Geochemistry of low-boiling hydrocarbons of oils in the northern Ob' region

Recognition of the genesis of oils and their differentiation according to t he settings of accumulation of parental petroliferous rocks and secondary p rocesses are an important achievement in organic geochemistry in the last f ew decades. In separating oils into genetic types, the information about th e composition of low-molecular hydrocarbons C-5-C-8 of oils may be highly u seful. In this work, we have studied 73 samples of Mesozoic oils from the n orthern Ob' region of West Siberia and have established that the compositio n of low-molecular hydrocarbons bears much detailed information about the n ature of the oils. The "genetic code" of the oils was studied by cluster an alysis. Before the automatic classification, we carried out a correlational analysis, which permitted us to estimate 200 analytical parameters of the composition of the gasoline fractions of oils and choose 22 which are the m ost informative. Cluster analysis allowed us to separate the studied oils i nto five families and to determine their spatial occurrence. Each of the fa milies correspond to a particular geochemical facies.