Nummulites biofabrics as tool for quality evaluation of the Eocene Jdeir Formation reservoir NW offshore, Libya

Abdusalam Ali Agail, University of Texas at El Paso


The southern Tethys margin constitutes an important hydrocarbon reservoir. It is formed mainly of Nummulite rich facies of the Jdeir Formation deposited during the Eocene epoch (Late Ypresian age) in the giant El-Bouri oil field-Sabratah Basin-NW Libya. Deposits of the Jdeir Formation directly overlay the Jirani dolomite and Bilal Formation, and unconformably underlay the Tellil Group and Ghallil Formation. Nummulite accumulations are good indicators for hydrocarbon studies and they have been targets for numerous studies around the world. Nummulite "Large foraminifera" tests are usually identified by two forms: A-form and B-form. Previous studies have highlighted many different aspects of foraminifers including taxonomy, test structure, test transport, abrasion, biofabric, climate, and ecological studies, and test morphology. However, previous studies have not studied in detail the distribution of A-form and B-form. This present study aims to use A/B Ratio distributions within facies and relate that to two aspects; depositional environments and physical processes. The present study will use a Minas's chart which summaries the relationship between A/B ratio, depositional environment, and physical processes. In addition, classification of death assemblages will be evaluated to distinguish the physical processes. This could provide insight into the vertical and lateral distribution of porosity and permeability, as well as understanding the relationships between Nummulite biofabrics and the physical processes. In addition, diagenesis processes will also be evaluated and examined within the Nummulittic texture of the Jdeir Formation.

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Recommended Citation

Agail, Abdusalam Ali, "Nummulites biofabrics as tool for quality evaluation of the Eocene Jdeir Formation reservoir NW offshore, Libya" (2011). ETD Collection for University of Texas, El Paso. AAI1498262.