In this work a distinction is made between two forms of cooperation in the exploration and exploitation of petroleum: proportional cooperation between oil companies who jointly own an exclusive petroleum right either an exclusive licence or a risk contract; and non-proportional cooperation between state enterprises and oil companies who enter into production-sharing agreements or other type of risk contracts. The book explains the reasons for cooperation and the strategies followed to minimise non-market-related risks. It provides detailed analysis of customary joint venture agreements and of special provisions in these agreements such as non-consent options and sole risk options. The work further covers compulsory cooperation in the form of either state participation or unitisation agreements. A separate chapter is devoted to production-sharing agreements. This book is intended for geologists and petroleum engineers in charge of extractive ventures and for international lawyers consultants and other professionals who are in charge of designing negotiating and promoting any type of cooperative agreement. The author has drawn on 34 years experience of the legal economic and technical aspects of the international petroleum industry most recently as senior concessions lawyer with Shell Internationale Petroleum Maatschappij in The Hague The Netherlands and as part- time professor at the Delft University of Technology.