**4. Conclusions**

In this research, e ffective equations for two critical petrophysical parameters of shale reservoirs (total porosity and water saturation) have been introduced. These equations are compensated based on kerogen e ffects for density logs to estimate more accurate total porosity. Similarly, the resistivity log was corrected based on kerogen and shale e ffects to compute the accurate water saturation for shale reservoirs. This study shows that the density log overestimates the total porosity (8–15%). Whereas the total porosity based on kerogen corrected density log and kerogen porosity matches perfectly with the core-based porosity having porosity ranged from 5 to 10%. In the same way, the Simandoux equation overestimated the water saturation with more than 100% Sw in most of the intervals. However, the proposed water saturation equation (modified Archie's equation) provided better results and correlation with core-based water saturation ranged from 35 to 80%. Moreover, the introduced modified Archie equation is independent of water resistivity and Archie parameters as these inputs are very di fficult to obtain for shale reservoirs. It is also revealed that the porosity and water saturation in shale reservoirs are mainly dependent on the specific rock type. Such as the cluster-2 (mixed shale lithofacies with mixed lithologies and moderate TOC value) and cluster-3 (siliceous shale lithofacies

with higher silica, less clay content and moderate to high TOC) have more shale gas potential in Goldwyer shale due to higher porosity and water saturation. This study has proposed a step to step workflow for accurate estimation of porosity and water saturation based on well logs for organic-rich shale. This workflow will be helpful for accurate reserve estimations in the shale reservoirs.

**Author Contributions:** Conceptualisation, M.A.I.; methodology, M.A.I, and R.R.; software, M.A.I.; data curation, M.A.I.; validation, M.A.I. and R.R.; writing—original draft, M.A.I.; writing—review and editing, R.R.; supervision, R.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors would like to acknowledge the contributions of Chief Minister Merit Scholarship (CMMS), Pakistan and the Unconventional Gas Research group at the department of Petroleum Engineering, Western Australia School of Mines: Minerals, Energy and Chemical Engineering, Curtin University and Senergy Interactive Petrophysics v4.5 software for supporting this research. Special thanks to Department of Mines Industry Regulation and Safety (DMIRS) Western Australia and Finder Exploration Pty Ltd. (Perth, Western Australia). for providing data and reports about core-based measurements for water saturation.

**Conflicts of Interest:** The authors declare no conflict of interest.
