Abstract
Formation damage in the near wellbore region, causes impairment to fluid flow, perforations are designed to bypass the near-wellbore drilling damage by generating deep perforation tunnels and bypassing the damaged zone, however, perforation tunnels are affected by additional damage surrounding the tunnel (crushed zone) and by the debris filling the tunnel that are generated during the creation of the tunnel.
Several perforation techniques developed and used to overcome the perforation damage; some techniques consider living with the perforation damage and create small fractures in this damage to improve permeability, such as Extreme Over Balance (EOB), other techniques consider removing all crushed zone and debris out from the perforation tunnels, such as Under Balance (UB), and Dynamic Under Balance (DUB), these different techniques are suitable for different environment as will be stated in this paper. By tailoring the perforations to the specific environment, a significant productivity improvement can be achieved. All the techniques are briefly explained in the paper with more details on the DUB which was successfully utilized for the case study.
A tailored perforation design was implemented for KOC, that utilized the deep penetration charges combined with dynamic underbalance method, which further improved the perforation tunnel cleanout. This improved design resulted in achieving more than 30% increase in production in comparison to conventional Over Balance (OB) perforation design that was implemented in nearby wells.
