The results of stimulation treatments in southern Mexico’s carbonate reservoirs have been significantly improved using a new fiber-assisted, self-diverting acid system. These reservoirs are thick, deep, and hot. Depths are usually greater than 15,000 feet, bottomhole temperatures reach up to 350°F, and permeabilities range from 1 to 1000 mD within the same interval. Wells are typically completed with multiple perforated intervals. In the past, high-viscosity diverting fluids have been used to improve zonal coverage during stimulation treatments. Despite repeated treatments during the life of the well, in many cases, post-treatment logs show that the treatment was not effectively diverted to lower permeability, less productive intervals. To overcome these challenges, we introduced an innovative degradable diverting acid system combining the properties of viscoelastic diverting acid (solid-free) and degradable fibers to southern Mexico. This, combined with a rigorous candidate selection process, resulted in improved zonal coverage, increased oil production, and higher ultimate reserve recovery.

Maximizing oil production using this diverter system requires a detailed understanding of the petrophysical properties of the reservoir and production history. This information helps determine treatment volumes and the volume and number of diverter stages. Wells with the highest permeability contrast are often the best candidates. In many cases, producing from natural fractures depends on correctly determining the number and volume of the diverter stages. The experienced gained from treating more than 10 wells has resulted in the development of clear guidelines with respect to the treating fluid, volume, and number of diverter stages. On average, the guidelines have resulted production increases of 1,500 BOPD. By applying the treatment guidelines with an effective diverter fluid, operators can significantly increase oil and gas production in previously stimulated or new wells within naturally fractured carbonate reservoirs.