Geochemical evaluation and genetic comparison of Fahliyan and Yamama oils in some of the west of Karun and Southern Iraq oilfields

The Fahliyan Formation, located in the Abadan Plain, is one of the most significant productive units in the Zagros Basin. Its Mesopotamian Basin equivalent, the Yamama Formation, also contains large quantities of hydrocarbons. Due to the geochemical similarities of these two reservoirs, investigating trapped oils and correlations can yield significant results. However, there have been limited studies describing the relationship and oil-oil correlation between the Fahliyan and Yamama oil samples. In this study, geochemical analyses such as GC, GC/MS, and stable carbon isotope were used to analyze the Fahliyan oil samples. Furthermore, Yamama data were taken from previously released studies in the Mesopotamian Basin. The results showed that both Yamama and Fahliyan oils were non-biodegraded and mostly paraffinic and light, indicating peak mature or late mature levels. The indices also suggested that the oils had a marine carbonate source with type II kerogen, which was deposited under anoxic and low salinity conditions of the deposition environment. The Jurassic source rock of these reservoirs was confirmed by the geological age biomarkers. Following this and previous research, it was concluded that the Sargelu and Garau (Sulaiy) formations are the most likely source rocks. Investigations of the oil biomarkers and the results of other studies in these areas deduced that the Fahliyan and Yamama oils in study areas are classified in the same genetic family. These results will affect the field development plan.