Hibernia Subsea Crude Loading Facilities
Authors: Ewida A. , Ferrario F. , Fiskerstrand R. 
Published: October 2008

This paper presents an overview of the subsea crude loading facilities developed for the Hibernia field on the Grand Banks. The paper addresses layout philosophy, contracting strategy, engineering, fabrication, integration testing and preparations for offshore installation. An innovative and yet cost effective subsea layout arrangement which provides redundancy in the event of unexpected malfunction or damage has been adopted for Hibernia. The design of the subsea crude loading facilities has been completed and the main components have been fabricated and delivered to Newfoundland. The successful completion of the integration testing programs between the OLS risers and OLS bases and between the OLS Risers and tanker loading equipment prove out the compatibility and functionality of the main components. This was a direct result of good planning/engineering, high quality fabrication and cooperative team work between HMDC, Saipem, Pennecon Ugland Loading Systems Inc. (PULS), Hibernia owners' tanker project team and main suppliers/subcontractors, including (but not limited to) Kongsberg Offshore AIS, J.P. Kenny/RDS, Maritime Pusnes AS, Coflexip Stena Offshore Inc., Newfoundland Dockyard Corporation and Tubular Supply Services Ltd. (British Steel). The installation of the Hibernia subsea crude loading facilities is planned for the summer of 1997.

Layout and System Description

The Hibernia subsea crude loading facilities consist of a closed loop offshore pipelines arrangement with two offshore loading system (OLS) bases and an OLS riser assembly to be installed onto one of the OLS bases.

The layout of the Hibernia subsea crude loading facilities is shown in Figure 1. The closed loop offshore pipelines arrangement consists of two 584.2 mm (24 inch) diameter main offshore pipelines (MOP), each running approximately 2 kilometres from the platform to an OLS base. An interconnecting offshore pipeline (IOP), approximately 400 metres in length, connects the two MOPS and OLS bases. Both OLS bases are designed to provide a stable connection between the pipelines and the OLS risers and will be securely anchored to the seabed by piles. A general arrangement for the OLS base is shown in Figure 2.

The OLS riser is divided into three flexible pipe segments, one vertically tensioned and two catenary suspended. The vertical riser will be tensioned through the gooseneck by a subsurface buoy. The lower end of the vertical riser will be connected to the OLS riser foot which serves as the active connection to the OLS base. During loading, the coupling head on the upper catenary riser will be connected to the tanker bow coupler. A general arrangement of the OLS riser is shown in Figure 3. During operation, the crude oil will be transferred from the platform through the offshore pipelines, OLS bases and the OLS riser to a dynamically positioned bow loading shuttle tanker for transport to market.

One of the main features of the Hibernia subsea crude loading facilities layout is the redundancy provided against unexpected malfunction or damage incidents.