HomeInhenyeriyavol. 1 no. 1 (2000)

Buffered Mainflush Formulation for Sandstone Acidizing

Noel P. Cabigon | Cristina G. Aquino

Discipline: Engineering



New non-hazardous mainflush mixtures for sandstone acidizing had been formulated. These formulations consisted of hydrofluoric acid or ammonium bifluoride and halogenated monocarboxylic acids, which served as buffering agents. The effectiveness of these formulations depended on buffering to enhance HF-silica reaction by controlling the pH and the available fluoride ions. Non-use of HCL eliminated the need for additives that were conventionally added to prevent casing damage. The solubility data indicated that the new formulations were comparable in terms of dissolving power to the formulation currently used by the geothermal industry. However, the new formulations were found to be more effective in controlling available fluoride ion concentration in solution, a property that enabled the mixtures to penetrate deep into the formation. The buffering ability of the new formulations to sustain the desired pH could be utilized to adjust the mixture to suit a particular acid job.