Research and Performance Evaluation of an Autogenic Acidic Fracturing Fluid System for High-Temperature Carbonate Reservoirs.

Carbonate reservoirs in Western China are characterized by deep burial, high temperature, and strong heterogeneity. In this paper, based on the physical properties of high-temperature carbonate reservoirs, the authors have developed an autogenic acidic fracturing fluid suitable for high-temperature carbonate reservoirs. The performance of the new acidic fluid has been experimentally evaluated. The results show that the fluid demonstrates satisfactory viscosity-temperature performance, and after continuous shear tests at 140°C for 2 h the viscosity of the fluid remains about 100 mPa∙s. At room temperature (RT), the pH value of the fluid is neutral, and the titratable acid concentration could reach 15.49% at 90°C. When subjected to high temperatures, the fluid is characterized by a high acid concentration, low acid generation rate, and moderate corrosion inhibition rate. The static rock corrosion rates of the fluid at room temperature and 140°C are 0.00009125 and 0.009575 g/min, respectively. The corrosion rate is slow, and the effective action distance of the fluid can be five times higher than that of a thickened acid and three times higher than that of a cross-linked acid. The experimental results verify the acid's ability to transform high-temperature carbonate reservoirs and good applicability in high-temperature carbonate reservoirs. The proposed autogenic acidic fracturing fluid system provides essential technical support for the efficient development of high-temperature carbonate reservoirs. [ABSTRACT FROM AUTHOR]