Rogersville Shale Formation has much to reveal edited-529 added From Upstream Online with edits . By Noah Brenner 07 November 2014 01:00 GMT . THE Rogersville formation of Kentucky and West Virginia is a Cambrian-aged dark-gray shale member of the Conasauga group that was only recently discovered to have a working petroleum system by US Geological Survey (USGS) researchers. It is sandwiched between the Marysville and Rutledge sandstone/limestones at depths ranging from 9000 feet to 14,000 feet at the base of the Rome Trough extensional basin. The Rome Trough structure runs south-west to north-east from central Kentucky through West Virginia and into southern Pennsylvania. The Rogersville itself is primarily a shale formation with some interbedded sandstone layers that lies at around 10,000 feet to 14,000 feet deep, trending from deep to shallow from east to west. Until recently, geologists did not think there was a Cambrian-aged source rock in the basin and attributed production from conventional Cambrian formations like the Rose Run and Knox to the Ordivician-aged Utica shale petroleum system. However, in 2005, USGS researchers published work based on a re-examination of logs and cores from a series of ExxxonMobil wells in West Virginia, including the Exxon 1 Smith well in Wayne County, West Virginia. The analysis showed total organic carbon readings for the Rogersville of up to 4.4% and oil produced from the Marysville formation above (in the White 529 well in Boyd County Kentucky) was eventually traced back to the Rogersville. The Rogersville “has good source rock potential that, combined with favourable oil-source rock correlations, demonstrates a new petroleum system in the Rome trough”, the researchers wrote. They theorised that the formation generated oil over an area extending from eastern Kentucky to “at least central West Virginia”. David Harris, head of the energy and minerals division of the Kentucky Geological Survey, said there are still a lot of unknowns surrounding the formation and how it might eventually be developed as a tight oil play. “I think seismic data is going to be a key part of the play,” he said. “It's structurally complex.” Operators are obviously chasing the liquids window of the play, whether that is tight oil or a lighter gas condensate. Harris said he expects that window to lie along the West Virginia border and into Kentucky where the formation is shallower and that the formation would trend toward dry gas as it deepens into West Virginia.