Research on type I kerogen molecular simulation and docking between kerogen and saturated hydrocarbon molecule during oil generation

Abstract

The interaction between kerogen and hydrocarbons is of great importance in the study of petroleum migration and reservoirs. In this study, type I kerogen was collected from Xinjiang Province, China and laboratory thermal maturation was used to investigate changes in the chemical structure of kerogen during hydrocarbon generation. A series of 2D and 3D kerogen molecular models were established with an increase in maturity, and the Gibbs free energy was calculated for the interacting kerogen and the selected free hydrocarbons. Based on the changes in kerogen structure, we found that during condensation reactions, protonated and branched aromatic carbon is continuously transformed into bridgehead aromatic carbon. fH a’, fB a’, fS a’ and fO a’ were proposed to evaluate this phenomenon. In addition, molecular docking was successfully applied to petroleum geochemistry. The results of the molecular docking indicated that both molecular size and relative proportion of methyl groups could affect the binding energy between geological organic matters. Therefore, kerogen might adsorb higher masses of n-C15 to n-C20 and isomers with more methyl groups. This study introduces the method of molecular docking into the research of oil and gas geological and it provides a new way for the selective adsorption phenomenon of solid–liquid organic matter interaction. And this research has important implications for method on oil migration and geochemical molecular simulation techniques.