Experimental study of the silica dissolution onto sandstone formation: Influence of PH, salinity, and temperature on dissolution

Abstract

Sand production has been acknowledged as a critical issue that causes various problems, such as surface and subsurface equipment damage, and affects the oil production economy. As the water saturation increases, sand production becomes more challenging. The most impactful factor affecting this phenomenon is silica dissolution, a chemical reaction between quartz and water that reduces formation strength. This study aims to investigate how water quality affects silica dissolution rates and contributes to sand production. A series of experiments were performed to determine the behavior of silica dissolution on pure quartz in different types of water (distilled water and electrolyte solutions including NaCl, CaCl2, MgCl2, and KCl) at various concentrations, temperatures, and pH levels. The Silica dissolution on quartz was determined using UV–Vis spectrophotometry (DR3900) to measure the concentration of silica dissolved in solution. The results showed that temperature and pH had a significant impact on silica dissolution, with an increase in dissolution as temperature increased at high and low pH. Among all brine types, NaCl and KCl had the highest effect on silica dissolution at 30 °C. The maximum amount of silica dissolution was found at 118 mg/l and 68 mg/l at pH 12 and 3, respectively. The study suggests that water quality could affect formation strength by enhancing or reducing silica dissolution. Thus, designing the optimum water quality with a neutral pH and minimizing free ions is the key to reducing sand production in water injection processes.