Patent ID: 7781381

Claim:
A method for enhancing the productivity of a hydrocarbon-bearing calcareous or siliceous formation which comprises: (A) introducing into a wellbore penetrating the formation an aqueous well treating composition comprising: (a) a boron containing compound selected from the group consisting of (i.) fluoroboric acid and (ii.) boron compounds capable of forming a BF 4 − complex when exposed to F 4 − or a hydrofluoric acid source; (b) a phosphonate acid, ester or salt thereof, wherein the phosphonate is of the formula: wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, aryl, phosphonic, phosphonate, phosphate, aminophosphonic acid, aminophosphonate, acyl, amine, hydroxy and carboxyl groups and R4 and R5 are independently selected from hydrogen, sodium, potassium, ammonium or an organic radical; and (c) a hydrofluoric acid source; and (B) preventing and/or inhibiting the formation of inorganic fluoride scales in the wellbore and/or formation by forming a BF 4 − complex and thereby enhancing the productivity of the formation wherein the combination of boron containing compound and the phosphonate acid, ester or salt creates a synergistic effect such that the amount of inorganic fluoride scales precipitated in the presence of the combination is less than the amount of inorganic fluoride scales precipitated when either the boron containing compound or phosphonate acid, ester or salt is used alone.