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Accueil du site → Doctorat → Royaume-Uni → 1992 → The organic geochemistry of sedimentary organic matter from the Algerian Sahara

University of Newcastle upon Tyne (1992)

The organic geochemistry of sedimentary organic matter from the Algerian Sahara

Aziez, Mebarka

Titre : The organic geochemistry of sedimentary organic matter from the Algerian Sahara.

Auteur : Aziez, Mebarka.

Université de soutenance : University of Newcastle upon Tyne

Grade : Doctor of Philosophy (Ph.D.) : 1992

Résumé
This study is composed of three parts :(i) organic geochemical and organic petrological analysis of source rock samples from the Ghadames-El Borma basin are described ;(ii) organic geochemical characterisation of oils from a number of occurrences in Algeria has been carried out to give families or groups of different oil types ;(iii) oil-source rock correlations in the Ghadames-El Borma basin between the oils in the Triassic reservoirs and the putative source rock sections are suggested.Sixty rock samples ranging from the Triassic to Ordovician in age from the Ghadames-El Borma basin, have been investigated using organic geochemical techniques in order to assess source rock potential. Rock-Eval pyrolysis data indicate that Devonian constitute excellent source rocks, Silurian and Ordovician are considered potentially moderate to good source beds, whereas Triassic sediments have little or no oil potential. Reflected and ultraviolet light microscopy show that amorphous organic matter and Graptolite dominate the Ordovician strata, while Silurian and Devonian contain predominantly liptinitic materials such as acritarchs, algal bodies (Tasmanites) and spores ; bitumen is moderately abundant. Biological marker investigation using capillary gas chromatography and the combined gas chromatography/mass spectrometry in energy impact (GC/MS/El) and metastable ion reaction monitoring (GC/MS/MRM) modes together with principal component analysis (PCA) have allowed a discrimination of samples into three groups : (i) Ordovician, (ii) Silurian and Devonian and (iii) Triassic.Oil-oil correlation procedure has been carried out in areas with a number of different oil occurrences from southern and northern Algeria, namely from the Ghadames-El Borma, Sbaa, Illizi, Triassic province and Southeast Constantine basins. A range of approaches can be used which depend on the nature of the oils. In the present study, correlation parameters include data derived from biological marker distributions as well as gasoline range hydrocarbons.

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