Oil Configuration Under High-Salinity and Low-Salinity Conditions at Pore Scale: A Parametric Investigation by Use of a Single-Channel Micromodel

Bartels, Willem-Bart (Utrecht University) | Mahani, Hassan (Shell Global Solutions International B.V.) | Berg, Steffen (Shell Global Solutions International B.V.) | Menezes, Robin (Delft University of Technology) | van der Hoeven, Jesse A. (Utrecht University) | Fadili, Ali (Shell Global Solutions International B.V.)


W.-B. Bartels, Utrecht University; H. Mahani and S. Berg, Shell Global Solutions International B.V.; R. Menezes, Delft University of Technology; J. A. van der Hoeven, Utrecht University; and A. Fadili, Shell Global Solutions International B.V. Summary Low-salinity waterflooding (LSF) is receiving increased interest as a promising method to improve oil-recovery efficiency. Most of the literature agrees that, on the Darcy scale, LSF can be regarded as a wettability-modification process, leading to a morewater-wet state, although no consensus on the microscopic mechanisms has been reached. To establish a link between the pore-scale and the Darcy-scale description, the flow dynamic at an intermediate scale--i.e., networks of multiple pores--should be investigated. One of the main challenges in addressing phenomena on this scale is to design a model system representative of natural rock. The model system should allow for a systematic investigation of influencing parameters with pore-scale resolution while simultaneously being large enough to capture larger-lengthscale effects such as saturation changes and the mobilization and connection of oil ganglia. In this paper, we use micromodels functionalized with active clay minerals as a model system to study the low-salinity effect (LSE) on the pore scale. A new method was devised to deposit clays in the micromodel. Clay suspensions were made by mixing natural clays (montmorillonite) with isopropyl alcohol (IPA) and were injected into optically transparent 2D glass micromodels. After drying the models, the clay particles were deposited and stick naturally to the glass surfaces. The micromodel was then used to investigate the dependence of the LSE on the type of oil (crude oil vs. n-decane), the presence of clay particles, and aging. Our results show that the system is responsive to low-salinity brine as the effective contact angle of crude oil shifts toward a more-water-wetting state when brine salinity is reduced.