Hydrocarbon Generation and Accumulation in the Eastern Kuqa Depression, Northwestern China: Insights from Basin and Petroleum System Modeling

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript is well-structured and formulated. At a few points throughout the text, I would kindly ask the authors to clarify their formulations, also keeping in mind the rather broad readership of a multi-disciplinary Journal such as Applied Sciences. Please see the attached PDF for more details.

The work presented seems thoroughly conducted and the drawn conclusions seem supported by the modeling results. The authors could try to improve the relevance of their work by more specifically highlighting the novelty of their approach at the end of the introduction. While the manuscript is currently nice to read, it remains a case study of the specific field studied and little can be transferred to other research studies as the used methodology seems well-established. The current manuscript is a purely regional study without further impact.

The authors need to explain in more detail how the used software is operating. Several used sentences in the Results chapter remain unclear for readers unfamiliar with the software.

The figures are mostly well-prepared. For a few slight variations please see the details in the attached pdf. In the final submission please increase the figures' resolution as some of them seem coarse in the draft. Also, the paper structure is non-ideal in the current form w.r.t. figure placement leaving pages half-empty.

The referencing is up-to-date without being overly excessive. I am happy to see that the authors included also non-Chinese authors where adequate. As much of the cited literature is only available in Chinese, I cannot check it - this is however not unusual for such a regional study as presented here.

I believe the manuscript can be accepted after revisions based on these comments and the detailed comments in the attached pdf.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The english is very good. Just check for minor typos.

Author Response

China University of Petroleum (East China)

No. 66 Changjiang West Road, Qingdao,

Shandong 266580, China

Jan. 20, 2024

 

Reviewer,

Interpretation

 

Dear reviewer,

 

Re: manuscript ID: applsci-2793366 and Title: Hydrocarbon generation and accumulation in the eastern Kuqa Depression, NW China: Insight from basin and petroleum system modeling

 

Thank you very much for your comments and suggestion to an early draft of our manuscript, which are quite constructive and helpful. We have studied your comments carefully and have made revision which marked in red underline and yellow highlight in the paper. We have tried our best to revise our manuscript according to the comments. Attached please find the revised version, which we would like to submit for your kind consideration.

 

We would like to express our great appreciation to you for comments on our paper. Looking forward to hearing from you.

 

Kind regards,

A.P. Jianliang Liu

School of Geosciences, China University of Petroleum (East China)

[email protected]

 

 

Some minor comments:

• Maybe rather use genesis as evolution sounds rather short term (<100 years). Line 14, “evolution”.

R: The expression is to emphasize the evolutionary history of the petroleum system, not its genesis, so we have not replaced the word “evolution”.

 

• Unclear wording. Line 48, “reveal the rule of petroleum basins”.

R: We modify the text to “and can directly reveal the laws of petroleum basin evolution”. Please see line 48.

 

• 3D would be even better to account for heterogeneity. Why is this not conducted and why is there no research represented about that? Line 53, “two-dimensional (2D) basin modeling”.

R: Yes, 3D basin modeling can be better to account for the heterogeneity of target layer and its migration simulation. While, it is hard to build a 3D geological model especially in a foreland basin where many thrust faults developed, because of the lack of detailed geological data especially 3D seismic data in this exploration frontier area and the difficult technique for 3D paleo geological model reconstruction. Meanwhile, a 2D basin modeling can also be sufficiently expressed the hydrocarbon generation history and subsequently migration direction and routines and accumulation areas. In addition, there are no 2D or 3D basin modeling studies in this area in previous work. Our study is a first time to carry 2D basin modeling in the study area.

 

• Unclear wording. Line 59, “reduction of the horizontal strata”.

R: We modify the text to “compression in the horizontal direction”. Please see line 59.

 

• Can these be dated? Line 96, “movements”.

R: We marked the specific age of the two tectonic movements. Please see line 95-96.

 

• Can Fig. 1b be supplemented with a topographical background map?

R: We have tried, but after adding the topographical background map, we can not clearly show the structural division of the Tarim Basin, and the topographical background map has no effect on the content of the paper, so we have not modified the Fig. 1b.

 

• There are more colors in the figure than in the legend. Do they fulfill a function (then they need to be explained) or is it just for visualization? Figure 1.

R: The color, not appearing in the legend, is just for visualization of the figure.

 

• Line 124. Add “the”.

R: We add “the” after “through” in line 124.

 

• Non-essential information can be removed. Line 133-134.

R: We remove the text “The 2Dmove software is used to prepare the balanced cross-section”. Please see line 133.

 

• Was a verification for mesh-independence conducted? Line 193-194.

R: Yes, we carefully checked reasonability of the model after built, including the mesh-independence verification. The model would not be run or some obvious mistakes would be occurred if the reasonability of the model was not be well carried out.

 

• Can you justify this selection and the chosen thickness? Line 206-209.

R: In the software, the horizontal direction of the formation thickness is heterogeneous, and the thickness measurement of different layers at different positions can also be realized. Here, the average value is selected for representation of each type of source rock.

 

• Please provide references. Line 214, “Several researchers”.

R: We have added some references after the sentence. Please see line 213-214.

 

• I am not familiar with the specific software but from my understanding the software needs information regarding the stress field during the different times. What has been assigned for the stresses? Page 7.

R: Thanks for your comment. Yes, we have considered the stress in different times. This was done by using a default assignment in the “Geomechanical boundary conditions” in “Boundary Conditions” module in the PetroMod software.

 

• Was in other studies (please provide references) or is it part of this work (then the grammar of the sentence is not correct). Line 219, “would”.

R: We have replaced “would” with “will”. Please see line 218.

 

• At which depth? Line 338, “the maximum ground temperature is 180 °C”.

R: We have rewritten this paragraph (line 336 -338) to make our viewpoints more clear and deleted this sentence you mentioned above.

 

• How can you quantify the amount if you speak about "large amounts"? Line 340, “still generate a large amount of oil and gas”.

R: We have modified this content to make our expression more accurate. Please see line 336-338.

 

• Frequency in % is confusing as it is unknown what 100% represent. Figure 10.

R: Thanks for your comment. We have added the explanation of the mean of 100% in the figure caption. Please see line 367-368 and line 388.

 

• In which way? Was fluid transport modelled? Line 417, “migrated”.

R: The migration path has been described in the paper. Please see line 416-417. In addition, the ‘multi-phase Darcy flow’ method was chosen to simulate fluids migration in this study.

 

• How can a dynamic process (migration) be similar in time? Please clarify. Line 429.

R: We have modified it in the paper. Please see line 428-429.

 

• Typo: o. Line 450, “Oil”.

R: We have modified it. Please see line 450.

 

• Figure size can be reduced. Figure 14.

R: We have adjusted the size of some figures to make them more suitable of the page. Please see figure 6, 9, 10, 11, 12, 14.

 

• Which one exactly? Line 494, “in the reservoir”.

R: We have elucidated all the reservoirs in line 494-495, making our expression more clear.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

 Dear Distinguished AUTHORS,

As a reviewer, I have found some small inconsistencies in your manuscript that need to be removed for the manuscript to be published. 

My congratulations on the article idea and the professionally presented results.

B) Weaknesses of the manuscript:

B 1.)- Figures 4, 7, 8 are composite figures, so they should be noted with (a), (b), etc.

B 2.)- Figure 5 has diagrams on the right side which should be marked (i), (ii), etc.

 

Author Response

China University of Petroleum (East China)

No. 66 Changjiang West Road, Qingdao,

Shandong 266580, China

Jan. 20, 2024

 

Reviewer,

Interpretation

 

Dear reviewer,

 

Re: manuscript ID: applsci-2793366 and Title: Hydrocarbon generation and accumulation in the eastern Kuqa Depression, NW China: Insight from basin and petroleum system modeling

 

Thank you very much for your comments and suggestion to an early draft of our manuscript, which are quite constructive and helpful. We have studied your comments carefully and have made revision which marked in red underline and yellow highlight in the paper. We have tried our best to revise our manuscript according to the comments. Attached please find the revised version, which we would like to submit for your kind consideration.

 

We would like to express our great appreciation to you for comments on our paper. Looking forward to hearing from you.

 

Kind regards,

A.P. Jianliang Liu

School of Geosciences, China University of Petroleum (East China)

[email protected]

 

 

Some minor comments:

Figures 4, 7, 8 are composite figures, so they should be noted with (a), (b), etc.

R: We note (a), (b), etc. on the lower left corner of each image in figures 4, 7, 8, and attach the age corresponding to the image. Please see figures 4, 7, 8.

 

Figure 5 has diagrams on the right side which should be marked (i), (ii), etc.

R: We note (a), (b), etc. on the figure, and modified the link of the figure in the text. Please see figure 5 and line 279-280.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

 The abstract is well structured and conveys information about geological and petroleum system analysis in the Kuqa Depression. It describes the problem and outlines the evolution of the petroleum system, the maturity of source rocks in different zones, the hydrocarbon generation periods, and the results.

Introduction: The authors introduce the Tarim Basin and its significance in China's oil and gas reserves. They give general information about the Tarim Basin and specifically describe the recent discoveries (Kuqa Depression) in addition to the challenges in basin modeling.

Geological Setting: The figures are clear and well done.

Please correct:

Line 46: basic principles of physics, chemistry, and geological processes

line 82: It was developed since the late Permian and experienced.  

Line 100: oil-prone lacustrine mudstone

Line 107: reservoir (without s) or these tight sandstone reservoirs.

Line 103: The source rocks are mainly comprised of mudstones.

Line 112: Source 111 rocks, reservoirs, and seal rocks

The authors describe well the geological development of the area since the late Permian period including the different stages the basin has undergone. The impact of tectonic deformations from the Neogene to the Quaternary period is discussed. Overall, this paragraph offers a comprehensive overview of the Kuqa Depression's geological and geographical characteristics.

Materials and Methods/Discussions

Line 137: which is  the operation process of the balanced cross-section technique.

Line 151: the length of the sedimentary layer

The authors describe the approaches they used, combining various software to analyze and model the structural and sedimentary evolution of a geological section, particularly in areas with complex tectonic histories. 2D basin modeling is described in addition to the challenges in modeling complex structural sections.

Results:

Figure 4:  The name of the figure should be on the same page as the figure.

Overall, the authors provide a comprehensive approach to the geological history of the eastern Kuqa Depression, with a focus on sedimentary processes, tectonic events, thermal and maturity, and hydrocarbon generation history.

 Conclusions

 

The conclusions are well-detailed and well-structured. The authors provide a complete study where they integrate geological, paleotemperatures, source rock properties data, etc. to assess the hydrocarbon potential in the area and this will be useful for guiding future exploration.

·        The impact of thermal anomalies caused by various geological processes that have a significant influence on the heat flow and the maturity evolution of source rocks was well reported.

·        They provide insights into the hydrocarbon generation and thermal evolution in the eastern part of the Kuqa Depression and the Northern slope area. The main hydrocarbon generation period has been identified.

Comments on the Quality of English Language

Minor editing is required.

Author Response

China University of Petroleum (East China)

No. 66 Changjiang West Road, Qingdao,

Shandong 266580, China

Jan. 20, 2024

 

Reviewer,

Interpretation

 

Dear reviewer,

 

Re: manuscript ID: applsci-2793366 and Title: Hydrocarbon generation and accumulation in the eastern Kuqa Depression, NW China: Insight from basin and petroleum system modeling

 

Thank you very much for your comments and suggestion to an early draft of our manuscript, which are quite constructive and helpful. We have studied your comments carefully and have made revision which marked in red underline and yellow highlight in the paper. We have tried our best to revise our manuscript according to the comments. Attached please find the revised version, which we would like to submit for your kind consideration.

 

We would like to express our great appreciation to you for comments on our paper. Looking forward to hearing from you.

 

Kind regards,

A.P. Jianliang Liu

School of Geosciences, China University of Petroleum (East China)

[email protected]

 

 

Some minor comments:

Line 46: basic principles of physics, chemistry, and geological processes

R: We add “,” after “chemistry”. Please see line 46.

 

Line 82: It was developed since the late Permian and experienced.

R: We delete the “,” after “Permian”. Please see line 81-82.

 

Line 100: oil-prone lacustrine mudstone.

R: We replace “mudstones” with “mudstone”. Please see line 100.

 

Line 107: reservoir (without s) or these tight sandstone reservoirs.

R: We replace “this” with “these”. Please see line 107-108.

 

Line 103: The source rocks are mainly comprised of mudstones.

R: We replace “by” with “of”. Please see line 103.

 

Line 112: Source 111 rocks, reservoirs, and seal rocks.

R: We add “,” after “reservoirs”. Please see line 111-112.

 

Line 137: which is the operation process of the balanced cross-section technique.

R: We add “the” after “of”. Please see line 135-136.

 

Line 151: the length of the sedimentary layer.

R: We add “the” after “of”. Please see line 150.

 

Figure 4: The name of the figure should be on the same page as the figure.

R: We have adjusted the layout of the article. Please see page 9.

 

Author Response File: Author Response.pdf