MIXTURE OF HTO/HF ACIDS TO STIMULATE SANDSTONE FORMATIONS

摘要

A composition of a mixture of at least three organic acids with hydrofluoric acid (HF) generates a system that stimulates subterranean sandstone formations, enhances the permeability thereof, and therefore increases the formation's productivity. This system has a very low corrosion rate and may start with a pH greater than about 2. It is suitable for high temperature wells (greater than about 250° F. (121° C.)) and wells completed with specialized metal alloys. The system is hydrochloric acid-free and is compatible with high clay formations. Particularly suitable organic acids include, but are not necessarily limited to, the dicarboxylic acids succinic acid, glutaric acid, adipic acid, and mixtures thereof. Alternatively, the hydrofluoric acid is supplied by a substance that hydrolyzes to HF (e.g. ammonium bifluoride) and boric acid is included to delay the hydrolyzing to HF.