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Independent Petroleum Consultants, Since 1961


Independent Petroleum Consultants

Cawley, Gillespie and Associates, Inc.

Independent Petroleum Consultants, Gillespie and Associates, Inc. (CG&A) began serving the oil and gas industry over 60 years ago. Though our methods and tools have evolved since that time, our values have not. We still provide ethical and independent petroleum engineering services. Our extremely capable team of professional petroleum engineering consultants have broad range of experience and capabilities to serve all your petroleum consulting needs. You deserve responsive engineers and geologists delivering reliable property evaluations… on time!

Putting our clients first, since 1961

As an Independent Petroleum Consultant, CG&A reviews and evaluates hundreds of thousands of oil and gas properties on an annual basis worth billions of dollars. Our clients include oil and gas companies, financial institutions, midstream/pipeline companies and individual investors. With diversified experience in oil and gas producing properties throughout North America and around the globe, CG&A’s proficient team of petroleum engineering consultants, reservoir engineers and geologists integrate geological, geophysical, engineering and economic data to produce high-quality reserve estimates and economic forecasts.

  • Office locations in Fort Worth, Houston, and Austin, Texas, USA
  • 30+ Petroleum Engineering Consultants, Geologists and Technical Analysts
  • Worldwide producing basin experience, unconventional and conventional
  • Approved by all major banks, key regional banks, and private equity firms
  • Deep experience with SEC, SPE-PRMS and COGEH guidelines and reporting

Our Services

CG&A’s talented staff of Independent Petroleum Consultants, Geologists, Technical Analysts, Economists, and Software Developers is here for all of your oil and gas property evaluation needs.

  • Texas Professional Engineering Firm (F-693)
  • Ability to pool resources from each office to prepare the best team for your project
  • Access to third-party experts and services for special projects
  • Deep experience in SEC, SPE-PRMS and COGEH reporting
  • Direct relationship with key SEC auditors
  • Regularly attend data rooms and assist clients with acquisitions and/or divestitures
  • Approached by all major banks, key regional banks, and private equity firms
  • Oil and Gas Reserves Evaluation
  • Oil and Gas Reserves Reporting

Estimation of petroleum reserves and resources


Analyzing wireline logs, mud & drilling logs, cores & core data


Economic evaluation of petroleum properties

Resource Studies

CG&A regularly prepares volume-oriented field studies and basin analyses for investors and midstream clients

Oil and Gas Reserve Reporting

Classifying and quantifying reserves & resources, and determining associated net present value.

Oil and Gas Reserves Evaluation Blog

October 19, 2023 in Oil & Gas Consulting

CG&A President, Todd Brooker, Shares His Oil and Gas M&A Market Outlook on Hart Energy’s A&D Minute

Jordan Soto, executive producer, Hart Energy: Where is the oil and gas M&A market heading next? Find out in this A&D Minute powered by BOK Financial Securities. Our editorial team…
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August 11, 2022 in Oil & Gas Consulting

Map data classes, how to you avoid creating a busy oil & gas map with too many similar colors

Question: When mapping data classes on a map, how do you avoid creating a busy oil & gas map with too many similar colors? Answer: A map legend with too…
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June 2, 2022 in Oil & Gas Consulting

Proved Reserves Beyond Low (LKO) and High (HKO) Known Oil

Warning This article and series is specifically targeted for anyone involved or interested in oil and gas reserves reporting guidelines, methods, issues, calculations and pitfalls. Proceed at your own risk!…
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