FEA of a Laminate Internal Buckle Arrestor for Deep Water Pipe-in-Pipe Flowlines

Development of deepwater oil reservoirs has been undertaken in the Gulf of Mexico (GoM) where flowlines are installed in water depths in the vicinity of 2,740m (9,000ft). Preventing the propagation of local collapse/buckle failures is one of the key engineering design limit states that is defined in the industry codes to ensure the pipeline integrity. Deep-water buckle propagation is almost unavoidable as the wall thickness selection cannot be directly driven by the buckle propagation limit state. Field data indicates that once a buckle happens, the flowline could collapse for many kilometers instantly. Buckle propagation could cause substantial economic impact if left uncontrolled. For Pipe-in-Pipe (PIP) flowline, due to lack of pressure differential, the jacket pipe is a fragile component in terms of buckle propagation. It is crucial to prevent any possible local buckling during the flowline installation and during the entire operational lifetime. One way to stop buckle propagation is to utilize buckle arrestors of various types. Successfully designed buckle arrestors can contain such disasters to a limited pipeline section. Internal buckle arrestors are a relatively new solution for PIP systems being investigated by the industry. As it is installed in the annulus of PIP, it becomes a preferred choice since it fits all types of installation methods. The objective of this paper is to present the design and finite element analysis (FEA) of a laminate type internal buckle arrestor, and to investigate the effectiveness of this innovative buckle arrestor design for deepwater flowline. Sensitivities of key design parameters are explored with the purpose of guiding detailed mechanical design.