Pre-frac’ #welltests have proven successful using closed chamber methods. Surface pressures are recorded during perforation. The surface pressure buildup is proportional to gas influx into the closed chamber (wellbore). Quantitative order-of-magnitude results (kh, s’) can be estimated using Perforation Inflow Test Analysis (PITA & Slug) methods. Analytical results are useful for deriving a permeability cutoff prior to frac’ing, weeding out high perm’ response from the frac’ program, or sizing frac’ treatments.
Closed-chamber tests have been utilized for many years as an alternative to drill stem tests. The technique is transferable to several alternative welltest solutions.