Introduction

Shell Singapore operates a single buoy mooring (SBM) offloading line, supplying crude to the Bukom refinery from VLCC  (Very Large Crude Carriers) tankers via an offshore berth. The offloading system consists of an SBM connected to a pipeline end manifold (PLEM) via two flexible bonded hoses and a concrete coated ~5.1 km long 48” carbon steel pipeline from the PLEM to the landfall. The offloading system was originally commissioned in 1975. Figure 1 provides an overview of the site location near Singapore harbour. Partial repair of the pipeline was carried out in 2013, wherein approximately 2.79 km length of pipeline starting from, and including the SBM/PLEM, to a midline tie-in point was replaced. The pipeline section was laid in a trench & rock armoured for anchor drag & drop protection. The remaining ~2.3 km of nearshore pipeline section rests on the seabed with partial burial along the length due to natural sedimentation.

This Pipeline Rejuvenation Project covers the replacement of the balance 2.3km 48” pipeline including replacing the onshore tie in spool. The new pipeline section was laid parallel to the existing section and welded to the pipeline section that was replaced in 2013 via an above water tie-in weld. Part of this project also entail the replacement of the existing 6 mooring lines and refurbishment of the existing SBM buoy to be performed by SOSB. At the landfall, the new pipeline section will be connected to the existing onshore piping system. The new pipeline section was laid in a trench & covered with armor rock, following the protection design philosophy agreed with the local authorities.

Sapura Offshore (Singapore Branch) was the main contractor for this project. OCS was subcontracted by Sapura to provide the following service:-

• Breaking and Reinstatement of Seawall (including geotextile)
• Design and Installation (and removal) of Sheet pile cofferdam at Tidal Zone (with BCA approval)
• Pre Trenching from seawall to offshore KP5.025 including design for BCA approval.
• Design and Install beach pull hold back wall. Beach pull support
• Backfill (trench).
• Removal of old 48” tie in spool
• Fabrication and installation onshore spool tie in connection to existing onshore pipeline.
• Onshore civil works including design, obtained QP and BCA approval and construction of onshore concrete open trench construction.
• Pre-commissioning of new tie in spools plus newly laid pipeline
• Removal of existing 48” crude pipeline (150m from existing onshore Tee).

Offshore section was cut by others but supported by OCS UB01.

OCS commenced this project in October 2021 with engineering and preparation.

Mobilization to site commences in Oct/Nov 2022 and the scope was completed in early August 2023.