Gigantic, gaseous mushwads in Cambrian shale: Conasauga Formation, southern Appalachians, USA

Giant duplexes called mushwads in the southern Appalachian thrust belt are estimated to contain a natural gas resource base of about 17.7 Tcm (625 Tcf). Early development efforts in mushwads of the Cambrian-age Conasauga Formation encountered significant challenges and highlight the need for an integrated, multidisciplinary approach to shale gas exploration. To facilitate development of this gigantic resource, an integrated geological analysis of stratigraphy, sedimentation, structural geology, basin hydrodynamics, petrology, geochemistry, gas storage and mobility, and reservoir volumetrics was conducted. The results of this analysis demonstrate the myriad geological factors that need to be considered when developing shale gas resources and suggest that the greatest reservoir potential lies deep in the mushwads, where free gas is concentrated. Meeting the challenges posed by deformed shale masses in thrust belts is a major frontier for hydrocarbon exploration that could result in a major expansion of natural gas reserves.

► Mushwads are giant, disharmonically deformed shale bodies in thrust belts. ► Undeveloped gas resource in Conasauga mushwads is estimated to be about 17.7 Tcm (625 Tcf). ► This study is an integrated geological analysis of stratigraphy, sedimentation, structural geology, basin hydrodynamics, petrology, geochemistry, gas storage and mobility, and reservoir volumetrics. ► Meeting the challenges posed by deformed shale masses in thrust belts is a major frontier for hydrocarbon exploration that could result in a major expansion of natural gas reserves.