Evaluation of Relative Permeability Curves in Sandstone Core Flooding Using Computational Fluid Dynamics

Round 1

Reviewer 1 Report

1. In Introduction, it is suggested to show the large discrepancies in the endpoint relative permeability to the non-wetting phase, and the advantages of CFD to simulate relative permeability.

2. The quality of most of Figures should be improved.

3. The presentation quality should be improved, and the wording need to be checked carefully, e.g. Figure 8.

4. Throughout the full text, the authors mainly described the simulation results, but the discussions is superficial.

Author Response

We thank you for your valuable comments. We believe that the quality of our manuscript improved through your review. We revised our manuscript based on your comments and following are our responses to your comments. All changes in the manuscript are highlighted in yellow and the revisions are marked through “track changes” on the MS Word document. 

Responses to comments by Reviewer 1:

1. In Introduction, it is suggested to show the large discrepancies in the endpoint relative permeability to the non-wetting phase, and the advantages of CFD to simulate relative permeability.

We thank you for your comment. As suggested, we have now mentioned the discrepancies in Introduction. In addition, we also mentioned the advantage of using CFD in the last paragraph of this section.

2. The quality of most of Figures should be improved.

Thank you for your valuable comment. We went ahead and improved the quality of the figures in our manuscript.

3. The presentation quality should be improved, and the wording need to be checked carefully, e.g. Figure 8.

Thank you for your comment. We have now improved the quality of our presentation and verified the wordings.

4. Throughout the full text, the authors mainly described the simulation results, but the discussions is superficial.

Thank you for your comment. We have now additional added in-depth discussions to support our results.

Reviewer 2 Report

General comments

Valid research that needs some implementations. Please, follow my guidelines to fix all the issues, and there is my availability to review the manuscript as a second time in case of request of the editor

Specific comments

Abstract

Lines 7-20. Sandstones tend to be very different from each other in terms of mineralogy, grain size distribution, and pore network structure. Please, specify in the abstract the type of sandstone samples that you have tested

Lines 41-43. “One of the key parameters associated with the injection of carbon dioxide into geological formations is relative permeability to carbon dioxide in relation to water or brine, which determines the flow characteristics within the formations”.  Sentence on the importance of permeability in sandstone geological media not backed up by references. Insert specific review papers on the permeability of sandstones that are proposed below:

- Medici, G., & West, L. J. (2022). Review of groundwater flow and contaminant transport modelling approaches for the Sherwood Sandstone aquifer, UK; insights from analogous successions worldwide. Quarterly Journal of Engineering Geology and Hydrogeology, 55(4), https://doi.org/10.1144/qjegh2021-176

- Tellam, J. H., & Barker, R. D. (2006). Towards prediction of saturated-zone pollutant movement in groundwaters in fractured permeable-matrix aquifers: the case of the UK Permo-Triassic sandstones. Geological Society, London, Special Publications, 263(1), 1-48.

Line 73. “In this area”, which area of the world?

Line 91. Clearly state the principal aim of your research, and the 3 to 4 multiple objectives of your research using numbers (e.g., i, ii, and iii)

Line 94. You mention here porosity. As you mention it, you need to specify the methodology used (e.g., Archimedes, NMR etc. etc.). One or more methods used? Different methods can provide differences of up to 20% for the porosity values of sandstones. Some authors cross three methods

Line 96. “Vedder Sandstone”. Insert age (i), and (ii) sedimentological nature of the sandstone. Turbidite? Fluvial? Deltaic? Tidal?

Lines 161. “Results and discussion”. No discussion appears, see my comment below (Line 260)

Line 260. No discussion on the degree of applicability of your research. How much is your research applicable to other sandstones? Which type of sandstone are you testing aside from the specific formation name? I’m trying to bring the impact out of your research, and fix the boundaries of applicability of a good research that needs to be published.

Line 262. Clearly explain in the main body why you have only three points in the graph in Figure 16

Line 279. Report in the conclusions: (i) type of research (experimental, modelling?), (ii) formation name, and characteristics of the sandstone object of study, and (iii) define the boundaries of applicability of your research.

Line 297. Insert the references suggested above

Figures and Tables

Figures 4, 6, 8, 9, 10, 13, 14, 15, and 16. Make figures larger, there is plenty of room for that

Two figures 8. One figure is 8, and the other one is 9

Author Response

We thank you for your valuable comments. We believe that the quality of our manuscript improved through your review. We revised our manuscript based on your comments and following are our responses to your comments. All changes in the manuscript are highlighted in yellow and the revisions are marked through “track changes” on the MS Word document. 

Responses to comments by Reviewer 2:

1. Abstract: Lines 7-20. Sandstones tend to be very different from each other in terms of mineralogy, grain size distribution, and pore network structure. Please, specify in the abstract the type of sandstone samples that you have tested.

Thank you very much for this comment. As suggested by you, we added the details in our abstract.

2. Lines 41-43. “One of the key parameters associated with the injection of carbon dioxide into geological formations is relative permeability to carbon dioxide in relation to water or brine, which determines the flow characteristics within the formations”.

Sentence on the importance of permeability in sandstone geological media not backed up by references.

Insert specific review papers on the permeability of sandstones that are proposed below: -

Medici, G., & West, L. J. (2022). Review of groundwater flow and contaminant transport modelling approaches for the Sherwood Sandstone aquifer, UK; insights from analogous successions worldwide. Quarterly Journal of Engineering Geology and Hydrogeology, 55(4), https://doi.org/10.1144/qjegh2021-176 -

Tellam, J. H., & Barker, R. D. (2006). Towards prediction of saturated-zone pollutant movement in groundwaters in fractured permeable-matrix aquifers: the case of the UK Permo-Triassic sandstones. Geological Society, London, Special Publications, 263(1), 1-48.

We thank you for your valuable suggestion. We went ahead and added these references.

3. Line 73. “In this area”, which area of the world?

Thank you for your comment. We added the details here.

4. Line 91. Clearly state the principal aim of your research, and the 3 to 4 multiple objectives of your research using numbers (e.g., i, ii, and iii)

Thank you very much for your valuable comment. We have now clearly mentioned the objectives of our research using numbers following your suggestion.

5. Line 94. You mention here porosity. As you mention it, you need to specify the methodology used (e.g., Archimedes, NMR etc. etc.). One or more methods used? Different methods can provide  differences of up to 20% for the porosity values of sandstones. Some authors cross three methods.

Thank you for your comments. Following your suggestion, we added the details in the ‘Materials and Methods’ section.

6. Line 96. “Vedder Sandstone”. Insert age (i), and (ii) sedimentological nature of the sandstone. Turbidite? Fluvial? Deltaic? Tidal?

Thank you again for your valuable comment. We added the details in the first paragraph in ‘Materials and Methods’ section.

7. Lines 161. “Results and discussion”. No discussion appears, see my comment below (Line 260)

Line 260. No discussion on the degree of applicability of your research. How much is your research applicable to other sandstones? Which type of sandstone are you testing aside from the specific formation name? I’m trying to bring the impact out of your research, and fix the boundaries of applicability of a good research that needs to be published.

Thank you for your valuable suggestion. We have now added the details in the last paragraph of our ‘Results and Discussion’ section.

8. Line 262. Clearly explain in the main body why you have only three points in the graph in Figure 16

Thank you for this suggestion. We went ahead and added the discussion in the paragraph immediately before Figure 16.

9. Line 279. Report in the conclusions: (i) type of research (experimental, modelling?), (ii) formation name, and characteristics of the sandstone object of study, and (iii) define the boundaries of applicability of your research.

Thank you for your comment. As suggested we added these details in conclusions.

10. Line 297. Insert the references suggested above

As suggested we added these references. These are reference # 14 and #15.

11. Figures and Tables Figures 4, 6, 8, 9, 10, 13, 14, 15, and 16. Make figures larger, there is plenty of room for that Two figures 8. One figure is 8, and the other one is 9

Thank you for your comment. We made the figures larger and fixed the inconsistencies.

Round 2

Reviewer 1 Report

It is advisable that the section3.2 and 3.3 should be improved by adding more analysis.

Author Response

We thank you for your valuable comments. We believe that the quality of our manuscript improved through your review. We revised our manuscript based on your comments and following are our responses to your comments. All changes in the manuscript are highlighted in yellow and the revisions are marked through “track changes” on the MS Word document. 

Responses to comments by Reviewer 1:

1. It is advisable that the section3.2 and 3.3 should be improved by adding more analysis.

Thank you for your suggestion. Based on your comments, we added four additional result plots. Figure 7 and Figure 8 show the pressure profile and mixture density profile with carbon dioxide in gas phase displacing water within the core sample. Figure 13 and Figure 14 show the pressure profile and mixture density profile with representative supercritical carbon dioxide displacing water within the core sample. We also added text to explain the additional result plots and corresponding analyses.