Mid-scale FLNG: a solution for stranded gas fields. With the increasing global demand for gas we expect there will be a strong market for FLNG vessels. FLNG has the potential to make a significant impact on the global LNG market over the coming decade.

This new market will be a good complement to SBM’s already strong position in the oil FPSO business. SBM has extensive experience in designing, building and operating FPSOs and is now drawing on this experience to develop its FLNG concept.

Our core position is for midscale FLNG (1.5- 2 mtpa) conversion. This size is suitable for the 700-plus stranded gas fields between 0.5 TCF and 2 TCF and is also a good fit with our current FPSO product line, in terms of project scale, risk and investment.

Many of the technologies and capabilities that SBM has in-house are applicable to the FLNG concept. For example, the same turret mooring systems used for FPSOs can be used for FLNG.

Although building a new facility is possible, SBM’s innovative option is to convert LNG tankers into FLNG facilities – in much the same way as has been successfully achieved for oil FPSOs. The advantage of this concept includes lower costs and a shorter schedule. With such a conversion, the process facilities along with the storage and crew living quarters are located on deck.
This novel topside layout is achieved by joining together two LNG tankers. This ‘twin hull’ concept allows adequate space for the process facilities with the necessary space between sections of equipment to satisfy safety requirements, while providing sufficient LNG storage capacity.

SBM has performed generic pre-FEED work, together with Linde Engineering, a strong and reliable LNG topsides partner, to cater for a wide range of potential reservoir compositions and environmental conditions, which can then be easily optimised for specific fields.
For the mid-scale FLNG concept, a pre-cooled dual nitrogen expansion process without natural gas liquid (NGL) recovery has been selected, providing an optimum balance between efficiency, simplicity, robustness and safety.

Avoiding the use of mixed refrigerants on the topside and the introduction of several innovative features achieves an efficiency level approaching that of the single mixed refrigerant (SMR) process. This design provides a highly economic solution for mid-scale applications.
SBM’s design will continue to be validated, not only in terms of economics but also for operability. Some wind tunnel testing has been performed to verify the effect of topside design on the loading of the vessel. The next step is to make a scale model of the vessel for testing in a tank.

The concept is at a sufficiently advanced stage of design whereby SBM can accept specific details of the potential field – for example wave and wind conditions and gas composition – in order to tailor an optimum FLNG design to the exact needs of the client.

Read the complete article in our Currents magazine issue 7