MICROFACIES ANALYSIS, DEPOSITIONAL ENVIRONMENT AND POROSITY TYPES OF THE ASMARI FORMATION IN TANG-E-PIRZAL AREA (NORTHEAST OF DEHDASHT), ZAGROS BASIN, IRAN

Document Type : research

Author

Research Assistant professor, Standard Research Center, Karaj, Iran

Abstract

The Asmari Formation (a giant hydrocarbon reservoir) is a thick carbonate sequence of the Oligocene-Miocene in the Zagros (SW Iran). Biostratigraphic analysis of this Formation (180 meter) at Tang-e-Pirzal in the northeast of Dehdashthas resulted in the recognition of three biozones attributed to the Oligocene (Chattian) to early Miocene (Aquitanian-Burdigalian). In this study, nine different microfacies types have been recognized, which have been deposited from tidal flat, to restricted lagoon, open lagoon, shoal and slope in a carbonated ramp. In this study, porosity types in this Formation were divided into primary (interparticle and intraparticle types) and secondary (vuggy and fructure types) porosity groups. Secondary porosity in this Formation results from the dissolution after of the sedimentation and is caused by a change in the primary porosity. In studied section, cementation lead to decrease porosity, but dissolution process lead to form vugy porosity and tectonic process lead to form fracture porosity. In this section, touching-vug Porosities (intergranular, intercrystalline and brecciate) increase the total porosity and and permeability, on the other side, separated-vug porosities (such as moldic) increase the total porosity But it does not play an important role in the permeability.

Keywords

Quarterly Journal of Tethys
Volume 5, Issue 4
December 2017
Pages 380-411

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