Abstract
Development well K14-FB 102 was completed as a dual lateral in 1997 to optimise production capacity and reservoir drainage from a tight, Rotliegend sandstone in an offshore gas play in the Dutch sector of the North Sea. The two 5 7/8" horizontal production intervals were drilled and completed openhole using a rheologically engineered, minimal solids, non-damaging sodium formate brine based fluid designed as a drill-in fluid for reservoir intervals. The system was designed around the Low-Shear-Rate-Viscosity (LSRV) which is critical not only for hole cleaning and drilling performance, but also for minimizing filtrate invasion and potential formation damage by using minimal solids. The formate system exhibited superior hole cleaning qualities during the entire interval and no significant drag was observed during drilling. No pills were pumped prior to pulling out of hole and tripping proceeded without problems, verifying excellent hole condition. As a result of high ROP's, a 35% reduction in total reservoir drilling time was achieved. The resulting production capacity was 40% above expectation and a nearzero mechanical skin indicated that the reservoir interval had been completed with minimal residual drilling induced damage. The formate system, with its unique rheological profile, differs from other water-based fluids, and provided advantages not only for drilling technique but also enhanced HSE criteria.
