Material Composition of Near-surface Section Dispersed Gases as an Indicator of the Genetic Heterogeneity of the Migration Hydrocarbon Flow

The relevance of the work results from the insufficiency of criteria for assessing the oil-bearing potential of territories and local geological features while conducting land geochemical surveys. Geochemical surveys are aimed at identifying surface hydrocarbon anomalies, the genesis of which is associated with microfluid and diffusive migration from oil and gas deposits. However, as the evidence from practice shows, not all hydrocarbon anomalies on the surface identified by the quantitative criteria indicate petroleum accumulations within the earth. Therefore, when interpreting surface geochemical fields to find oil and gas deposits, it is necessary to take into account not only migration intensity indicators but also the material composition of the migration flow. The purpose of the work is to analyze the material composition of near-surface section dispersed gases and identify intercomponent correlations that would help to determine the genesis of detectable components. To solve this problem, the authors subjected core samples from shallow (up to ۳۰ m) wells drilled in an oil and gas-bearing territory of the north of Western Siberia to thermal vacuum degassing and then conducted statistical processing of data on the content of gas components. The obtained results showed the genetic heterogeneity of dispersed hydrocarbon and inorganic gases in the upper part of the sedimentary cover.

Keywords:

Hydrocarbon migration , Gas diffusion in sedimentary rocks , Near-surface section gases , Geochemical surveys , Geochemical field