Petroleum source rock characteristics of the Mesozoic units, Mekelle Basin, northern Ethiopia

Abstract

The Mekelle Basin comprises carbonate and siliciclastic rocks which could have potential for petroleum as previous studies reported without enough evidence. This research is intended to assess source rock characteristics of selected samples from the Adigrat Sandstone, Antalo Limestone and Agula Shale. Four outcrop sections were investigated and fifteen limestone and shale samples were collected. TOC was deduced by Leco SC-632 carbon analyzer, and Rock-Eval pyrolysis was determined using Rock-Eval 6. The TOC values range from 0.11 wt.% to 0.42 wt % for 80% of the samples which is less than the minimum requirements for source rocks. However, a few samples have TOC between 0.5 wt % and 1.0 wt %, indicating fair organic matter richness. The kerogen is mainly Type IV and inert. The S1 (0–0.02 mgHC/g) and S2 (0–0.07 mgHC/g) values are very low, with very high Tmax (475–527 °C), indicating very poor potential with over-mature dry gas. Therefore, the analyzed samples have low organic content for hydrocarbon, implying that the studied units have no feasible source rock potential.