Royal Dutch Shell Plc, Europe's largest oil company, may have let the opportunity slide, after Putin said in May that it would be a "comfortable partner" to replace BP in the Kara Sea, according to Bloomberg. Shell, which works with state-controlled OAO Gazprom in Siberia and Sakhalin Island, agreed to further expand cooperation with the gas producer in June.

Also in the Rosneft-Exxon deal, the two will implement a program of staff exchanges of technical and management employees which will help strengthen the relationships between the companies and provide valuable career development opportunities for personnel of both companies.