Assessing silica-based gel system for high-temperature water shut-off applications

Abstract

Excessive water production in oil and gas wells poses a significant challenge for reservoir management, necessitating effective water shut-off solutions. This study focuses on the development and evaluation of a colloidal silica-based fluid system tailored for high temperature water shut-off applications in challenging reservoir conditions. The system comprises colloidal silica and an activating salt, characterized by its low viscosity, enabling deep penetration and effective treatment. The evaluation methodology employed in this study encompasses visual assessment of gelation time and precise viscosity measurements. Key findings include the influence of temperature, salt concentration, silica content, and activating salt concentration on gelation kinetics. Higher temperatures, increased salt concentration, and elevated silica content were found to significantly expedite gelation, impacting the system’s efficiency. Moreover, different activator ions exhibited varying effects on gelation, primarily attributed to their charge density and size, adding nuance to the gelation dynamics. The study also revealed the system’s sensitivity to even minor variations in salt concentration, particularly when exposed to elevated temperatures. Based on these findings, a practical application strategy is proposed. When deploying silica gels in formations characterized by high salinity formation water and elevated temperatures, the introduction of a low-salinity water preflush is advised. This strategic approach mitigates premature gelation, ensuring the effectiveness of water shut-off operations. Keywords: water shut-off; silica gel; gelation time; sandpack; high temperature.