Solubility of silica in alkaline solutions: Implications for alkaline flooding

The expected loss of useful alkalinity for a pure quartz sand via the slow dissolution of silica is shown for some ''typical'' alkaline flooding solutions (ca. 1% NaOH or 1.25% sodium orthosilicate) to be only about 10-20%. This conclusion is based on the observation that alkaline solutions equilibrate with quartz. Titration curves of the equilibrated solution, when compared to similar curves for the initial alkaline solution show relatively small alkaline losses. Furthermore, the dissolution of quartz in alkaline flooding can be eliminated by employing solutions which are saturated in silica with respect to quartz. Such formulations may be useful in controlling the erosion of the wellbore and gravel pack.