Noble Corporation’s ultra-deepwater semi-submersible drilling rig Noble Jim Day was running 20-inch casing last week at Walker Ridge 508 when sources tell gCaptain currents of up to 4.5 knots began to seriously complicate operations.
Sources who requested anonymity in exchange for the information tell us that with thrusters and engines maxed out, the rig was unable to remain in position over the wellhead where they were set to run approximately 3000 feet of steel casing into the wellbore.
After unsuccessful attempts to pick up the casing or hold position, the decision was made to drift off station, but in the end, the casing sheared away at or near the rotary table on the rig.
A source tells gCaptain attempts are being made to locate the casing on the sea floor, however currents are hampering subsea ROV operations.
Based on the information received, it seems likely that extreme sheer forces exerted on the casing by the current created a situation where the pipe did not hang vertically from the rig, hindering the ability of the drillers to lift the casing out of the hanger. Additionally, vortex induced vibrations resulting from the flow of water past the casing would have also likely been a contributing factor in the structural degradation of the pipe at the hang-off point.
While in the Netherlands today, Leon Adegeest, General Manager and founder of Amarcon B.V., a fully-owned subsidiary of ABB, notes in a presentation his company’s Octopus program could likely have been used to model and predict this incident prior to it occurring.
Octopus is a system acquired by ABB in 2012 that enables bridge watch-standers to continuously monitor, simulate, and forecast ship responses and performance through complex calculations derived from sea state data, weather forecasts, real-time navigation data, the voyage plan, the vessel’s hydrodynamic characteristics, the loading condition and motion sensors.
The core market for Octopus has been the heavy lift industry, but Adegeest notes that pipelay operators utilizing dynamic positioning have also used this program heavily. He says that Octopus interfaces seamlessly with OrcaFlex, a system utilized by riser engineers to simulate subsea conditions encountered by subsea flexibles such as risers, umbilicals and pipelines.
Utilizing Octopus for drilling contractors would have to be a rather custom situation, but considering the casing that broke from the Noble Jim Day was essentially the same thing as a 20 inch riser from a hydrodynamic standpoint, the Octopus system may have provided useful guidance prior to the incident had it been utilized.
We have reached out to Noble Corporation for comment, but have not yet heard back.
The Noble Jim Day is under contract to Shell at the Stones field in water depths of up to 9,568 feet.