Our Board of Directors

Donald L. Evans

Independent Director

Donald L. Evans was appointed as the 34th Secretary of the Commerce by President George W. Bush in 2001, where he served until 2005. He was a strong advocate for the free-enterprise system, free and fair trade agreements, and responsible corporate stewardship. To encourage job creation, Evans worked closely with President Bush to reduce taxes, open markets for American goods and services, and promote a level playing field abroad. A trusted friend and advisor for more than three decades, Evans worked on President Bush’s successful Texas gubernatorial campaigns in 1994 and 1998 and served as chairman of the 2000 Bush-Cheney Presidential Campaign.

Born in Houston, Texas, in 1946, Evans attended the University of Texas at Austin, receiving a B.S. degree in mechanical engineering in 1969 and an M.B.A. in 1973. During school breaks, he worked in a Texas steel mill. In 1975, Evans moved to Midland, Texas from Houston and began his career as a “roughneck” working on oil rigs for Tom Brown, Inc., a large independent energy company. Ten years later, he took the helm of the company as CEO, continuing in that position until being tapped by the President to lead the Commerce Department. He also served as the Chairman of Energy Future Holdings Company, formerly TXU Energy, from 2007-2018, and currently he serves as Chairman of The Permian Strategic Partnership.

In 1995, Evans was appointed to the University of Texas Board of Regents; he was elected chairman in February 1997 and served two consecutive terms. Evans was also a board member of the Scleroderma Research Foundation for eight years. He was named a University of Texas Distinguished Engineering Alumnus and inducted into the University of Texas’ McCombs School of Business Hall of Fame in 2002.

Currently, Evans serves as the Vice Chair of the Board of Visitors at MD Anderson and is an Independent Director at Extraction Oil & Gas. Also, he is a senior partner at Quintana Capital Group, senior advisor at Energy Capital Partners, and member of the advisory board of the Energy Institute at the University of Texas at Austin. Evans has remained active in his hometown community of Midland, Texas where he resides with his wife, Susan Marinis Evans, and serves on the Midland Memorial Hospital Board of Governors. His passions in life are his faith, family, and friends. They have two daughters, one son, and five grandchildren.

Don Hrap

Independent Director

Mr. Hrap most recently served as President, Lower 48 at ConocoPhillips, a position he held from 2009 – 2018. While at ConocoPhillips Mr. Hrap also served as president of the Lower 48 and Latin America, and prior to that, senior vice president of Western Canada Gas with the company. He joined ConocoPhillips in 2006 through the merger with Burlington Resources, serving as senior vice president of operations for Burlington Canada. Earlier, he was vice president for the North American Division at Gulf Canada Resources, where he worked for 17 years. Mr. Hrap is a former chairman and currently serves as a member of the API Upstream Committee and is an At-Large Director for the Independent Petroleum Association of America (IPAA). He also is a member of the executive committee of the U.S. Oil and Gas Association. Mr. Hrap graduated from the University of Manitoba with a Bachelor of Science in Mechanical Engineering in 1982. In 1995, he graduated from the University of Calgary with a Master in Business Administration.

David B. Krieger

Managing Director, Warburg Pincus

David B. Krieger is based in Houston, joined Warburg Pincus in 2000 and focuses on energy investments. Previously, he worked at McKinsey & Company in Atlanta and throughout Europe. Mr. Krieger is a Director of Black Swan Energy, Conquest Completion Services, Ensign Natural Resources, MEG Energy, Ridge Runner Resources, Rubicon Oilfield International, Sheridan Production, Tall City Exploration, Trident Energy and Velvet Energy. He also serves as a Trustee of the Kaufman Center for the Performing Arts. Mr. Krieger received a B.S. in economics summa cum laude from the Wharton School of the University of Pennsylvania, an M.S. with high honors from the Georgia Institute of Technology and an M.B.A. with distinction from Harvard Business School.

David S. Habachy

Managing Director, Warburg Pincus

David S. Habachy is based in Houston, joined Warburg Pincus in 2017 and is a member of the firms Energy team. Previously, he was a Managing Director and a member of the Investment Committee of the Kayne Anderson Energy Funds. Additionally, while at Kayne Anderson, Mr. Habachy served on numerous boards of oil and gas upstream E&P and midstream companies in the U.S. and Canada from 2008 to 2017. Prior to entering into Private Equity in 2008, he spent 10 years in asset management, operations and consulting in the upstream E&P business, starting his Petroleum Engineering career at Arco/Vastar in 1998. He is a Director of Ridge Runner Resources, LLC; Stronghold Energy II Holdings, LLC; and Tall City Exploration III LLC. Mr. Habachy holds a B.S. in chemical engineering and an MBA degree with George Kozmetsky highest honors distinction from The University of Texas at Austin.

C. Ryan Dalton

Principal, Warburg Pincus

C. Ryan Dalton is based in Houston and focuses on energy investments. Mr. Dalton worked at Warburg Pincus from 2008 to 2010 and, following the completion of an MBA, rejoined Warburg Pincus in 2012. Previously he worked in the financial institution’s investment banking group at Merrill Lynch in New York. Mr. Dalton received a B.A. and B.S. cum laude in Computer Science and Economics, respectively, from Southern Methodist University and an M.B.A. from Harvard Business School. He is a Director of Tall City Exploration III, Ensign Natural Resources, Chisholm Energy Partners and Sheridan Production Partners.

Steven Kantowitz

Vice President, Warburg Pincus

Steven Kantowitz is based in New York and focuses on energy investments. Mr. Kantowitz worked at Warburg Pincus from 2012 to 2014, and following the completion of an M.B.A., rejoined Warburg Pincus in 2016. Previously, he worked in the Energy investment banking group at Credit Suisse. Mr. Kantowitz is a director of Stronghold Energy, Solar Mosaic and Tall City Exploration, and also works with Artis Exploration and Venari Resources. He received a B.S. summa cum laude in finance and economics from The Leonard N. Stern School of Business at New York University and an M.B.A. with distinction from Harvard Business School.

Michael Oestmann

President & Chief Executive Officer

Mr. Oestmann has over 37 years of experience in all aspects of the oil and gas business, with a particular focus on company start-ups, exploration, asset management and development. Mr. Oestmann has experience in numerous geologic basins with primary focus in the Permian Basin and has a consistent record of increasing production in existing fields, exploration success and company development and sale. Mr. Oestmann began his career with Exxon Co. USA in 1982 after graduating from Rice University with a bachelor’s degree in geology with a geophysics option. He worked 15 years with Exxon, 7 years with Titan/Pure Resources/Unocal, 2 years with Celero/Whiting, and 1 year with Lothian Oil in various exploration, development and senior management positions. In 2007 he co-founded Piedra Resources with private equity partners. Piedra sold its assets in 2011 for over $120 million. Mr. Oestmann began Tall City Exploration in May of 2012 with a $200 Million equity commitment from Denham Capital. Tall City completed the sale of its assets in 2015 for a total of $1.2B. He is a 35 year member of the AAPG and SEG, member of the PBGS (having served as President) WTGS and SPE. He is a certified geologist with the Texas Board of Professional Geoscientists and the DPA of the AAPG, and serves as an elder at Westway Church of Christ. He and Cathy, his wife of 34 years, live in Midland, Texas.

Michael Marziani

Executive Vice President & Chief Financial Officer

Prior to joining Tall City, Mr. Marziani spent five years as an investment banker and Principal with Greenhill & Co., a boutique M&A advisory firm. He helped to found Greenhill’s Houston office and advised on a number corporate energy M&A transactions, most notably: the $4.8 billion Devon Energy/Crosstex midstream combination in 2013, Linn Energy’s $4.9 billion acquisition of Berry Petroleum in 2013, Superior Energy Services’ $3.2 billion acquisition of Complete Production Services in 2011 and BJ Services Company’s $7.6 billion merger with Baker Hughes in 2009. Prior to his time at Greenhill, Mr. Marziani was a Vice President with Merrill Lynch and spent over five years in the Global Energy & Power investment banking team in Houston. While at Merrill Lynch, he was a member of transaction teams that completed over $6.5 billion in energy-focused M&A advisory transactions and over $13.5 billion in capital markets underwriting transactions. Prior to joining Merrill Lynch, he worked in a variety of petroleum and reservoir engineering roles for BP in Houston. Mike holds a B.S. in Mechanical Engineering from Rice University and received an M.B.A. with high honors from the McCombs School of Business at the University of Texas at Austin.


Gary L. Pitts

Independent Director

I graduated from Texas A&M University in 1973 with Bachelor’s Degree in Geophysics and was in the Naval Aviation Reserves until 1974. First job in the industry after graduating was with Gulf Oil in various Divisions including Houston, Harmarville, Pennsylvania Research Lab and finally Midland, Tx. and the Permian Basin. After Gulf OiI, I joined Texas Oil and Gas for 3 years as Division Geophysicist in Dallas and then moved to Midland. After Texas Oil and Gas, my primary duties were as Exploration Manager, Union Texas Petroleum Midland and then to Houston as Exploration Manager Offshore, then to Vice President E&P and Vice President of Operations for Neste Oy. The first 22 years were primarily exploration oriented in multiple basins within North America including offshore Gulf Coast and some international work with Neste Oy, the Finnish National Oil Company. After joining Henry Petroleum in 1995, I was the Vice President of Business Development and worked primarily in new ventures, acquisitions and new exploration projects. The last position with Henry was as VP Business Development and Exploration and then joined EOG Resources in February 2008 as Vice President and General Manager Midland Division and retired from EOG May 2014.

After retiring from EOG, I tried retirement, but my love for this industry and its people just kept after me and I was able to join Quantum Energy Partners January 1, 2015 as a Senior Geosciences Advisor to assist them with their existing portfolio of companies and possible new adds to their portfolio companies. My primary role was to evaluate the plays and assist in implementation of current technology for their existing portfolio companies and to evaluate the possible companies employees and their exploration and production portfolios for investment possibilities. This was fun and enjoyable and the QEP personnel were great to work with, but I was falling behind on expanding technology so I resigned the retainer position effective January 1, 2018. The owners and several of the key staff at ExL Petroleum were friends and past coworkers so they called me up and I worked with them for a while, March 2018-February 2019, aiding them as a Geosciences Advisor in reviewing their ongoing leasehold and working on some of my old ideas. 

I have had a wide, varied and fun experience including exploration of all major producing basins of U. S., Canada, Gulf of Mexico and Alaska with minor international including Mexico, Central and South America, North Africa and North Sea. I have been responsible for evaluating companies and fields for acquisition, starting new plays, designed development proposals for future development of existing fields, aided in design and implementation of water floods and have assisted in the negotiation of multiple different types of contracts