Negative Equipment LL with Wellesley

Kallåsen (35/12-6 S) – Surface section

What happened:

The WHIM or “funnel” on the seabed for pumping mud up to the rig, filled up with gumbo and large cuttings. It was attempted to clean this out by back-flushing mud from mud hose going up to rig, without success. The volume inside the WHIM was therefore reduced significantly and this made it hard for operators to ensure fluid level was correct when pumping at high flowrate (4000 lpm). In the end, the WHIM was pumped off the 30″ WHH, and SW was sucked in. BU time was 23 min with 4000 lpm. The leak was discovered after 30 min., during this time the entire mud system was made useless (went from 155 kg/m3 KCl to 100.).

What was planned:

Use IKM MRR system to pump mud from seabed to surface

What was learned:

The WHIM design was not adequate for cleaning out gumbo and large cuttings.

What actions are required:

For next operation with MRR system, evaluate to use a WHIM with hi-pressure nozzles in bottom that can jet and clean out gumbo.