Angolas national Oil company, Sociedade Nacional de Combustiveis de Angola (Sonangol), was established in 1976 and made the sole concessionaire for exploration and production in 1978. Sonangol works with foreign companies through both joint ventures (JVs) and production sharing agreements (PSAs), funding its share of production through oil-backed borrowing. The top foreign oil companies operating in Angola are US-based ChevronTexaco and ExxonMobil, Frances Total, UKs BP, UK /Dutch Shell, and Italys Agip/Eni Oil Company.