This work looks at co-operation between companies active in the exploration and exploitation of petroleum. It explains the reasons for co-operation and the strategies followed to minimize non-market related risks. Analysis is provided of customary joint venture agreements and of special provisions in these agreements, such as non-consent options and sole risk options. There is also coverage of compulsory co-operation in the form of either state participation or utilization agreements, and a separate chapter looks at production-sharing agreements.