Evaluation of Organic Matter Richness of Eocene Strata Based on Calcareous Nannofossils and Rock-Eval Analysis in North Dezful, Iran

Abstract

Hydrocarbon source potential of the Paleogene Pabdeh Formation was studied by means of organic geochemistry and distribution of calcareous nannofossils. Based on the results, an Eocene-aged organic matter (OM)-rich interval was identified and traced across different parts of the North Dezful zone and partly Abadan Plain. In order to characterize the OM quality and richness of the studied intervals, Rock-Eval pyrolysis and nannofossils evaluation were performed, and the geochemical data collected along selected wells were correlated to capture the variations of thickness and source potential of the OM-rich interval. Accordingly, remarkable variations were identified within the depth ranges of 2 480–2 552 m and also 2 200–2 210 m, which were attributed to the maximum increase in the rate of growth R-selected species. This increase in the productivity rate was found to be well correlated to high Rock-Eval total organic carbon (TOC) and hydrogen index (HI) values. Given that the maturity of Pabdeh Formation in the studied area was found to have reached the oil window, we expect significant hydrocarbon generation (Type II kerogen), making the play economically highly promising.

Keywords

calcareous nannofossils / Rock-Eval / organic geochemistry / Paleogene / paleo-productivity / diversity / Dezful

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