Semieu has responsibility for economic and fiscal research and related content such as fiscal remarks, contracts, model assignments, economic fiscal modelling, and support of product development with regard to his subject matter expertise. Areas of specialisation include fiscal regime and economic modelling, investment analysis, contractual negotiations, hydrocarbon accounting, policy research, and analysis.

Before joining S&P Global Commodity Insights, Semieu has experience working within the global oil and gas consultancy firm Gaffney Cline on upstream oil and gas economics and regulatory issues in Africa. Also, Semieu has experience with the French investment bank Société Générale on their commodity desk as a commodity product controller. Semieu has field experience working previously for New African Global Energy (NewAge) and Schlumberger. His duties there focused on well-test analysis. He is multilingual and proficient in French and English.

He holds a bachelor's degree with honours in Petroleum Engineering from the University of Portsmouth and a Master's degree in Petroleum, Energy Economics, and Finance from The University of Aberdeen Business School.