Permeability modelling in a highly heterogeneous tight carbonate reservoir using comparative evaluating learning-based and fitting-based approaches

Ehsan Hajibolouri; Ali Akbar Roozshenas; Rohaldin Miri; Aboozar Soleymanzadeh; Shahin Kord; Ali Shafiei

doi:10.1038/s41598-024-60995-7

Permeability modelling in a highly heterogeneous tight carbonate reservoir using comparative evaluating learning-based and fitting-based approaches

Sci Rep. 2024 May 3;14(1):10209. doi: 10.1038/s41598-024-60995-7.

Authors

Ehsan Hajibolouri¹, Ali Akbar Roozshenas², Rohaldin Miri^{3

4}, Aboozar Soleymanzadeh⁵, Shahin Kord⁵, Ali Shafiei¹

Affiliations

¹ Petroleum Engineering Program, School of Mining & Geosciences, Nazarbayev University, 010000, Astana, Kazakhstan.
² School of Chemical Engineering, Iran University of Science and Technology (IUST), PO Box 16765-163, Tehran, Iran.
³ School of Chemical Engineering, Iran University of Science and Technology (IUST), PO Box 16765-163, Tehran, Iran. rohaldinmiri@iust.ac.ir.
⁴ Department of Geosciences, University of Oslo, Blindern, PO Box 1047, 0316, Oslo, Norway. rohaldinmiri@iust.ac.ir.
⁵ Department of Petroleum Engineering, Ahwaz Faculty of Petroleum, Petroleum University of Technology, Ahvaz, Iran.

Abstract

Permeability modelling is considered a complex task in reservoir characterization and a key component of reservoir simulation. A common method for permeability modelling involves performing static rock typing (SRT) using routine core analysis data and developing simple fitting-based mathematical relations that link permeability to reservoir rock porosity. In the case of carbonate reservoirs, which are associated with high heterogeneities, fitting-based approaches may fail due to porosity-permeability data scattering. Accurate modelling of permeability using petrophysical well log data seems more promising since they comprise a vast array of information about the intrinsic properties of the geological formations. Furthermore, well log data exhibit continuity throughout the entire reservoir interval, whereas core data are discrete and limited in availability and coverage. In this research work, porosity, permeability and log data of two oil wells from a tight carbonate reservoir were used to predict permeability at un-cored intervals. Machine learning (ML) and fitting models were used to develop predictive models. Then, the developed ML models were compared to exponential and statistical fitting modelling approaches. The integrated ML permeability model based on Random Forest method performed significantly superior to exponential and statistical fitting-based methods. Accordingly, for horizontal and vertical permeability of test samples, the Root Mean Squared Error (RMSE) values were 3.7 and 4.5 for well 2, and 1.7 and 0.86 for well 4, respectively. Hence, using log data, permeability modelling was improved as it incorporates more comprehensive reservoir rock physics. The outcomes of this reach work can be used to improve the distribution of both horizontal and vertical permeability in the 3D model for future dynamic reservoir simulations in such a complex and heterogeneous reservoir system.

Keywords: Data modelling; Heterogeneity; Machine learning; Permeability modelling; Random forest; Reservoir simulation.