Failure analysis of the tripping operation and its impact on well control

• Published in: Volume 1: Offshore Technology; Offshore Geotechnics
• Main Authors: Abimbola, M, Khan, F, Garaniya, V, Butt, S
• Format: Conference Object
• Language: English
• Published: American Society of Mechanical Engineers 2015
• Subjects: Engineering; Maritime Engineering; Ocean Engineering; Arctic
• Online Access: http://proceedings.asmedigitalcollection.asme.org/ConferenceProceedings.aspx; https://doi.org/10.1115/OMAE2015-42245; http://ecite.utas.edu.au/99597

As the cost of drilling and completion of offshore well issoaring, efforts are required for better well planning. Safety isto be given the highest priority over all other aspects of wellplanning. Among different element of drilling, well control isone of the most critical components for the safety of theoperation, employees and the environment. Primary wellcontrol is ensured by keeping the hydrostatic pressure of themud above the pore pressure across an open hole section. A lossof well control implies an influx of formation fluid into thewellbore which can culminate to a blowout if uncontrollable.Among the factors that contribute to a blowout are: stuck pipe,casing failure, swabbing, cementing, equipment failure anddrilling into other well. Swabbing often occurs during trippingout of an open hole. In this study, investigations of the effectsof tripping operation on primary well control are conducted.Failure scenarios of tripping operations in conventionaloverbalanced drilling and managed pressure drilling are studiedusing fault tree analysis. These scenarios are subsequentlymapped into Bayesian Networks to overcome fault treemodelling limitations such s dependability assessment andcommon cause failure. The analysis of the BN modelsidentified RCD failure, BHP reduction due to insufficient muddensity and lost circulation, DAPC integrated control system,DAPC choke manifold, DAPC back pressure pump, and humanerror as critical elements in the loss of well control throughtripping out operation.