A novel foamed acid treatment has proven effective in the workover of more than 20 wells in the Permian Basin Delaware, Grayburg, and Upper Clearfork formations. The treatment described uses a foaming mutual solvent/acid system. This system provides the desirable wetting and solubilization properties of a mutual solvent and acid along with the inherent advantages of foam. The uniqueness of this treatment is derived from the prolonged stability of the foam, a property not characteristic of foamed mutual solvent systems.

Data is presented from both laboratory and field tests comparing this procedure to conventional foamed acid techniques. Detailed treatment designs are presented which are applicable in coiled tubing and workover strings. These procedures have been used in treatment of injection and producing wells. The treatment described is especially effective in low pressure wells where previous workovers have resulted in poor performance.

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