Leif Colson obtained his Master of Science in Geophysics from Colorado School of Mines (2005) and is a graduate of engineering physics (CSM 1972). He started work in 1977 with Schlumberger Well Services as a wireline logging engineer. He held various positions in Rocky Mountain operations before beginning a career in well log interpretation in Denver in 1980. Leif has worked as an interpretation development engineer in Alaska, Gulf of Mexico and Texas Onshore and in the Rocky Mountain Region. He has published papers on naturally fractured reservoirs, coalbed methane logging and evaluation, enhanced vertical resolution logs and interpretation of geochemical logs. Leif has experience interpreting production logs in three phase production wells in California and gas wells in the Rocky Mountain Area since 1994. He retired in 2005 as a Principal Petrophysicist for Schlumberger Data Services in Denver, Colorado. Leif is currently consulting and is the owner of Colson Petrophysical Consulting, LLC.