Wettability of Quartz Surface As Observed By NMR Transverse Relaxation Time (T2)

Injection of optimized water composition (smart water) is an advanced water flooding method for Enhanced Oil Recovery (EOR). Low saline waterflooding has proven successful in sandstone reservoirs. However, there is still controversy on the mechanism of smart water flooding. We studied the wettability property of the quartz surface by using Nuclear Magnetic Resonance (NMR) method. The principle of this method is that protons in water relax faster when it comes close to solid surface. We observed that quartz is highly water wet. A layer of water (bound water) forms on the quartz surface when they are mixed. The amount of bound water increases with the second power of specific surface area of particles. Addition of metal ions to the water in some cases increases the amount of bound water for same amount of surface area. We studied the affect of Ca2+, Mg2+ and Na+ ions and observed that among these ions, the Mg2+ ion produces the maximum amount of bound water while the Ca2+ ion produces the least. The method demonstrated in this study could be used to decide the optimized water composition for waterflooding in sandstone reservoirs.