A safe and environmental-friendly solid acid with sustained release, high etching, and low corrosion

Abstract

Solid acid has attracted immense research interest in the deep acidification and acid fracturing of carbonate reservoirs. However, most of the current solid acid systems showed poor sustained release, anti-corrosion properties, acid-generating capacity (<6 wt% HCl), and harm to the environment, even the risk of explosion. Herein, a new solid acid, SAA, was obtained based on a modified organic anhydride. The sustained release property of SAA was up to 140 min at 60 °C, and the final acid concentration was almost equal to 8 wt% HCl. Additionally, the SAA showed stable acid-generating capacity in different temperatures, salinities, and polymer solutions. More importantly, the SAA showed excellent etching properties (>80% at 95 °C) and low corrosion properties to the mild steel coupons (<2.0 g/m2⸱h at 90 °C). Most importantly, SAA is beneficial to the pollution removal of drilling and completion fluid near the wellbore based on the pilot test. Therefore, the SAA has a bright potential in deep acidification, and in depressurization during hydraulic fracturing.