Reservoir Potential Assessment of Apsheron and Aghchagil Formations in One of the Southern Caspian Wells: Based on Sedimentary Facies and Electrofacies

This article aimed to explore the reservoir potential of the two formations, namely Apsheron and Aghchagil which primarily are comprised of sand, silt and shail. To this end, the existing thin sections taken from cutting drilling pertaining well A were considered. Consequently, four facies of sandy silt, sandy mud, silt and mud were discovered. Based on the variations taken place in the gamma ray (GR) log and sedimentary facies, the intended well was divided into eight zones. Given its completeness of the petrophysical and geological data for considering reservoir quality, the zone #7 proved to be the best case for this study. Following this process, corrected gamma ray (CGR), neutron porosity hydrogen index (NPHI) and density log (RHOZ) were selected as the input data for electrofacies modeling; therefore, through making use of MRGC clustering model, the amounts of these logs were clustered in five electrofacies clusters. Electrofacies #1 was marked, in terms of high degrees of CGR and RHOZ and low degree of NPHI, as possessing the lowest level of reservoir potential. Similarly, electrofacies #5 was marked, in terms of low degree of CGR and RHOZ and high degree of NPHI, as possessing the highest level of reservoir potential. On the other hand, the comparison between the electrofacies and sedimentary facies demonstrates the electrofacies correlation ranging from the highest to lowest quality facies, namely silt, sandy mud and mud, respectively. The results have revealed that the petrophysical data within the wells demonstrating incomplete data might come in handy for the reservoir potential analysis.