Empty oil wells get a fill-up to reduce greenhouse gas

A short distance from Spindletop oil field, site of the gusher that triggered the Texas oil rush more than a century ago, scientists have found a purpose for the long-disused underground reservoirs - as storage for the pollution emitted by burning fossil fuels.

At the depleted South Liberty oil field near the town of Dayton, a University of Texas team pumped 1600 tonnes of carbon dioxide - the principal greenhouse gas - into the reservoirs of briny water more than 1500m underground.

Scientists say those porous rock formations, which extend for hundreds of kilometres from Mexico to Alabama, could be ideal for storing the greenhouse gases widely blamed for global warming.

"We have a lot of oil and gas fields in this area that are in decline," said Susan Hovorka, a University of Texas geologist and the lead researcher on the pilot project.

"The Gulf Coast is one of the best places on Earth for this."

The technology, known as carbon sequestration, has attracted worldwide attention from industries and governments keen to capture the gas that can linger in the atmosphere for decades.

Scientists say the gases released by burning fossil fuels are the main cause of global warming, which is expected to lift temperatures and sharply alter weather patterns, raising sea levels and causing devastating storms.

Russia's ratification of the Kyoto Protocol early last month cleared the way for the environment pact to come into force in February and the European Union's carbon dioxide emissions trading market is due to open in a month, so demand for methods of eliminating or storing the gas is rising.

President George W. Bush pulled out of the Kyoto pact in 2001, claiming it was too expensive and wrongly excluded developing nations, but American research into carbon sequestration has continued, aided by Government funding.

The pact calls for industrialised nations to reduce carbon dioxide emissions by 10 per cent of 1990 levels by 2012.

Because it has so many oil, chemical and refining industries, Texas' rate of carbon dioxide emission is exceeded only by China, Russia, Japan and India.

And it is perhaps best equipped to put the gas back in the ground.

"This is going to be the place in the world where this is done," said Charles Christopher, oil giant BP's liaison with the Texas research project.

Hovorka said a preliminary estimate of the amount of carbon dioxide storage capacity along the coast regions of the Gulf of Mexico put the figure at about 300 billion tons - enough to hold 1000 years of pollution from the region at the present rate.

Christopher said many technical and economic hurdles remained before carbon sequestration became a practical enterprise, but much of the expertise and at least a limited transport network existed.

Since the 1970s, oil and gas drillers have injected carbon dioxide into oil wells to increase their output.

"This is something we know how to do," Christopher said. "We've been doing it for 30 years in west Texas."

Houston energy company Kinder Morgan ships nearly 30 million cubic metres a day of the gas through its 1770km pipeline network, much of it from Colorado into the west Texas oil fields.

That pipeline system would need to be vastly expanded to reach the major carbon dioxide emitters on the other side of the state - an expensive and complicated endeavour, but one the company has considered.

"If the opportunity is there and it's attractive, we want to be a part of it," said Kinder Morgan spokesman Rick Rainey.

- REUTERS