Our Team

Anthony G. Petrello has served as our President, Chief Executive Officer, Secretary and Director since March 2021, as well as Chairman of our board of directors. Mr. Petrello has served as the Chairman of the Board of Nabors since 2012 and director since 1991; Deputy Chairman of Nabors from 2003 to 2012; President and CEO of Nabors and Nabors Industries, Inc. since 2011; President and Chief Operating Officer of Nabors and Nabors Industries, Inc. from 1991 to 2011. Mr. Petrello holds a J.D. degree from Harvard Law School and B.S. and M.S. degrees in Mathematics from Yale University. Mr. Petrello also serves as a director of Hilcorp Energy Company. In 2018, Mr. Petrello was the recipient of the Offshore Energy Center Pinnacle Award, recognizing outstanding individuals who have taken today’s leading-edge tools and technologies and applied them to real world challenges.

William J. Restrepo has served as our Chief Financial Officer since April 2021. He has served as Chief Financial Officer of Nabors since March 2014. Mr. Restrepo previously served as Chief Financial Officer at Pacific Drilling S.A. from February 2011 to February 2014. He also previously served as Chief Financial Officer at Seitel from 2005 to 2009, and at Smith from 2009 to 2010 until its merger with Schlumberger Limited. Prior to that, from 1985 to 2005, Mr. Restrepo served in various senior strategic, financial and operational positions for Schlumberger Limited, including operational responsibility for all product lines in the Continental Europe and Arabian Gulf markets, as well as senior financial executive roles in Corporate Treasury and worldwide controller positions with international posts in Europe, South America and Asia. Mr. Restrepo currently serves on the board of Reelwell As, a Norwegian-based provider of advanced drilling technology. He previously served on the board of directors of SANAD (Nabors’ joint venture with Saudi Aramco) and previously served on the boards of directors of C&J Energy Services Ltd. from 2015 to 2017, Probe Technology Services from 2008 to 2016, and Platinum Energy Solutions, Inc. from 2012 to 2013. Mr. Restrepo holds a B.A. in Economics and an M.B.A, both from Cornell University, as well as a B.S. in Civil Engineering from the University of Miami.

Guillermo Sierra is our Vice President, Strategic Initiatives—Energy Transition. Mr. Sierra has served in the same position at Nabors since April 2021. Mr. Sierra has extensive experience in energy infrastructure, logistics, capital markets and M&A given his work on over 60 transactions with combined value of over $200 billion over the last approximately 15 years through various advisory and corporate strategy roles. Mr. Sierra was a Partner at Blackline Partners, serving as Executive Vice President, Head of Strategy for Blackline Midstream from August 2019 to March 2020 and in the same position for Blackline Cold Storage from March 2020 to November 2020. From September 2016 to December 2018, Mr. Sierra served as Managing Director, Head of North America Midstream Advisory at Macquarie Capital. Prior to Macquarie Capital, Mr. Sierra served as Senior Director, Head of MLP/Midstream M&A at Credit Suisse from July 2015 to September 2016. Mr. Sierra’s earlier experiences include positions at USD Group LLC & USD Partners (VP, Chief Strategy Officer and Head of M&A), Evercore Partners (Vice President — Energy M&A), and Barclays Capital (as a member of the Global Natural Resources Group). Mr. Sierra graduated Cum Laude from the Wharton School of the University of Pennsylvania, where he received a B.S. in Economics with concentrations in Finance and Operations & Information Management.

Siggi Meissner is our President of Engineering and Technology. Mr. Meissner has served as Nabors’ President of Global Drilling and Engineering since 2015, leading one of the largest drilling contractors in the world. Mr. Meissner has over 40 years of energy and technology industry experience and is recognized as a drilling engineering subject matter expert. Since joining Nabors in 1993, Mr. Meissner has been instrumental in expanding Nabors footprint worldwide from a development, commercial and operational standpoint. Under Mr. Meissner’s leadership, Nabors has evolved to become an advanced technology, digitalization, automation and innovation leader in the energy complex. Mr. Meissner currently leads Nabors’ operational and technological efforts to develop and deploy cleaner and more energy efficient drilling operations, including complex data systems and controls, automation, robotics and other sustainable fuel technologies to significantly lower greenhouse gas emissions. Historically, Mr. Meissner played a role in the development of several geothermal energy developments. Mr. Meissner also currently serves on the board of directors of SANAD. He earned his degree in Petroleum Engineering from the Technical University of Calusthan-Zellerfeld in Germany.

John Yearwood currently serves on our board of directors. Mr. Yearwood also currently serves on the board of directors of Nabors, TechnipFMC plc, Sheridan Production Partners, Barra Energia, Foro Energy LLC, Bazean LLC, and Coil Tubing Partners LLC. He previously served on the boards of Sabine Oil & Gas, LLC until August 2016, Premium Oilfield Services, LLC until April 2017, and Dixie Electric LLC until November 2018. Until August 2010, he served as the Chief Executive Officer, President and Chief Operating Officer of Smith International, Inc. (“Smith”). He was first elected to Smith’s board of directors in 2006 and remained on the board until he successfully negotiated and completed the sale of Smith to Schlumberger Limited in August 2010. Mr. Yearwood has extensive experience in the energy industry, including throughout Latin America, Europe, North Africa and North America. Before joining Smith, Mr. Yearwood spent 27 years with Schlumberger Limited in numerous operations, management and staff positions throughout Latin America, Europe, North Africa and North America, including as President and in financial director positions. He also previously served as Financial Director of WesternGeco, a 70:30 joint venture between Schlumberger and Baker Hughes from 2000 to 2004. Mr. Yearwood received a B.S. Honors Degree in Geology and the Environment from Oxford Brookes University in England.

Maria Jelescu Dreyfus currently serves on our board of directors. Ms. Dreyfus also currently serves as the Chief Executive Officer of Ardinall Investment Management, a position she held since co-founding the company in April 2017. Prior to Ardinall, Ms. Dreyfus spent 15 years at Goldman Sachs, most recently serving as Portfolio Manager and Managing Director from 2008 to April 2017. Additionally, Ms. Dreyfus serves on the board of directors of Macquarie Infrastructure Corporation (NYSE: MIC), since September 2018, CDPQ, one of Canada’s largest pension plans, since November 2019 and is on the advisory board of Eni Next, the corporate venture arm of Eni SpA, since 2019.

Additionally, Ms. Dreyfus is on the advisory board of the Center on Global Energy Policy at Columbia University, since 2015, and co-chair of its Women in Energy program. Ms. Dreyfus is also a member of the MIT Corporation’s Development Committee and sits on the MIT Economics Department’s Visiting Committee. Ms. Dreyfus currently serves on the board of the non-profit organization Girls Inc. of NYC, and her past non-profit board memberships include New America Alliance and Breakthrough New York.

Ms. Dreyfus holds a BS in Management Science and a BS in Economics from MIT.

Colleen Calhoun currently serves on our board of directors. Ms. Calhoun also currently serves as Vice President of XL Fleet (NYSE: XL), a provider of fleet electrification solutions, and General Manager of XL Grid, a division of XL Fleet, positions she has held since January 2021. Prior to this, Ms. Calhoun served as Founder and Principal Advisor at Helios Consulting, LLC from November 2019 to December 2020. Ms. Calhoun spent twenty-five years at GE across several roles at the company, including Chief Marketing Officer and Head of Business Development (August 2018 to October 2019) and Head of Business Development and Partnerships (January 2016 to August 2018) at GE Current, a leading provider of energy efficiency and digital productivity solutions for commercial buildings and cities, where she was instrumental in the divesture of the business from GE in 2019; Global Senior Director of Energy Ventures at GE Ventures (January 2013 to December 2015); Executive Director, Marketing, Strategy and Project Development at GE Power & Water (October 2010 to December 2012); and Managing Director, Global Growth Markets at GE Energy Financial Services (January 2006 to September 2010). Ms. Calhoun is presently a member of the board of directors at Quaise, Inc. and the Clean Energy Trust. She also previously served on the Advisory Board at NYSERDA REV Connect.

Ms. Calhoun earned her bachelor’s degree in engineering from the University of Pennsylvania and an MBA from the University of Michigan.

Jennifer Gill Roberts currently serves on our board of directors. Ms. Roberts is a technologist, repeat entrepreneur and seasoned venture capitalist. She co-founded her current venture fund, Grit Ventures, in 2017 to focus on pre-seed investments in artificial intelligence and robotics. Ms. Roberts currently serves as the Managing Partner of Grit Ventures. Prior to Grit Ventures, Ms. Roberts co-founded RallyOn, a wellness gaming startup, and served as Chair and Chief Marketing Officer from July 2008 to November 2013. Prior to that, she was a founder and Managing Partner of Maven Venture Partners from March 2005 to September 2008 and Managing Partner at top tier venture capital firm, Sevin Rosen Funds, from August 1994 to November 2003, where she focused on investments in seed-stage market leading companies in optical and wireless equipment. Prior to her career in venture capital, Ms. Roberts led product and technical efforts at Apple Computer, Hewlett-Packard Company, and Sun Microsystems. Ms. Roberts currently serves on the board of directors of Cognitive Space, an artificial intelligence company in the satellite industry, RIOS Corporation, an artificial intelligence and robotics company focused on factory automation and Apptronik, a leader in robotic logistics platforms for government and commercial applications. Ms. Roberts has a BS in Electrical Engineering and an MBA from Stanford and an MS in Electrical Engineering from the University of Texas at Austin.