Concept Evaluation of Concrete Floating Liquefied Natural Gas (FLNG)

Abstract

The world has a quarter of its natural gas reserves (approximately 2 billion TCF) undeveloped or "Stranded" in offshore fields. Many gas fields were discovered decades ago, but until just recently these reserves were considered to be commercially and technically non-viable. Floating Liquefied Natural Gas, or FLNG, is now seen as a potentially viable solution to monetize these reserves. Technology developments in offshore Liquefied Natural Gas (LNG) liquefaction, containment and transfer have made offshore FLNG production commercially viable. Although land-based LNG and offshore FPSOs are each successfully proven in operations, combining the two technologies into a FLNG is complicated and faces various technical challenges. These include safety, ship motion, topside processing, hull & containment, offloading, integration and operation. One of the critical aspects of a FLNG facility are the space constraints inherent in any floater.. A concrete hull structure can be a good answer to these challenges. It can provide a floater with larger deck area and high built-in load-bearing capacity. Concrete has excellent durability in marine environments, is not subject to fatigue, and offers far better insulation properties than steel. This paper serves to highlight the benefits of a proposed concrete hull structure for FLNG production facility. The proposed concrete monohull concept benefits from significant flexibility with regards to topsides weight, equipment lay-out, simplification of operations and maintenance. Concrete has better fire resistance and corrosive resistance than steel structures and it is not susceptible to brittle fracture in the case of an LNG spill. These are considered to be of major importance for a FLNG production vessel. Building cost and time-scale are competitive.