GableGotwals Expands Houston Office

August 5, 2025 | GableGotwals is excited to announce the expansion of its Houston office. Initially launched by litigation attorneys John Sullivan and Brian Tully, the office has expanded to include transactional attorneys Alan Buckner and Mark Nawfal, as well as environmental attorney Win Colbert. Learn more below.

Alan Buckner brings extensive transactional knowledge across all areas of the energy industry. His experience includes mergers and acquisitions, joint ventures, private equity/finance transactions, project development, sales and transportation agreements, joint operating agreements, EPC contracts, and other commercial leases.

Prior to joining the Firm, Alan worked in general counsel and business development roles at private oil and gas companies, as well as practiced law at several AmLaw 100 firms.

Alan received his J.D. with honors from The University of Tulsa College of Law and his B.A. from the University of Texas at Austin. He is admitted to practice in Texas.

Mark Nawfal brings more than 15 years of international legal experience advising multinational companies, private equity funds, and partnerships on a wide range of corporate and transactional matters. His practice focuses on mergers and acquisitions, taxation, and energy law.

Prior to joining the Firm, Mark practiced at law firms in Houston, New York, and the Middle East. He is fluent in French and Arabic and proficient in Spanish. He is admitted to practice in Texas, New York, and Florida.

Mark earned his J.D. from Northeastern University School of Law, holds an LL.M. in Global Energy from The University of Texas at Austin School of Law, and an LL.M. in Taxation with a Certificate in International Taxation from Georgetown University Law Center. He received his B.A. in Economics and International Relations from Tufts University.

Winfred T. (“Win”) Colbert has extensive experience advising public and private sector clients on complex environmental, health, and safety (EHS) matters. Win enhances the Firm’s capabilities in regulatory compliance, enforcement defense, and strategic environmental counseling across key industries.

Prior to joining GableGotwals, Win served as Senior Assistant City Attorney for the City of Houston. In that role, he advised the Mayor’s Office and several city departments, including the Airport System, Public Works, Health, and Solid Waste, on environmental, regulatory, and legislative issues. He also served as a liaison with the U.S. Environmental Protection Agency (EPA) and the Texas Commission on Environmental Quality (TCEQ).

He received his J.D. from Columbia Law School and his B.A. in Political Science from Yale University.

Meet the rest of our team:

John Sullivan has more than 35 years of litigation experience, trying many types of cases in state and federal courts throughout the country. He focuses on civil trials and arbitration of cases dealing with complex energy issues, commercial disputes, wrongful death and catastrophic injuries, environmental contamination, and insurance claims and coverage disputes.

Prior to joining the Firm, John served as in-house litigation counsel for more than 25 years at Texaco Inc. and Shell Oil Company. He was involved in a wide range of litigation matters and disputes covering all aspects of the energy business including onshore and offshore exploration and production, pipelines and terminals, refineries and chemical plants, service station and retail operations, lubricants, shipping, and trading.

Brian Tully has more than 20 years of business litigation and appellate experience, representing clients in state and federal courts in a broad range of disputes, including breach of contract, misappropriation of trade secrets, negligence, professional negligence, and fraud.

He previously served as a Law Clerk to the Hon. Nathan L. Hecht of the Supreme Court of Texas.

About GableGotwals

GableGotwals® is a full-service law firm with 100 attorneys and more than 70 other business professionals in Oklahoma and Texas. We represent a diversified client base across the nation, and our connections and reach are global. Fortune 500 corporations, privately owned companies, entrepreneurs, foundations, and individuals entrust us every day with the stewardship and strategic management of their legal challenges.