Integrated mineralogical, geochemical, and log derived TOC evaluation of source rock potential in the Khatatba Formation (Western Desert, Egypt)

Abstract

Abstract The Middle Jurassic Khatatba Formation represents one of the principal petroleum system elements in the Western Desert of Egypt and contains important organic-rich shale intervals within the Upper Safa Member. This study integrates mineralogical, geochemical, and calibrated log-derived TOC analyses to evaluate the source rock potential of the Upper Safa Member in the Obaiyed Field. A total of 100 ditch-cutting samples from four wells were examined using XRD, XRF, TOC, TS, and Rock-Eval pyrolysis analyses, combined with continuous log-derived TOC prediction. Mineralogical results indicate a kaolinite-rich siliciclastic assemblage with quartz and minor calcite, while geochemical data suggest mixed siliciclastic and marine influence. TOC values range from 0.50 to 3.90 wt% (average ~ 1.8 wt%), indicating moderate to very good organic richness. Rock-Eval data reveal mixed Type II/III kerogen with HI values of 99–186 mg HC/g TOC and Tmax values between 441 °C and 457 °C, confirming thermal maturity within the hydrocarbon generation window. Log-derived TOC calibrated against laboratory measurements shows strong agreement (R² = 0.93), demonstrating the reliability of the integrated workflow for continuous source rock characterization. TOC–TS relationships suggest deposition under oxygen-restricted conditions interpreted conservatively as dysoxic to suboxic, favorable for organic matter preservation. The Upper Safa Member is interpreted as a mature, gas-prone source rock with fair to good hydrocarbon generation potential and strong source–reservoir coupling with adjacent Safa sandstone reservoirs. The integrated workflow presented in this study provides a reliable framework for continuous source rock evaluation and improved exploration targeting in the northwestern Western Desert of Egypt.