Employing an Asymmetrical Anchoring Solution for Rigid Flowline Riser System Adopting Single Torpedo Piles

This paper introduces the technical pipeline anchoring solution deployed for rigid flowlines of the Buzios field. Based on the usual combination of an anchoring pile, a chain and an In-Line Anchor mounted as part of a rigid flowline, this solution stands out on two accounts: the use of torpedo piles, and an asymmetrical configuration with a single fixed point. This paper addresses the technical challenges associated to it in terms of flowline design in order to guarantee the robustness of the system. Chain slack management stood as the most critical challenge, due to the inherent extra chain length needed to connect the torpedo pile to the ILA, with the relative angle between the chain and the flowline coming second. Although one might surmise the design to be governed by the extreme values of these parameters, the analyses carried out demonstrated specific limit states to be occasionally maximized at intermediate values instead, thus requiring more scrutiny and precision in the load cases matrices. This paper also discusses the importance of properly implementing and modelling the ILA in global flowline models. Lastly, the benefits of this new solution are discussed, in terms of how it improved installation requirements and overall project readiness.