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The Team
NSAI specializes in projects encompassing multiple disciplines. Our technical staff includes reservoir and operations engineers, petrophysicists, and geoscientists who are generally cross-trained in geology and geophysics. We also employ staff specializing in geologic modeling, reservoir simulations, complex computer mapping, and non-routine time-to-depth conversion. We apply the right combination of people, expertise, and technology to each assignment.
Our present organization consists of approximately 55 reservoir engineers, geoscientists, and petrophysicists; 70 engineering and geologic analysts; and additional support staff. Our technical staff is carefully recruited from the industry’s most qualified candidates. The average experience level of these individuals exceeds 20 years, including 5 to 15 years with a major oil company. Most of our engineers, geoscientists, and petrophysicists obtained their initial training and experience with BP, British Gas, Chevron, ConocoPhillips, or ExxonMobil. We recruit only those with academic excellence, sound judgment, intuitive skills, relevant experience, and an understanding of the critical relationship that exists between petroleum and the financial industry.
Executive Leadership
Richard B. Talley, Jr.
Chairman and Chief Executive Officer
Houston
Rick Talley joined NSAI in 2004 and had over 23 years of oil and gas experience when he was promoted to Chief Executive Officer in 2022. He has significant experience with preparing reserves evaluations for conventional and unconventional assets in most major onshore United States producing basins, as well as Gulf of Mexico and international properties. Rick began his career at ExxonMobil Production Company and has a B.S. in Mechanical Engineering from University of Oklahoma and an M.B.A. from Tulane University. Rick is licensed Professional Engineer in the States of Texas and Louisiana, is a member of the Society of Petroleum Evaluation Engineers (SPEE) and the Society of Petroleum Engineers (SPE), and has taught various courses in the University of Oklahoma College of Business.
Eric J. Stevens
President and Chief Operating Officer
Dallas
Eric Stevens joined NSAI in 2007 and had over 20 years of oil and gas experience when he was promoted to President and Chief Operating Officer in 2022. Eric has demonstrated expertise in overseeing complex projects and managing multi-disciplinary teams in the evaluation of oil and gas fields located throughout the world but with particular emphasis in Central and South America, West Africa, and the United States. He started his career as a reservoir engineer and development planner with ExxonMobil Development Company working on projects located in Russia and West Africa. Eric has a B.S. in Mechanical Engineering from BYU, is a licensed Professional Engineer in the State of Texas, and is a member of the Society of Petroleum Evaluation Engineers (SPEE), Society of Petroleum Engineers (SPE), ADAM Energy Forum, and Dallas Petroleum Club.
Senior Management
Robert C. Barg
Senior Vice President / Executive Committee
Engineering • Dallas
B.S. in Mechanical Engineering, Purdue University, 1983. Bob joined NSAI in 1989. He had previously been a Staff Engineer with Exxon Company, U.S.A. Bob has significant experience throughout the tight gas basins and shale gas and oil basins of the United States, all parts of Mexico, and western Canada. His work includes performing property evaluations and field studies, analyzing drilling proposals, and conducting field optimization studies used by clients in arranging financing, evaluating potential acquisitions and sales, and reporting to the SEC.
John R. Cliver
Senior Vice President
Engineering • Houston
M.B.A., University of Texas at Austin, 2008; B.S. in Chemical Engineering, Rice University, 2004. Prior to joining NSAI in 2009, John was a Staff Reservoir Engineer with ExxonMobil Production Company. John has evaluated reserves, resources, and development plans for onshore and offshore assets worldwide, with extensive experience in deepwater environments in particular. He leverages his expertise in reservoir, well, and facility modeling to support his assessments where appropriate.
P. Scott Frost
Senior Vice President and Chief Financial Officer / Executive Committee
Engineering • Dallas
Scott Frost has been with NSAI since 1984 and has over 40 years of oil and gas evaluation experience. He was promoted to CFO in 2002. Scott has extensive experience in multi-disciplinary large project management, deepwater field evaluations, equity determinations, and probabilistic analysis of exploration prospects and new discoveries. He has evaluated oil and gas fields throughout the world with particular emphasis on all United States producing basins, the North Sea, Southeast Asia, and Brazil. Scott began his career at Exxon Company, U.S.A. and has an M.B.A. in Finance from Tulane University and a B.E. in Mechanical Engineering from Vanderbilt University.
Randolph K. Green
Senior Vice President
Engineering • Dallas
B.S. in Petroleum Engineering, Texas Tech University, 1982. Randy joined NSAI in 1983. His work includes project coordination, technical analyses and studies, and property evaluations for sales, acquisitions, and reporting to the SEC. Randy’s areas of domestic expertise include the Rocky Mountain, Mid-Continent, Texas, and Gulf of Mexico regions. His areas of international expertise includes Mexico’s Northern, Southern, and offshore Bay of Campeche regions. Randy is a licensed professional engineer in the State of Texas and a member of the Society of Petroleum Engineers and the Dallas Petroleum Club.
John G. Hattner
Senior Vice President / Executive Committee
Geology and Geophysics • Dallas
M.B.A., Saint Mary’s College of California, 1989; M.S. in Geological Oceanography, Florida State University, 1980; B.S. in Geology, University of Miami, Florida, 1976. John joined NSAI in 1991. He was previously a Geophysicist for Chevron Overseas Petroleum, Amoseas Indonesia, and Chevron Petroleum U.K. John has served as the geologic leader on large projects in Mexico and Bolivia, a significant number of coalbed methane evaluations in domestic and international basins, and several evaluations for large international independents covering their worldwide exploration portfolios in Australia, Southeast Asia, the United States, Gulf of Mexico deepwater, the North Sea, and West Africa.
Joseph J. Spellman
Senior Vice President / Executive Committee
Engineering • Dallas
B.S. in Civil Engineering, University of Wisconsin – Platteville, 1980. Joe was a Senior Supervising Engineer with Exxon Company, U.S.A. before joining NSAI in 1989. Joe’s geographic areas of expertise include all major United States producing basins, the Gulf of Mexico, the Middle East, Africa, the northwest shelf of Australia, Papua New Guinea, the Former Soviet Union, Eastern Europe, and the United Kingdom. His work includes project coordination and property evaluations for use by clients in arranging financing and evaluating potential acquisitions or sales, with a focus on project finance and major gas certifications used for LNG and pipeline projects.
Geoscience, Engineering, and Petrophysics Experts
Jose A. Aburto
Vice President
Engineering • Houston
B.S. in Chemical Engineering, University of Illinois at Urbana-Champaign, 2009. Prior to joining NSAI in 2018, Jose worked at ExxonMobil as a Senior Reservoir Engineer and development planner supporting assets in Russia, the Middle East, and Guyana. His experience includes oil and gas reserves and resources estimation, field development planning, reservoir simulation modeling, and property evaluations for acquisitions and divestitures.
Craig H. Adams
Senior Associate
Engineering • Dallas
B.S. in Petroleum Engineering, Texas Tech University, 1985. Prior to joining NSAI in 1997, Craig was an Acquisitions Engineer at Vintage Petroleum, Inc. and a Staff Engineer at Exxon Company, U.S.A. His work includes field studies, drilling proposal analyses, and property evaluations for use by clients in arranging financing, evaluating potential acquisitions or sales, and reporting to the SEC. Craig’s areas of expertise include the Rocky Mountain, Permian Basin, Eagle Ford, SCOOP, and STACK regions of the United States; coalbed methane in China and India; and properties offshore and onshore Mexico.
Diana W. Ball
Senior Associate
Engineering • Dallas
M.B.A. with Finance concentration, University of St. Thomas, Houston, 1985; B.S. in Petroleum Engineering, University of Tulsa, 1980. Diana joined NSAI in 1994. Her work includes reserves estimation, reservoir analyses and geologic studies, secondary recovery studies, gas processing and plant analyses, drilling prospect evaluations, and economic evaluations using deterministic and probabilistic methods. Diana has extensive experience in evaluating coalbed methane (CBM) projects and has served as leader on multiple CBM projects in both domestic and international basins.
Michael B. Begland
Senior Advisor
Engineering • Dallas
B.S. in Chemical Engineering, Ohio State University, 1983. Mike joined NSAI in 1993 after serving as a Staff Engineer with Exxon Company, U.S.A. He performs technical reservoir engineering and economic analyses for domestic and international projects, including reserves certifications and asset sale and acquisition packages. Mike has focused on domestic resource play evaluations for the past 10 years. He has specific technical expertise with gas storage and gas injection EOR projects.
James D. Berry
Vice President
Engineering • Dallas
B.S. in Chemical Engineering, University of Oklahoma, 2008. Prior to joining NSAI in 2014, James worked at ExxonMobil Development and ExxonMobil Production companies as a Senior Engineer for new developments in the Gulf of Mexico as well as for development and production projects in the North Field in Qatar. His work includes oil and gas reserves and resources estimations, depletion planning and optimization, drilling and workover prospect evaluations, reservoir simulation modeling, and economic evaluations using deterministic and probabilistic methodologies.
Tony P. Blanker
Petroleum Engineer
Engineering • Houston
B.S. in Petroleum Engineering and B.S. in Energy Business Finance, The Pennsylvania State University, 2018. Prior to joining NSAI, Tony held various reservoir engineering positions with ExxonMobil supporting assets in Guyana, Brazil, and North Dakota. His experience includes deterministic and probabilistic oil and gas reserves estimation, reserve audits, economic evaluations, fair market value evaluations, appraisal planning, well testing, depletion planning, and reservoir simulation modeling. Tony is a licensed Professional Engineer in the State of Texas and a member of the Society of Petroleum Engineers. Tony speaks Portuguese fluently and is conversational in Spanish.
Michelle L. Burnham
Vice President
Engineering • Dallas
M.B.A., University of Texas at Austin, 2011; B.S. in Electrical Engineering, Brigham Young University, 2006. Before joining NSAI in 2015, Michelle worked at Anadarko Petroleum Corporation and ExxonMobil Production Company as a Senior Reservoir Engineer. Her experience includes oil and gas reserves estimation, drilling and workover prospect evaluation using analytical modeling and reservoir simulation, property evaluations for sales and acquisitions, volumes forecasting, surveillance, and economic evaluations using deterministic and probabilistic methodologies.
Wayne K. Burton II
Vice President and Senior Technical Advisor
Engineering • Houston
B.S. in Chemical Engineering, University of Nevada, 2001. Prior to joining NSAI in 2005, Wayne was a reservoir engineer for Amerada Hess Corporation and ExxonMobil Production Company. Wayne has performed reserves and resources evaluations and provided advisory services on conventional and unconventional properties in most emerging and major producing basins both onshore and offshore North America and in international basins throughout Europe, Australia, India, South America, and Africa. His experience includes reserves estimation, integrated production modeling, enhanced recovery projects, deliverability studies and optimizations, prospect evaluations, and economic evaluations utilizing both deterministic and probabilistic methodologies.
Andres F. Castaño
Vice President and Technical Advisor
Engineering • Dallas
M.S. in Petroleum Engineering, University of Oklahoma, 2009; B.S. in Petroleum Engineering, Universidad Nacional de Colombia, 2004. Prior to join NSAI in 2013, Andres worked at BP in reservoir engineering roles for fields located onshore North America and Colombia. His work includes deterministic and probabilistic oil and gas reserves estimation, reserves audits, property evaluation for sales and acquisitions, field studies, contingent and prospective resources evaluations, and economic evaluations. His main geographical area of expertise is Latin America, including projects in Mexico, Colombia, Ecuador, Peru, Brazil, and other countries in the region. Andres is a Licensed Petroleum Engineer in the State of Texas and the Republic of Colombia and a member of the Society of Petroleum Engineers. Andres speaks Spanish fluently and is conversational in Portuguese.
Lily W. Cheung
Vice President and Team Leader
Engineering • Houston
M.B.A., University of Texas at Austin, 2007; B.S. in Mechanical Engineering, Massachusetts Institute of Technology, 2003. Prior to joining NSAI in 2007, Lily worked at ExxonMobil Production Company as a Senior Engineer supporting the Gulf of Mexico and Piceance Basin. Her experience includes oil and gas reserves estimation, drilling and workover prospect evaluation, volumes forecasting, operations engineering, property evaluations for acquisitions and divestitures, economic evaluations, artificial lift and well stimulation studies, and reserves-based lending analysis. Lily is a licenced Professional Engineer in the State of Texas.
Daniel C. Clements
Petroleum Engineer
Engineering • Dallas
M. Eng. in Petroleum Engineering, University of North Dakota, 2024; B.S. in Computer Science, The University of Texas at Arlington, 2009. Daniel joined NSAI in 2013 as a Petroleum Analyst and moved to the role of Petroleum Engineer in 2025. His work includes unconventional reserves estimation, production forecasting, economic evaluations, and machine learning modeling. He is a member of the Society of Petroleum Engineers.
Greg S. Cohen
Senior Associate
Engineering • Dallas
M.B.A., Anderson Graduate School of Management at UCLA, 1993; B.S., Chemical Engineering, Carnegie Mellon University, 1980. Prior to joining NSAI in 2013, Greg worked for ExxonMobil in a variety of technical lead roles within reservoir engineering and development planning. Greg has specific expertise with waterfloods and other enhanced recovery projects. His work includes project coordination, reserves evaluations, exploration resources assessments, property evaluations related to asset sales and acquisitions, and economic evaluations using deterministic and probabilistic methodologies.
Matt T. Dalka
Vice President and Team Leader
Engineering • Dallas
B.S., Chemical Engineering / Engineering and Public Policy, Carnegie Mellon University, 2005. Prior to joining NSAI in 2013, Matt worked at ExxonMobil in a variety of technical and supervisory roles within reservoir, development planning, facilities, and process engineering. His work includes project coordination, oil and gas reserves and resources estimations, field studies, property evaluations for sales and acquisitions, prospect evaluations, and economic evaluations using deterministic and probabilistic methodologies.
James A. Davidson
Vice President and Senior Technical Advisor
Petrophysics • Dallas
Ph.D. in Petroleum Engineering, University of Texas at Austin, 1998; M.S. in Petroleum Engineering, University of Texas at Austin, 1993; B.S. in Petroleum Engineering, Texas Tech University, 1979. Jim was a geoscientist with Landmark Graphics Corp. and a Senior Reservoir Engineer with Atlantic Richfield Indonesia Inc. before joining NSAI in 1998. Jim has performed petrophysical evaluations for wells located in most of the major petroleum provinces of the world.
Ruurdjan (Rudi) de Zoeten
Vice President and Technical Advisor
Geology and Geophysics • Dallas
M.A. in Geology, University of Texas, 1988; B.S. in Geology, University of Wisconsin, 1985. Rudi joined NSAI in 2008 with 19 years of worldwide exploration and development experience, primarily with Unocal Corporation. He performs integrated technical analyses and geocellular modeling to estimate reserves and resources for conventional and unconventional oil and gas properties. His areas of expertise include 3-D seismic interpretation, geological mapping, reservoir characterization, prospect evaluations, and reservoir engineering in terrestrial, shelf, and deepwater plays in the Gulf of Mexico, South America, West Africa, Asia, and onshore United States.
Helena P. Doran
Petroleum Engineer
Engineering • Houston
B.S. in Chemical Engineering, The University of Texas at Austin, 2013. Before joining NSAI, Helena held various reservoir engineering and planning positions with ExxonMobil and XTO Energy supporting assets in Angola (deepwater), Oklahoma, Texas, and New Mexico. Her experience includes business planning, depletion planning and optimization, production surveillance, reserves and resources estimation, and reservoir simulation modeling.
Lee E. George
Senior Associate
Engineering • Houston
B.S. in Civil Engineering, University of Texas at Austin, 1981. Lee joined NSAI in 1997 after serving as a Staff Engineer with Exxon Company, U.S.A. His areas of specific expertise include waterflooding, CO2 projects, well test and nodal analysis, abnormally pressured reservoirs, retrograde condensate reservoirs, gas deliverability, and material balance/reservoir simulation studies.
Nicholas M. Gnyra
Vice President
Engineering • Dallas
B. Sc., Petroleum Engineering, University of Alberta, 2004. Prior to joining NSAI in 2013, Nick worked at Encana Corporation in a variety of technical and supervisory roles within reservoir, development, production, and facilities engineering along with business development and strategic planning. Nick has experience in many of the major producing basins across Canada and throughout the United States. His work includes project coordination, oil and gas reserves and resources estimations, field studies, property evaluations for acquisitions and divestitures, economic evaluations using deterministic and probabilistic methodologies, and production optimization.
Kyle B. Haft
Vice President
Engineering • Houston
Engineering • Houston
M. Eng. in Petroleum Engineering, Texas A&M University, 2016; B.S. in Civil Engineering, Georgia Institute of Technology, 2011. Before joining NSAI in 2019, Kyle held various reservoir engineering positions with ExxonMobil and XTO Energy for assets in Wyoming, New Mexico, Gulf of Mexico, and Guyana. His experience includes reserves and resources estimation, drilling and workover opportunity evaluations, reservoir simulation modeling, depletion planning and optimization, production surveillance, and economic evaluations.
Justin S. Hamilton
Vice President and Team Leader
Engineering • Dallas
M.B.A, University of Texas at Austin, 2007; B.S. in Mechanical Engineering, Brigham Young University, 2000. Prior to joining NSAI in 2004, Justin was a Senior Project Engineer with ExxonMobil Production Company. His specific areas of expertise include reserves and resources estimation, property evaluation for sales and acquisitions, field studies, economic evaluations, and oil and gas reserves certifications. He has evaluated reserves and resources for oil and gas fields throughout the world, with particular emphasis on onshore and offshore basins in the United States, Mexico, South America, and West Africa.
Kathy J. Hartman
Senior Associate
Engineering • Dallas
B.S. in Chemical Engineering, Texas A&M University, 1980. Kathy worked for Mobil affiliates worldwide in a variety of positions, and later as an independent consultant, before joining NSAI in 2005. Her work includes reservoir engineering analyses for domestic and international projects including equity determinations, field studies, and reserves certifications of oil and gas properties, with specific expertise in reservoir simulation.
Michelle F. Herrera
Vice President and Team Leader
Geology and Geophysics • Dallas
B.S. in Geosciences, University of Texas at Dallas, 2002. Prior to joining NSAI in 2013, Michelle was a geophysicist with Encana Oil & Gas, Inc. (now Ovintiv Inc.) and Hunt Oil Company. Her area of expertise is focused on the integration of geologic, geophysical, and engineering data for reserves and resources assessments, including seismic data interpretation, well log correlation and analysis, and geocellular modeling. Michelle has over 20 years experience with both conventional and unconventional plays in the United States, West Africa, Mexico, Southeast Asia, Australia, and South America.
Philip R. Hodgson
Senior Associate
Geology and Geophysics • Dallas
M.S. in Geophysics, Purdue University, 1984; B.S. in Geology, University of Illinois, 1982. Prior to joining NSAI in 1998, Phil was a geophysicist with Triton Energy, British Gas Exploration & Production, and Mobil Exploration & Production. Phil’s work involves the integration of geological and geophysical data in support of reserves and resources estimations worldwide. His areas of specialization include reservoir description and characterization, geocellular modeling, prospective resources assessments, evaluation of turbidite reservoirs in deepwater areas, and dispute resolution including litigation, expert witness testimony, and equity redetermination.
Chad E. Ireton
Vice President
Engineering • Houston
B.S. in Petroleum Engineering, The University of Tulsa, 2000. Prior to joining NSAI in 2012, Chad held multiple Reservoir Engineer positions with ExxonMobil Production Company and worked several years as a Drilling Engineer with ExxonMobil Development Company. His experience includes project coordination, reserves and resources evaluations, field studies, production optimization projects, volumes forecasting, property evaluations for acquisitions and divestitures, economic evaluations, and reserves based lending analysis.
Akshay N. Jayaram
Vice President
Engineering • Dallas
M. Eng. in Petroleum Engineering, Texas A&M University, 2017; B.S. in Mechanical Engineering, Carnegie Mellon University, 2009. Prior to joining NSAI in 2018, Akshay held various reservoir engineering positions with ExxonMobil supporting assets in the Middle East, Guyana, Russia, and Gulf of Mexico. His experience includes oil and gas reserves and resources estimation, field development planning, reservoir simulation modeling, well testing, and economic evaluations using deterministic and probabilistic methodologies.
Benjamin W. Johnson
Vice President and Team Leader
Engineering • Dallas
B.S. in Petroleum Engineering, Texas Tech University, 2005. Benjamin was an operations engineer at Merit Energy Company before joining NSAI in 2007. He has evaluated properties on six continents, with a domestic focus on unconventional plays in the Rockies. His client base ranges from small independents to government agencies around the world. Benjamin works projects with operators, non-operators, and capital providers seeking reserves evaluations and technical expertise for year-end reports or potential acquisitions/divestitures.
Alexander V. Karpov
Vice President and Technical Advisor
Engineering • Houston
B.S. in Geology, State Academy of Oil and Gas, Moscow, 1992; M.S. in Petroleum Engineering, Texas A&M University, 2001. Alex was a reservoir engineer with BP before joining NSAI in 2008; before that he worked several years in petroleum exploration and production in Western Siberia. His background includes conventional and unconventional reserves assessment, production forecasting, nodal analysis, enhanced recovery projects, helium resources evaluation, and coalbed methane project evaluation.
Michael J. Kingrey
Vice President
Engineering • Dallas
B.S. in Chemical Engineering, Texas A&M University, 2009. Michael started his career with ExxonMobil, gaining technical experience in the reservoir, production, and completion engineering disciplines while working as a senior engineer on several international assets, with a focus on West Africa. While at ExxonMobil he also served as a production surveillance and optimization advisor to ExxonMobil’s global affiliates and NOC partners before joining NSAI in 2015. He has extensive experience in deterministic reserves evaluation and cash flow modeling for reserves certifications, transaction due diligence, and fair market valuations for both domestic and international oil and gas assets.
William J. Knights
Vice President and Senior Technical Advisor
Geology and Geophysics • Dallas
M.S. in Geology, Texas Christian University, 1984; B.S. in Geology, Texas Christian University, 1981. Bill worked as an independent geologist, evaluating domestic and international exploration and development projects, before joining NSAI in 1991. Since 2002 he has had extensive experience in all the productive and emerging unconventional shale plays in the United States and Canada, and in many prospective unconventional plays internationally. He has been involved in the estimation and classification of hydrocarbon volumes from prospective and contingent resources through to proved, probable, and possible reserves in both unconventional and conventional reservoirs.
Michael F. Krehel, Jr.
Vice President and Senior Technical Advisor
Engineering • Dallas
B.S. in Petroleum and Natural Gas Engineering, The Pennsylvania State University, 1983. Mike was a Production Engineer/Asset Team Leader at Conoco Inc. and later Operations Manager at Mueller Engineering Corp. before joining NSAI in 1998. Mike performs reservoir engineering and economic analyses for domestic and international projects, including reserves certifications and asset acquisition evaluations. He has an extensive background in surface and subsurface operations; areas of expertise include well completions and workovers and production and facility optimization. Mike is also active in dispute resolution, including litigation, expert witness testimony, and mediation/arbitration.
Richard F. Krenek II
Vice President and Team Leader
Engineering • Dallas
B.S. in Chemical Engineering, University of Oklahoma, 1986. Rick joined NSAI in 1990 after starting his career with Exxon Company, U.S.A. His work at NSAI has included oil and gas reserves and resources estimations, property evaluations, and advisory for properties located throughout the United States and in over 40 other countries throughout Europe, Asia, Africa, Australia, and the Americas. Rick has performed international expert testimony work and has led a number of large, complex field studies and equity determinations.
Rick is a Licensed Professional Engineer in the State of Texas. He has been an active member of the Society of Petroleum Evaluation Engineers (SPEE) and has served in many committee and leadership positions in the organization including President, Executive Committee, Board of Directors, and Council of Past Presidents. Rick is a member of the Society of Petroleum Engineers (SPE) and is currently a member of SPE’s Oil and Gas Reserves Committee (OGRC).
Neil H. Little
Vice President and Team Leader
Engineering • Houston
M.B.A., University of Houston, 2007; B.S. in Chemical Engineering, Rice University, 2002. Before originally joining NSAI in 2006, Neil worked at ExxonMobil Production Company as a Senior Reservoir Engineer. Neil rejoined NSAI in 2011 after spending 3 years at MEI, LLC as a senior process engineer working on midstream and LNG projects. His experience includes property evaluations for reserves reporting to government and financial institutions, sales and acquisitions evaluations, and prospect evaluation. His specific areas of expertise include international evaluations with complex financial analysis and unconventional hydrocarbon evaluations.
Zachary R. Long
Vice President and Senior Technical Advisor
Geology and Geophysics • Houston
M.S. in Geophysics, Texas A&M University, 2005; B.S. in Petroleum Geology, University of Louisiana at Lafayette, 2003. Before joining NSAI in 2007, Zach worked as a Petrel reservoir modeling consultant for Schlumberger. During his time at NSAI, Zach has continued to apply his expertise in reservoir modeling for the purposes of field studies, reserves and resources estimation, and CCUS applications. His skill set also includes performing geologic and geophysical evaluations of onshore and offshore reservoirs through seismic interpretation and attribute analysis, geologic mapping, reservoir characterization, and probabilistic analysis. Zach has experience in numerous basins, both domestic and international.
Joseph M. Mello
Vice President and Team Leader
Engineering • Houston
B.S. in Chemical Engineering, Rice University, 2010. Joe joined NSAI in 2015 after working over five years as a Reservoir Engineer at ExxonMobil Production Company. Joe has worked extensively in the offshore deepwater environment, where he leverages significant simulation experience to understand complex behavior. He also employs his simulation expertise to evaluate reservoirs for carbon sequestration projects.
Charles L. Melvin
Petroleum Engineer
Engineering • Dallas
B.S. in Chemical Engineering, North Carolina A&T State University, 2010. Charles joined NSAI in 2023 after working at BKV Corporation and ExxonMobil. Prior to joining NSAI, he held various reservoir engineering positions supporting unconventional assets within the United States. His primary experience includes reserves and resource estimation, depletion planning and optimization, valuations for M&A and Joint Ventures, evaluating recompletions in horizontal wells, and economic evaluations using deterministic and probabilistic methodologies.
Derek F. Newton
Senior Associate
Engineering • Houston
M.S. in Petroleum Engineering, Strathclyde University, Scotland, 1986; B.S. in Mechanical Engineering, University College Cardiff, Wales, 1983. Derek was a Principal Petroleum Engineer and Technical Manager for BG plc before joining NSAI in 1997. Derek uses his expertise with reservoir simulation on field development, gas storage, equity, and enhanced recovery project evaluations. He specializes in reservoir characterization and integration of geological and petrophysical data, usually involving simulation models scaled up from geo-cellular geological models.
Laurie K. O’Halla
Senior Associate
Engineering • Houston
M.S. in Chemical Engineering, University of Florida, 1984; B.S. in Engineering Science, The Pennsylvania State University, 1982. Laurie worked at Exxon Company, U.S.A. in several engineering and supervisory roles including reservoir, planning, facilities, and regulatory before joining NSAI in 1999. Her work includes oil and gas reserves estimation, property evaluations for acquisition and divestiture, equity evaluations, and field studies. Her geographic areas of expertise include the Gulf of Mexico, the Permian Basin, and Bohai Bay, China.
Matthew D. Pankey
Vice President
Engineering • Houston
B.S. in Chemical Engineering, Auburn University, 2012. Before joining NSAI in 2019, Matt held various reservoir and production engineering positions with ExxonMobil for assets in California, Wyoming, and Central Africa. His experience includes reserves assessments, economic analysis, production surveillance and optimization, workover execution, and facilities design. Matt’s specific areas of expertise include unconventional oil and gas evaluations, surface and subsurface operations, and carbon capture and sequestration projects. He is a licensed Professional Engineer in the state of Texas and a member of the Society of Petroleum Engineers (SPE).
Connor B. Riseden
Vice President and Team Leader
Engineering • Houston
M.B.A., Tulane University, 2005; B.S. in Petroleum Engineering, Texas A&M University, 2001. Connor joined NSAI in 2006 after working as a Senior Engineer with ExxonMobil Production Company. His experience includes asset evaluations for acquisitions, sales, and reserves reporting to government and financial institutions. Connor’s specific areas of expertise include unconventional oil and gas evaluations and Gulf of Mexico properties.
Wilson O. Rodriguez
Petroleum Engineer
Engineering • Dallas
M.S. in Petroleum Engineering, University of Oklahoma, 2002; B.S. in Petroleum Engineering, Universidad de America, 1998. Before joining NSAI in 2023, Wilson worked as a senior reservoir engineer at Lukoil, QuarterNorth Energy, Hess Corporation, Murphy Oil and Schlumberger contributing expertise to diverse domestic and international assets, spanning offshore and onshore operations. His experience in operated assets encompasses reserves evaluation and certification, reservoir characterization and simulation of conventional and unconventional reservoirs, well testing, well and reservoir surveillance, reservoir management, field development plan updates, improved and enhanced oil recovery (IOR/EOR), economic analysis, budget and plan processes, and procurement procedures.
Edward C. Roy III
Vice President and Team Leader
Geology and Geophysics • Houston
M.S. in Geology, Texas A&M University, 1996; B.S. in Geology, Texas Christian University, 1992. Ed has significant experience in evaluating development projects, primarily in the Gulf of Mexico and West Africa. Before joining NSAI in 2008, he was a Senior Geologist with Marathon Oil Company. His skills include deepwater stratigraphy, seismic interpretation, attribute analysis, geologic mapping and modeling, reservoir characterization, and probabilistic analysis.
Jason C. Sanford
Geoscientist
Geology and Geophysics • Dallas
M.S. in Geological Sciences, The University of Texas at Austin, 2015; B.A. in Geology and Spanish (magna cum laude), Middlebury College, 2010. Prior to joining NSAI in 2023, Jason held various earth science and advisory positions at Chevron and independents in the Gulf of Mexico, Neuquén, Permian, Appalachian, and Anadarko basins. His skills include seismic interpretation, well log analysis and correlation, reservoir description and characterization, deterministic and probabilistic volumetric estimation, and risk assessment.
Matt J. Sasso
Petroleum Engineer
Engineering • Dallas
B.S. in Petroleum Engineering, Texas A&M University, 2015. Prior to joining NSAI in 2024, Matt held various reservoir and completions engineering positions with Pioneer Natural Resources and Matador Resources Company. His experience includes hydraulic fracturing and wireline operations, workover and fishing execution, oil and gas reserves and resources estimation, property evaluations for acquisitions and divestitures, field development planning, volumes forecasting, and economic evaluations using deterministic and probabilistic methodologies. Matt is a licensed Professional Engineer in the State of Texas.
Nathan C. Shahan
Vice President and Team Leader
Engineering • Dallas
M.Eng. in Petroleum Engineering, Texas A&M University, 2007; B.S. in Petroleum Engineering, Texas A&M University, 2002. Nathan was a reservoir engineer with Anadarko Petroleum Corporation before joining NSAI in 2007. His primary experience includes international and domestic CBM and conventional gas reserves and resources estimation, enhanced oil recovery reserves evaluations, and unconventional oil reserves evaluations. He has prepared detailed technical reports for public offerings on Hong Kong, London, Singapore, and Toronto stock exchanges.
C. Ashley Smith
Vice President and Team Leader
Engineering • Houston
B.S. in Petroleum Engineering, University of Missouri-Rolla, 2000. Ashley has been a petroleum engineering consultant at NSAI since 2006. His work primarily includes independent audits and evaluations of oil and gas assets for the purpose of arranging for investment in the United States and worldwide equity markets. In addition, he provides evaluations for potential acquisitions and divestitures, conducts efficiency and process reviews, and coordinates projects. While his experience spans North and South America, Europe, and Africa, his specific geographic areas of expertise include deepwater West Africa, the Gulf of Mexico, Eagle Ford, and onshore California. His technical expertise includes estimation of oil and gas reserves, reserves maturation, reservoir development planning, and reservoir simulation modeling. Prior to joining NSAI, Ashley worked at ExxonMobil within both their Development Company and Production Company organizations.
Lauren P. Vernon
Vice President and Technical Advisor
Engineering • Houston
M.Eng. in Petroleum Engineering, Texas A&M University, 2010; B.A. in Anthropology, Baylor University, 1998. Lauren joined NSAI in 1999 as a petroleum analyst and in 2010 transitioned into the role of reservoir engineer. Her experience includes reserves assessment, production forecasting, and economic evaluations using deterministic and probabilistic methodologies.
Ryan J. Wagner
Petroleum Engineer
Engineering • Houston
M.S. in Petroleum Engineering, University of Texas at Austin, 2020; B.S. in Petroleum Engineering, The Pennsylvania State University, 2017. Prior to joining NSAI, Ryan held various reservoir engineering positions with ExxonMobil supporting assets in Guyana, Angola, Russia, and Wyoming. His experience includes reservoir simulation modeling, field development planning, and economic analysis.
Joseph M. Wolfe
Vice President and Team Leader
Engineering • Dallas
M. Eng. in Petroleum Engineering, Texas A&M University, 2009; B.S., Mathematics, Northwestern State University, 1999. Joe joined NSAI in 2013 after working for Pioneer Natural Resources and Sovereign Resources, LLC. His work includes oil and gas reserves estimation and auditing, volumetric analyses, and economic evaluations for international and domestic oil and gas projects.
Melanie D. Ybarra
Petrophysical Specialist
Petrophysics • Dallas
M.S. in Geology, University of Texas at Arlington, 2014; B.S. in Mathematics, University of Houston, 2005. Melanie has been with NSAI since 2005. She has extensive experience in formation evaluation of both unconventional and conventional reservoirs around the world. She provides advanced petrophysical support for reserves and resource evaluations, major field studies, and reservoir simulation studies.
Analyst Coordinators
Our staff of petroleum analysts are integral to each evaluation, working closely with the engineers and geoscientists and with our clients. They generally have 3 to 15 years experience and have degrees in mathematics, computer science, geology, or business. They have diverse skills in data loading, database management, economic modeling, spreadsheet manipulation, computer mapping, well log processing, and report preparation.
Amy H. Arnold
Dallas • Contact Info
Jake S. Bontrager
Dallas • Contact info
Diana E. Castillo
Houston • Contact info
Levi E. Enslow
Dallas • Contact info
Lisa R. Green
Houston • Contact info
Maddie B. Gulick
Dallas • Contact info
Natalie F. Hudson
Houston • Contact info
Rachel K. Lowrance
Dallas • Contact info
Shannon R. Mapes
Houston • Contact info
Heather R. Maresh
Houston • Contact info
Jeremiah B. Scott
Dallas • Contact info
Ram Shoham
Houston • Contact info
Dawn S. Smith
Dallas • Contact info
Michael S. Strohmann
Houston • Contact info
Julie C. Wilburn
Dallas • Contact info