The article provides an analysis of the variability of the composition of hydrocarbon fluids from the Bovanenkovo field (Yamal, Western Siberia) in order to better understand the geological processes that led to the formation of this field and the reformation of the composition of fluids in the layers of this field. It is shown that geochemical information on the composition and properties of oil, condensate and gas allows to “reconstruct” the geological stages of the formation of deposits in their modern form. The data on the properties of fluids, group and molecular composition of the light and middle parts of oils and condensates of various layers are given. Differences in the composition of hydrocarbons from different reservoirs of the field, the relationship of the composition of fluids with oil deposits and superimposed geological reorganizations in the Yamal area already formed were demonstrated. In terms of composition, three groups of oils were identified: residual, whose composition was formed as a result of the migration of relatively low-molecular components, light oils with a high content of paraffins and light (low-paraffinic) oils and condensates. It is shown that differences in the composition of oils are due both to the composition of the original organic matter for them and to migration processes after the formation of accumulations of hydrocarbon fluids.