John O. Robertson, PhD, is the owner of Earth Engineering, Inc. and an adjunct professor at ITT Tech in National City, CA. He has over 50 years of experience in petroleum and environmental engineering and geology and is the author of over 12 textbooks and 75 articles. George V. Chilingar, PhD, is an Emeritus Professor of Engineering at the University of Southern California in Los Angeles, CA. He is one of the most well-known petroleum geologists in the world and the founder of several prestigious journals in the oil and gas industry. He has published over 70 books and 500 articles and has received over 100 awards over his career.