Negative Operational LL with Faroe

Rungne (30/6-30) – Intermediate section

What happened:

Unable to set 9 5/8″ seal assembly. Observed initial pressure increase but unable to pass 100-120 bar before pressure broke down. Confirmed no increase in TT (BOP holding pressure). Confirmed no returns up DP (RT seals holding pressure). Observed cuttings/clay packed around RT after POOH. Observed no deformation of lead pins inside seal assembly that was pulled out with RT, hence seal assembly had not moved down over the casing hanger.

What was planned:

Setting 9 5/8″ seal assembly.

What was learned:

Likely cause of problem was cuttings in the wellhead area–> ran mill and flush tool to clean profile for seal assembly. Observed nylon pins inside tool were deformed after run. Indicated tool had washed down and touched top of casing hanger. Other posssibility was insufficient landing string weight to fully set the seal assembly. Casing was landed on 5 1/2″ DP which was only 6 mt at this water depth. Hung off 10 mt 5 1/2″ HWDP below seal assembly RT when setting back-up seal assembly. Third possibility is that Dril-Quip recommend 690 bar pressure to force-set seal assembly, but only 345 bar was used. Decided to increase this pressure to 431 bar (BOP test pressure) on second attempt setting back-up seal assembly.

What actions are required:

Recommend to use 5 1/2″HWDP in future which will give about 11 mt landing string weight.