Geochemical Evaluation of Oils from the Asmari Reservoir of the Qale-Nar Oilfield: Implication for Field-Scale Reservoir Compartmentalization

The Qale-Nar oilfield is an asymmetric two-humped anticline located in the northernmost part of the Dezful embayment, in which the fractured Asmari carbonates are the primary reservoir rock. In this study, for the first time, the organic geochemistry of oils produced from the Asmari reservoir is used to investigate the reservoir continuity and possible compartmentalization. To this end, geological information from the studied oilfield was combined with bulk geochemistry (e.g., °API gravity) and molecular characteristics (e.g., gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) data) of the produced oils. Two oil samples obtained from wells 6 and 10 of the studied oilfields indicate significant differences in their bulk and molecular geochemical properties. Accordingly, a scenario was presented to better explain the reservoir charging and compartmentalization in the Qale-Nar oilfield. In this scenario, low-maturity hydrocarbon pulses first charge the eastern culmination of the Qale-Nar oilfield. The activity of a fault plane located between wells 6 and 10 could induce a barrier between the two wells. Consequently, the late hydrocarbon charges with higher maturity could only charge the compartment belonging to well 6. Therefore, well 10 could not receive these high-maturity hydrocarbon pulses due to the lack of lateral connectivity. The information obtained from this study can be of great help in future reservoir studies with important implications for field development projects and enhanced-recovery plans.

Geochemical Evaluation of Oils from the Asmari Reservoir of the Qale-Nar Oilfield: Implication for Field-Scale Reservoir Compartmentalization Keywords:

Asmari Reservoir , Gas chromatography , mass spectrometry (GC , MS) , Compartmentalization , Qale-Nar oilfield , Gas Chromatography (GC) , Reservoir continuity