Controles composicionales, diagenéticos y de microfábrica sobre las características de la roca madre jurásica del petróleo del Campo de Salam (Western Desert, Egipto)

Resumen

Petrographic, mineralogical (XRD), bulk geochemical (TEM, SEM and BSE) and petrophysical analysis of selected shales, siltstones, coaly shales and coals from Jurassic Khatatba Fm. and Cretaceous Alam El Bueib (AEB) Fm. in the Salam oil field (Western Desert; Egipt) reveal a similar whole mineralogical composition but with variable clay composition. This is composed of kaolinite and subordinated I-S mixed layers in the Khatatba Fm. being composed of kaolinite, illite, I-S mixed layers and chlorite in the AEB Fm.. This difference could have influenced on the type of HC generated as several authors have shown. AIso the clay microfabric shows some difference between the more open structure of the flocculated continental kaolinite in the Khatatba Fm. and the oriented and more compacted marine clays (in both formations). The abundant silt quartz grains in the shales of the two formations have favoured the conected microporosity on the primary migration of HC to the interbedded sandstones. The high content in globular organic remains replaced by framboidal pyrite and bitumen and the amorphous organic ground mass of the Khatatba shales indicates that the best oil-source rock could be the organic shales instead of the carbonaceous shales in the Khatatba Fm.