The combination of the liquefaction efficiency, water cooling and elimination of gas compression to shore within Shell’s FLNG design yields a considerably reduced environmental footprint as compared to a typical offshore-to-onshore development.
This reduction can be measured in terms of greenhouse gas emissions, which are typically 15 per cent lower, the use of fewer construction materials by approximately 50 per cent, and a 90 per cent reduction in disturbance of land/seabed.
In July 2009, Shell signed master agreements with Technip and Samsung Heavy Industries to design and build multiple FLNG facilities over a period of 15 years. As such, Shell’s FLNG facilities will be built in Samsung’s shipyards in Korea, one of the few places in the world large enough to accommodate construction of a facility of this size.
The FLNG facility to be used for Prelude is generic in design, following Shell’s “design one, build many” approach, meaning that the facility can be easily replicated for other projects.
The design builds on Shell’s experience in LNG technology, LNG shipping, floating production, storage and offtake vessels (FPSOs) and offshore operations. The FLNG facility concept is similar to that of an FPSO.
A key feature of Shell’s FLNG design is that it is very flexible; it can process a wide range of gas compositions, can accommodate a wide range of sub-sea configurations, has multiple solutions for hydrate management, can export LPG as well as LNG, and uses an efficient dual-mixed refrigerant liquefaction cycle.
The facility can also stay on station, its sheer size allowing it to withstand very severe weather conditions. With a hull life of 50 years, the facility is also able to be re-deployed after one field has been fully developed.
Safety first at Shell
Managing safety has been at the centre of technical studies since Shell first embarked on FLNG in earnest in the 1990s. Areas of focus have related to those aspects of FLNG which are different to other offshore structures. These include compactness, extreme weather survivability, product loading, motion responses and turret and mooring systems.