Offshore Gas-To-Solids Technology

Abstract

Abstract BG Group's Hydrates Gas-to-Solids (GtS) technology has been established to investigate ways of managing gas in regions lacking suitable gas infrastructure and/or local markets. Put simply, the technology amounts to adding natural gas to water and stirring. This converts the gas into hydrate that is then shipped to market for regasification to supply power generation facilities or other gas customers. The low complexity of this technology and the potential for small-scale modular operation is particularly appropriate for offshore associated gas applications where growing environmental pressures to reduce or eliminate gas flaring frequently create situations in which oil developments cannot proceed if there is no technical or economic means for gas disposal. BG is progressing further pilot plant scale testing and engineering definition programmes with the aim of targeting a potential commercial plant operation by 2006. Introduction The Hydrates Technology Programme was launched by BG in 1993 to investigate ways of establishing a low cost alternative means of transocean gas transportation. The technology entails converting the gas into a hydrate that is then shipped to market and re-gasified at the delivery point. To date, the technology development has been undertaken for BG by Advantica Technologies Ltd (formally BG Technology) and has included laboratory testing, construction and testing of a pilot plant and preliminary engineering and commercial realisation studies. Natural Gas Hydrates. Natural gas hydrates are crystalline solids composed of water and natural gas in physical combination where individual gas molecules exist within ‘cages’ of water molecules and are more familiar in the Oil and Gas Industry as a traditional nuisance for their propensity to block pipelines if precautions, such as chemical inhibition, are not taken. However, establishing a comprehensive understanding of their behaviour has allowed BG to investigate the possible positive application of gas hydrates for transoceanic gas transportation. Dry Hydrate Technology. The initial focus of the Hydrate Technology programme was on bulk gas transportation with the technology being deployed as either floating offshore or coastal onshore facilities. Considerable work was undertaken including:Extensive laboratory testing enabling reactor design and process model validationConstruction and testing of 1 tonne/day pilot plantDevelopment and application of dewatering techniquesLong term hydrate storage at stable conditions and controlled regeneration of gas from storageTechno-economic studiesShipping studies The decision was then taken to target stranded associated gas as entry into the gas transportation market and development switched to investigating a lower cost slurry process for smaller gas volumes. Slurry Hydrate Technology. Technology for handling offshore associated gas, such as GtL, LNG, CNG, etc., has received increasing interest in response to the pull from the Oil and Gas Industry for technology solutions to dispose of and/or monetise associated gas, which is often viewed as a nuisance, and the push from governments and environmentalists to prevent its flaring. However, there remain considerable barriers and challenges before the technology can be marinised.