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Norwegians study Barents hydrocarbon leakage Improved techniques for monitoring ecological impact may apply to natural seepage and to accidental leaks from damaged vessels By Sarah Hurst For Petroleum News
The Geological Survey of Norway is launching a study of natural seepage of hydrocarbons around the Snohvit and Goliat fields in the Barents Sea, the agency’s Jochen Knies said in a presentation at the 4th Norway-Russia Arctic Offshore Workshop in Oslo June 18. Snohvit is currently producing gas for operator StatoilHydro, and Goliat is an oil and gas field that operator Eni Norge plans to bring into production in 2013.
“The goal is to provide an improved risk assessment of Arctic marine geo-bio systems through impregnation of hydrocarbon leakage around existing and future production fields in the Barents Sea,” Knies told Petroleum News in an e-mail. “We wish to develop an integrated approach of water column, near seafloor detection, and sub-sea detection tools to quantify and trace hydrocarbon leakage from production fields,” he added.
“As viewed from the current heavy oil leak from a Panama-registered Chinese vessel off the southern coast of Norway, this project may be relevant for a large group of experts from industry and other administrative authorities,” Knies said.
The 548-foot-long “Full City” vessel that Knies was referring to drifted aground July 31 when its engines failed and anchor chains snapped in stormy weather conditions. At least 200 tons of heavy fuel oil leaked from the vessel, China’s People’s Daily reported.
Project objective for this fall Project objectives for fall 2009 include monitoring the geophysical properties of near-seafloor fluid flow structures using 4-D seismic data to improve the understanding of the evolution of fluid pathways; integrating a full range of geo-bio-oceanic monitoring data to provide 4-D views on weak zones for hydrocarbon leakage; and expanding knowledge and techniques for monitoring early ecological impact from hydrocarbon leakage, Knies said in his presentation.
In the Goliat area the project will build on the work of Shyam Chand, whose paper on the subject was published in the journal Marine and Petroleum Geology in 2008. “Surface and near-surface indications of migrating hydrocarbons provide the petroleum systems analyst critical information about source, maturation and migration,” Chand wrote. “The rate and volume of hydrocarbon seepage to the surface greatly controls near-surface biological and geological responses. Analysis of these parameters is therefore the most effective method for detection of hydrocarbon leakage.”
Pockmarks — circular to oval depressions found on the seafloor—which may appear individually or as groups or chains, indicate active gas migration and leakage of hydrocarbons to the surface, according to Chand.
Analysis of high-resolution multibeam bathymetry, 2-D and 3-D seismic data and gas hydrate stability modeling showed an area with very high pockmarks intensity in the hydrocarbon province where the Goliat field is located in the southern Barents Sea.
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