Subscour Displacements for Pipeline Design: State of Practice for Kashagan Project

摘要

The Kashagan field is located in an area of the Caspian Sea that is subject to ice scouring of the seabed. Offshore pipelines are buried to mitigate the ice loads arising from scours, and the optimum burial depth is an important design consideration. Within the design process, it is the displacements in the soils below the scouring keel (subscour displacements) which need to be estimated as inputs to the pipeline design. Quantifying subscour displacements has been the subject of intense study for the Kashagan project in the last 10 years, involving physical tests at a range of scales, advanced numerical modelling and several join industry research projects. This paper describes the development of subscour displacement models for sands and clays for the Kashagan project. It starts with a background to the work that has been done in a broader context before describing the specific relationships defined for Phase 2 of the project, as well as some of the uncertainties involved. There is still much work to be done to refine the models that are still a work-in-progress.