About Chief Oil & Gas


Trevor D. Rees-Jones, Founder and CEO

After practicing oil and gas reorganization law, Mr. Rees-Jones entered the oil and gas business in 1984 as an independent involved in exploration and production. In 1994, he founded Chief Oil & Gas, which was an early operator in the development of the Barnett Shale field in North Texas and the Marcellus Shale in Pennsylvania and West Virginia. Chief continues as a leading privately-held, independent oil and natural gas exploration and production company, with substantial acreage position in the Marcellus, as well as holdings and activity in many other oil and gas basins throughout the United States. Mr. Rees-Jones is past president of both the Dallas Petroleum Club and the Dallas Hardhatters Committee (now the Dallas Wildcatters Committee). He is a member of the Board of Trustees at Texas Christian University. He received the Folsom Award for civic and community service in 2011. In 2013, he was awarded the Circle Ten Council Distinguished Eagle Scout Award. In 2017, Rees-Jones was the recipient of the Pitts Energy Leadership Award from the Maguire Energy Institute at the Cox School of Business - Southern Methodist University (SMU) in Dallas, Texas. Mr. Rees-Jones received his BA from Dartmouth College and his JD from SMU School of Law.

Andrew (Andy) E. Levine, President

Mr. Levine joined Chief Oil & Gas in 2014 as Senior Vice President of Marketing, and was later promoted to President of Chief Oil & Gas in the Spring of 2021. Prior to joining Chief, he served as VP of Transportation at Chesapeake Energy Marketing, Inc. managing negotiation of transportation capacity, market origination, customer relations and regulatory activities. Prior to joining Chesapeake in 2009, Mr. Levine was Director of Supply Development for Tennessee Gas Pipeline. He worked for Tennessee for 20 years and held commercial positions in Marketing, Supply and Business Development as well as in accounting. He graduated from Texas State University in 1988 with a BBA in Accounting and received a CPA certification in the state of Texas.

Marcia Simpson, Senior Vice President - Engineering & Operations

Mrs. Simpson joined Chief Oil & Gas in 2016 as Senior Vice President, Engineering & Operations. Prior to Chief, Mrs. Simpson held the position of Vice President of Engineering with EXCO Resources. Throughout her career in the oil and natural gas industry, she has held positions in engineering, operations, reserves reporting, acquisitions and divestitures with Gulf Oil, Chevron, Mobil Oil, J-W Operating Company and EXCO Resources. She is a graduate of Penn State University where she received a Bachelor of Science in Petroleum and Natural Gas Engineering and is a registered Professional Engineer.

Justin Hernandez, Senior Vice President & Chief Financial Officer

Mr. Hernandez joined Chief Oil & Gas in 2013 as Financial Reporting Manager then later as Director of Finance. Mr. Hernandez was promoted to Senior Vice-President and Chief Financial Officer of Chief Oil & Gas in the Spring of 2021. Prior to joining the company, he worked at Lockheed Martin where he evaluated acquisitions and divestitures, assessed foreign currency risk, and led strategic initiatives for the Aeronautics division. Mr. Hernandez holds a BBA in Finance from Texas State University and an MBA in Finance from Texas Christian University. He is a CFA charter holder and sits on the Board of Directors for Impossible Possibilities.

Tim Mullen, Vice President - Operations

Mr. Mullen joined Chief Oil & Gas in 2015 as Director of Operations and was promoted to Vice President of Operations in 2017. Prior to Chief, Mr. Mullen held the position of Asset Manager for a small private equity backed E&P company. Throughout his career in the oil and natural gas industry, he has held various Engineering and Operations Leadership positions with companies such as Newfield Exploration, EOG Resources, Anadarko Petroleum Corporation and Union Pacific Resources. Mr. Mullen is a graduate of Penn State University where he received a Bachelor of Science in Chemical Engineering and is also a graduate of Texas Christian University where he earned an MBA specializing in Operations Management.

Justin Clarke, Vice President and General Counsel

Justin Clarke joined Chief Oil & Gas in 2019 as Vice President and General Counsel. Prior to joining Chief, Mr. Clarke served as Executive Vice President of Acquisitions and Divestitures and General Counsel of Saddle Operating, a portfolio company of First Reserve, where he was responsible for legal initiatives and the evaluation and execution of new business opportunities. Mr. Clarke also previously served as Vice President and General Counsel of EXCO Resources and Thompson Petroleum Corporation. Mr. Clarke began his career in the corporate section of Haynes and Boone, LLP, in Dallas, Texas. Mr. Clarke received his JD from Texas Tech University School of Law and his BBA in Finance from The University of Texas at Arlington. Mr. Clarke serves on the Finance Committee of the Board of Directors of St John’s Episcopal School of Dallas.