Principal Researcher at the Uni Centre for Integrated Petroleum Research in Bergen, NorwayEditor-in-Chief, SPE journals, 2013- Board of Directors, Resoptima AS, Oslo, Norway, 2012-Mewbourne Chair Professor in the Mewbourne School of Petroleum and Geologic Engineering, The University of Oklahoma, Norman, Oklahoma, since 2006.Executive Editor of SPE Journal, 2005-2009Eberly Family Chair Professor and Director of the Mewbourne School of Petroleum and Geologic Engineering, The University of Oklahoma, Norman, Oklahoma, 2002--2006.Professor and interim chairman of petroleum engineering, The University of Tulsa, Tulsa, Oklahoma, 2001--2002.Associate professor of petroleum engineering, The University of Tulsa, Tulsa, Oklahoma,1999--2001.Assistant professor of petroleum engineering, The University of Tulsa, Tulsa, Oklahoma, 1997--1999.Staff research scientist in reservoir characterization, Chevron Petroleum Technology Co., La Habra, California, 1991--1997.Lead petroleum engineer for Safaniya Field, Arabian Chevron, Inc., Dhahran, Saudi Arabia, 1987--1991.Senior reservoir engineer, Chevron USA, San Ramon, California, 1983--1987.Research geophysicist in production research, Chevron Oil Field Research Company, La Habra, California, 1980--1983.Specialties: Reservoir engineering, petroleum inverse theory, reservoir characterization