Energy ExpertsÂ
Engineers
Engineering Professionals
Herman G. Acuña, P.E.
With over 30 years of experience in petroleum engineering and project management, Herman G. Acuña, P.E., joined Ryder Scott in 1997 and is part of the Executive team and Board of Directors. He has led high-profile projects across the Middle East, South America, and Central Asia, assisting major clients such as ADNOC and ECOPETROL with complex evaluations. Fluent in English, Spanish, and German, Herman is a licensed Professional Engineer in Texas and an active member of SPE and AIPN. He holds a Master’s (1989) and a Bachelor’s (1987) degree in Petroleum Engineering from the University of Tulsa, with additional training through Exxon-sponsored industry seminars.
Deji A. Adeyeye, P.E.
With over 25 years of industry experience, Deji has been part of Ryder Scott since 2014, focusing on reserves evaluations, economic assessments, reservoir management, and expert witness testimony in legal arbitrations. Prior to this, he worked at Murphy Oil Corp., where he planned and managed non-operated offshore assets, delivering significant operational efficiencies. Deji holds an M.Sc. in Petroleum Engineering from Texas A&M University, a B.Sc. in Chemical Engineering from the University of Lagos, and an MBA from Rice University. He has evaluated reserves and provided due diligence for global mergers, acquisitions, and divestitures.
Freddy Alvarado, Ph.D.
With 20 years of industry experience, Freddy has been part of Ryder Scott since 2021, focusing on reservoir engineering, reserves evaluation, and economic analysis. Prior to this, he worked at Miller and Lents, Ltd., where he delivered evaluations of oil and gas reserves for global projects. Freddy holds a Ph.D. in Petroleum and Natural Gas Engineering, an M.Sc. in Petroleum Engineering, and a B.Sc. in Petroleum Engineering from Penn State University and Universidad Central de Venezuela, bringing a diverse academic foundation to his work in reservoir engineering, reserves evaluation, and economic analysis.
Carlos E. Alvarez
With over 30 years of industry experience, Carlos has been part of Ryder Scott since 2021, focusing on the evaluation of improved oil recovery (IOR), enhanced oil recovery (EOR) projects, and reserves evaluations from the mentioned Projects. Prior to this, he worked as a Principal Advisor and Project Manager at Gaffney, Cline & Associates, leading IOR and EOR evaluations for projects in the Gulf of Mexico and South America. Carlos holds a B.Sc. degree in Mechanical Engineering from the University of Zulia and an MBA from Universidad Católica Andres Bello, both in Venezuela. He has expertise in heavy and extra-heavy oil reservoir evaluations, multidisciplinary team leadership, and technical feasibility studies, with geographical experience spanning North America, South America, Europe, Asia, and Oceania.
Mario A. Ballesteros, P.E.
With approximately 30 years of industry experience, Mario has been part of Ryder Scott since 2006, focusing on reserves evaluations, economic assessments, and international projects. Prior to this, he worked at Chevron International E&P Co., where he optimized gas networks for offshore fields and managed reserves estimation for major onshore production operations. Mario holds an M.Sc. in Petroleum Engineering from the University of Tulsa, an M.Sc. in Finance from Universidad del Meta in Colombia, and a B.Sc. in Mechanical Engineering from the University of Oklahoma. He has contributed significantly to reserves certifications and field development for national oil companies across the globe.
Pablo Cástellon
With over 15 years of industry experience, Pablo A. Castellón has been part of Ryder Scott since 2010. He specializes in reservoir engineering and has worked extensively on reserves and resources evaluations and audits (both conventional and unconventional), expert comment letters, economic assessments, technical due diligence, field development plan studies, secondary recovery and enhanced oil recovery (EOR) methods, technical training, and consulting for acquisitions and divestitures. Pablo has led major projects for national oil companies, private firms, regulatory agencies, financial institutions, and equity firms across Latin America. Pablo holds a B.Sc. in Civil Engineering from Michigan State University and has contributed to projects across North America, Central and South America, Africa, Europe, and Asia.
Vitaliy Charkovskyy, P.Eng.
With over 15 years of industry experience, Vitaliy has been part of Ryder Scott since 2012, focusing on reserves evaluations, reservoir modeling, and enhanced oil recovery (EOR) methods. Prior to this, Vitaliy worked at the Saskatchewan Research Council, where he performed core flood simulations and reservoir fluid characterizations for miscible CO2 injection projects. Vitaliy holds an M.Sc. in Petroleum Engineering from the University of Regina and dual degrees in Engineering for Oil and Gas Recovery from Ivano-Frankivsk National Technical University of Oil and Gas. He has advanced gas deliverability studies, heavy oil field evaluations, and unconventional resource studies globally.
Dr. Allan Chen, P.E., SPEC
With more than 20 years of global experience, Allan Chen serves as Advising Senior Vice President and Head of Applied Technology at Ryder Scott. He specializes in reservoir technology, reserves evaluations, asset valuations, geothermal and carbon capture and storage (CCS) projects, with a track record spanning over 200 fields worldwide and supporting transactions exceeding $20 billion. Prior to Ryder Scott, Allan held leadership and technical roles at Quantum Reservoir Impact, Roc Oil, and GeothermEx, and co-founded advisory firms focused on oil & gas, geothermal, and CCS. He holds a Ph.D. in Petroleum Engineering from Stanford University and is a licensed Professional Engineer in Texas.
Tosin Famurewa, P.E.
With over 25 years of industry experience and having been with Ryder Scott since 2006, Tosin Famurewa, P.E., is part of the Executive team and Board of Directors. He leads global teams evaluating resources for acquisition, divestiture, strategic planning, and regulatory filings. His major clients include Chevron, BP, ExxonMobil, ADNOC, and others. A former Chairman of the Society of Petroleum Evaluation Engineers, Houston Chapter, Tosin’s leadership strengthens Ryder Scott’s global consulting reputation. He holds dual bachelor’s degrees in chemical engineering and Materials Science/Engineering from UC Berkeley and a master’s in petroleum engineering from University of Southern California.
Kosta Filis
With approximately 18 years of experience in the oil and gas industry, Kostantinos began his career at Ryder Scott in 2007, specializing in developing comprehensive economic models for evaluating the viability of oil and gas projects. His expertise includes analyzing historical performance, joint venture contracts, regulatory compliance, and financial statements, as well as preparing cash flow reports using advanced economic software. Kostantinos has contributed to various SEC filings, NI-5101 filings, ANH filings, CNH filings, property sales, acquisitions, and fair market value assessments. He has worked on projects across both domestic and international fields, including the Offshore Gulf of Mexico, U.S. shale plays, the Middle East, and countries such as China, Colombia, Angola, Mexico, and Algeria. Before joining Ryder Scott, he worked at Hewitt Associates as a Systems Analyst, where he developed and tested coding logic for pension plan implementations for Fortune 500 companies. Kostantinos holds a BA in Mathematics from the University of St. Thomas.
Joshua Firestone
With nearly 15 years of experience in the energy industry, financial modeling, and data analytics, Joshua recently rejoined Ryder Scott, where he previously worked from 2016 to 2019, before spending six years as a Principal Economist at Wood Mackenzie from 2019 to 2025. He specializes in economic evaluations, risk management, and data analytics. Joshua has extensive experience evaluating commercial oil and gas properties for NOCs, IOCs, and independent producers globally, focusing on reserve audits, economic sensitivity, and fiscal terms analysis. He has also developed advanced statistical methods for forecasting production and optimizing well design. Joshua holds a BS in Finance from the University of Tulsa, an MBA in Energy and Risk Management from the University of Oklahoma, and a Master of Petroleum Economics and Management from École Nationale Supérieure du Pétrole et des Moteurs in France.
David A. Garcia, P.E.
With 16 years of industry experience, David has been part of Ryder Scott since 2015, focusing on reservoir engineering, economic evaluations, and secondary recovery methods. Prior to this, David worked at Occidental Petroleum Corporation, where he generated life-of-field plans and development strategies for tight gas reservoirs. David holds an M.Sc. in Petroleum Engineering and a B.Sc. in Petroleum Engineering from the University of Oklahoma, bringing a diverse academic foundation to his work in reservoir engineering, economic evaluations, and secondary recovery methods.
Marylena Garcia, P.E.
With over 25 years of industry experience, Marylena has been part of Ryder Scott since 2010 and currently serves as Managing Senior Vice President and Head of the Sustainable Energy Division. She focuses on carbon capture utilization and storage (CCUS), CO2 tax credits, GHG emissions validation and verification, as well as reserves certifications and audits. Her expertise in GHG assessments includes conducting comprehensive evaluations of Scope 1, Scope 2, and Scope 3 emissions for energy companies, ensuring compliance with regulatory frameworks such as the EPA GHG Reporting Program, ISO 14064 standards, and voluntary carbon markets. Prior to this, Marylena worked at Occidental Oil & Gas, managing one of the world’s largest CO2 EOR projects in the Permian Basin. She holds an M.Sc. in Petroleum Engineering from Texas A&M University and a B.Sc. in Petroleum Engineering from Universidad de Oriente in Venezuela. She has contributed to CCS feasibility studies, WAG process evaluations, and international reserves certifications across five continents, applying her expertise to align projects with sustainability goals and regulatory compliance standards.
Stephen E. Gardner, P.E.
With over 20 years of industry experience, Steve has been part of Ryder Scott since 2006, specializing in reserves evaluations, unconventional resource play analysis, and SEC and SPE-PRMS compliance. As Managing Senior Vice President, Manager of the Denver Office, and a Ryder Scott Board of Directors member, he plays a key role in overseeing reserves and resource evaluations, economic assessments, and reserves audits. Additionally, Steve leads Ryder Scott's geothermal energy consulting services, including geothermal reserves evaluations that leverage the SPE-PRMS framework for hydrocarbons. Before joining Ryder Scott, Steve worked at ExxonMobil, where he evaluated carbonate oil reservoirs undergoing secondary and tertiary recovery. He holds a B.Sc. in Mechanical Engineering from Brigham Young University, graduating summa cum laude. His expertise includes integrated reservoir studies, type well analysis and regulatory filings for unconventional resource projects across North America and internationally.
Daniel E. Guzman
With over 30 years of industry experience, Daniel Guzman has been part of Ryder Scott since 2006, focusing on reserves and resources evaluations and field development plan studies. He has extensive experience in reservoir engineering and field operations. Prior to joining Ryder Scott, he worked as a reservoir engineer in both operating and service companies, focusing on integrated studies and *thermal-enhanced oil recovery (EOR) methods. Daniel holds a B.Sc. in Petroleum Engineering from the National University of Engineering, Peru, and an M.Sc. in Oil and Gas Management from the University of Madrid. He has contributed to projects across Asia, South America, and the Middle East.
Bethany L. Hancock
With over 10 years of upstream oil and gas experience, Bethany Hancock specializes in reserves audits, field development planning, and acquisition evaluations for conventional and unconventional assets across North America, Australia, Europe, and Asia. She has led technical assessments for over 50 acquisition packages valued between $10 million and $2 billion, developing automated workflows and data integration tools to streamline evaluations. Bethany holds an M.Sc. in Petroleum Engineering from the University of Utah and a B.Sc. in Finance with minors in Mathematics and Economics from The Ohio State University. Her expertise spans reserves classification, economic modeling, and reservoir performance analysis, supporting major audits, valuations, and strategic decision-making in the industry.
Anna M. Hardesty, P.E. SPEC
With over 40 years of industry experience, Anna has been a key member of Ryder Scott since 2006, currently serving as Senior Vice President. Her expertise encompasses reserves and resources evaluations, economic analysis, and project management. Prior to joining Ryder Scott, Anna founded Hardesty & Associates, where she managed reserves calculations and economic forecasts for a global portfolio, frequently collaborating with Ryder Scott on projects since 1997. She began her career at Exxon Company USA. Anna holds an M.Sc. in Business (with honors) from the University of Texas at Austin and a B.Sc. in Mechanical Engineering magna cum laude from Tulane University. Fluent in both English and Spanish, Anna is a licensed professional engineer in Texas and Florida and is actively involved in industry organizations, including SPEE, SPE, AIEN, and the World Affairs Council.
Dainee Hurtado
With over 20 years of industry experience, Dainee has been part of Ryder Scott since 2012, focusing on reserves estimation, economic evaluations, and enhanced oil recovery (EOR) methods. As a Senior Petroleum Engineer, she evaluates oil and gas reserves under SEC and SPE-PRMS standards, with expertise spanning heavy oil fields, waterflooding, and production optimization. Prior to Ryder Scott, Dainee worked at RPS Scotia and Petroleos de Venezuela SA, where she conducted reservoir forecasts, managed mature reservoirs, and optimized production operations. Dainee holds a B.Sc. in Petroleum Engineering from Zulia University in Venezuela. Fluent in Spanish and English, Dainee has contributed to projects across North America, Asia, Europe, Africa, and Latin America, specializing in complex reservoir performance analysis and EOR strategies.
Mariella Infante
With 19 years of industry experience, Mariella has been a member of Ryder Scott since 2018, specializing in reserves evaluations, reservoir simulation, and field development planning. Prior to joining Ryder Scott, she gained valuable experience at Miller and Lents, Southwestern Energy, where she led numerical simulation studies for the Fayetteville and Marcellus shale plays and Schlumberger. Mariella holds a B.Sc. in Petroleum Engineering from the Universidad Central de Venezuela and has made significant contributions to global reserves evaluations and the optimization of reservoir characterization workflows
D.J. Jeong, P.L.(Eng.)
With over 15 years of industry experience, D.J. has been part of Ryder Scott for approximately 13 years and currently serves as an Engineering Technologist, focusing on reservoir engineering and petroleum reserves evaluation. His expertise includes reserves estimation, field performance analysis, and economic evaluations in accordance with SPE-PRMS, NI 51-101, and U.S. SEC guidelines. He is proficient in decline curve analysis, type well analysis, rate transient analysis, volumetric calculations, material balance, and data analytics. Before joining Ryder Scott, Jeong held technical roles at Q’Max and Weatherford Laboratories, specializing in drilling fluids programming and PVT laboratory analysis. He holds a technical diploma in Petroleum Engineering Technology from the Southern Alberta Institute of Technology and is a Professional Licensee of Engineering with APEGA. Jeong is a member of the Society of Petroleum Engineers (SPE) and is fluent in English and Korean.
Sandeep Khurana, P.E.
With more than 30 years of industry experience, Sandeep has been part of Ryder Scott since 2019 and currently serves as Managing Senior Vice President and Head of Upstream & Midstream Integrated Services, providing asset management from resource development to market distribution. Prior to this, he worked at E&P companies such as Devon Energy, Kerr McGee (now Oxy), Noble (now Chevron), and others, and service providers such as Halliburton and KBR, among others, where he led global oil and gas development, production, operations and product sales. Sandeep holds an M.Sc. and a B.Sc. in Civil Engineering from Rice University and IIT Delhi, bringing a strong academic foundation and diversified experience to energy portfolio evaluations, assessments, audits, risk management, due diligence, and optimization.
Hilary McKenna
With 15 years of onshore and offshore reservoir engineering experience, Hilary McKenna has been with Ryder Scott since 2026 as a Senior Petroleum Engineer supporting reserves and resources evaluations. Her work includes reserves estimation, production forecasting, and economic analysis using decline curve analysis, type curves, and integrated reservoir studies to assess hydrocarbon volumes and forecast performance. Prior to Ryder Scott, she spent nearly a decade at Chevron’s Rockies business unit, advancing into leadership roles including Reserves and Reservoir Engineering Team Lead, managing engineers responsible for forecasting, reserves reporting, development economics, and completion optimization while driving process improvements and acquisition integration. Earlier at Chevron, she supported reserves reporting and development planning. She began her career at BHP Billiton Petroleum in the Gulf of Mexico and Fayetteville assets, focused on reservoir engineering and production analysis. Hilary holds a B.S. in Chemical Engineering, Summa Cum Laude, from Colorado School of Mines.
Eric T. Nelson, P.E.
With over 22 years of industry experience, Eric has been part of Ryder Scott since 2005 and is part of the Executive team and Board of Directors. He specializes in reserves evaluations and auditing, working across diverse geographic regions, including the Gulf of Mexico, U.S. unconventional plays, Southeast Asia, the Middle East, and offshore Africa. Eric has extensive experience in acquisitions and divestitures (A&D), leading due diligence efforts on transactions totaling nearly $7 billion since 2018. Prior to joining Ryder Scott, Eric worked at ExxonMobil Corp., where he led reservoir simulation efforts on a top asset. Eric holds a B.Sc. in Chemical Engineering from the University of Tulsa and an MBA from the University of Texas at Austin.
Christine E. Neylon, P.E.
With approximately 15 years of industry experience, Christine has been part of Ryder Scott since 2008, specializing in reserves evaluations, economic modeling, and integrated reservoir studies. As Vice President, she evaluates reserves and field performance under SEC and SPE-PRMS guidelines, contributing to SEC filings, property sales, and acquisition evaluations. Christine holds a B.Sc. in Mathematics from the University of St. Thomas and an M.Sc. in Petroleum Engineering from the University of Houston. Her expertise spans the Gulf of Mexico, Africa, Southeast Asia, and South America, focusing on shelf and deepwater assets. Christine is a Society of Petroleum Engineers member and has chaired the Houston Reservoir Study Group.
Mark A. Nieberding, P.E.
With over 37 years of industry experience, Mark has been part of Ryder Scott since 2018, specializing in reserves evaluations, integrated reservoir studies, and CCUS projects. As Vice President, he evaluates reserves and resources under SEC and SPE-PRMS guidelines and provides economic assessments for acquisitions and divestitures. Prior to this, Mark worked at BP Lower 48 as a Reserves Planning Engineer, where he developed strategic field development schedules and optimized capital expenditure. Mark holds a B.Sc. and M.Sc. in Petroleum Engineering from the University of Tulsa and an MBA from the University of Texas at Dallas. His expertise spans traditional reservoir engineering, economic modeling, and international projects across North America, South America, Europe, and Asia.
Ekene Ohagebu
With 17 years of industry experience, Ekene has been a part of Ryder Scott since 2022, specializing in reserves evaluation under SEC and SPE-PRMS guidelines, reservoir management, and economic evaluations. Prior to this, she worked at EP Valuation, where she conducted technical evaluations to support multi-million-dollar oil and gas transactions. Ekene holds an M.Sc. and a B.Sc. in Petroleum Engineering from Texas A&M University and the Federal University of Technology, Owerri, in Nigeria. She has contributed to reserves evaluation and certifications, and economic assessments for various oil and gas assets in North America and West Africa
Amara N. Okafor, P.E.
With 19 years of industry experience, Amara has been with Ryder Scott since 2015, serving as Senior Vice President and Project coordinator. Her expertise encompasses integrated reservoir studies, reservoir simulation, reserves and resource evaluations, as well as managing international projects across North America, Europe, and West Africa. Prior to this, she worked at Marathon Oil Co., where she served as the Asset Reservoir Engineer for Gulf of Mexico projects. Amara holds an M.Sc. in Petroleum Engineering from Texas A&M University and is a licensed Professional Engineer in the state of Texas.
Dan R. Olds, P.E.
With 43 years of industry experience, Dan has been part of Ryder Scott since 2001 and currently serves as Managing Senior Vice President and a member of the Ryder Scott Board of Directors. He specializes in reserves certifications, economic evaluations, and expert witness testimony. Prior to joining Ryder Scott, Dan worked at Wintershall Energy, where he managed offshore and onshore production evaluations across major basins. Dan holds an M.B.A. from the University of Houston and a B.Sc. in Petroleum Engineering from West Virginia University, bringing a diverse academic foundation to his work in reserves certifications, economic evaluations, and expert witness testimony.
Hugo A. Ovalle, P.E.
With over 15 years of industry experience, Hugo has been part of Ryder Scott since 2010, focusing on reserves evaluations, CO2 flood evaluations, and enhanced oil recovery (EOR) methods. Prior to this, he worked as a consultant at Accumyn Consulting, where he conducted data analysis and supported petrophysical modeling for multiple reservoirs. Hugo holds a B.Sc. in Petroleum Engineering from the University of Oklahoma. He has contributed significantly to evaluating reserves and resources for projects across North America, Australia, and Latin America, adhering to SEC, SPE, and WPC guidelines.
Bruce A. Palmer, P.E.
With approximately 30 years of industry experience, Bruce has been part of Ryder Scott since 2006, focusing on reserves evaluations, reservoir simulation, and integrated geoscience/engineering studies. As Vice President and Technical Advisor, he specializes in pre-production development studies, gas deliverability analyses, and reserves estimations for complex reservoirs. Prior to this, he worked at ExxonMobil, where he led simulation studies and implemented reservoir simulation networks across the Asia Pacific region. Bruce holds both an M.Sc. and a B.Sc. in Chemical Engineering from Brigham Young University. He has contributed to field development planning, enhanced simulation workflows, and reserves certifications globally, with expertise spanning North America, Asia, and the Middle East.
Robert J. Paradiso, P.E.
With 40 years of industry experience, Robert has been part of Ryder Scott since 2008, focusing on reservoir engineering, field performance analysis, and reserves estimations. Prior to this, he worked at Devon Energy Corp., where he performed evaluations of reserves for international acquisitions and divestitures. Robert holds a B.Sc. in Petroleum Engineering from Texas Tech University and has contributed to streamlined regulatory reserve reporting processes for Ryder Scott.
Clark D. Parrott, P.E.
With approximately 40 years of industry experience, Clark has been part of Ryder Scott since 2013, focusing on reserves evaluations and reservoir engineering. As Vice President and Senior Petroleum Engineer, he specializes in unconventional resource plays, waterflooding, and integrated reservoir studies, applying both traditional and statistical methods. Prior to joining Ryder Scott, he served at Norstar Petroleum, where he managed exploration and development, completion design, and production operations. Clark holds a B.Sc. in Petroleum Engineering from the Colorado School of Mines. He has contributed to reserves certifications and economic evaluations for SEC and SPE-PRMS compliance across North America’s major basins, including the DJ, Permian, Powder River, and Williston.
Laurymar Perez-Mejias
With over 14 years of industry experience, Laurymar has been part of Ryder Scott since 2010, focusing on reserves evaluations, reservoir modeling, and thermal enhanced oil recovery (EOR) methods. As a Senior Petroleum Engineer, she specializes in reserves estimation under SEC and SPE-PRMS guidelines, performing full-field analyses, economic evaluations, and feasibility studies for acquisitions and regulatory filings. She has conducted reserves certifications for Pemex, Ecopetrol SA, PDVSA, and Trinidad and Tobago’s gas fields. Laurymar holds a B.Sc. in Petroleum Engineering from Oriente University in Venezuela and has contributed to projects across North America, Central and South America, Africa, the Middle East, and Southeast Asia.
Edward Polishuk
With nearly 30 years of industry experience, Ed has been part of Ryder Scott since 2019, serving as Senior Petroleum Evaluator. He specializes in reserves evaluations, acquisition and divestiture analysis, and strategic planning. Prior to this, Ed worked at Bonanza Creek Energy as a Development Manager, where he optimized development strategies for the Wattenberg field. He holds a B.Sc. in Geology from Virginia Tech. He has contributed to evaluations of unconventional resource plays across major U.S. basins, including the Rockies, Permian, and Marcellus/Utica.
Trevor Pollock
With over 14 years of industry experience, Trevor joined Ryder Scott in 2026 as a Senior Petroleum Engineer, supporting reserves evaluations, certifications, and SEC and PRMS audits. Previously, he held reservoir engineering roles at Hilcorp Energy and Marathon Oil, leading development planning, reserves growth, and field optimization across the Gulf Coast, Rockies, and Bakken regions. Trevor holds graduate degrees in Analytics and Petroleum Engineering and has delivered significant reserve additions across conventional and unconventional assets.
Ali A. Porbandarwala, P.E.
With 20 years of industry experience, Ali has been part of Ryder Scott since 2008 and currently serves as Managing Senior Vice President and a member of the Ryder Scott Board of Directors. He specializes in reserves evaluations, reserves audits, process audits, due diligence work, and management consulting. Ali works across diverse geographic regions, including the Gulf of Mexico, U.S. unconventional plays, Southeast Asia, the Middle East, and offshore West Africa. He also has extensive experience in acquisitions and divestitures (A&D), having been an integral part of many US deals. Prior to joining Ryder Scott, Ali worked at ExxonMobil Corp., where he led risk assessments and reserves audits for major offshore projects. Ali holds an M.B.A. from the University of Texas at Austin and a B.Sc. in Chemical Engineering from the University of Kansas, bringing a diverse academic foundation to his work in reserves evaluations, process audits, and unconventional analysis.
Raza Rizvi
With over 20 years of industry experience, Raza has been part of Ryder Scott since 2013, specializing in economic evaluations, reserves assessments, and systems analysis. As a Senior Petroleum Engineer, he leverages his expertise in SQL and database management to optimize engineering processes and improve functionality through software solutions. Prior to joining Ryder Scott, he worked as a Senior Systems Analyst at Enterprise Product Partners, where he designed enterprise-level architectures and integrated systems to manage petroleum data and enhance reporting. Raza holds a B.Sc. in Petroleum Engineering and an M.Sc. degree in Computer Science from Texas A&M University. He has contributed to production engineering software development and reserves evaluations for projects across North America, Africa, and the Middle East, including offshore South Africa and the Gulf of Mexico.
Saba Sadiq
With over 5 years of industry experience, Saba has been part of Ryder Scott since 2024. Saba focuses on the project development of upstream and midstream oil and gas assets internationally in both onshore and offshore environments. Prior to this, Saba worked at Imperial Oil’s world-class heavy-oil asset in Western Canada, where he supported reservoir surveillance and asset management teams, as well as other operational technical groups in leveraging well-testing data more effectively. Saba holds a B.Sc. in Petroleum Engineering from the University of Wyoming and a diploma in Petroleum Engineering Technology from SAIT’s MacPhail School of Energy. Saba continues to support various project engineering and asset evaluation assignments across different specialty groups at Ryder Scott.
Eric A. Sepolio, P.E.
With over 17 years of industry experience, Eric has been part of Ryder Scott since 2008, focusing on reserves evaluation, economic assessments, and acquisition and divestiture work. As Vice President, he has conducted evaluations under SEC, SPE, and WPC guidelines and performed due diligence studies for investment groups and private equity firms. Eric holds a B.Sc. in Petroleum Engineering with a minor in Geology from Texas A&M University. His expertise includes full-field analysis, infill drilling studies, and fair market value evaluations, with geographical experience spanning North America, Africa, the Middle East, and more.
Andrés F. Suarez, P.E.
With over 30 years of industry experience, Andrés has been part of Ryder Scott since 2015, focusing on reserves evaluations, water flooding, and field development planning. Before this, he served as Technical Manager at Hocol SA, managing corporate reserves audits, developing Chemical EOR pilots, and implementing integrated reservoir studies. Andres holds an M.Sc. in Petroleum Engineering with a Minor in International Petroleum Management from Texas A&M University and a B.Sc. in Petroleum Engineering from Universidad de América in Bogotá, Colombia. He has contributed to reserves assessments and enhanced oil recovery techniques across regions including North America, South America, the Middle East, and Africa.
Andrew J. Thompson, P.Eng.
With over 30 years of industry experience, Andy has been part of Ryder Scott for approximately 16 years, including his tenure from 1995 to 2008 and rejoining in March 2022. He currently serves as Managing Senior Vice President and Manager of the Calgary Office. His expertise includes reserves and resource evaluations, EOR methods, and asset optimization. Prior to this, he worked at Macquarie Energy Capital, where he provided technical support for financings and investments, overseeing due diligence and post-investment monitoring. Andy holds a B.Sc. in Petroleum Engineering from the New Mexico Institute of Mining and Technology and a Petroleum Production Technology Diploma from the Southern Alberta Institute of Technology. He has contributed to reserves certifications and economic appraisals globally, with projects spanning North America, South America, Africa, and Southeast Asia.
Marsha E. Wellmann, P.E.
With over 20 years of industry experience, Marsha has been part of Ryder Scott since 2012, currently serving as a Managing Senior Vice President. She specializes in reserves determinations, economic evaluations, and SEC-compliant reserves reporting. Marsha is a SPE-Qualified Reserves Estimator with expertise in traditional reservoir engineering methods and volumetric assessments. Marsha holds a B.Sc. in Petroleum Engineering and a Business Foundations Certificate from the University of Texas at Austin. She has extensive experience in reserve estimation and SEC and SPE-PRMS compliant reporting, with projects spanning the Gulf of Mexico, Permian Basin, Uinta Basin, and Eagleford, focusing on both conventional and unconventional resource evaluations.
Scott J. Wilson, P.E.
With nearly 40 years of industry experience, Scott has been part of Ryder Scott since 2000, currently serving as Senior Vice President – Technical Advisor. He specializes in reserves evaluations, artificial lift optimization, well surveillance, and reservoir simulation. Prior to joining Ryder Scott, he was a Principal Engineering Consultant at Atlantic Richfield Corp., where he led fieldwide deliverability optimization and evaluations across international assets. Scott holds a B.Sc. in Petroleum Engineering from the Colorado School of Mines and an MBA in Finance from the University of Colorado. While specializing in integrated planning models, gas lift troubleshooting, and nodal analysis, he has taught over 500 industry professionals worldwide.
Keith (Lehi) Woodrome, P.E.
With over 23 years of industry experience, Lehi has been part of Ryder Scott since 2007, currently serving as Vice President. He specializes in reserves evaluations, economic assessments, and reservoir studies, with expertise in conventional (both onshore and offshore) and unconventional resource analysis. Prior to joining Ryder Scott, he worked at ExxonMobil Development Co., focusing on project management and economic planning. Lehi holds a B.Sc. in Chemical Engineering from Texas A&M University. He has extensive experience in reserve estimation, SEC and SPE-PRMS-compliant reporting, and financial modeling, with projects spanning North America, Africa, and Asia. Since 2023, Lehi has provided strategic guidance on commodity price forecasting and economic planning.
Jeremy Xia
With over 10 years of industry experience, Jeremy has been part of Ryder Scott since 2018, focusing on reserves evaluations, field performance analysis, and economic assessments. Prior to this, he worked at Quantum Reservoir Impact, where he conducted reservoir and economic evaluations for domestic and international onshore oil and gas properties, including EOR studies. Jeremy holds an M.Sc. in Petroleum Engineering from Texas A&M University and a B.Sc. in Chemical and Biomolecular Engineering from Nanyang Technological University. His expertise spans integrated reservoir studies, unconventional resource play evaluations, and SEC-compliant reserves estimations, with global experience across Asia, North America, the Middle East, and South America.
Zheng Zhang, Ph.D.
With over 14 years of industry experience, Zheng has been part of Ryder Scott since 2022, specializing in reservoir simulation, gas storage management, reserves estimation, and economic evaluations. Prior to this, she worked as a Senior Reservoir Engineer at ConocoPhillips, where she optimized CO2 WAG scheduling and developed workflows for monitoring and evaluating reservoir performance. Zheng holds a Ph.D. in Petroleum Engineering from Texas A&M University, along with an M.Sc. and a B.Sc. in Petroleum Engineering from the China University of Petroleum, Beijing. Her expertise spans gas storage modeling, CCS projects, and enhanced oil recovery techniques, with project experience in North America, the Gulf of Mexico, and international fields. Fluent in English and Chinese, Zheng has contributed to numerous industry publications and innovative reservoir management solutions.
Geologists
Professional Geologists
Enzo Aconcha, C.P.G.
With more than 20 years of experience in geoscience and subsurface energy projects, Enzo Aconcha serves as Senior Vice President of Geoscience at Ryder Scott, where he previously worked from 2015 to 2020 before rejoining the firm in 2026. He specializes in integrated subsurface evaluations, including basin analysis, seismic interpretation, and reservoir characterization, supporting reserves and resources assessments across oil and gas as well as emerging energy applications such as geothermal, carbon sequestration, and hydrogen storage. Throughout his career, Enzo has worked closely with multidisciplinary teams to integrate geological, geophysical, petrophysical, and engineering analyses in accordance with international standards such as PRMS, SRMS, and UNFC. Before Ryder Scott, he held technical roles at Chevron Energy Technology Company and Afren Resources, contributing to projects in North and South America, the Middle East, Africa, and Europe. Enzo holds an MBA in Renewable Energies from Berlin University of Applied Sciences and Technology, a master’s degree in Geological Sciences from The University of Texas at Austin and IFP School, and a bachelor’s degree in Geophysical Engineering from Simón BolÃvar University. He is a Certified Petroleum Geologist and an associate member of AAPG and SEG.
Melanie Adelman
With over 6 years of industry experience, Melanie has been part of Ryder Scott since 2020, focusing on reserves evaluations, reservoir modeling, and data science. Prior to this, she worked at Gardline Surveys (now part of Xodus, previously Ocean Geo Solutions) from 2013 to 2014, where she mapped shallow hazards using seismic data and generated comprehensive geological reports. She also interned at Halliburton (Landmark) in 2018 as part of the Research and Development department, contributing to the development of a method to predict gamma rays in real-time by building 3D geological models for proof of concept. Melanie holds an M.Sc. in Geology from the University of Houston, where she integrated geostatistical reservoir modeling and machine learning techniques to address missing values and sparse data challenges. Her expertise spans reservoir characterization, seismic interpretation, and advanced data analytics for field development.
Corey Barton, P.G.
With 15 years of industry experience, Corey has been part of Ryder Scott since 2023, focusing on geological interpretation, reserves certifications, and audits. Prior to this, he worked in both development and exploration roles focused on onshore US, Gulf of Mexico, and international projects. Corey holds an M.Sc. in Structural Geology from Utah State University and a Professional M.B.A. from the University of Oklahoma. Using his diverse geologic experience, he has contributed to advancing reserves certifications and geologic interpretations.
Rebecca Carson, P.G.
With over 40 years of industry experience, Rebecca has been part of Ryder Scott since 1997, focusing on reserves evaluations, integrated reservoir studies, and property acquisitions. As Vice President and Geoscientist, she evaluates proved, probable, and possible reserves of properties in the U.S. and internationally using integrated petrophysical and geological methods. Prior to this, Rebecca worked at Tenneco Gas Pipeline, evaluating gas fields for pipeline expansions. Rebecca holds a B.Sc. in Geology from Texas Tech University. She is a licensed Professional Geologist in the State of Texas and a member of the American Association of Petroleum Geologists. Rebecca’s expertise includes geological and petrophysical evaluations.
Inty Cerezo, P.G.
With over 23 years in the energy sector, Inty has been part of Ryder Scott since 2018, specializing in reserves determination, geomodeling, and resource analysis. Previously, he was a senior geomodeler at Schlumberger, optimizing geological workflows and seismic interpretation. He holds a Geological Engineering degree from Universidad de Oriente, Venezuela, and an M.Sc. in Analytics from Texas A&M, where he received the Best Oil & Gas Project award. Inty has contributed to COâ‚‚ storage evaluations and CCS projects, integrating geophysical and fracture analyses to optimize reservoir performance and recommend geological storage formations.
Robert Decesari, Ph.D., P.G., C.P.G.
With 19 years of industry experience, Robert has been part of Ryder Scott since 2023, focusing on geological and geophysical interpretation, CCS evaluations, and reservoir characterization. Prior to this, Robert spent 15 years at ExxonMobil Corp., working and managing global exploration and production assets in numerous basins across 4 continents. He also spent several years at Dunn Exploration LLC, where he led geological operations and evaluations, resulting in over 3 MMBOE discoveries. Robert holds a Ph.D. in Geological Sciences and a B.Sc. in Earth Sciences from the University of California, Santa Barbara, and the University of California, San Diego, bringing a diverse academic foundation to his work in geological and geophysical interpretation, CCS evaluations, and reservoir characterization.
Gabe Gallegos
With 6 years of industry experience, Gabe has been part of Ryder Scott since 2020, focusing on reserves certification, well-log analysis, and geological mapping. Prior to this, Gabe worked at Halliburton, where he executed over 700 stages of hydraulic fracturing operations. Gabe holds an M.Sc. in Geological Sciences and a B.Sc. in Geological Sciences from Rutgers University and the University of Texas at Austin, bringing a diverse academic foundation to his work in reserves certification, well-log analysis, and geological mapping.
Brett A. Gray, P.G.
With over 18 years of industry experience, Brett has been part of Ryder Scott since 2007, specializing in petrophysical evaluation, reserve and resource assessment, and static reservoir modeling for dynamic simulation. As Senior Vice President and Project Coordinator, he focuses on petrophysical evaluations, integrated reservoir studies, reserve and resource certifications, process audits, acquisition and divestiture due diligence, and providing expert opinions supporting litigation, unitization, and government audits. Brett holds a B.Sc. in Geology from Texas A&M University. He currently serves as Secretary of the SPWLA Hydrocarbon Resources Special Interest Group (SIG) and contributed to the 2022 revision of the Guidelines for Application of the Petroleum Resources Management System (AG), as well as the upcoming update to the Storage Resources Management System (SRMS). Brett's global expertise spans evaluations of conventional and unconventional reservoirs, underground storage, geothermal systems, and mineral extraction projects, including notable work in the Gulf of Mexico, the North Sea, the Middle East, South America, and Southeast Asia.
Mike Lam, P.Geol.
With over 20 years of industry experience, Michael has been part of Ryder Scott since 2006, serving as Vice President and Technical Specialist. His expertise includes reserves certifications, unconventional resource evaluations, and volumetric assessments. Michael has worked extensively within the Western Canadian Sedimentary Basin, evaluating oil sands, shale gas plays, and helium plays. He holds a B.Sc. in Geology from the University of Calgary. Michael has provided reservoir characterization, integrated petrophysical analysis, and advisory support for audits and evaluations globally, with a focus on North America and Australia.
Olga Logvinova, P.G.
With 34 years of industry experience, Olga has been part of Ryder Scott since 2015, focusing on subsurface mapping, petrophysical evaluation, and 3D geological modeling. Prior to this, she worked at FDP Engineering LLP, where she evaluated oil and gas reserves under international standards. Olga holds a B.Sc. in Geology and an M.Sc. in Geology from the Moscow University of Oil and Gas Industry, bringing a diverse academic foundation to her work in reserves audits, resource certifications, subsurface mapping, petrophysical evaluation, and geologic interpretations.
Thomas M. Talley, P.G.
With nearly 50 years of industry experience, Tom has been part of Ryder Scott since 2005 and currently serves as Senior Vice President and Group Coordinator. He specializes in reserves evaluations, reservoir characterization, and geologic mapping for domestic and international projects. Prior to this, he worked at Enron Corp., leading a team of geotechnical professionals in upstream reserve analysis and valuation, and Fina Oil and Chemical Co., where he supervised geological evaluations for major acquisitions. Tom holds an M.Sc. and a B.Sc. in Geology and a bachelor’s degree in photography from Northeast Louisiana University. His expertise spans deepwater evaluations in the Gulf of Mexico, structured finance, and portfolio management, with notable contributions to projects across North America, Africa, Asia, and Europe.
Sara K. Tirado, P.G.
With over 20 years of industry experience, Sara Tirado has been part of Ryder Scott since 2018, focusing on reserves evaluations, reservoir characterization, and seismic interpretation. Prior to this, she served as a Senior Exploration Geophysicist at Chevron from 2004 to 2016, where she provided comprehensive geophysical assistance for pre- and post-drill environmental response activities and designed, managed, and implemented velocity models for deepwater gas exploration, screening regional leads, and enhancing seismic analysis quality. Sara also conducted detailed seismic analysis to optimize well placement and assess risks and reserves, integrating rock and fluid property data with reservoir simulation models. In addition to her contributions to Ryder Scott, Sara is an adjunct faculty member at Houston Christian University. She holds an M.Sc. and a B.Sc. in Geophysics from the University of Oklahoma. She has contributed to regional and field-level exploration, deepwater asset evaluations, and geophysical mentoring across Africa, North America, and Oceania.
Robert D. Walters, Ph.D., C.P.G.
With nearly 35 years of industry experience, Robert has been part of Ryder Scott since 2004, focusing on reserves evaluations, geophysical data analysis, and geologic modeling. Before this, he worked at ExxonMobil Corp., conducting seismic facies analysis and advising exploration teams on 3D interpretation techniques for projects in Angola, Chad, Brazil, and the Gulf of Mexico. Robert holds a Ph.D. and an M.Sc. in Geological Sciences (Geophysics) from the University of Texas and a B.Sc. in Geology/Physics from Rice University. He has contributed to reserves audits, resource certifications, and exploration evaluations globally, with expertise in deepwater, onshore, and offshore fields, with emphasis on West Africa.