1D petroleum system modeling was performed on wells in each of four oil fields in South Iraq, Zubair (well Zb-47), Nahr Umr (well NR-9), West Qurna (well WQ-15 and 23), and Majnoon (well Mj-8). In each of these fields, deposition of the Zubair Formation was followed by continuous burial, reaching maximum temperatures of 100°C (equivalent to 0.70%Ro) at depths of 3,344-3,750 m of well Zb-47 and 3,081.5-3,420 m of well WQ-15, 120°C (equivalent to 0.78%Ro) at depths of 3,353-3,645 m of well NR-9, and 3,391-3,691.5 m of well Mj-8