Thermal maturity history reconstruction and hydrocarbon generation/expulsion modeling of the syn-rift Rudeis and Kareem source rocks in the Red Sea Rift Basin, Sudan

Abstract

Modeling of maturity and hydrocarbon generation has been performed on syn-rift Rudies and Kareem source rocks from four wells along the Sudanese Red Sea Basin to examine their hydrocarbon generation and expulsion history. The reconstruction of the burial and thermal history curves show that the Red Sea evolved initially as a rift basin during late Eocene-Oligocene that accelerated considerably during early Miocene with strong regional uplift in the late Miocene. Heat flow models show that the present-day heat flow in the Sudanese Red Sea Basin varies from 72 to 109 mW/m2. The great differences in the present-day heat flow values have been attributed to the regularly increasing geothermal gradient from margins to the east toward offshore, where the axial trough is the main source of the heat. The paleo-heat flow increased from Oligocene to Early Pliocene, reached peak heat flow values of approximately 103–107 mW/m2, since the main rifting occurred during Oligocene and lasted through the Early Pliocene. These in turn explain the high heat flow values reported in Oligocene to Early Pliocene, thus has a considerable influence on source rock maturation and hydrocarbon generation as quite younger rock is currently passing oil generation window. The modeled thermal history indicates that the syn-rift Rudies and Kareem source rocks were passed late oil generation stage and generated oils that converted to dry gas during late Miocene. The modeled hydrocarbon expulsion suggests that the Rudeis and Kareem are active source rock units and have probably completed all their potential hydrocarbon commenced since end of late Miocene time.