Source Rock Characterization for the Hydrocarbon Generative Potential and Thermal Maturity of Carboniferous Strata in the Tendrara–Missour Basin, Northeastern Morocco

Abstract

The Tendrara–Missour Basin in eastern Morocco hosts the country's largest gas field, featuring a proven petroleum system with Paleozoic source rocks and a Triassic siliciclastic reservoir sealed by Late Triassic and Early Jurassic salt formations. This study evaluated the hydrocarbon generative potential and thermal maturity of Carboniferous source rocks via geochemical analysis of 215 samples from four wells (OSD-1, TE-1, TE-2, and TE-3). The results indicate that the majority of the samples were characterized by a poor to fair content of organic matter, with the total organic carbon (TOC) values less than 1%. These samples were composed mainly of type III (gas prone) and type IV (non-generative) kerogen, with the hydrogen index (HI) < 150 mg HC/g TOC. However, certain intervals, particularly in the OSD-1 well, displayed excellent source rock characteristics with the TOC values exceeding 4% and a mixture of the type II/III kerogen with the HI values exceeding 150 mg HC/g TOC. The maturity levels across the well ranged from immature to post-mature, with vitrinite values varied within 0.58–2.56%. The burial history modeling in the OSD-1 and TE-3 wells indicated that the hydrocarbon generation from the Carboniferous source rocks started during the Late Carboniferous–Permian period, i.e., during the Hercynian orogeny. Volumetric calculations based on the Monte Carlo simulation estimated the generative potential of the Carboniferous source rocks to be approximately 200 000 tons/km² (P50). The accumulated volumes derived from the Carboniferous source rocks (P50) are estimated at approximately 300 million barrels of oil and 2.5 trillion cubic feet (TCF) of gas.