A Novel Multi-Phase Strategy for Optimizing CO2 Utilization and Storage in an Oil Reservoir
Round 1
Reviewer 1 Report
This paper presents numerical study of A Novel Multi-Phase Strategy for Optimizing CO2 Utilization and Storage in an Oil Reservoir. Overall, the paper is well-written. The main comment is to highlight the novelty and aims of this work. Here are the comments to further strength this manuscript.
1) The abstract is too long and is confusing. Make it according to the journal’s standards. Keep it short but clear.
2) L.59-60 What is the source? Add citation. This is stored only in Alberta or in Canada?
3) The introduction is lack of information about previous numerical studies of scCO2 injection and storage. Add some data about results of other researchers, e.g. what was the injection scheme, what was the efficiency of storing etc. How your study differs from what have been already done? Highlight the scientific novelty. Use these papers: https://doi.org/10.2118/214045-MS, https://doi.org/10.1016/j.petsci.2021.12.009, https://doi.org/10.3390/en16031167, https://doi.org/10.2118/171520-PA, https://doi.org/10.1016/j.jngse.2016.01.038.
4) Fig.1 looks very poor. Make it less and correct the texts.
5) Did authors study the permeability and porosity changes during CO2 injection? The reservoir is carbonate; it would be interesting to see any changes in reservoir properties.
6) The total injection period was 12 years? For how many years the efficiency of storing was assessed?
Minor editing of English language is recommended.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
General comment:
In this paper, an optimized strategy (CO2-WAG strategy for suitable segments) is developed to optimize reservoir utilization and increase CO2 storage with carbon dioxide to reduce negative environmental impacts, as well as extend the utilization life of wells, and can use existing wells to convert depleted oil reservoirs into CO2 storage sites, which is a novel extraction technology.
Major comment：
1. I think that the description of the previous research in the introduction of this article has two whole paragraphs, which are too bloated, and these contents should be compared with the new technologies highlighted in this article in the discussion to reflect the innovative value of this research, and only list and introduce the goals of this research in the introduction.
2. This article lacks practical experiments, perhaps the results are a little unconvincing?
3. The description of this article is in the order of pictures, and I think it is better to add a summary discussion to the above part of conclution, for example, you can combine the energy consumption in fig.10 with the CO2 storage in fig.5, and comprehensively analyze the value of the three strategies. In conclusion, this article lacks a summative analysis section.
Minor comment:
1. In line 53 of the introduction, "production" may mean "producing region"
2. In line 55, "in Canada" here could perhaps be deleted
3. In line 58, replace "to" with "which"
4. Perhaps "life" could be deleted from line 65
5. On line 82, replace "have made it with make it."
6. In line 108, it is best to explain the reasons that limit the conversion of depleted reservoirs into CO2 storage sites, such as simple cost increases, reduced efficiency, and other possible factors. And if the high cost below is the reason, the sentence and the link below should not apply furthermore
7. In line 287, replace "a half amount of"
8. Line 292, perhaps with "these findings imply two views, first,..."
Author Response
Please see the attachment
Author Response File: Author Response.docx
