The fall of the Soviet Union and the subsequent opening of its borders to western oil companies have seen the search for oil turn increasingly to the east. This formation evaluation manual by The London Petrophysical Society, a chapter of the SPWLA, is designed to help explorationists and geoscientists who are used to high-quality, abundant North Sea data, to understand and interpret Russian-style logs. In addition to the Soviet Union, these logs were run in every country which was under the Soviet sphere of influence.