Identification of sedimentary environment and microfacies of Asmari Formation in one of the Lorestan basin oil fields

Abstract

Depositional microfacies identification plays a key role in the exploration and development of oil and gas reservoirs. Asmari Formation in Oligo-Miocene is one of the most important reservoir Formations for the production and exploration of hydrocarbons in the Middle East and has a high reputation globally for a long time. In the Lorestan region, the sequences of the Asmari Formation have a carbonate-evaporate mixture of the late Miocene. The main aim of this research is to describe and interpret the different facies observations. Investigation of this sequence in one of the wells in this region has led to the identification of 17 sedimentary microfacies that belong to a homoclinal ramp-type carbonate platform. The nature and distribution of facies and environmental conditions of the Asmari Basin have undergone fundamental changes over time so that in the first part of this Formation (containing the first sequence of this Formation), the facies and their distribution pattern are similar to those of Tertiary and also others Zagros regions like Khuzestan and Fars. Still, in the second part (second sequence), there is a significant change in the Asmari basin, the most important of which is the replacement of red coral algae by a rare group of red algae with Aragonite wall. Our findings allows better characterizing and understanding which sedimentological features control the mechanical and its distribution throughout the formation.