Monitoring wettability alteration of porous media by streaming potential measurements: Experimental and modeling investigation

Abstract

Streaming potential can be used as a promising tool to determine and quantify wetting state of a porous media. Despite the importance, there are few experimental and modeling studies to investigate the effect of wetting alteration on streaming potential measurements. In order to improve our understanding, a set of experiments was conducted to determine the zeta potential and streaming potential coupling coefficient of a crystalline granular quartz pack under different wetting conditions. The electrokinetic experiments were performed for the completely water-wet and oil-wet and also partial oil-wet sand packs. The tests were conducted by various aqueous solutions having different pHs and salinities. The results demonstrate that streaming potential measurably changes with the wetting state of the rock surface. When wettability of rock partially changes to the oil-wet, the overall zeta potential and coupling coefficient approach to their values for the completely oil-wet sand particles. The amount of this approach is proportional to the magnitude of wetting transition. Furthermore, we used bundle-of-tubes (BOT) model to simulate the experiments and quantify wetting transitions. The results show reasonable agreement with the experimental data and introduce a new method for monitoring the wettability change of porous media during a dynamic injection process.