Study On The Reaction Characteristics Of Cleaning Steering Acid Rock

The viscoelastic surfactant acid is a new type of acid system which can be used for acid fracturing; it has excellent diverting ability, no residue and no damage to reservoir. In the acidification process, it is mainly by increasing the viscosity to block the high permeability layer temporarily, so that the acid can also enter the low-permeability layer, so it has great application prospects. Most of the current researches were focused on the rheology at low concentrations, while ignoring the acid-rock reaction rate, or researched only preliminary reaction rate, and ignoring the rate in the interim and latter part. Therefore, this paper studied the reaction properties of the reaction rate to explore the reaction characteristics.We synthesized erucic acid amide propyl betaine, by infrared spectra analysis showed that the molecular structure of the intermediate and final goals consistent with the design of molecular structure. Comparing with titration measurement results, a high concentration of hydrochloric acid pH value does not reflect the actual concentration of hydrochloric acid.In this paper, static method was used to study acid rock reaction characteristics under certain conditions. Use epoxy resin to wrap the upper bottom surface and the side of the core. So there was only one bottom surface had the chance to react with acid. Weight loss in unit time can be used to calculate the rate of reaction of calcium carbonate. Studies prove that the pure hydrochloric acid concentration of20%, the acid-rock reaction rate reached its maximum; and when the acid concentration in viscoelastic surfactant acid is about20%, acid-rock reaction rate of the minimum Ca2+will make a small increase viscosity of fresh acid but also increase the reaction rate. Preliminary reaction of acid rock, hydrochloric acid concentration decreased and Ca2+concentration increases, the synergy make the viscosity acid increased significantly, but only a slight decline in the rate of reactionTo study the dynamic reaction characteristics, drainage gas unit was designed and assembled; calculate the reaction rate by carbon dioxide increased per unit time. Only in the5%VES+20%HCl+additives, the viscosity first increase significantly and then decrease sharply; meanwhile, the reaction rate decrease significantly and then increase sharply, eventually dropped to0. Reaction rate is inversely proportional to the viscosity. This group is the most suitable formula for diverting acid fracturing operations in theoretically.