Transient Pressure Behavior of Volume Fracturing Horizontal Wells in Fractured Stress-Sensitive Tight Oil Reservoirs

Round 1

Reviewer 1 Report

The authors presented a good study on Research on Seepage Modeling of Volume Fracturing Horizontal Wells in Fractured Stress-Sensitive Tight Oil Reservoirs. The paper is well written and sounds technically good.

Authors are requested to revise the manuscript for typos and grammatical mistakes. Afterward, the paper will be ready for acceptance.

Author Response

Thank you for your approval. We have checked the manuscript carefully and revised the manuscript for typos and grammatical mistakes.

Reviewer 2 Report

See attached Word document.

Comments for author File: Comments.pdf

Author Response

1-  Question: 69-75 This is instruction to authors. Eliminate this paragraph.

Response: Thank you for your very careful review. We have deleted this paragraph.

 

2-  Question: Figure 2. Convert Chinese terms to English.

Response: Thank you for your comment. We have revised this error.

 

3-  Question: Define the two cases being described in Figure 2.

Response: Thank you for your comment. We have revised as follow: “The green line in Figure 2 is the test curve when stress sensitivity, wellbore storage, and well skin are not considered, and the red line is the test curve when these factors are considered.”

 

4-  Question: After the above listing of seven seepage steps, define “scramble flow.”

Response: Thank you for your comment. We are sorry that we make it wrong. This flow regimes should be called “Interporosity flow” rather than “scramble flow”. In this seepage stages, fluid from the matrix system begins to flow into the natural fracture system. We have revised it in the manuscript.

 

5-  Question: Use exponents 10 -6 , 10 -4 , 10 -2 ,…

Response: Thank you for your careful comment. We have revised as follows “The oil reservoir base parameters are shown in Table 1, and when the interporosity flow coefficient is 10^-6, 10^-4, and 10^-2, respectively”.

 

6-  Question: use V. rather than Volume.

Response: Thank you for your careful comment. We have revised the reference carefully.

 

7-  Question: Numerical inversion of Laplace transforms.

Response: Thank you for your careful comment. We have revised the reference carefully.

As for the other problems you mentioned, we have modified them as far as possible. Thank you very much for your review again.

Author Response File: Author Response.pdf

Reviewer 3 Report

The article “Research on Seepage Modeling of Volume Fracturing Horizontal Wells in Fractured Stress-Sensitive Tight Oil Reservoirs” is simple. Figures 2-7 can be merged into a single figure in the form of a,b,c,d,e,f. The authors can add more analysis and discussion sections to improve the overall quality of the manuscript.

1. The authors should address all the comments in the attached pdf file.
2. I would suggest the authors alter the manuscript in the conventional form. The methods and materials section and results and discussion section should be added so that the readers can understand the gist of the study. Sensitivity analysis is results, add it to the results section.
3. There are some claims in the study without proper latest references. Add the suggested references.
4. Authors can remove the word "research on" within the title and modify it to an attractive one.
5. Modify the abstract and add some results of performed sensitivity analysis.
6. Line 31: it is suggested to write the sentence at the end of the sentence. Make changes throughout
7. Lines 69-75: Remove these lines
8. Figure 1: Remove Chinese words and edit them into English words
9. Figures 2-7: Right the whole word on the x-axis and y-axis.
10. Add a discussion section to explain your results in the light of the literature
11. Add the sections related to the abbreviations at the end of the conclusions to the nomenclature section.
12. Conclusions should be concise and made the changes accordingly after revising the manuscript.

Comments for author File: Comments.pdf

Author Response

1-  Question: The authors should address all the comments in the attached pdf file.

Response: Thank you for your very careful review. We read your comments carefully, wrote them down and responded to each one as follow.

 

2-  Question: I would suggest the authors alter the manuscript in the conventional form. The methods and materials section and results and discussion section should be added so that the readers can understand the gist of the study. Sensitivity analysis is results, add it to the results section.

Response: Thank you for your comment. We have revised as follow: “2. Mathematical methods, 3. Results, 3.1 Seepage staging of volume fracturing horizontal well in tight oil reservoir, 3.2 Sensitivity analysis... ”. The modification has been marked in red.

 

3-  Question: There are some claims in the study without proper latest references. Add the suggested references.

Response: We didn't find the suggested references, we cited several other new papers.

 

4-  Question: Authors can remove the word "research on" within the title and modify it to an attractive one.

Response: Thank you for your comment. We have transformed the title “Research on Seepage Modeling of Volume Fracturing Horizontal Wells in Fractured Stress-Sensitive Tight Oil Reservoirs” to “Transient Pressure Behavior Research on Seepage Modeling of Volume Fracturing Horizontal Wells in Fractured Stress-Sensitive Tight Oil Reservoirs”.

 

5-  Question: Modify the abstract and add some results of performed sensitivity analysis.

Response: Thank you for your comment. We have revised it as follow: “We apply the model to delineate the seepage stages of volume fracturing horizontal wells , it can be divided into seven seepage stagesⅠ wellbore storage flow, Ⅱ surface flow stage, Ⅲ transition flow, Ⅳ natural fracture system proposed radial flow, Ⅴ interporosity flow, Ⅵ system proposed radial flow, and Ⅶ stress-sensitive flow stage. Wellbore storage coefficient mainly affects the flow in the wellbore storage stage. The larger the wellbore storage coefficient is, the longer the duration of wellbore storage flow will be. The higher the skin coefficient is, the greater the pressure drop is. The storage capacity ratio has a greater influence on the flow before the occurrence of channeling flow, and the "groove" depth on the derivative curve of dimensionless pressure drop becomes shallower with the increase of storage capacity ratio. The higher the channeling coefficient is, the earlier the channeling occurs from the matrix system to the natural fracture system, and the more leftwing the "groove" position is”. The modification has been marked in red.

 

6-  Question: Line 31: it is suggested to write the sentence at the end of the sentence. Make changes throughout.

Response: We are so sorry that we didn't get the meaning of this comment.

7-  Question: Lines 69-75: Remove these lines.

Response: Thank you for your comment. This paragraph is not in our article, but it is in the PDF file automatically generated by the submission system, which may be a problem of the system.

8-  Question: Figure 1: Remove Chinese words and edit them into English words.

Response: Thank you for your carefully review. We have removed Chinese words and edit them into English words as follow:

 

9-  Question: Figures 2-7: Right the whole word on the x-axis and y-axis.

Response: Thank you for your carefully review. We have given the full axes names on the x-axis and y-axis.

10-  Question: Add a discussion section to explain your results in the light of the literature.

Response: Thank you for your comment. We have revised it as follow:

“4. Discussion

The model can be divided into seven stages: linear flow in fracture, bilinear flow between fracture and formation, linear flow in formation, transition flow, quasi-radial flow in natural fracture system, interporosity flow and stress-sensitive flow. In the linear flow stage, most of the fluid comes from inside the fracture. The slope of the well test curve at this stage is 0.5. Bilinear flow between fracture and formation, in this stage the fluid is mainly from the fracture and near the fracture. The slope of the well test curve is 0.25, which is consistent with the results in the literature of Cinco-Ley et al in 1978. Formation linear flow, fluid is mainly from the formation. The slope of the well test curve is 0.5, which is consistent with Gringarten and Ramey, 1974a; Gringarten et al., 1974b; Horne and Temeng, 1995; Chu et al., 2019. The transition flow is between the linear flow of the formation and the quasi-radial flow of the natural fracture system. Natural fracture system quasi-radial flow, at this stage the slope of well test curve is 0. The interporosity phase, in which fluid from the matrix system begins to flow toward the natural fracture system, well test curve appears as a "trough", consistent with results reported by Chen Zhiming et al., 2015. Stress sensitivity flow, in this stage stress sensitivity has obvious influence on reservoir pressure drop, and the well test curve is obviously upwarped.”

 

11-  Question: Add the sections related to the abbreviations at the end of the conclusions to the nomenclature section.

Response: Thank you for your comment. We have revised it and the modification has been marked in red.

 

12-  Question: Conclusions should be concise and made the changes accordingly after revising the manuscript.

Response: Thank you for your comment. We have revised it and the modification has been marked in red.

 

13-  Question: The article “Research on Seepage Modeling of Volume Fracturing Horizontal Wells in Fractured Stress-Sensitive Tight Oil Reservoirs” is simple. Figures 2-7 can be merged into a single figure in the form of a,b,c,d,e,f. The authors can add more analysis and discussion sections to improve the overall quality of the manuscript.

Response: Thank you for your insightful comment. In this paper, we only focus on the establishment, solution of the seepage model and the sensitivity analysis of the model. We want to write another article to analyze more discussions about the model.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

1. The authors HAVE NOT addressed all the comments in the previously attached pdf file.
2. There are some claims in the study without proper latest references. Add the suggested references. THE AUTHORS HAVE NOT ADDED NOT EVEN A SINGLE REFERENCE FROM THE SUGGESTED LITERATURE. Still, there are many claims without proper proof and the latest relevant references. There are only 7 sentences with references in the introduction section, which is quite less.
3. For example, at the end of the first sentence of the introduction section, I suggested some references to prove that statement from the literature. But authors have ignored that. To claim the “ATTENTION OF WORLDWIDE COMPANIES”, there should be as many references from different international studies other than Chinese literature.
4. The authors have not removed extra space from table 1.
5. Line 31: it is suggested to write the REFERENCES at the end of the sentence. Make changes throughout
6. Lines 69-75: Remove these lines. AUTHORS should take all the comments otherwise this study is already very weak and cannot be published.
7. Section 2: Materials and method section is the lengthiest section of the study, and it looks like it is taken from the literature. If it is, then shift it to the appendix. Focus on the novelty.
8. The discussion of the study is quite weak. More details should be added to make this paper presentable.
9. The conclusion section is lengthier than the discussion section. Authors should take help from a professional member to improve the gist of the manuscript.
10. Figures 2-7: The whole word should be written on the outer side of the x-axis and y-axis.
11. The way authors have presented the citation style within the text, they have not followed the MDPI reference style. It is not acceptable in its current form.
12. Authors have answered that “. In this paper, we only focus on the establishment, solution of the seepage model and the sensitivity analysis of the model. We want to write another article to analyze more discussions about the model.” THE AUTHORS SHOULD ADD MORE RESULTS TO MAKE THIS STUDY A RELIABLE ONE, OTHERWISE, IT IS NOT ACCEPTABLE.
13. I already stated that the whole study can be compiled into 2 figures. Figure 1, whereas figures 2-7 can be changed to Figure 2. More results should be added.
14. Authors have already published a similar study which is as follows; clarify the difference;

Zongxiao, R., Xiaodong, W., Guoqing, H., Lingyan, L., Xiaojun, W., Guanghui, Z., ... & Xianwei, Z. (2017). Transient pressure behavior of multi-stage fractured horizontal wells in stress-sensitive tight oil reservoirs. Journal of Petroleum Science and Engineering, 157, 1197-1208.

15. Authors should prove their study as an innovative one; Many studies have already been discussed same as this study;

Wu, Z., Cui, C., Lv, G., Bing, S., & Cao, G. (2019). A multi-linear transient pressure model for multistage fractured horizontal well in tight oil reservoirs with considering threshold pressure gradient and stress sensitivity. Journal of Petroleum Science and Engineering, 172, 839-854.

Li, Z., Wu, X., Han, G., Ma, G., Zhang, L., Wang, B., & Shi, S. (2019). Transient pressure analysis of volume-fractured horizontal wells considering complex fracture networks and stress sensitivity in tight reservoirs. ACS omega, 4(11), 14466-14477.

Wang, H., Ran, Q., & Liao, X. (2017). Pressure transient responses study on the hydraulic volume fracturing vertical well in stress-sensitive tight hydrocarbon reservoirs. International Journal of Hydrogen Energy, 42(29), 18343-18349.

 

 

Comments for author File: Comments.pdf

Author Response

Thank you for your email and your comments concerning our manuscript entitled “Research on Seepage Modeling of Volume Fracturing Horizontal Wells in Fractured Stress-Sensitive Tight Oil Reservoirs”. These comments are all valuable and very helpful for revising and improving our manuscript. We tried our best to improve the manuscript and revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewers’ comments are shown in the attachment.

Author Response File: Author Response.pdf