The Effect of Water Salinity and Reservoir Temperature on Silica Dissolution During ASP Flood: Static Model

Abstract

Silica scaling has been studied by many researchers in the last four decades, in order to identify the roots of the silica scaling problem, understand the process of scale formation, and find the possible ways to inhibit the scaling from occurrence. Silicate scaling occurs inside the production tubing, progressive cavity pumps and other surface equipment, causeing continual work-overs, which increases the cost and non-productive time to the operator. Silicate scale is a multi-step process which involves silica dissolution, polymerization, and precipitation with other ions, and multiple factors including pH, temperature, and magnesium concentration affect the scaling tendency and the severity of the problem. This paper describes the results obtained from scanning electron microscopy (SEM), spectrophotometer DR/2800, and X-ray diffraction (XRD) techniques that addresses the impact of brine salinity and temperature on silica dissolution. Based on the results, the silica dissolution increased slightly with the salinity increase; 6.2 mg/L of silica has been dissolved in 20,000 ppm brine, while 60,000 ppm brine has dissolved 15.5 mg/L. Increase in temperature has a significant influence on silica dissolution. The 60,000 ppm brine solution dissolved 15.5 mg/L of silica at 25 °C, while the same solution dissolved 67.8 mg/L of silica when the temperature was elevated to 80 °C. It was also observed that by adding 250 ppm of Mg²⁺ and Ca²⁺ each to the 40,000 ppm brine solution, the silica dissolution increased from 8.3 to 19.1 mg/L.