Mark Rothenberg, CEO

Mark is founder of Apex Energy, LLC. Prior to starting Apex, he was an executive in the EXCO-BG Appalachia Joint Venture and before that he was part of the team at Vantage Energy. His career spans over 20 years of operations and reservoir engineering, as well as business development and executive management in some of the most prolific oil and gas basins throughout the United States. Mark started his career with Amoco and progressed into leadership positions at mid-sized public companies and small private companies. He has specialized in unconventional resources and has successfully applied cutting edge technological advances in drilling and completion techniques to these projects. His experience includes exploration and exploitation of shale plays, coalbed methane reservoirs, and tight gas sands. Mark emphasizes a combination of strong subsurface understandings with industry leading practices to successfully develop these unconventional assets.  Mark has a degree in chemical engineering from the University of Colorado and is a long time member of the Society of Petroleum Engineers.

Chris Hess, GC & VP of Land/BD

Chris started with Apex Energy, LLC in May 2013. Prior to Apex, Chris served in the land and legal departments of the EXCO-BG Appalachia Joint Venture. A graduate of the University of Pittsburgh School of Law and the University of Pittsburgh College of Arts and Sciences (B.S., Biology), Chris has more than 20 years of experience as an attorney in both private and public practice. He has worked in the Pittsburgh office of national law firms and served as the manager of corporate services for the Port Authority of Allegheny County—a position consisting of the chief of staff and chief legal counsel functions for the agency. Chris’s experience includes corporate acquisitions and divestitures, managing leasing programs and multidisciplinary capital projects, and serving as corporate secretary. 

Minh Nguyen, VP of Operations









Minh started with Apex Energy (PA), LLC in February 2018.  He has over 21 years of drilling and operations experience with a main focus on unconventional plays.  Minh started his career in the Gulf of Mexico and international markets, and he then translated his knowledge base into onshore drilling at Mitchell Energy in 2000.  He spent about 9 years at Range Resources drilling unconventional horizontal wells and played integral roles to establish Range’s successes in drilling core and expansion areas in Texas and Pennsylvania.  Minh also consulted for a number of private, independent oil & gas companies helping to successfully develop their unconventional reservoirs.  Minh is a long time member of the Appalachian Basin AADE and serves as their Program Committee Chair since 2010.  He is also a long time member of SPE.  Minh has a Bachelor of Science degree in Petroleum Engineering from The University of Texas at Austin. 

Eric Shullenberger, Exploration Manager

Eric serves as the Exploration Manager for Apex Energy, LLC and is a geologist by background.  Eric’s career spans over 11 years and his experience covers a wide variety of projects, both international and domestic, including shallow water Gulf of Mexico, international heavy oil reservoirs and US Rockies basins.  He has focused the last 7 years on exploring, appraising and developing US Onshore unconventional plays.  Prior to joining Apex in 2017, Eric served as a geologist and project lead at Anadarko Petroleum Corporation and as a geologist at Chevron Corporation.  His experience ranges from hands-on operations and development, exploration, project management, A&D deal evaluation and preparation, and team leadership.  Eric is a degreed geologist, with a Bachelor’s of Science degree from Miami University and a Master’s of Science degree from the University of Wisconsin—Madison.  Eric is a long-time member of the American Association of Petroleum Geologists.

Rich Mangene, Controller

Rich is the Controller for Apex Energy, LLC. Since joining Apex in 2014, his primary responsibilities have been the company’s accounting and reporting, treasury management and budgeting. Rich has 18 years of accounting and finance experience in public and privately held companies. His career began at KPMG where he advised domestic and worldwide companies on various SEC filings, public and private debt offerings and the initial implementation of the Sarbanes-Oxley Act. He then spent several years overseeing the accounting and finance of Alcoa’s global rolled products business where his work also included due diligence on mergers and acquisitions. Rich then spent two years as the Corporate Controller for Dynavox Inc. where he was responsible for technical accounting, SEC reporting and Financial Planning and Analysis. Rich is a graduate of Duquesne University with a Bachelor of Science and Business Administration – Accounting and a Certified Public Accountant in Pennsylvania.