Session: 04-04-05: Rigid Pipelines V

Submission Number: 156605

Deepwater RCM and SRI Performance on Production Rigid Flowline Loops 

Deepwater High Pressure High Temperature (HPHT) rigid flowlines laid on large slope seabed morphology, with complex operational loading and multiple subsea well tie-in locations, impose significant design challenges. This paper demonstrates the effective performance of a novel thermomechanical design for the production flowline loops of a project in West Africa, based on the surveys which were carried out post pipelay, pressure test and thermal loading. The design employed the Residual Curvature Method (RCM) to control lateral buckling and Subsea Rock Installation (SRI) to partially restrain the flowlines and control the flowline displacements at the tie-ins. This paper focuses on the as-laid configuration of the RC sections and the initial formation of the engineered lateral buckles, for a large range of RC section as-landed angles, considering also the formation of soil berms and the effect of transverse slopes. Furthermore, the effect of the cooldown of thick insulated flowlines, on the seabed just after pipelay from as-laid to ambient seawater temperature, is quantified. Additionally, the performance of the rock berms, during the pressure test and the first thermal loading, is evaluated. Moreover, the benefits of gradually heating up the flowline loops during hot-commissioning are discussed, considering the response of the flowlines and the objectives of this thermal pre-conditioning operation. Finally, this paper provides recommendations for future RCM and SRI designs based on lessons learned from this project.

Presenting Author: Nikolaos Chatzimanolis Subsea7

Presenting Author Biography: I’m a mechanical engineer working for the offshore oil and gas / energy industry for the last 15+ years. I hold a BEng/MEng in mechanical engineering from Aristotle University, Greece and a MSc in energy engineering from Heriot Watt University, UK. I currently work for Subsea 7, on rigid subsea pipeline design, based in London. My current role is the Discipline Manager for Rigid Pipelines for the Global Project Centres (GPCs), managing a team of 100+ pipeline engineers, in seven countries, providing engineering services for concept definition, tenders, FEEDs, EPCIs and internal developments across the globe. Additional, I am the chairman for Subsea7’s community of experts for rigid pipelines. My previous experience includes working for consultancies for the offshore oil and gas / energy industry as well as for building services. I am a member of the Institution of Mechanical Engineers in the UK (CEng MIMechE) and a licensed mechanical engineer in Greece by the Technical Chamber of Greece.