damaged cores suggesting that the mechanism of incremental production during low salinity injection is not solely related to fines migration.