AN ATTEMPT TO QUANTITATIVE CORRELATION BE TWEEN MACERAL MATURITY AND REFLECTANCE

The parameters quantifying the chemistry of a homogenous maceral which strongly correlate with maceral reflectance are discussed. This first implies to argue the existence of subclasses among vitrinite. In Nige r delta areas where thermal history and fluxes are homogeneous, where present day gives the maximum temperature, where vitrinite is neither oxidized nor contaminated by hydrocarbons, where local vitrinite subcl asses may hardly arise from biological origins, the temperature range where a given vitrinite reflectance (PR(V)) is observed is as wide as 40 degrees C. This lack of coherence between the vitrinite reflectance and the thermal constraint is observed for low diagenetic conditions (PR(v) = 0.2%) and in the very heart of the catagenetic process (PR(v) = 1.0%) as well. In view of petroleum exploration, this is extremely sensitive for source rock maturity mapping from iso-PR(v). A hypothesi s is developed where an irreversible transformation and the amount of hydrophilic functions chemically bonded to the vitrinite hydrocarbon s keleton, as a result of early diagenesis, may be the main triggers in the final choice for the maturity scale measured by vitrinite reflecta nce during the catagenetic evolution. Considering structurally hydroph obic macerals like exinites or inertinites, and vitrinites belonging t o the maximal trend for reflectance at a given temperature (structural ly hydrophobic vitrinites?), a universal correlation is observed betwe en the Rock Eval IH and maceral reflectance. This acts whether maturat ion is natural or artificial.