Benthic foraminiferal and calcareous algal biostratigraphy of the Fahliyan Formation in oil well X1, Dorood Oilfield, Persian Gulf

Abstract

The Dorood oilfield is located offshore in the northern part of the Persian Gulf. It partly underlies the Kharg Island. The Neocomian Fahliyan Formation represents the high-quality reservoir in the oilfield. It includes five carbonate members: The Manifa, Middle and Upper Yamama, Khami and Lower Ratawi. The Fahliyan Formation in the studied well attains a thickness of 378.1 m and mainly consists of thin-bedded limestones. It unconformably overlies the evaporate Hith Formation and conformably underlies the Gadvan Formation. An integrated biostratigraphic (benthic foraminifera and algae) and lithostratigraphic study is presented. Paleontological studies led to the identification of 19 genera and 29 species of benthic foraminifera and 10 genera and 9 species of calcareous algae. Two biozones of Berriasian through Valanginian age have been recognized. These are Lithocodium aggregatum-Salpingoporella muehlbergii assemblage zone (Valanginian) and Pseudocyclammina lituus- Coscinoconus assemblage zone (Berriasian-Valanginian).