The discovery of vast natural gas resources in shale deposits around the world has changed the map as far as supplies are concerned, although not as much as you might expect. A decade ago, most gas reserves were believed to be concentrated in Russia and the Middle East, particularly Iran and Saudi Arabia. The successful development of gas from shale deposits and other tight formations has catapulted the United States and China into the forefront. China in particular had almost no conventional gas reserves but its huge estimated shale deposits and coalbed methane have moved it into third place in the world, ahead of Iran and Saudi Arabia. The United States, formerly in fourth place for conventional supplies, now ranks second, but still far behind Russia, which remains in first place from its conventional supplies alone.
The bar chart represents gas supplies from four sources: 1) conventional gas (blue); 2) shale gas (yellow); 3) tight formations (red); and 4) coalbed methane (purple). Conventional sources are the younger formations, mostly from the Tertiary (post-dinosaur) Era, where the sedimentary rock has not yet been subject to severe pressures and the gas escapes easiliy when tapped. Shale formations were the first pre-Tertiary formations to be accessed through hydraulic fracturing (“fracking”). They are compressed clay that must be broken up by high-pressure water injection before the gas can escape. “Tight gas” is in ancient limestone or sandstone formations similar to shale where the rock has been so compressed and hardened that it must also be broken up by fracking. Coalbed methane is methane gas that seeps naturally from coal formations near the surface of the earth. Often capture involves little more than installing small, ground-level collectors
The discovery of shale deposits has also vaulted Western Hemisphere countries such as Argentina, Mexico and Canada into the upper ranks. Australia has almost equal amounts from all sources and figures to be a big exporter over the next decade. The countries that continue doing the most importing will be Europe and Japan, which do not have appreciable reserves from any source, although Norway has offshore gas and Britain is now discovering some shale reserves.
As usually happens, the first exploration has occurred in the developed countries. It is more than likely, however, that huge reserves are still waiting to be discovered in Africa, the South Pacific and unexplored areas of the Arctic and South America. One way or another, the International Energy Agency appears to be right when it says we are entering a “Golden Age of Natural Gas.”