This article examines peculiarities of the contractual regulation of transborder carbon deposit development relations. Unitization agreements between subsoil users have become the most widespread. International unitization agreements acquire particular significance. The most efficient exploitation of a field that crosses the border between states requires close cooperation between such states and the contractors or license holders operating in the corresponding field. The main goal of a unitization agreement is that if a field is developed jointly by several subsoil users, the latter, although acting on their own behalf, will do good and facilitate the activities of other parties to the agreement for the purposes of the most efficient exploitation of the field. The author studies varieties of a unitization agreement, gives examples from the law enforcement practice.