GAS HYDRATE RESOURCES OF NORTHERN ALASKA

Large amounts of natural gas, composed mainly of methane, can occur in arctic sedimentary basins in the form of gas hydrates under appropria te temperature and pressure conditions. Gas hydrates are solids, compo sed of rigid cages of water molecules that trap molecules of gas. Thes e substances are regarded as a potential unconventional source of natu ral gas because of their enormous gas-storage capacity. Most published gas hydrate resource estimates are highly simplified and based on lim ited geological data. The gas hydrate resource assessment for northern Alaska presented in this paper is based on a ''play analysis'' scheme , in which geological factors controlling the accumulation and preserv ation of gas hydrates are individually evaluated and risked for each h ydrate play. This resource assessment identified two gas hydrate plays ; the in-place gas resources within the gas hydrates of northern Alask a are estimated to range from 6.7 to 66.8 trillion cubic metres of gas (236 to 2,357 trillion cubic feet of gas), at the 0.50 and 0.05 proba bility levels respectively. The mean in-place hydrate resource estimat e for northern Alaska is calculated to be 16.7 trillion cubic metres o f gas (590 trillion cubic feet of gas). If this assessment is valid, t he amount of natural gas stored as gas hydrates in northern Alaska cou ld be almost seven times larger then the estimated total remaining rec overable conventional natural gas resources in the entire United State s.