The composition of saturated cyclic hydrocarbons in crude oils from deposits of different ages located in various oil and gas basins has been studied. It has been found that the concentration of cyclanes in the oils decreases on passing from Paleozoic to Cenozoic deposits. For Cenozoic and Mesozoic oils, the con-centration of cyclanes also decreases with the increasing occurrence depth of sediments within the same age. The group type composition of saturated cyclic hydrocarbons in oils from deposits of different ages is similar in character, where the concentration of cyclanes follows the order: monocyclanes > bicyclanes > tri-cyclanes > tetracyclanes >
