Protection of Subsea Pipelines Against Ice Ridge Gouging in Conditions of Substantial Surface Ice

Abstract

The development of Arctic offshore hydrocarbon fields involves transportation systems for oil and gas, which comprise their shipping by tankers or pipeline systems. The later have sustained behavior with respect to hydrocarbons delivery and relatively non-sophisticated operational requirements.</jats:p> <jats:p>However, some important challenges regarding Arctic conditions have to be assessed before the pipeline is constructed. Attention is given to the conditions of a specific hydrocarbon field off the Sakhalin Island, and the design of an offshore pipeline. The issue of the pipelines’ interaction with first year ice ridges is described, a design ridge is selected and two theoretical models for evaluation of the maximum scour depth produced by the ridge ploughing the seabed are introduced.</jats:p> <jats:p>Thereafter a beam model of a pipeline exposed to bending and tension in terms of combined transverse and lateral loadings is established and analyzed. Based on the limit state design criteria the required trench features for different soil conditions for the safety of the pipeline are specified. Following the required pipeline failure probability, it is documented that the pipeline might be buried just below the probable scour depth if certain conditions of a “sandwich” backfilling with a weak soil layer on the bottom are met.</jats:p> <jats:p>Conclusions summarizing the acquired findings provide reasonable recommendations for offshore pipeline design in the Arctic regions and suggest a scope for future works and studies.