Prediction of Hydrocarbon Generation from Upper Jurassic Hot Shale Source Rock Using Bulk Kinetics in the Masila Basin, Eastern Yemen

The hot shales of Madbi Formation generally contain more than 2.0 wt % TOC and have very good to excellent hydrocarbon potential. Kerogen is predominantly algal Type II with minor Type I, and is of varies maturity levels. To enhance the geochemical source rock characterization as well as to predict hydrocarbon phases and timing of generation, bulk and phase kinetics were performed by 1 D basin modeling. Thermal and burial history models indicate that the Madbi hot shale in the studied wells began to generate oil between 97 and 71 Ma and reached peak generation between 71 and 56 Ma. Oil expulsion started in the end of Late Cretaceous and Early Tertiary time between 71 and 56 Ma and the maximum expulsion reached during the Early Tertiary time (56-50 Ma). The cumulative amount of oil generated from a unit volume of source rock is related to the amount, type, and maturity of its kerogen. The maturity of a kerogen can be expressed by its transformation ratio, which of peak generation is in the range of 30 to 70% with amount of oil generation and expulsion potential reaching up to 400 mg HC/g TOC e.g. 70% during Early Tertiary.