Dynamic Under Balanced Perforating Eliminates Near Wellbore Acid Stimulation in Low-Pressure Weber Formation

Abstract

Completions in the Weber formation have historically been perforated over balanced and then acid stimulated. Flow rates before acidizing were virtually 0 Mcf/D. Acid was an important step in the completion process. The Weber gas reservoir has low permeability (0.5 - 1.5 mD) and is now low pressure (2800 to 2300 psi at 14,000 ft). Typical flowing rates for these wells range from 1 to 5 MMcf/D. A new perforating technique utilizing the dynamic under balanced method was implemented in two wells, Brady 38W and Brady 56W. The wells were perforated with tubing-conveyed guns with initial over balances of 3250 and 3750 psi. The dynamic under balanced method creates an instantaneous under balance even though the annular space between the gun and the casing is initially over balanced. This perforating method also leaves significantly less perforation