Shell has been cleared to resume drilling offshore Canada following a review to its procedures after an incident saw a 2km riser section drop to the seafloor.
Shell was drilling the Cheshire L-97 well, in about 2000m water depth, in the Shelburne basin, 225km off Canada, using the Stena IceMAX drillship, at the time of the incident on 5 March. The firm had appropriately followed procedures to mitigate heavy weather, suspending drilling, installing two barriers, displaced drilling fluid and disconnecting from the well to ride out the weather.
But, the tensioner system, which was holding the riser fully retracted with the anti-recoil system inactive, was unable to compensate for the heave of the vessel.
The Canada-Nova Scotia Offshore Petroleum Board (CNSOPB) halted operations operations after the incident and has reviewed in the incident and investigation board, with the help of Aberdeen Drilling Management (ADM).
The CNSOPB has required Shell lower its well disconnect criteria on the Stena IceMAX vessel to a heave of 5m, from the previous 8m.
CNSOPB CEO Stuart Pinks said: “We are satisfied that the cause of the incident has been properly determined and that appropriate corrective actions have been taken so that drilling may resume safely. As an additional safeguard, the CNSOPB has introduced a condition further tightening operating limits under which drilling may occur.”
Pinks says the CNSOPB continues to review the incident, including the investigation report, to determine if future regulatory actions or changes are required. No decisions have yet been made with respect to the riser that remains on the seafloor.
Image: The Stena IceMAX from Stena.