David Simpson is currently the Principal Engineer and Owner of MuleShoe Engineering. His role involves providing engineering consulting services for the oil and gas industry focused on artificial lift, coalbed methane, and facility design. He has authored numerous journal articles, earned three patents, and is active in SPE, ASME, NACE, and NSPE. He is also an independent instructor teaching unconventional upstream operations and unconventional upstream operations engineering for practicing oil and gas engineers. David earned a BSc in industrial management from the University of Arkansas, a MSc in mechanical engineering from the University of Colorado, and is a registered professional engineer in Colorado and New Mexico. P. Scott Northrop is the Owner and Principal Engineer of Northrop Consulting, LLC. He provides consulting services on treating processes for the hydrocarbon industry, specializing in adsorption and absorption processes. He has written a number of articles and authored/co-authored over 50 US patents. He was on the Thermodynamic Research Committee for the GPA Midstream Association, and on the Editorial Review Board for the GPSA DataBook for several years. He is currently a member of the American Chemical Society and Alberta Sulphur Research, Ltd. Scott earned his BSc in Chem Eng from Washington University in St. Louis, and his MSc and PhD (also in Chem Eng) from the California Institute of Technology.