JOURNAL OF ROCK MECHANICS

JOURNAL OF ROCK MECHANICS

Geomechanical unit Determination using a combination of clustering methods and laboratory test results for the Kangan and Dalan formations in the southern Iranian reservoirs

Document Type : Original Article

Authors
Mohamadali Chamanzad 1
Majid Nikkhah 2
Ahmad Ramezanzadeh 3
Misha Pezeshki 4
Imandokht Mostafavi 4
1 Faculty of Mining, Petroleum & Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran
2 Faculty of Mining, Petroleum & Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran
3 Faculty of Mining, Petroleum & Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran
4 Pars Oil and Gas Company, Tehran, Iran.
10.22034/IRSRM.2023.480084.1901
Abstract
Summary

Determining geomechanical units is the first step in understanding the reservoir conditions for advancing any engineering process. In this study, geomechanical units are determined for the Kangan and Dalan formations, the main reservoirs of the Persian Gulf. To reduce errors arising from observation and engineering judgment, three clustering methods—hierarchical clustering, density-based clustering, and k-means clustering—were employed using MATLAB software to determine the geomechanical units. The petrophysical logs of density, neutron, gamma, shear sonic, and compressional sonic are used as inputs for the clustering methods. The advantage of using these data lies in their comprehensiveness and availability. Subsequently, 43 core samples were classified based on porosity and permeability, and the correspondence between the determined geomechanical units and the classification of samples was identified. Additionally, the Silhouette index was used to evaluate the clustering quality for each method. Finally, five geomechanical units were established, showing a suitable distribution and distinct differentiation in the log values along the wellbore. The hierarchical clustering algorithm provided more acceptable results compared to the k-means and density-based methods for determining the geomechanical units. The hierarchical clustering algorithm, using the standard Euclidean metric and the minimum variance linkage criterion (ward), showed the best agreement with laboratory results (94%) and a Silhouette index of 0.48.
Keywords
Geomechanical unit
Clustering algorithm
Petrophysical logs
Porosity and permeability
Carbonate reservoir
Subjects
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JOURNAL OF ROCK MECHANICS
Volume 7, Issue 3
Autumn 2023
Pages 41-49