Abstract

Unburied pipelines are used for the transport of product and water in deepwater hydrocarbon developments. A critical design issue is the accommodation of thermal loading due to expansion and contraction of the pipeline with the changes in the temperature and pressure that occur during shutdown and restart cycles. A critical design parameter, with significant uncertainty, is the resistance to axial movement of the pipeline created by interaction with the seabed. This gave the impetus for the present study.

This study commenced with element testing using a simple interface strength testing device developed at the Schofield Centre to cope up with the low strengths and stresses associated with the problem. A number of model scale tests with actual pipe sections were also conducted. The influence of a range of parameters including pipe diameter, pipe length, pipe weight, pipe speed, surface roughness, cyclic loading, pause between cycles, and OCR of the clay were studied. The results are intriguing, yet challenging to interpret.