Enzyme formulations should stay active and devoid of all possible inactivation processes during transport and long-term storage. The stabilization of enzymatic activity, especially in presence of critical functional components for specialized application, has been a long-standing obstacle when stored over an extended period of time. One such obstacle is the stability of enzyme in presence of weak acids in formulation, which is often desired to efficiently break down biopolymer filtercake embedded in a carbonate matrix, in the open-hole section of a horizontal well, for hydrocarbon production. The invention comprises methods and compositions to enhance the long-term storage stability of an enzyme formulation consisting of an in-situ acid precursor system, where in-situ generated precursors are mainly ester compounds that dissociate by slow hydrolysis to generate organic acid, shifting the pH of the formulation outside the pKa of the enzyme protein. The methods and compositions include the addition of high concentrations of metal halide salts, a pH control additive, and a water activity reducing agent. The methods and compositions of the invention provide a high degree of stability for enzyme formulation at long-term storage conditions.