Marine Technology Reporter Blogs - collapse

The quality of a cementing job is vital to the safety, efficiency and cost effectiveness of deepwater well. Yet, well casings can be made even safer by the addition of a barrier in the annulus between casings. Offshore service providers have developed a variety of ways to create this extra barrier. Baker Hughes has developed its version of a secondary mechanical pressure barrier above the uppermost hydrocarbon zone, designed to prevent any unintended and uncontrolled flow of reservoir fluids to surface in the event of failure of the cement barrier, and also help boost production rates by eliminating flow that would otherwise be lost to the annulus (if positioned in the B-Annulus*). Their solution is an electronically actuated packer with proven zero-extrusion gap seal technology.

Deepwater O&G pipelines, used to transport oil and gas from offshore production units to onshore refineries, are subjected to the corrosive effects of salt water and to massive internal and external pressures. The risk of structural collapse in a pipeline is largely dependent on the levels of internal and external corrosion affecting pipe sections and on the amount of internal and external pressure on the pipe. Corrosion is a time dependent phenomenon that usually requires several years to produce a corrosion defect sufficiently large to cause a significant reduction in the collapse pressure of a pipeline. Consequently during installation it is considered that the pipeline is free of any metal loss due to corrosion.

Based on project experience, research, and joint industry development work, DNV issues a number of pipeline codes. These comprise service specifications, standards and recommended practices, and are highly regarded within the international pipeline community. The DNV OS-F101 ‘Offshore Standard for Submarine Pipeline Systems’ provides acceptance criteria and design procedures for pipelines. The standard applies modern limit-state-design principles with ‘safety classes’ linked to consequences of failure. The DNV standard is complemented by several recommended practices (RPs), which give detailed advice on how to analyze specific technical aspects according to stated criteria.