Bulk property and geochemical analyses were performed on 15 crude oil samples collected from the Early Cretaceous clastic reservoirs in the oilfields of the southern Mesopotamian Basin, South Iraq. Specific gravities ranging between 25.4 and 31.6 API and relatively high sulfur concentrations of up to 1.97 wt % suggest that the samples were generated from kerogen Type II-S at relatively low maturity level. Biomarker ratios and parameters as well as carbon isotope ratios, indicate that the oils were derived from marine carbonate-rich source rocks deposited under reducing environmental conditions during the Jurassic to Early Cretaceous. Furthermore, biomarker maturity suggests two maturity subgroups for the samples based on their sulfur concentrations and specific gravity values. Sub-group (A) is characterized by oils generated from low-mature source rocks from the Late Jurassic-Early Cretaceous Sulaiy Formation; while the relatively high mature oils of sub-group (B) were generated from organic-rich intervals in the Jurassic Sargelu and Najmah formations. Basin model results revealed that these formations reached a peak oil-generation window at different times, expelling various quantities of oil. The basin model results further suggest that the organic-rich interval in the Sulaiy Formation began to expel little amounts of oil, corresponding to transformation ratio (TR) between 50 and 63% since the Late Miocene to present-day, while the organic-rich intervals in the Sargelu and Najmah formations were the earliest to expel significant amounts of oil, with relatively high TR values of 50–90% during the end of the Late Cretaceous to Early Eocene and continued to the present-day. These generated oils subsequently migrated to the shallow stratigraphic reservoir intervals through the vertical pathway of faults, and are currently extracted for use in the oil industry.

对伊拉克南部美索不达米亚盆地南部油田早白垩纪碎屑岩储层中收集的15个原油样品进行了大块性质和地球化学分析。API在25.4至31.6之间的比重和高达1.97 wt％的相对较高的硫浓度表明，样品是从II-S型干酪根在相对较低的成熟度水平下产生的。生物标志物比率和参数以及碳同位素比率表明，这些油来自侏罗纪至早白垩世期间在减少的环境条件下沉积的富含海碳酸盐的烃源岩。此外，生物标记物的成熟度基于其硫浓度和比重值，建议两个成熟度亚组。（A）组的特征是晚侏罗世-早白垩世苏莱伊组低成熟烃源岩产生的油。而（B）组相对较高的成熟油是从侏罗纪Sargelu和Najmah地层中富含有机物的层段中产生的。盆地模型结果表明，这些地层在不同的时间达到了一个峰值产油窗口，驱逐了各种数量的石油。盆地模型结果进一步表明，苏莱伊组的有机质富集层开始驱出少量的石油，相当于中新世以来至今的50％至63％的转化率（TR），而有机质丰富的Sargelu和Najmah地层中的油层间隔是最早排出大量石油的地方，在白垩纪晚期至始新世末期并一直持续到今天，TR值相对较高，为50-90％。这些生成的油随后通过断层的垂直通道迁移到浅层地层储层段，目前被提取出来用于石油工业。