West Sole Pipeline Stabilisation

Abstract

The BP West Sole gas field is located in Block 48/6 in the UK sector of the southern North Sea, about 70 km off the Holderness coast. Production from the gas field is exported to a shore terminal at Easington by two pipelines. Both pipelines were trenched at installation. Pipeline surveys over the last few years show that both pipelines are substantially exposed at the shore approach and inshore sections. This has occurred in part due to the retreat of the cliffs in Easington and subsequent lowering of the sea bed level and also the migration of sand from around the pipelines leaving them largely unburied and sitting on the local clay abrasion platform. It has been concluded that both pipelines require stabilisation sooner rather than later to reduce the risk of pipeline failure. Pipeline stabilisation options need to take account of the environment in which they have been placed. Easington is at a critical position along the Holderness coast. All net sediment transport from the Holderness coastline passes through this section. Any interruption to this movement could result in a change to the adjacent coast. Maintenance of the sediment budget is important to a wider area of the East coast of England. Stabilisation options must not reduce the net amount of sediment moving southwards past Dimlington and must not result in any long term negative impact on the coastal evolution. This paper outlines consultancy required and problems process regarding the geomorphological issues in getting acceptance from government and non-government bodies. A methodology has been developed that allows quantification of impacts of different options on the sediment budget and on the long-term coastal evolution (see also Chen et al 1998, 2001 and 2002). Application of this method aimed at providing understanding and information which is considered to be important in the process of selecting an optimal solution for the pipeline stabilisation in such an environmental sensitive coast.