The revolutionary concept of offshore LNG installations (FLNG) is said to have economic and environmental advantages. A distinct disadvantage however is that the risks to health and safety of persons employed offshore on the LNG FPSO’s, such as Prelude, will be higher, when compared to onshore LNG plants of similar capacity, specifically the potential for loss of life; …loss of containment of hydrocarbons is likely to occur on Prelude during its operational life, either through flaws in the design, human error or failure to inspect and maintain. It’s almost inevitable. It’s only to be hoped that the consequences of these losses never reach their full potential.
By Bill Campbell, Retired HSE Group Auditor, Shell International
Prelude FLNG turns conventional wisdom on its head
The revolutionary concept of offshore LNG installations (FLNG) is said to have economic and environmental advantages. A distinct disadvantage however is that the risks to health and safety of persons employed offshore on the LNG FPSO’s, such as Prelude, will be higher, when compared to onshore LNG plants of similar capacity, specifically the potential for loss of life.
This article concentrates on the perfect contradiction that exists between managing risks on an onshore LNG plant when compared with floating LNG. Whereas onshore plants, handling hazardous substances reduce risk by physical separation, such separation, although attempted on Prelude would not be accepted onshore because the separation distances are inadequate. Prelude will store high quantities of cryogenic hydrocarbon liquids on the installation. The heat energy of the liquids is enormous. This contradicts the £6 billion or so expenditure in the North Sea, post Piper Alpha, to do as much as reasonably practicable, to reduce the heat energy available so that escalation of hydrocarbon events are limited such that the Temporary refuge (TR), normally the Living quarters, and including escape routes to the TR and evacuation from it, will not be impaired within one hour to allow safe evacuation of the facility. The frequency of TR impairment should be demonstrated to be no more than once in 1000 yrs. It’s a high standard to achieve.
Finally, because of the measures taken in the design and layout of onshore plants, the potential loss of life is much reduced. This is contradicted by offshore installations where the total population is determined to be at risk.
Is Prelude a cause for celebration or concern?
Shell has for many years had considerable expertise and experience in the production, storage and transport of LNG, in many respects world leaders. Society in general has benefited hugely from advances in technology, which are shown in the long term to be to the common good. Such as the North Sea black gold rush of the 70’s. Doing something different, something that has not been done before, is a risky business, and risk takers are needed if mankind is to advance. This FLNG technology is necessary to develop significant sources of isolated gas deposits located under the sea, in many cases in remote locations. So floating LNG is revolutionary, a bold and adventurous move, but is it a step too far? Only time will tell. Will all the design assumptions made by Shell be valid, or are there some critical factors that have been overlooked, or are we simply being expedient as human beings, because FLNG is the only viable economic way to obtain these gas reserves, and these reserves are essential and will benefit many, is it acceptable to close our minds and forget what happened in the past?
Doing something different, we have been here before
When offshore installations were first installed in the North Sea is was the compactness of these facilities, the juxtaposition of many hazardous areas and activities with hundreds of workers constantly present that was the principal concern. What would happen if something went badly wrong? Miles from land the installation would be required to deal with emergencies on its own, and unlike onshore plants, the 200 or more workers on the platform would be all poten