Over 300 matrix and fracture acidizing treatments, utilizing a thermally stable acid gelling agent, were performed in carbonate formations, worldwide. The initial results of several treatments were presented earlier (Ref. 1). Since then, trends toward sustained increases in production have been documented and are presented. Reductions in production decline rates have resulted in improved recovery of reserves.

Improved live acid penetration results from the effects of stable viscosity, retarded reaction rate and proper treatment design. In addition, the gelling agent must be non-damaging, requiring tolerance to calcium and magnesium ions in the spent acid during cleanup. A gelling agent is described that provides the features of thermal stability and solubility in the live and spent acid.

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