Malampaya Deep Water Gas-to-Power Project: Subsea Umbilical Challenge

Abstract

The Malampaya field development in the South China Sea comprises subsea wells in 820 metres water-depth producing via a subsea manifold and two 16 inch diameter inconel clad flowlines to a shallow water platform 30 km distant in 43 metres water-depth. Condensate is removed on the platform and the dry gas is then transported via a 24 inch diameter, 504km long export pipeline to an onshore gas plant at Tabangao (Batangas, Luzon Island) for extraction of H 2 S. The condensate is stored in the platform concrete gravity structure (CGS) caisson prior to export via shuttle tanker from a catenary anchor leg mooring (CALM) buoy located 3km from the platform.Two umbilicals are installed between the Malampaya platform and the ten slot subsea production manifold. Each umbilical provides methanol injection, annulus vent service and electric and hydraulic control.The dual umbilical solution for Malampaya is perhaps unique in that the cross sections are identical and the system design features redundancy within each umbilical and between the two umbilicals. The services are routed subsea to facilitate safe isolation and permit limited production in the event that all services in one umbilical are not available. This availability objective was driven by the high priority placed on cost effectively minimizing downtime across the entire system and the discipline to concentrate on lifecycle cost rather than capital expenditure (this subsea development is the sole source of gas to a major electrical power generation network and downtime is a major concern). The majority of steel tubes in the cross section were required for methanol service to the subsea manifold for injection at the manifold headers and the trees. Unlike common methanol injection lines for hydrate prevention, the tubes were required to transport regenerated methanol with potential H 2 S carryover from the produced gas stream.To prepare for the installation campaign in a region with minimal supporting infrastructure, contingency planning was emphasized and included an onshore full scale evaluation of vessel tensioner holding capacity in order to safely increase the operating envelope of the vessel lay spread.The paper concentrates on the numerous challenges associated with design and logistics; material selection, the novel procurement strategy for steel tubes, delivery logistics for 768km of tubes, the extensive welding campaign and the remote installation.

Mechanical characteristics analysis of horizontal lifting of subsea pipeline with different burial depths

“…The dynamic analysis of pipelines was made by Bai and Zhang, from which the lumped mass method was derived (Bai et al, 2018). The research on subsea pipelines involves all aspects, including structural analysis (Knapp and Shimabukuro, 2007), dynamic response analysis (Williams and Paton, 2002;Ajayi and Aribike, 2015), renewable energy (Martinelli et al, 2010), vortex-induced vibration (Liu et al, 2022), and installation process (Gao et al, 2014;Gong et al, 2014).…”