In this paper we describe the challenges and the techniques used to deliver zero perforation skin wells in the Blacktip gas field offshore Australia. We describe the software models used to evaluate both the well perforation design and the operational risks, and the approach used to reduce rig time. Software modelling based on historical experimental data and newly developed rock perforating models, showed that cleanup with dynamic underbalance would deliver the highest well productivity. Minimum rig time utilization was achieved with wireline conveyed guns. Two methods of deployment were used. To perforate long intervals quickly and safely guns were conveyed on wireline and anchored in the casing with a system that automatically dropped the entire string into the sump after firing. This technique requires less rig time, but it is only applicable to wells with a total gunstring weight lower than the wireline safe working load. The second technique for multiple spaced out payzones used conventional, multiple wireline trips.

All relevant aspects of the perforating jobs, including gun carrier filling after firing, wellbore pressure waves, reservoir flow, and perforation tunnel cleanup were predicted. For each job, guns were custom loaded so as to produce enough dynamic underbalance (DUB) to remove the low permeability crushed rock zone around perforations, thus minimizing perforation skin and maximizing well productivity.

The Blacktip wells were safely perforated for Eni Australia. In addition, we achieved the objective of zero perforation skin and saved more than one day of rig time. The technologies described in this paper can be applied worldwide, saving significant amounts of money and delivering highly productive wells.