About NSAI

Netherland, Sewell & Associates, Inc. (NSAI) is a worldwide leader of petroleum property analysis for industry and financial organizations and government agencies. We deliver high quality, fully integrated engineering, operational, geological, geophysical, petrophysical, and economic solutions for all facets of the upstream energy industry.

Established in 1961
Offices in Dallas and Houston, Texas
55+ Engineers, Geologists, Geophysicists, and Petrophysicists
70+ Engineering and Geology Analysts
Expertise in most producing basins worldwide
Well known within the oil & gas and financial communities
Chosen by more companies for their SEC reserves reporting than any other petroleum consulting firm
Focused on building client relationships and delivering exceptional service

Our Story

Clarence Netherland and Fred Sewell

In 1961 Clarence Netherland started his own petroleum consulting firm, and decided from the outset that it would be the top organization of its kind in the world. He handpicked each employee with the right combination of experience, technical skills, and professional judgment. He knew that relationships built on trust would be the key to our success, and developed a culture based on serving the needs of our clients and the financial community.

When Clarence decided, in 1969, that he needed some help with his growing consulting business, he turned to his friend Fred Sewell. He knew that Fred had a head for business, and that he embodied the spirit and ethics that Clarence had built the business on. When Fred joined NSAI it had fewer than six employees, and when he retired in 2008 they had grown the firm into the most respected global upstream petroleum organization in the world. Fred was instrumental in developing the firm’s business model, the concept of teamwork and integration, and the “core values” that permeate the company today. His emphasis on reputation and respect served both our clients and our employees well.

Among Clarence and Fred’s early additions were Scott Rees and Danny Simmons. Danny started at NSAI in 1976 in Dallas, the third engineering hire by Clarence and Fred, and was a leader within NSAI as it grew over the next 15 years. In the early 1990s and with the continued growth of the industry in the Houston area, NSAI decided that a Houston office, founded and led by Danny, would allow the firm to continue to grow and provide support to the industry.

Danny Simmons and Scott Rees

Scott joined NSAI in 1988 in Dallas and was promoted to Team Leader within a few years. He worked on projects around the globe and was instrumental in NSAI’s growth internationally, from being heavily involved in the firm’s early work with the Mexican government on their oil and gas assets to the early appraisal and assessment of coalbed methane projects in Australia. When Fred retired in 2008, Scott was promoted to Chairman and Chief Executive Officer and Danny was promoted to President and Chief Operating Officer. They later jointly assumed the role of Executive Chairman in 2022 before retiring in 2024.

Today, we continue to provide services to the worldwide petroleum industry that include reserves reports and audits, acquisition and divestiture evaluations, simulation studies, exploration resources assessments, equity determinations, and management and advisory services. Although technologies and methodologies have changed over time and will continue to evolve, we recognize that professional expertise, sound judgment, integrity, and top quality service are always valued.