Estudio de las rocas madre del Albiense medio-superior de la región de Bir M'Cherga, Túnez: interacción de la diagénesis orgànica-inorgànica con la migración primaria de hidrocarburos

Abstract

Geochemical, mineralógicaI and petrophysic examination of the source rocks of the Middle-Upper Albien maristones and chalks from the Bir M'Cherga region (Tunisia) provide insights into factors which control the organic and inorganic migration of hydrocarbons. Differences in the quantity and composition of clay minerals, type of organic matter, microfabric and porosity observed between chalks and maristones, reflect the different behaviour and intensity of the diagenetic processes: A) cementation, concretion growth, dissolution and mechanical compaction, in the maristones and B) overgrowth cements, recrystallization and chemical compaction, in the chalks. In these latter the microporosity has been reduced to very low levels, hindering the possibility of an additional avenue of early expulsion of hydrocarbons