APPLICATION OF PETROLEUM SEEP TECHNOLOGY IN MITIGATING THE RISK OF SOURCE-ROCK ADEQUACY AND YIELD-TIMING IN A FRONTIER BASIN: THE ROCKALL TROUGH, UK

Geochemical evaluation of shallow seafloor samples provide compelling evidence for thermogenic hydrocarbon generation in the Rockall Trough. Well and borehole data from other basins along the northeast Atlantic margin, together with the geochemical characteristics of the seeps, strongly suggest that a Kimmeridge Clay-equivalent source rock is effective along the western UK margin. Geohistory and hydrocarbon-yield modeling integrated with the character of the seafloor seeps indicate that the eastern margin of the Rockall Trough has experienced a recent (Neogene to present-day) charge of oil and gas from an Upper Jurassic source. Although many key exploration parameters are poorly constrained, a common problem in frontier basins, sensitivity analyses suggest that while some of these uncertainties are substantial, they have little impact on the viability of the hydrocarbon system in the region. The seep hydrocarbons are typically not biodegraded even though biodegradation is expected at the prevailing temperatures and oxygen-levels. We suggest that significant bacterial activity is only initiated once the concentration of hydrocarbons exceeds a minimum threshold.