Alexey Miller, chairman of the Gazprom Management Committee and Nguyen Xuan Son, chairman of the PetroVietnam Oil and Gas Group (PVN) board of directors, have signed today a framework agreement on joint development of the Nagumanovskoye (Orenburg Region) and Severo-Purovskoye (Yamal-Nenets Autonomous Area) fields, at a meeting in Sochi yesterday