Dropping anchor

Furthermore, while onshore storage and regasification terminals continue to be developed – particularly in established LNG markets, such as Asia – the industry has also seen a growing interest in floating LNG (FLNG) production units, as well as the emergence of floating storage units (FSUs) and floating storage regasification units (FSRUs).

Industry analysts Douglas-Westwood (DW) forecast a significant increase in global CAPEX spent on FLNG facilities between 2016 and 2022 – from US$11.4 billion between 2011 and 2015 to US$41.6 billion between 2016 and 2022.²

In addition, the International Group of Liquefied Natural Gas Importers’ (GIIGNL’s) 2015 annual report pointed to a live fleet of 23 FSRUs with a combined capacity of nearly 3.5 million m³.³ As of January 2016, 14 out of 33 current import markets had floating capacity.

FSUs and FSRUs come with significant financial and deployment benefits, providing a quicker and more cost-effective alternative to land-based LNG import terminals and enabling the rapid ramping up of LNG imports. FSRUs, for example, are often converted ships that can be mobilised quickly, pre-empting requirements for expensive onshore LNG facilities. FSU deployment alongside onshore regasification has also supported the economical and rapid development of LNG import infrastructures.

According to the IGU’s 2016 World LNG Report, Egypt, Jordan and Pakistan became LNG importing countries in 2015 via the commissioning of FSRUs. Multiple FSRUs have also been announced for 2017, particularly in Bangladesh, Benin and Uruguay, all of which are likely to become new import markets.

In addition to FSUs and FSRUs, actual FLNG production facilities are also likely to come on the market in the near future. Chief among these is Shell’s Prelude, located offshore Australia, which has the potential to become a vital new energy resource offshore, without the need for pipelines and expensive onshore processing plants.

Mooring and anchoring challenges

Yet, just as the FLNG market continues to build momentum, so do the challenges in ensuring safe and effective mooring and anchoring operations to secure such structures. It is supporting technologies, such as mooring and anchoring, which can have a significant impact on investment and operational costs, as well as safety and reliability.

So, what issues should operators be aware of in mooring and anchoring operations?

Firstly, with many FSUs and FSRUs being positioned alongside existing infrastructure (such as jetties) or close to land-based operations, it is vital that mooring and anchoring arrangements are precise and accurate.

There is also the need to ensure safe operations in difficult environments.

Many FSUs and FSRUs, for example, will be attached to a jetty during regular operations. If there are challenging weather conditions, thought needs to go into whether such structures can be disengaged from the jetty and what alternative mooring system is put in place that does not require the FSUs or FSRUs to leave the harbours. Different seabed and soil conditions also need to be considered, in order to ensure that the anchors will be effective.

Such challenges require flexibility – not just in regard to weather conditions, but also in relation to the fatigue and wear and tear of the mooring equipment, all of which can fluctuate over time. This requires the real-time monitoring of mooring systems both in their deployment and to track their condition with a lack of monitoring and tracking potentially leading to mooring line replacement or failure.

Finally, there is cost and the need to balance the pressures of cost, while still ensuring the highest standards of mooring effectiveness and safety. There is subsequently a demand for a complete mooring solution with fast deployment and transportation as well as economies of scale.

New solutions for new challenges

Anchors are vital for securing LNG infrastructure. To this end, Global Maritime Vryhof provides a variety of ultra high holding power anchors for large scale LNG floating units. These can also be used in different seabed conditions.

One such example is the patented Stevtensioner technology, which makes it possible to install anchors with smaller leads, thereby enabling the use of smaller and cheaper vessels in LNG installations. This technology is essentially a chain-shortening clutch with the active mooring chain connected on one side and a reaction chain running through it. A vertical pull can induce more than double the pull in the horizontal leg. A repeated heaving up and slacking of the Stevtensioner in yo-yo action builds up the load in the mooring chain until the required tension is achieved.

On the mooring side, other solutions include pre-lay mooring operations that enable mooring lines to be installed prior to the LNG vessel’s arrival and ensure that less rig time is spent connecting and disconnecting to the mooring system. This is also particularly useful if vessels have to be moved due to poor weather, as is sometimes the case. The latest in hydrodynamic, mooring dynamic positioning and vessel motion analyses also ensures an optimal mooring system and location for LNG floating structures.

This is backed up by a wide selection of mooring equipment, including certified chains of different dimensions; fibre ropes that are widely used to reduce weight and increase mooring line elasticity; slide and roller bearing swivels for mooring lines and anchor handling purposes; wires; and a wide range of connectors.

Many of the challenges in FLNG infrastructure are also being addressed through other forms of technology innovation. Deep Sea Mooring’s Advanced Distance and Positioning System (ADAPS), for example, directly addresses the need for mooring and anchoring precision mentioned earlier in this article.

The system helps attach the anchors prior to deployment, ensures that the anchor lands in the required position and provides the pitch and roll of the anchor along with the depth of penetration. This is vital when placing anchors in close proximity to other structures, as can often be the case with LNG floating infrastructure so close to shore.

One other recent technology innovation is a newly patented Radio-Frequency Identification (RFID) marking and identification system. The system can be found on all mooring equipment, and ensures the real-time monitoring of mooring systems to confirm their effectiveness.

With the new RFID system, each piece of mooring equipment will have a marking band that contains a printed identification for physical reading, a quick response (QR) and/or data matrix code for optical reading by handheld devices and an RFID tag for reading with radio waves from a handheld device.

The new system ensures complete traceability and identification of all mooring equipment and increased efficiencies. The fact that the system results in accurate data capture – from planning through to mooring line documentation – leads to a greatly reduced risk in misreading identification information. It also means that less effort is required to handle equipment, and less time is spent on tasks such as steel brushing or locating the necessary information. This all impacts positively upon safety and efficiency with a reduction in operational time during mooring operations.

The end result is increased levels of visibility in mooring operations, a reduction in operational time and risk, and a positive impact on safety and efficiencies.

Supporting an FSU installation in the Mediterranean

It is with these issues in mind that Vryhof has provided a complete mooring system for an FSU in the Mediterranean. The project is taking place with the support of Global Maritime Consultancy & Engineering, who provided mooring analysis and installation engineering.

In this case, Vryhof is providing the equipment for the project that consists of all anchors, complete mooring chains, the mooring arrangement for a complex eight-point mooring system, all connectors and accessories, installation aids, offshore engineering, and class certification.

Conclusion

There is no doubt that the FLNG market is likely to increase significantly over the next few years. It is important that anchoring and mooring technologies continue to innovate to meet current day LNG challenges.

References

1. International Gas Union (IGU), 2016 World LNG Report, (April 2016).
2. Douglas-Westwood, World FLNG Market Forecast, (August 2016).
3. International Group of Liquefied Natural Gas Importers (GIIGNL), 2015 Annual Report. Accessed: www.giignl.org.

Written by Wolfgang Wandl, Global Maritime Vryhof and Deep Sea Mooring, Singapore.

Read the article online at: https://www.lngindustry.com/special-reports/06122016/dropping-anchor/