Written by Elizabeth Jones
|Tuesday, 26 June 2012|
North Sea Gas Leak
Although the cause of the Total gas leak has not yet been discovered, it is believed that natural gas entered the casing of a plugged well from another, non-producing reservoir four kilometers underground. Natural gas then travelled up the well pipe to the surface, where it began to leak out.
The most immediate concern following the discovery of the leak was to evacuate the platform and any surrounding operations. The gas plume surrounding the platform was a serious danger. Officials were worried that if the flammable plume found a source of ignition, there would be an explosion and fire. A shipping exclusion zone was instituted two miles around the platform, and three miles around for aircraft. A flare burning 75 feet above the platform made it unapproachable until the flare finally extinguished itself about a week after the leak was initially discovered.5
With the flare out, Total was able to send in a few crewmembers to assess the situation. The company began two separate remediation operations. A “top fill,” or “mud kill” operation was initiated to plug the leak by pumping in mud.7 As a fail-safe, Total began to drill two relief wells, which are extremely expensive to construct and take up to six months to drill. Relief wells are drilled to intersect an oil or gas well that has experienced a blowout. Specialized liquid, such as dense drilling mud and cement, can then be pumped down the relief well in order to stop the flow from the reservoir in the damaged well.8
By mid-April the gas company’s methods successfully cut the amount of gas streaming from below the platform by two thirds.9 As the construction of the relief wells continues, Total should be able to stop the flow of gas completely. At that time the company will determine whether or not to reopen operations at the Elgin site, or to abandon the platform completely.
BP’s Deepwater Horizon exploded on April 20, 2010,11 triggering the largest offshore oil spill in U.S. history in the Gulf of New Mexico. Because the Gulf spill is so fresh in everyone’s collective memory, comparisons between the two spills are inevitable.12 However, the representatives from Total are trying to reassure the public that the comparison is unwarranted. The biggest difference between the two events is that the Elgin leak is occurring at the surface, and involves only natural gas (there is no crude oil). “Natural gas typically dissolves in sea water or evaporates at the surface, meaning there isn't much to clean up as in the case of an oil spill.”13 In addition, the Elgin field is in much shallower seas… [w]ater depth is just 93 meters, compared with more than 1,500 meters for Macondo, making it considerably easier to access the well head at the sea bed.”14 As one professor put it, the Elgin leak is “more of a very dangerous situation rather than a disaster so they may be able to get it back under control with minimal losses."15
Scottish authorities completed a series of chemical and taste tests on fish in the North Sea near the leaking platforms which yielded no signs of hydrocarbon contamination. The Scottish Environment Secretary thus concluded that the leak had not directly contaminated the marine environment.16 The environmental organization, Greenpeace, has not been as convinced that the gas leak will not cause any negative environmental impacts. In early April, Greenpeace sent a vessel to the North Sea to observe the damage for themselves. "We are here because oil companies often withhold information on accidents," said Christian Bussau, chief scientist and ocean expert at Greenpeace. "We want to get our own picture of the environmental damage from the scene." Greenpeace will have to wait until their ship returns to dock in Germany before analyzing any water samples.17 In addition to immediate impacts, John Sauven, executive director of Greenpeace, reminds us that, "[a]ccording to Total, if the leak continues at its current flow for six months it will amount to nearly 800,000 tonnes of CO2 equivalent, adding to the burden of greenhouse gases already going into the atmosphere.”18
Even if the environmental damage caused by the Total natural gas leak is negligible, this event is an important reminder of our dependence on fossil fuels and the dangers that this dependence constantly poses. Britain could be facing as much as a 6 percent cut to gas supplies this summer due to the closure of the Elgin and two neighboring gas fields, National Grid said on Tuesday.19 Perhaps this is a good time to make the best of a bad situation by accelerating the transition to renewable resources .
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|Last Updated ( Friday, 19 October 2012 )|