Bifurcation Diagram and Dynamic Response of a Drill String Applied in NGH Drilling

Round 1

Reviewer 1 Report

Dear authors,

I carefully read your interesting manuscript related to the drill string vibration. I agree with you that hydrates tend to become future global energy sources, and this kind of research is very important because natural gas hydrates reservoirs require the development of the new technology for gas extraction underground. Although the topic of your manuscript is very interesting, the quality of the manuscript is very low. I am of the opinion, for the quality of the manuscript, is the equally important theoretical assumptions, literature review of the previous work, quality research design and presentation of result. Unfortunately, in your work some parts of the manuscript are incomplete. For example, the drill string length of about 500 m you selected based on which data? or missing explanation why the incorporation of hydrates into drilling fluid changes its properties and consequently influences drill string vibration? Or at the beginning, you discuss the influence of drilling fluid (flow, density, and dynamic pressure) on drill string vibration and after that, you research the influence of drill string rotation and length; etc…,

Lines 24-25: „low pollution“ – can you explain more in detail?

Line 28: each abbreviation such as NGH should be fully defined at its first appearance in the text of the manuscript;

Line 29: “below the floor“?

Lines 31-32: Drilling fluid properties will change because of the incorporation of the gas into drilling fluid flow or?

Line 39: fracture or failure?

Line 40: Drilling accidents only related to drill string failure or cumulative?

Lines 42-43: Please move the first sentence in this paragraph above figure 1.

Figure 1: Figure title should be more specific.

Lines 45-46: Unfortunately figure 2 presents the main components of the drill string for horizontal drilling without any connection with vibrations;

Line 56: Ghasemloonia et al. regarded… (because there is more than one author);

Line 58: Sanos et al. studied…(because there is more than one author);

Lines 77-79: The sentence is somewhat unclear? Also, is completely unclear, whether are mentioned studies and research consider vibration during drilling through NGH or the regular drilling operations?

Line 144: the lateral amplitude of the drill string vibration decrease?

Lines 142-150: Can you explain the difference between x2, x4 and x6 in figure 3, and X1, X2 and x3 in equations 25, 26 and 27; the Whole paragraph should be revised to make it clearer to the reader.

General: In the manuscript title you have the expression bifurcation and in the text of your manuscript the first time mentioned is on page 6 (figure 3.). I suggest that you add to the introduction section a short explanation of bifurcation theory, as well as the relation between bifurcation theory and drill string vibration.

Figure: I suppose that your data presented in figure 3 calculate by using the early mentioned equation, but there isn’t any information about input data, as well as the unit of measurement for input data and the calculated result presented in figure 3 (a, b and c). Additionally, I suppose that ω on the x-axis represents a change in angular velocity but the missing unit of measurement. Can you explain the relation between ω in figure 3, with an explanation for ω on line 100 (normal velocity) or line 110 (lateral dispatched at any point)?

Lines 175-184: Can you explain why you chose a drill string length of about 500 m for your calculation? Also, missing very important information about drill string rotation, the diameter of the drill string as well as a wellbore, etc.

General: please place figures 8 and 9, after line 197 and after line 201 respectively;

Best regards,

reviewer

Author Response

Dear Editor and Reviewers：

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled " Bifurcation Diagram and Dynamic Response of Drill string Applied in NGH Drilling" (Manuscript Number processes-1735836). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections which we hope to meet with approval. We highlight the changes to our manuscript within the document by using the "track changes" in Latex. The changes are marked by red font. The main corrections in the paper and the responds to the reviewer’s comments are in the file（author-coverletter-19556739.v3.pdf）.

We appreciate for Editors/Reviewers warm work earnestly, and hope that the correction will meet with your approval.

Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf

Reviewer 2 Report

Overall, the manuscript deserves publications with small adjustments, as mentioned on the attached pdf. file.

Also, I would recommend a thoroughly revision of the manuscript by a native English speaking.

Comments for author File: Comments.pdf

Author Response

Dear Editor and Reviewers：

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled " Bifurcation Diagram and Dynamic Response of Drill string Applied in NGH Drilling" (Manuscript Number processes-1735836). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections which we hope to meet with approval. We highlight the changes to our manuscript within the document by using the "track changes" in Latex. The changes are marked by red font.

We appreciate for Editors/Reviewers warm work earnestly, and hope that the correction will meet with your approval.

Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear authors,

I read the revised version of your manuscript, and I am fully satisfied with the improvements you made. You answered all my questions and confusion in detail.

Best regards,

reviewer