Abstract

The subsea PLEM were connected with two flexible risers of "Chinese Lantern" configuration in CALM Buoy System. A hybrid pile foundation were applied as the super soft clay soil condition. This paper presents the process from preliminary foundation proposal, design phase to pile subsea installation in Brunei. Taking into account the effects of CAPEX and installability, an innovative pile-sleeve connection were used instead of traditional methods.

INTRODUCTION

The SPM (Single Point Mooring) CALM (Catenary Anchor Leg Mooring) buoy system is located at North PMB (Pulau Muara Besar), Eastern Brunei, the 44-inch subsea pipeline will pass through the Pelumpong Spit to the refinery. The water depth around the single point buoy of the SPM system is about 33 m, which will allow the oil tanker of 300,000 DWT class to berth and operate.

The SPM CALM Buoy System provides the supporting role to the Hengyi Industries Sdn Bhd's PMB petrochemical project. It is a typical offshore oil receiving terminal and has been widely used over the world.

The SPM CALM Configuration consists of a single buoy, a tanker mooring, floating hoses, subsea risers, PLEM and subsea pipeline (Ming He, 2000). The PLEM facilitates the subsea termination of the pipeline and the connection to the subsea risers. A PLEM comprises a structural base supporting a piping manifold. The PLEM base structure is typically secured to the seabed as a gravity base, but a hybrid pile foundation may also be applied coupled with mudmat depending on the soil, loads and installation preferences.

PRELIMINARY PROPOSAL

The PLEM is installed at the seabed with a water depth of 35m. The header O.D. is at 48″ which is equal to the subsea pipeline O.D., and the two branches O.D. is at 24″. The two branches connect with the two 24″ subsea flexible pipes by flanges. Crude oil from the SPM system flows into the PLEM branches through the subsea flexible hoses, and then is collected in the PLEM header, and finally transported to the onshore termination through the subsea pipeline. PFD of the PLEM is shown in Fig. 3.

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