A Brown field, offshore Malaysia, has been in production for over 30 years. The Brown field has low rock strength in shallow reservoirs, while the deeper reservoirs consist of stronger and stiffer formations. As a result, the completion for shallow reservoirs requires gravel pack treatment, whereas the deeper reservoirs can be completed without particular requirements of sand control.
Big hole charges followed by mechanical surge are the preferred perforating technique for an optimum gravel pack. For consolidated formations, deep penetration charges, with a dynamic underbalance, are more suitable to maximize inflow. Historically, multi-zone completions in field wells are performed in stages: the deeper zone is perforated and conditioned first; followed by the upper interval, which is perforated, gravel packed, completed and connected to the lower section.
This paper presents the combination of the two perforating techniques in one operation. It also discusses the candidate identification process, perforation design, formation damage analysis, execution and results. The gravel packs were performed successfully with a GP factor higher than predicted by simulations, and the initial production behavior suggests no evidence of adverse effect on formation damage even when the mechanical surge required for the big hole charges was done higher than conventionally.
Considerable rig time savings were achieved by eliminating a Tubing Conveyed Perforations (TCP) run and clean out operation. The operation was performed in 60.8% of the time observed in a previous similar well. The combined perforating technique is suitable for cases where the reservoir properties are very well known.
Based on the result of the world first combination of these techniques, continue supporting the implementation of this optimized solution in future wells is high recommended.