Influence of Reservoir Heterogeneity on Simultaneous Geothermal Energy Extraction and CO₂ Storage

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study presented how the reservoir heterogeneity interacted with geothermal energy extraction and CO2 sequestration. It is an established fact that searching for alternative energy resources as well as CO2 conversion and storage would be able to alleviate the global warming issues. Here, by utilizing a finite element model, the authors find that the heterogeneities of the reservoir definitively determine their capability. This work offers fellow researchers new pathways and tools to build more efficient two-phase CO2 geothermal systems.

I think the authors did a great job in terms of citing others' work in the same field to show the readers additional information as well as the limitations of this field. I think it would be beneficial to explain how the parameters were chosen for the study in the Methodology section. Also, there are a few typos in the article, such as in Figure 13, the caption is spelt incorrectly.

 

Overall, I think this is a solid work with good presentation and should be accepted

Author Response

Please consider the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Topic: Influence of Reservoir Heterogeneity on Simultaneous Geothermal Energy and CO2 Storage.

Recommendations: The box model is used in this study to simulate CO2 dynamics in a virtually-replicated reservoir system in order to determine how this approach impacts the efficiency of geothermal energy extraction. Although the work could be of interest to audiences interested in fluid transport in porous media/materials, it would require some modifications before it would be accepted for publication in Sustainability. The following recommendations are provided:

1.    Table 1: Residual CO2 saturation. Rewrite the carbon dioxide using the subscript for the numerical character 2.

2.    No 307 -369. This study needs to explicitly explain the type of mesh structure adopted and how the meshing parameters affect the targeted results, namely the pressure/velocity simulated data for the CO2 disposition within a reservoir.

3.    373: The use of personal pronouns such as "we, they, etc" is not recommended in scientific research.

4.    In the current discussion, there is no comparison between the research data and those found in the literature. Modelling and simulation are made even more robust by substantiating with published data. This is the appropriate way to discuss such data.

5.    What is the method used to calculate 2.5mD permeability from pressure-velocity data? How are these data classified into porous media flow regimes, and why?

6.    The modelling confidence should be substantiated by either simple experiments or empirical data from the literature, or by substantiated analytical models.

 

7.    The conclusion needs to include: a summary of the results obtained, and how the data relate to the overall aim of the study. In addition, this should include a summary of the objectives of the work and how they were addressed.

Comments on the Quality of English Language

Minor modification

Author Response

Please consider the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this study aim to show the influence of reservoir heterogeneity on simultaneous geothermal energy extraction and CO2 storage by using simulation method. The sensitivity analysis of parameters including injection rate, reservoir permeability, capillary trapping has been simulated and discussed. The research ideas and results of the paper are well shown in the pictures. However, it does not show how the results apply to geothermal extraction and CO2 sequestration. the regulations and writing of the article still need to be improved, which is not quite in line with the title, and further amendments are suggested.

 

Some comments as follows:

1.      The introduction is too long and the summary is not concise enough. It is suggested to further review the relevant research progress and summarize the existing problems in the study of the reservoir heterogeneity.

2.      Figure 2 need list reference?

3.      Table 2, What are the values of the parameters in Table 2 based on, are there any references, or are the reservoirs case located somewhere? Are there any relevant reservoir geological characteristics?

4.      In the method, the simulation scenarios should be listed in detail and the design basis should be explained.

 

Author Response

Please consider the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Unfortunately, the introduction is not well revised.

The introduction part of the article is too long, there are four pages, which is very unreasonable, it needs to be highly generalized and summarized, and it is better to control it in about one page. Otherwise, it looks top-heavy and the structure of the article is not coordinated. This is a research article, not a review article. Therefore, the introduction sector suggests further revision.

Author Response

We appreciate the time and attention you devoted to reviewing our manuscript. The document has been revised in accordance with your suggestions, and the introduction section has been summarized.

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

The article has made great progress after revision and is proposed to be accepted for publication. No anyother comments.