Effect of bitumen and migrated oil on hydrocarbon generation kinetic parameters derived from Rock-Eval pyrolysis

Abstract

Thermally immature whole rock and related bitumen-extracted samples were pyrolyzed. Investigating the influence of high molecular weight hydrocarbons and degradation products of non-hydrocarbon constituents of bitumen and associated migrated oil (i.e. resins and asphaltenes) on petroleum generation kinetic parameters derived from Rock-Eval pyrolysis is the main aim of this study. Based on the optimized kinetic parameters, frequency factor values of the bitumen-free samples show an obvious increase compared to whole rocks, while the range of activation energies for them is narrower. On the other hand, the predicted geological temperatures of the onset (TR 10%) and the peak hydrocarbon generation (geological T_max) from the whole rocks are generally lower than the corresponding extracted samples. In other words, the whole rock samples underestimate the petroleum formation temperatures. Thus, the results of this study suggest the extraction of bitumen prior to Rock-Eval pyrolysis in order to obtain precise kinetic parameters for the source rocks bearing a large amounts of heavy bitumen or migrated oil.

Keywords:

• bitumen-extracted rock
• hydrocarbon generation
• kinetic modeling
• migrated oil
• Rock-Eval pyrolysis

Acknowledgments

The authors would like to express their gratitude to National Iranian South Oil Company (NISOC), especially the Research and Technology office, for supplying the samples and the financial support of the work. Petroleum Geology and Geochemistry Research Centre (PGGRC) of Shahid Chamran University of Ahvaz is also gratefully acknowledged for providing laboratory facilities.