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.