Abstract: In response to the problems of the impact of residual acid backflow on the production process and the insufficient corrosion performance of chelating neutral plugging removal agents during the acidizing plugging removal process of oil wells in the Bohai Oilfield, a new type of buffered direct - discharge acid system was developed. This system uses carboxylic acid with a low relative molecular mass and its ammonium salt as the main components of the buffer solution. A low - mass - fraction hydrochloric acid is introduced as the pre - fluid to improve the initial corrosion efficiency. Ammonium hydrogen fluoride, hydrofluoric acid, iron ion stabilizers (hydroxyethylidene diphosphonic acid and citric acid) suitable for high pH values and other additives are compounded in the treatment fluid. Combined with the secondary pH adjustment process, the unity of high corrosion performance and backflow compatibility is achieved. The experimental results show that the pH value of the pre - fluid of the system is 0.300, the pH of the treatment fluid is 3.534, the pH of the residual acid is stable between 5 and 7, the corrosion rates of calcium carbonate, bentonite and cuttings reach 75.25%, 34.70% and 15.73% - 20.91% respectively, and the iron ion stabilization capacity reaches 175 mg/L. Field application shows that this system does not require alkali neutralization, the backflow fluid can directly enter the production process, the production increase ratio reaches 1.38 - 2.18 times, and the effect is comparable to that of conventional acidizing. This research provides a new technical path for efficient and environmentally friendly acidizing plugging removal in offshore oilfields.