Hydrates for Transport of Stranded Natural Gas

Abstract

Abstract This paper addresses the feasibility of using a Natural Gas Hydrate, NGH, transport-system to economically convey remote, stranded, and/or associated natural gas to market. Such a transport system could convey NGH either on retrofitted crude oil carriers, carrying both NGH and oil, or on new custom-built carrier designed specifically for NGH. Introduction Close to 142 m3 trillion (5,000 trillion cubic feet) of natural gas (either associated with crude oil, or non-associated) is stranded worldwide, largely because of the relatively high costs of transporting the gas to market, particularly where pipelines are impractical. However, natural gas is in high demand in the global market place, because it is a clean fuel and is well suited for use in the existing industrial infrastructure. Therefore, considerable effort, and progress, is being made throughout the industry to reduce transport costs for natural gas, for example: the cost of building LNG plants have declined by approximately 60% since 1989, and many gas-conversion plants are planned for construction over the next ten years. Nevertheless, still other opportunities exist to further reduce the costs of transporting natural gas, and systems for the transport of natural gas in hydrate form represents one such cost reducing technology that, for specific cases, has the potential for driving the cost of natural gas down toward comparable costs for transporting crude oil. Briefly stated, such hydrate systems would use gas hydrates to reduce the volume of natural gas by approximately 169 times, and then to store the natural gas hydrates, NGH at a range of potential temperatures and associated pressures. Figure 1 presents an image of the burning of natural gas released from melting hydrates. Generally, hydrate transport systems are attractive for fields in such areas as the Deepwater Gulf of Mexico, Alaska, Eastern Canada, Venezuela, Trinidad & Tobago, Egypt, and Indonesia; which are relatively close to markets.