Kharazmi Journal of Earth Sciences

Kharazmi Journal of Earth Sciences

Comparative analysis of petrophysical and statistical methods for reflecting the geological characteristics of the Kangan Formation, Central Persian Gulf

Authors
Vahid Tavakoli 1
Aliakbar Jahanpanah 1
Mehdi Nakhostin Mortazavi 2
1 University of Tehran
2 ACECR
10.22034/KJES.2025.11.2.102062
Abstract
Heterogeneity of carbonate reservoirs resulting from lithological, textural, and diagenetic variations makes fluid flow behavior complex and unpredictable. This study was carried out to perform a comparative analysis of petrophysical and statistical methods in reflecting the geological attributes of the Kangan Formation in the central Persian Gulf. Core data and thin sections were analyzed to examine the relationships between geological characteristics and petrophysical and statistical approaches. Porosity and permeability, the percentage of lithologic components, and diagenetic parameters including the type and rate of cementation, compaction, and dolomitization have been used. Four approaches were employed for data classification, including (1) the Winland method, (2) the Flow Zone Indicator (FZI), (3) the Jenks statistical method based on porosity and combined porosity–permeability, and (4) a newly defined Geological Quality Index derived from the integration of dolomite content, effective porosity, and the rate of cementation as the main controlling factors of reservoir quality. The results showed that for all methods, reservoir quality increases from the lower to the upper groups and is accompanied by increasing dolomite, decreasing cementation and decreasing anhydrite. In the FZI method and in the Jenks method based on GQI, the separation of rocks in terms of lithologic and petrophysical characteristics was more orderly and more interpretable than with the other methods. Mean porosity and permeability vary from about 8% and 3 mD in the lower groups to more than 22% and 230 mD in the higher groups, which indicates a strong correlation between reservoir quality and diagenetic processes. The Winland method defined the overall boundaries well but was less sensitive to lithological differences. Overall, the results of this study indicate that combining geological data with statistical and petrophysical methods, can provide a more accurate and realistic representation of reservoir heterogeneities in carbonate formations and can be applied in modeling complex reservoirs.
Keywords
Winland
Flow Zone Indicator (FZI)
Jenks statistical method
Geological Quality Index (GQI)
Subjects
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Kharazmi Journal of Earth Sciences
Volume 11, Issue 2 - Serial Number 22
December 2025
Pages 433-460