The aims of this study were to design a cost-effective stimulation treatment to remove formation damage from water injectors in a recently developed sandstone field in Saudi Arabia and enhance well injectivity, while maintaining formation integrity. This paper examines the design of the treatment, field monitoring, and analysis of acid returns. Core flow experiments were performed to screen various acid formulations, and evaluate acid additives.

The designed treatment was applied on several water injectors. Acid returns were analyzed to evaluate the effectiveness of each treatment. It was found that a preflush of 5wt% NH4Cl solution was effective in displacing potassium and sodium ions from feldspars and clay minerals compared to a preflush that contained hydrochloric acid only. A multi-stage treatment was designed to remove formation damage encountered in several water injectors in this field. The treatment significantly improved the injectivity index of the treated wells.

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