Patent ID: 7704926

Claim:
A wellbore service fluid, comprising: an aqueous viscoelastic composition that comprises cleavable surfactant, the cleavable surfactant comprising a reverse amide surfactant or a reverse ester surfactant and having the structure of formula 1, formula 2 or formula 3: R 1 —X—(CR 5 R 6 ) m —Y ⊕ Z ⊖ Formula 1 or R 1 —X—(CR 5 R 6 ) m -A ⊖ B ⊕ Formula 2 or R 1 —X—(CR 5 R 6 ) m —Y ⊕ -A ⊖ Formula 3 where (i) R 1 is a saturated or unsaturated, linear or branched aliphatic chain of at least 18 carbon atoms; (ii) X is an —, or R 7 N(CO) group; (iii) m is at least one; (iv) Y ⊕ is —NR 2 R 3 R 4 ; (v) R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently hydrogen; a linear or branched, saturated aliphatic chain of at least 1 carbon atom; or a linear or branched, saturated aliphatic chain of at least 1 carbon atom with one or more of the hydrogen atoms replaced by a hydroxyl group; (vi) A ⊖ is a sulfonate or carboxylate anionic group; (vii) Z ⊖ and B ⊕ are ionic counterions associated with a cleavable surfactant of formula 1 or formula 2, where Z ⊖ is a monovalent anion or divalent anion and B ⊕ is hydrogen or a monovalent cation; wherein: the cleavable surfactant is cleavable at the group X into breakdown products that are soluble in oil or water and include the alcohol R 1 —OH or the amine R 1 —NHR 7 ; and the cleaving of the cleavable surfactants into the oil or water soluble breakdown products removes viscoelastic and viscosifying properties of the wellbore service fluid and reduces potential for the wellbore service fluid to form emulsions.