Estimation of Burial Depths for Pipelines in Arctic Regions

Abstract

Ice scouring poses a significant threat to underwater pipelines for offshore oil production facilities in ice-infested waters. For most locations, the only options against this hazard are to protect the pipeline by trenching, burial, or creative alignment. The optimal burial depths along the length of a pipeline are usually selected on the basis of a hazard model that describes the recurrence rate and severity of scouring along its length. Although sufficient data at a specific site are rarely available to accurately estimate the hazard model, several thousand scours have been documented over extended regions and can provide an estimate of scouring hazards at preliminary stages of design. The main features of the proposed model are a parametrization of the scouring hazard model as a function of water depth and exposure to the ice environment, and the propagation of uncertainties due to model incompleteness and sample size. The proposed model can be validated or readjusted at later stages of the project as more site-specific data become available. The application of the proposed model is demonstrated for the determination of the optimal burial depth for a hypothetical pipeline route.