Hassene Affouri

Title : Geological applications of biomarkers: Examples from organic rich rocks from sedimentary Tunisian Basins

Abstract:

Total organic carbon (TOC) determination, Rock-Eval pyrolysis, extractable organic matter content (EOM) fractionation, as well as gas chromatography-mass spectrometry (GC-MS) analyses, were carried out on organic rich samples from outcrop cross sections of the Albian (Lower Fahdene Formation), Cenomanian-Turonian (Bahloul Formation) and Ypresian (Bou Dabbous Formation) ages in central and northern Tunisia.

The organic matter (OM) richness as evaluated by the total organic carbon (TOC) values and Rock-Eval analysis showed that these Formations had preserved Type II/III marine and continental OM. The disparity in hydrogen index (HI) values was relevant for distinctive of OM preservation and thermal maturity among localities.

These formations are rich in organic molecules namely biological markers or biomarkers such as alkanes, steranes and hopanes. These molecules were used to assess the thermal maturity levels and to reconstruct the OM precursors and their deposition environments. The thermal maturity varies between the late diagenesis to the main-stage of petroleum production based on the optic and the cis-trans isomerisation of the C29 sterane and the hopanes.

Furthermore, these OM were deposited under an open marine to estuarine of algal communities with a specific bacterial contribution as revealed by the relative abundance of the ααα-20R C27, C28 and C29 steranes. Locally, good conservation of the C34 and C35 homohopanes molecules and high abundance of gammacerane are characteristics of a highly bacterial activities and their contribution to the organic supply under extremely anoxic deposition environments.

Audience Takeaway Notes:

• Organic geochemistry
• Organic geochemistry application to petroleum source rocks characterization
• This research can be used to expand research and teaching
• Source rock-Source rock and Oil-Source rock correlations
• Biomarkers applications to source rock organic matter supply and environment deposition

Biography:

Dr. Hassene Affouri obtained his Engineering diploma (Geology) from the National School of Engineers of Sfax,  University of Sfax, Tunisia and his PhD (Geology) from the University of Tunis El Manar. He is actually working as lecturer at the Faculty of Sciences of Sfax, University of Sfax, Tunisia. His PhD research was based on the study of the organic matter of petroleum source rocks in Tunisia. He is currently teaching organic and petroleum geochemistry at the University of Sfax. His area of interest is organic matter and biological markers characterization of ancient rocks and recent sediments. He published various papers in peer reviewed journals.