Madbi-Biyadh/Qishn (!) petroleum system in the onshore Masila Basin of the Eastern Yemen

► One petroleum system has been identified in the Masila Basin: the known Upper Jurassic system. ► The Upper Jurassic Madbi Formation is the most important source rock in the Masila Basin. ► The main reservoir rock is the Biyadh Formation (Qishn Clastic). ► The traps in the basin are mainly structural traps, including anticlines, and faulted block. ► Hydrocarbon generation and expulsion during late Cretaceous to Early Tertiary time.