Even though there are many problems plaguing Guinea's economy, not all foreign investors are reluctant to come to Guinea. Global Alumina's proposed alumina refinery has a price tag above $2 billion. Alcoa and Alcan are proposing a slightly smaller refinery worth about $1.5 billion. Taken together, they represent the largest private investment in sub-Saharan Africa since the Chad-Cameroon oil pipeline. Also, Hyperdynamics Corporation, an American oil company, signed an agreement in 2006 to develop Guinea's offshore Senegal Basin oil deposits in a concession of ; it is pursuing seismic exploration.