Estimated gas and NGL reserves-proved + probable + potential-for the world are 6950 Tcf (200 Tcm) and 174 billion bbl(24 billion mt). The proved plus probable reserves, if consumed at present rates, could last until the year 2000. However, at the present rate of increase in consumption, new reserves will have to be found quickly for gas and NGL to be major energy sources after the year 2000. The areas with the greatest potential are the West Siberian and Arabian Gulf basins. Canada also has a large but untapped gas and NGL resource potential. Other promising areas of the world include southeastern Asia, the shelf north of Australia, offshore China and limited shelf areas of the Americas. Study of the gas sources in the various basins indicates that the major gas source is coal, an observation not emphasized in literature. The huge gas reserves of the Southern North Sea and Northwest German basins originated in Carboniferous coals; the giant fields of the northern part of the West Siberian basin had Cretaceous coal sources. Future searches for major gas reserves should be in coal-bearing basins. Geologically, about 50% of all proved and probable reserves are in Cretaceous strata, with another 22% or more in Permian beds (mainly with a Carboniferous source). Less important gas-reserve peaks are in the Miocene and Proterozoic. Oniy4% of ali gas iiin Cambrian through Devonian rocks.
Although there is sufficient gas to last the world for several decades, the concentration of major reserves in a few selected areas makes gas a less desirable fuel for some countries, particularly the United States. In places where gas is likely to be in short supply, searches for alternative energy sources should begin at once.
Les réserves estimées de gaz naturel et de GNL, prouvées +probables + potentielles pour le monde, sont de 6 950 milliards de pieds cubes (200 10l8 m3) et 174 milliards de barils (24 milliards de tonnes). Les réserves prouvées + probables, si la consommation continue au rythme actuel, peuvent durer juqu'en 2000. Cependant au taux actuel de croissance de la consommation, on devra trouver rapidement de nouvelles réserves de gaz et de GNL qui deviendront les plus importantes sources d'énergie après l'an 2000. Les régions au potentiel le plus élevé sont la Sibérie Occidentale et le Golfe Persique. Le Canada aussi a un important potentiel encore non exploité de gaz et de GNL. D'autres régions prometteuses sont l'Asie du Sud-Est, le plateau continental Nord de l'Australie, l'offshore de la Chine et certaines régions bien délimitées du plateau continental des deux Amériques. L'étude des sources de gaz dans les différents bassins montre que la principale source de gaz est le charbon, observation qui n'est pas mise en évidence d
