A North Sea operator planned to drill a horizontal production well using a water-base drill-in fluid followed by a gravel-pack completion. Due to interbedded, water-sensitive claystone, the operator sought an inhibitive reservoir drilling fluid and a reliable, noncorrosive filtercake cleanup solution.
M-I SWACO recommended a combination of technologies to optimize compatibility with the reservoir crude, stabilize the shale, and maximize cleanup efficiency—including FLOPRO NT water-base reservoir drill-in fluid and WELLZYME starch-specific enzymes. The drilling team drilled to total depth with minimal losses, ran the sand screens, and gravel packed the well using a high-rate water pack. When the screens were set, the operator experienced average returns of 60% and screenout at 145% of the expected gravel pumped. The treatment enabled the operator to overcome the challenges of drilling and completing in sensitive shale, meeting production targets as planned.