Collapse Propagation of Deep Water Pipelines

Nowadays, the global trend is an increasing need for oil and gas. As the easily recoverable fields have been already developed, the trend in the offshore oil and gas industry is going deeper into the more challenging outlook, such as outside West Africa, the Brazilian Pre-Salt developments and in the Gulf of Mexico. For ultra-deep waters the main design challenge is related to the high external pressure that may cause collapse of pipelines. This potential failure mode is normally dealt with by increasing the pipe wall thickness, but at ultra-deep waters this may require very thick pipe that becomes very costly, difficult to manufacture and hard to install due to its weight. Facing the challenges of the pipeline design for ultra-deep waters, the Collapse Joint Industry Project (JIP) was started to develop a guideline for wall thickness design optimization for offshore pipelines with external diameter to wall thickness ratio less than 20 (D/t < 20). As part of the JIP, nine buckle propagation tests were conducted on full scale seamless pipes. This paper describes these experiments and new conclusions that were raised in light of the test results.