70 Years of Experience Serving the Energy Industry

We are a registered engineering firm specializing in oil and gas reserves analysis, economic and analytic modeling, fair market value, forensic engineering, site inspection, geology, geophysics, litigation support, and more

Our clients include major integrated energy companies, independent oil and gas producers, government agencies, banks, private equity firms, venture capitalists, and attorney groups. Our annual reserve reports, performed for our client's public filings, are accepted by the U.S. Securities and Exchange Commission, and our economic projections for asset evaluation are accepted by financial intitutions worldwide. We have completed contracts for the U.S. Government, and our security clearances are current.

Our Services

We offer complete petroleum engineering, geoscience, analytical expertise.

We provide expertise in 2-D and 3-D seismic interpretations. Our work has spanned the globe from the Gulf of Mexico to Australia, Alaska, the Nortrh Sea, Iraq, and New Zealand.

Our contract geologists have extensive experience in structural geology and structrual modeling supplemented by skill in sedimentology, zonation, and geostatistics. We have a robust understanding of production geology and the importance of using data sources such as fluid production, pressure transient analysis, and material balance in the process of generating final maps. *

Our petrophysics are well versed in core analysis, open-hole and cased-hole log interpretation. We analyze MWD logs, TCL data, and other forms of advanced logging data and processed log displays.

The Gruy petroleum engineers possess considerable experience in applying reservoir and field analysis techniques. These include commonly applied performance extrapolation techniques, material balance computations, and secondary or tertiary recovery forecasting methods, including carbon dioxide flooding and thermal recovery. Our engineers are highly capable in the applicationof numerical reservoir simulation, PVT modeling, and probabalistic techniques.

All our engineers have field experience that allows them to incorporate operations data into their reservoir work and provides complete understanding for field and site inspections.

Additionally, our engineers have a wealth of experience in the application of advanced DCA methods such as Duong, Stretched Exponential, Power Law, and Logistic Growth to resource forecasting.

Read more about our services here: SERVICES

* H.J. Gruy and Associates, Inc. will retain the services of a properly registered firm to perform any work which involves the non-exempt public practice of geoscience in Texas or elsewhere.

Our Story of Dedication and Excellence

At age 35, Hank Gruy founded H.J. Gruy and Associates, Inc. During his tenure as chairman of Gruy, he was active in professional associations at the international, national, and state levels.He was awarded the DeGolyer Distinguished Service Medal by the Society of Petroleum Engineers and the Lifetime Achievement Award from the Independent Petroleum Association of America. Among Hank’s industry achievements was serving as president of the Society of Petroleum Engineers (SPE) and serving as president of the Society of Petroleum Evaluation Engineers (SPEE). Hank was also recognized for Outstanding Achievements in the Field of Engineering by the Texas Society of Professional Engineers. He was a member of the National Academy of Engineering.

In 1996, the Gruy board of directors elected Marilyn Wilson as president of H.J. Gruy and Associates, Inc. Marilyn graduated from Texas A&M with a bachelor’s degree in petroleum engineering. She joined Gruy in 1982 following employment with a large pipeline company and a mid-sized independent E&P company.Marilyn served 6 years on the national board of the Society of Petroleum Evaluation Engineers, culminating in her election as president of the Society in 2002—the first woman to serve in that capacity. During her tenure on the board of SPEE, she was an active founding member of the SPEE/SEC Steering Committee from 2000-2003. This committee created the SPE/SEC joint forum attended by industry leaders from all categories of public and private E&P producers, and the engineering staff of the United States Securities and Exchange Commission (SEC). This forum created the gateway for the current dialogue between the public energy companies and the SEC regarding reserves reporting compliance and SEC definitions.

Prior to her very active role with SPEE, Marilyn was chairman of the board of directors of the Gulf Coast Section of SPE (1996-1997), chairman of the Houston Chapter of SPEE (1997-1998), and chairman of the Reservoir Study Group of SPEE (1990-1991). She also served on the board of the Women’s Energy Network from 1999-2001.

Marilyn is currently the CEO of H.J. Gruy and Associates, Inc. and has devoted her career to the advancement of professionalism in reservoir engineering.

H.J. Gruy Energy Advisors

Registered engineering firm specializing in oil and gas reserves analysis, economic and analytic modeling, fair market value, forensic engineering, site inspection, litigation support, ESG advice, and more

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