One of the critical measures of success in matrix acidizing is having the acid distributed across all the zones of interest, thus ensuring they are all stimulated. This applies to production and injection wells where most zones are not homogeneous in terms of permeability, porosity, water saturation, or the degree of damage they have experienced; therefore uniform distribution of acid during the acid job is seldom achieved. For producing wells, this task is further complicated when high water-saturation zones form part of the pay interval; not only do the producing zones get inadequate stimulation, but the water zones get preferentially stimulated to produce large quantities of unwanted water that can kill the well or increase the lifting and disposal costs for the well.
Many acid-diversion techniques, mechanical and chemical, are available to help achieve even distribution of acid, but addressing water control and stimulation of the preferred zones in one treatment is uncommon. A new acid-diversion technique using associate polymer technology (APT) applied in the western-desert region of Egypt achieved tremendous results when compared to similar wells treated in the area. In one case, the production results from the well treated with APT were as high as 5,000 BFPD with negligible (0.02%) water cut compared to another well that produced similar fluid quantities, but with more than 50% water cut.
This paper discusses the first use of APT technology in the Al-Amein dolomite reservoir of Egypt and compares it with the earlier uses of other diverting methods in the same field. This same diversion technique was also recently used in another carbonate reservoir Abu Roash "G" (in the same field) on an injector well and it improved its injectivity index eight-fold. These successful stimulation case histories from the two reservoirs are elaborated in this paper.