Despite being one of the most abundant energy sources on the planet, more than one-third of global natural gas reserves are classified as stranded (Thackeray & Leckie, 2002). Stranded gas refers to reserves that have been discovered, but have not been developed because, for whatever reason, they are uneconomic to deliver to market.

For almost a century, natural gas has been transported safely, reliably, and economically via pipeline, and pipelines were ideally suited to the supply and market conditions of the twentieth century, when large reservoirs of gas could be found in accessible locations that provided the stability and long-term security that pipeline projects demand. Now, in the 21st century, the vast majority of the large, easy, gas plays have been tapped in North America, and attention is shifting to stranded reservoirs that were previously thought too small, too remote, or too geographically harsh to develop.

Compressed natural gas (CNG) is one of the technologies by which these stranded reserves can be economically brought to market, and is especially well suited to transporting offshore natural gas by barge and ship.

The majority of the offshore industry is geared toward the production of crude oil, which, being a liquid, can be easily transported by tanker to virtually any market in the world. The natural gas produced in association with the crude oil, however, presents a problem. Natural gas, being a gas, cannot simply be poured into a tanker and shipped to market, and undersea pipelines are extremely expensive in all but the most ideal conditions. With the current trend toward deep water drilling in the Gulf of Mexico and the Atlantic coast, pipelines are often not technically or economically feasible.

In the past, stranded offshore gas was simply flared (burned-off) at the well head as nothing more than an annoying by-product of oil production. Currently, gas is more likely re-injected into the reservoir to help maintain pressure, but with natural gas becoming such an important and marketable commodity, producers would much rather sell the gas at market than flare it off or inject it back down the well.

Marine CNG technologies, such as TransCanada’s GTM system, are solving the problem of stranded offshore gas. By mounting GTM tubes on barges and ships, gas can be compressed into those tubes and transported to market. By controlling the number and speed of the ships, flow out of the well-head and into market is very nearly constant. In effect, the system of ships becomes a floating pipeline, constantly receiving gas from the reservoir and delivering it constantly to market.

While the current focus is on marine CNG, GTM technology can also be used to transport stranded gas onshore. Natural gas stranded in small, isolated reservoirs can now be transported to market in pressure vessels mounted on trucks or rail cars.

CNG, and TransCanada’s GTM technology, give us the opportunity to de-strand some of the worlds 4,500 trillion cubic feet of stranded gas (Zeus Development Corp., 2004), allowing us to utilize the world’s natural gas reserves more efficiently and with less waste.

Works Consulted

Thackeray, F and Leckie, G. (2002). Stranded Gas: A Vital Resource. Petroleum Economist, 69(5), 10.

Zeus Development Corp. (2003). Stranded Gas Locations and Statistics. World LNG/GTL Review. Retrieved July 9, 2004, from http://www.lngexpress.com/lngrev/intro_sglocs.asp