Paper: Heated Acids For Improved Stimulation Results

Heated acids have been used extensively with excellent results as shown by field data and laboratory tests. A primary use of heated acids is to increase dissolution and reactivity in relatively cold formations for improved flow capacities in, for example, cold dolomites. This aids treatment (1) technique effectiveness by increasing the acid reaction rate, (2) removing acid retarding materials such as oil, asphaltenes, and paraffins from formation surfaces for a better acid-formation contact, (3) helping prevent the precipitation of organic materials from oils that have been cooled by acids, and (4) limiting temperature contraction of tubing during a treatment. On acidizing treatments conducted during the winter , acid temperatures can be less than 32_F. The effectiveness of these treatments can be improved by heating the acid and thus avoiding the problems of slow reaction rate,-precipitation, and tubing contraction. Three general acid heating techniques are used: (1) an exothermic chemical reaction with a portion of the acid as one of the reactants, (2) adding live steam to the acid, or (3) using hot oilers to heat the water portion prior to dilution.