The Soviet Union, including its Republics and Autonomous Regions, although remaining the world's largest oil and gas producer, is seeking the co-operation of the international oil industry to assist in further developing its vast reserves and potential resources. A legislation and taxation system that allows for foreign investment in the Soviet oil industry is being created. Many international oil companies, large and small, are currently evaluating opportunities in the country. Western companies have not been directly involved in Soviet oil operations since 1918. During the intervening years significant diversities of approach, particularly with regard to exploration methods and geological analysis, have emerged between Soviet and western geoscientists. Such differences have caused a myriad of special problems for geologists and geophysicists employed by western oil companies newly evaluating the petroleum potential of the country. These probems must be addressed and overcome before embarking on an expensive exploration or development venture.