--> Abstract: Radioactive Irradiation Factor of Hydrocarbon Source Rock Evaluation, by George Mirkin; #90072 (2007)
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Radioactive Irradiation Factor of Hydrocarbon Source Rock Evaluation

George Mirkin
Quanto Intenational Co., Ltd, Toronto, ON

Hydrocarbon (HC) source rock evaluation is the important tool for hydrocarbon exploration. Presently applied techniques are based on thermodynamic principles. Only geothermal factor is taken into accounts.
Four major types of evaluation methods are applied: Tisso' method; Lopatin' method; Lab-pyrolysis; Vitrinite reflectance index.
Historical application of these methods to the same objects provided quite different results. Methodological problems are also aggravated by used geological parameter uncertainness (paleotemperature, paleodepth etc.).
Many HC source rocks are enrichment by radioactive elements. Radioactive decay is the important cause of kerogen chemical alterations. The quantitative evaluation of Bazhenov Shale (Western Siberia) shows that energy produced by decayed Uranium is sufficient for a high degree of kerogen Previous HitmaturationNext Hit.
Radiation paleo-organic geochemistry is quite different from paleo-organic geochemistry based on thermodynamic principles. Therefore, hydrocarbon radicals produced by kerogen irradiation are different from radicals produced by heating:
Hydrocarbon radical concentration produced by irradiation, in contrast to geothermal heating, doesn't depend from formation temperature but from radiation dose. Geothermal kerogen Previous HitmaturationNext Hit requires significantly higher heating temperature to produce similar hydrocarbon radical concentration. Thus, radiogenic hydrocarbon output from source rocks is different quantitatively and qualitatively from geothermal output.
Natural clay catalysts adsorb HC radicals produced under lower geotemperature. Accumulated radicals are abruptly released due to clay structure collapse when formation temperature rises above 100oC. This way highest concentration of radicals is created. Further combined geothermal and radiogenic (but enthalpy) heat contributes to Previous HitmaturationTop of residual kerogen.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece