A Large Potential Methane Source—Natural Gas Hydrates

Abstract

Natural gas, essentially methane, can be obtained from natural gas hydrate (NGH). NGH reserves are difficult to pinpoint in the subsurface, but large sources have been identified by seismic reflection. This is particularly so below the sea floor near continental shelf plates in the oceans deeper than 300 m as NGH is stable at 4°C and 50 bar pressure. When extracted, 1 m³ of NGH can contain 160 sm³ of gas. Currently, estimates of this gas resource are very uncertain, but recent estimates suggest perhaps 2,500 trillion sm³, but how much gas can actually be produced from these accumulations is totally unclear at present. NGH could possibly solve much of the energy needs after 2020, but safe ways of extraction still have to be designed. Possible methods include the injection of hot water or inhibitor or reduction of reservoir pressure, but none have yet been commercially tested. Great caution will be needed because catastrophic environmental damage is likely if the methane is carelessly released from the sediments. This article reviews the ‘state of the art’ of NGH.

Keywords:

• energy
• gas resources
• methane
• natural gas
• natural gas hydrate

Acknowledgments

We thank the UWI Research and Publication Committee and CDB for support, and J.-A. Babwah for help with an early draft of this paper.