In both fields, initial well rates were disappointing, mostly due to a combination of difficult perforating conditions and significant drilling induced damage. However, more concerning than this was that as well production history was obtained, it became increasingly clear that the relative permeability effects were unusually severe in these quartz-arenite formations and that associated decline rates on the wells (due to GOR and condensate banking) were dramatic and severe.
Typically wells would have been immediately fracture stimulated to address this. However, early experience had already demonstrated that the regional tectonic effects were quite considerable and as the completions had not been designed for high-pressure fracturing operations and with many wells already drilled, this presented a significant complication.
In response to this, a team was formed to determine if and how BP could fracture stimulate in the most effective manner possible. This team proposed a number of solutions for both the fields, which were subsequently implemented. Issues that were addressed included coping with well deviation/azimuth, rigorous pre-frac well-bore preparation, novel frac-string deployment, fracturing (for condensate-banking) and an efficient remedial stacking of fracs.
Production rates increased dramatically and the decline(s) and condensate-banking issues were reduced, allowing the economic development of the two fields to continue.