Fluid–Solid Coupling Model and Simulation of Gas-Bearing Coal for Energy Security and Sustainability
Round 1
Reviewer 1 Report
Line 162, is (Mpa-1), should be: (MPa-1)
Line 233 is (Pn = 0.10325 Mpa) should be: (Pn = 0.101325 MPa)
Please explain because once the density is in kg / m3 (line 230) and another Mg / m3 (Line 163)
Line 342, no citation: “According to the investigation of Henan Polytechnic University”
Line 443, no citation: “The effective extraction radius of the bedding borehole of Xin’an Mine is mainly determined with the SF6 gas tracer method.”
Author Response
Please see the attachment.
We appreciate your help and your patience.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Authors put some effort to improve their paper.
Unfortunately, I have to say that the paper is not ready for publishing and that the authors did not revise all as suggested. As the most suggestions were related to grammatical issues in the text, and I proposed to stop resending this paper to reviewers, I'll only count the critical issues in this, 4th version.
Again I will repeat that reviewers should not spend their time on proofreading (which is paid service), and that you did not carefully check for language and grammar issues in the paper:
In the introduction, after quick review 4 grammatical mistakes were found ("bull cleats", "principal place", "the gap width", "conditions of homogeneous and heterogeneous coal seams")
Figures 1, 2, 3 (worse quality than in the second and first round of review) might be copy/pasted without credit to the authors of the original publication (picture descriptions are in very low resolution).
Citing the authors with name initials is not a common practice in scientific papers.
The term "ground stress" seems to be inappropriate.
Explanation of porosity is redundant and text in lines 128-129 seems to be too trivial. - this is not changed from the previous review round.
The purpose of the equation (1) was obviously to describe the change of porosity, not the porosity itself.
Trivial equations like equation (21) are not removed, despite the recommendation of reviewers.
"Z is the gas 232 compressibility factor (approximately 1 in the case of a small temperature difference)," - the statement within the brackets is not correct.
"Mpa" should be "MPa"
Equation 36 is not correct for gas flow (dimensional analysis of units for each parameter also does not make any sense). There are two possibilities - to use quadratic pressure difference or average flowing pressure. However, the authors state that the Klinkenberg effect occurs due to non-Darcy flow, but in the list of assumptions they assumed Darcy's flow. This is inconsistent and it is not clear what authors tried to state with that assumption combined with the respective equation.
"plates of the coal seam" sounds strange.
This also was not improved after the last (3rd) review round:
In the introduction is stated that: "The drilling design is optimized by 92 numerical simulation, which makes the drilling arrangement of gas extraction more scientific,
93 reasonable, safe and effective.". This is not confirmed in the conclusions.
Author Response
Please see the attachment.
We appreciate your help and your patience.
Author Response File: Author Response.pdf
Reviewer 3 Report
It is a good numerical paper, difficult to follow because there are missing references to the equations in the text.
It must correct:
Lines 49 to 69: all references must include the date or write all the paragraphs by deleting the author and keeping the appointment number.
Review in the text all the equations are missing 1, 2, 12, 13, 14, 24, 25…….
Author Response
Please see the attachment.
We appreciate your help and your patience.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
After 5 rounds of review and language editing, I think the paper is ready for publication.
One small issue is related to using k_g as "absolute permeability" (eq. 28), which I would not agree that is correct. Absolute permeability should be Klinkenberg corrected permeability as for the same sample it is the convergence permeability for all gases when extrapolated from measurements at different pressures to infinite high pressure.
In this form, absolute permeability would be pressure-dependent (i.e. relative), which is not true.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper has improved a lot. It's OK nowAuthor Response
Comment: The paper has improved a lot. It's OK now
Response: Thank you again for your recognition of this paper. I am very honored. At the same time, many thanks for your careful guidance many times.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Dear authors,
I reviewed this paper for the second time, and found unacceptable your English wording, style and grammar. Reviewers should not spend their time on proofreading (which is paid service), and you did not check for language and grammar issues in the paper, after our first review.
You provided some brief comments about methodology and theoretical assumptions, but still I think there is a fundamentally wrong assumption about coal rock structure, because such structures are (this can be accompanied by published scientific literature, such as in this paper cited: Zhu, W.C., Wei, C.H., Liu, J. et al. Rock Mech Rock Eng (2013) 46: 1353) alway dual porosity and dual permeability systems, with micro or macro fractures always present.
I kindly please to find my second proofread and commented document in the attachment.
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
The paper under review No 658192.
The research study is original. The authors show design, models, experiments and conslusions. The experimental part of the article contains crucial information regarding the research model, method and experimental technique. It also includes the information on the available equipment and presents the research outcomes and their detailed description. A structure of the paper is in accordance with principles of good scientific reports. The paper is written in good English.
In opinion of the reviewer the article can be accepted for publication in Processes.
Author Response
Response to Reviewer 1 Comments
The research study is original. The authors show design, models, experiments and conslusions. The experimental part of the article contains crucial information regarding the research model, method and experimental technique. It also includes the information on the available equipment and presents the research outcomes and their detailed description. A structure of the paper is in accordance with principles of good scientific reports. The paper is written in good English.
In opinion of the reviewer the article can be accepted for publication in Processes.
Response: Thank you again for your recognition of this paper. I am very honored. I will continue to work hard to live up to your expectations.
Reviewer 3 Report
l. 345, how was the initial gas pressure measured in the coal seam is 0.9 MPa?
l. 370, table 1, how measured / determined Initial porosity of coal? how measured / determined Initial permeability of coal?
In table 1, is the virgin methane content missing in coal?
l. 416-418, on what basis (no reference to literature) drainage radius measured?.
You cannot agree with the conclusions in l. 500 - 505, thesis has not been proven, the authors' supposition. Delete or correct.
I. 515, what graph shows the performance of methane from the well? (l. 515: With the continuous change of simulation time, the effect of gas extraction is clearly shown in the graph), for change or improvement!
In addition, the terms used in the article raise doubts, they do not properly convey the meaning:
Verses 32, 39, 42 etc: seepage process ?, seepage fields? , seepage characteristic ? ect.
Verse 104: burial? depth of coal seam
Verse 344, 370 (table 1): negative pressure?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Authors put some effort to improve their paper.
Unfortunately, I have to say that the paper is not ready for publishing and that the authors did not revise all as suggested. As the most suggestions were related to grammatical issues in the text, I would really stop resending this paper to the reviewers.
I will repeat in this review: reviewers should not spend their time on proofreading (which is paid service), and you did not check for language and grammar issues in the paper, after our first review.
Figures 1, 2, 3 (worse quality than in the previous review) might be copy/pasted without credit to the authors of the original publication (picture descriptions are in very low resolution)
line 37: "Coal is a complex porous medium" - this sentence is unnecessary.
Line 79-81. The sentence is unnecessary and in a way not correct as Klinkenberg effect is not related to permeability, but to the type of flow, which is mostly affected by the pressure.
Explanation of porosity is redundant and text in lines 133-135 seems to be too trivial.
It is not clear what does mean "coal appearance", the sentences in lines 31-33, 58-60, 160, 351-353, 422-425 (and many more) are grammatically incorrect.
Line 214 - different gases have very different sorption coefficients.
The authors did not remove trivial equations like eqn 22.
the text is still full of errors in terms of omitted spaces (mostly between words and parentheses, eg. lines 242, 243, 345, 392, 394, 459)
The wrong term is used for Z-factor, even though I marked that in the text in the last (second) review.
Line 286, along with equation 31 is still not clear (3Ks in the denominator)
Line 345, an asterisk is not the multiplication symbol.
capital letter K is not a valid mark for "kilo" (eg. line 349).
"Virgin gas content" in table one was not mentioned in the text and it is not clear where this parameter is used.
The sentence in 426-427 is still incorrect.
The sentence in 469-471 is still incorrect, despite it is changed.
In the introduction is stated that: "The drilling design is optimized by 92 numerical simulation, which makes the drilling arrangement of gas extraction more scientific,
93 reasonable, safe and effective.". This is not confirmed in the conclusions.
