Yann Mossé
Yann Mossé joined DeGolyer and MacNaughton in 2025, specializing in reserves and resources certifications and integrated reservoir evaluations. Prior to joining D&M, Mossé worked at Glencore UK and GDF Suez E&P. He has more than 20 years of international upstream oil and gas experience spanning operated and non-operated assets, field development planning, reserves evaluation, production optimization, and commercial support.
Mossé graduated with a degree in reservoir engineering from Ecole Nationale Supérieure de Géologie in Nancy, France in 2004. He is a member of the Society of Petroleum Engineers. He is fluent in French and English.
Geographical Experience
- Algeria
- Cameroon
- Chad
- Equatorial Guinea
- France
- Germany
- United Kingdom
- United States
Topical Areas of Expertise
- Reserves and resources evaluation
- Reservoir engineering
- Simulation modeling
- Merger and acquisition projects
- Production optimization
- Performance analysis
- Integrated field development planning
- Economic evaluation and forecasting
- Technical due diligence
- Operated asset management
Major Projects
At D&M, Mossé brings expertise in reservoir and petroleum engineering, year-end reserves and resources certifications, and merger and acquisition projects in Africa, Asia, the Middle East, and Europe. His work integrates subsurface evaluation, production performance analysis, and economic considerations to support independent assessments and strategic transactions.
For Glencore UK, he supported structured finance and trading activities through technical due diligence reports and reserves-based lending models across global upstream assets. He delivered production forecasts, cost profiles, and field economics for investment decisions and acted as technical lead for gas-condensate and oil fields in West and Central Africa. As asset manager for operated fields in Chad, he led the technical, commercial, and administrative management of three producing oil fields, delivered integrated business plans, and achieved significant production growth through drilling campaigns, reservoir management, and field development initiatives.
At GDF Suez E&P, Mossé built and validated numerical simulation models in Eclipse from appraisal through pre-development for gas and oil fields in the United Kingdom and Algeria. He conducted well-test analysis and production forecasting for North Sea and continental European assets and led carbon capture and sequestration studies. He also supported reserves booking and portfolio evaluations and contributed to data rooms and acquisition projects.
