Optimize perforation performance in overbalance environments

To perforate long horizontal North Sea wells, Statoil sought a safer, more efficient technique that would not compromise well performance in the process. An overbalanced shoot-and-pull technique using conventional completion fluids would have resulted in unclean perforations, leaving the operator with low productivity. However, with a completion fluid customized to meet specific reservoir needs, Statoil could continue using the shoot-and-pull technique while obtaining optimal productivity.

Design field-specific technique and fluid

To address Statoil's specific needs in this North Sea scenario, a custom completion fluid was designed with the operator's reservoir characteristics in mind. Additionally, a proposed perforating system and dynamic underbalance technique were designed and tested to further optimize production. Both the fluid and the technique were evaluated at the Schlumberger Performance Enhancement Research Facility (PERF) near Houston using the same perforating gun technology and dynamic underbalance as was used in the field. Prior to deployment, studies from the PERF lab demonstrated that the combination of a customized perforating strategy and fluid system could deliver superior well performance in challenging conditions.

Enhance productivity through efficiency

After safely and efficiently perforating several wells in its program with the proven, optimized technique developed at the PERF lab, Statoil recorded excellent productivity in the field. According to the operator, the development of a unique perforating fluid designed specifically for long horizontal wells played an important role in the overall perforating strategy. In addition to improving the productivity of Statoil's completions program, the customized fluid and dynamic underbalanced perforating technique contributed to the cost-effective operation.

Additional reading:

Chang, F.F., Walton, I.C., Kageson-Loe, N.M., Mathisen, A.M., and Svanes, G.S., “Perforating in Overbalance—Is it Really Sinful?” SPE paper 82203, presented at the SPE European Formation Damage Conference, 13–14 May, The Hague, Netherlands, 2003.

Chang, F.F., and I.C. Walton, Schlumberger; A.M. Mathisen, R.E. Midtbø, I. Bakken, J. Rykkje, and O. Nedrebø, Norsk Hydro A/S; N. Kågeson-Loe, BP; G. Svane, M-I Norge, “Recommended Practice for Overbalanced Perforating in Long Horizontal Wells,” SPE paper 94596, presented at the SPE European Formation Damage Conference, 25–27 May, Sheveningen, The Netherlands, 2005.