Challenge: Underream 6 1/2-in rathole to 8-in with a separate cleanout BHA, which would also be used for effective high-flow-rate hole cleaning and mud conditioning prior to a completion run.
Solution: Drill and underream 6 1/2-in × 8-in hole section with directional tools below Rhino XS hydraulically expandable reamer, then underream 6 1/2-in rathole to 8-in with a separate cleanout BHA; use 5-in WELL COMMANDER ball-activated drilling circulating valve above reamer to bypass flow to annulus and keep cutter arms collapsed.
Results: Saved 2 days of rig time on an offshore platform; achieved operator’s goals and set the benchmark for future underreaming operations for at least two other BP offshore platforms.