He teaches courses in petroleum project evaluation, advanced production engineering, and natural gas engineering, while conducting research in decline curve analysis in tight sand and shale gas reservoirs. Prior to joining OU, Callard worked for 16 years in exploration and production and related industry. He received his degrees in petroleum engineering from OU, Stanford and LSU. Callard is a member of SPE and has previously published papers on decline curve analysis in its journal. He also currently serves as an undergraduate adviser in the Mewbourne School of Petroleum and Geological Engineering.