Geochemical Characteristics of Six Formations Based on Organic Geochemical Parameters, Murzuq Basin, Libya

Cutting samples (n = 150) and Core samples (n = 6) from the Taouratine, Dembaba, Assedjefar
Marar, Awaynat Wanin, Tanezzuft and Mamuniyat Formations (Jurassic to Ordovician), derived from
wells (A-3, B-1, H-1 and H-15), locate in the A, B and H fields, present in Murzuq Basin were
analysed. Rock-Eval Pyrolysis, Total Organic Carbon and specific Aromatic Molecular Biomarker (by
the use of chromatography- mass spectrometry GC-MS) as geochemical parameters implemented to
investigate their Lithology, kerogen type, organic matter (OM) richness and maturity evaluation. Such
Formations are fair to very good quantity of organic matter passing in the course of excellent source
rocks, have average of organic carbon richness (TOC) value ranged between 0.2% to 16.7% with
one anomalously rich sample at 666m (well H-1) where a dark grey shale has a TOC content of
46.1% and high potential yield over 90000 ppm. The studied rocks are ranged from immature to
mature of hydrogen index (HI) ranged between 24 - 302 mg HC/g TOC versus pyrolysis Tmax, with
dominance of kerogen II/III Type, resulted based on HI versus oxygen index (OI), ranged from 3 to
161 mg CO2/g TOC. The Tmax , spore colouration (SCI) and Vitrinite Reflectance (% Ro) as maturity
parameters ranged among 425 - 445, 5 - 8.5 and 0.35 - 3 respectively. Aromatic hydrocarbon ratios
by use of gas chromatography - mass spectrometry pointed to two levels of thermal maturity, where
the high level of thermal maturity recorded in lower Silurian, whereas the less maturity was from other
formations.