The Implications of Seeping Hydrocarbon Gases in the Gunsan Basin, Central Yellow Sea, off the Southwest of Korea

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Summary

Inspired by seeping hydrocarbon gases, the manuscript approaches the prospect of oil and gas exploitation in the Gunsan Basin in the Yellow Sea by analyzing the chirp seismic profiles of the region as well as sediment methane content and carbon isotope composition. In addition, the study discusses the significance of various geological structures and the tidal impact. In conclusion the study finds the conditions in the basin be like other regions in the Yellow Sea with significant hydrocarbon exploitation.

General comments

This is a solid work displaying genuine geological background knowledge as well as careful geochemical analysis. Furthermore, the topic of the study is most suitable for Geosciences journal. Moreover, the sectional structure of the manuscript is in line with what is typical for a scientific article. As for figures and the table, the former are visually clear and the latter is well organized, but both would benefit from additional explanations for those readers who are not familiar with the geological concepts. Finally, the English of the manuscript is very fluent.

Specific comments

Figure 2: What is the significance of the thin black lines? Are seismic data available for all the lines or just for the thick portions? Is there a reason for selecting the portions for Figure 3 or are the just a random selection?

Table 1: Here it would be helpful to have explanations for the notations Mz, TOC and C/N for example as footnotes to the table. Also, the symbol Φ apparently refers to the Krumbein phi scale, but the manuscript fails to provide that information. Likewise, it is not obvious what the abbreviation No. in the first column of the table header stands for.

Figure 3: In Subfigure C, how to interpret the red and blue colors?

Figure 4: Maybe you could also report the correlation coefficients.

Lines 276-278: The clay portion estimate in EEZ21-8G and the silt portion estimate in EEZ21-17G both have one decimal, whereas the sand portion estimate in EEZ21-9G lacks a decimal. Does that mean that the latter estimate is less accurate?

 

Author Response

We would like to thank you for review of our manuscript and constructive suggestions. Given below is our response to the major and other issues noted by the reviewers. The original reviewer’s comments are in black text, our response is in red text.   Reviewer 1 Summary Inspired by seeping hydrocarbon gases, the manuscript approaches the prospect of oil and gas exploitation in the Gunsan Basin in the Yellow Sea by analyzing the chirp seismic profiles of the region as well as sediment methane content and carbon isotope composition. In addition, the study discusses the significance of various geological structures and the tidal impact. In conclusion the study finds the conditions in the basin be like other regions in the Yellow Sea with significant hydrocarbon exploitation. General comments This is a solid work displaying genuine geological background knowledge as well as careful geochemical analysis. Furthermore, the topic of the study is most suitable for Geosciences journal. Moreover, the sectional structure of the manuscript is in line with what is typical for a scientific article. As for figures and the table, the former are visually clear and the latter is well organized, but both would benefit from additional explanations for those readers who are not familiar with the geological concepts. Finally, the English of the manuscript is very fluent. Specific comments (1)   Figure 2: What is the significance of the thin black lines? Are seismic data available for all the lines or just for the thick portions? Is there a reason for selecting the portions for Figure 3 or are the just a random selection? : The thin black lines are the high-resolution seismic lines we acquired (Sparker and Chirp). Figure 3 is one of the examples of seismic profiles in our study area where shallow gas is visible. (2)   Table 1: Here it would be helpful to have explanations for the notations Mz, TOC and C/N for example as footnotes to the table. Also, the symbol Φ apparently refers to the Krumbein phi scale, but the manuscript fails to provide that information. Likewise, it is not obvious what the abbreviation No. in the first column of the table header stands for. : I added notes explaining the abbreviations in the header to the bottom of the table. I also changed the symbol of the phi scale for particle size. (3)   Figure 3: In Subfigure C, how to interpret the red and blue colors? : In KINGDOM geological interpreting software, the user can change the color of the seismic profiles. In Figure 3C, black indicates the peak of the seismic trace, and red means the trough. (4)   Figure 4: Maybe you could also report the correlation coefficients. : The number of plumes and tide exhibit a negative correlation. However, a larger sample size may be required to establish a correlation with plume height. (5)   Lines 276-278: The clay portion estimate in EEZ21-8G and the silt portion estimate in EEZ21-17G both have one decimal, whereas the sand portion estimate in EEZ21-9G lacks a decimal. Does that mean that the latter estimate is less accurate? : It was expressed by rounding, and it was a simple mistake. I corrected it.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors and Editor,

 

I have reviewed the work by Cho et al regarding HC gas seepages in central Yellow sea. I find the manuscript well written and structured with well presented methodology and result. Furthermore, I think it covers one of the important aspects for future research of hydrocarbons in Gunsan Basin. There is a need for minor changes, mostly regarding quality of some figures. I have put all of my comments in a pdf.

Comments for author File: Comments.pdf

Author Response

We would like to thank you for review of our manuscript and constructive suggestions. Given below is our response to the major and other issues noted by the reviewers.

The original reviewer’s comments are in black text, our response is in red text.

Reviewer 2

have reviewed the work by Cho et al regarding HC gas seepages in central Yellow sea. I find the manuscript well written and structured with well presented methodology and result. Furthermore, I think it covers one of the important aspects for future research of hydrocarbons in Gunsan Basin. There is a need for minor changes, mostly regarding quality of some figures. I have put all of my comments in a pdf.
：We included my response in the attachment file.

 

Response to Comments on the Quality of English Language

Other typos and English corrections have been corrected as per your comments.

Author Response File: Author Response.pdf