US Patent 7318475 Matrix acidizing high permeability contrast formations

A method for stimulating thick or multilayered heterogeneous or homogeneous formations in a single trip without packers involves perforating with tubing conveyed perforation, then injecting a self-diverting acid, then moving the tubing string and perforating at a new location, and then injecting additional self-diverting acid. The sequence may be repeated. The acid is preferably a viscoelastic diverting acid. The self-diverting acid may be alternated with conventional treatment fluid. The job is designed to treat the least permeable zone(s) first and maximizes acid efficiency.