Predicting Reservoir Petrophysical Geobodies from Seismic Data Using Enhanced Extended Elastic Impedance Inversion
Xiangmin Zhang
Round 1
Reviewer 1 Report
Very nice paper and the practical application of the enhancement of EEI approach is very much needed in the exploration and production (E&P) workflows.
Author Response
Dear Reviewer,
Thank you so much for your appreciation, valuable comment and suggestion. It’s very motivating.
Authors would like to improve the article to meet MDPI standard and format, in particular.
Once again thanks so much.
Best Regards,
Eko Widi Purnomo
Reviewer 2 Report
Dear Authors,
Thank you for your interesting paper. Although you presented the necessary theoretical background to each of the applied procedures, the methods are not properly marshalled out. Each of the steps in the method section needs a subheading. You need to explain why each of them is necessary, how, and where it was applied in the project, and then show corresponding results (figures/s).
Furthermore, the entire manuscript, starting with the abstract, needs a complete rewrite. Although you have very strong technical points, there are too many grammatical errors that render your paper unacceptable for publication in its present form. To enable you correct the paper, I attached herewith an edited copy (PDF file) of your manuscript, pointing out some of these errors for your attention. Note that these are just some of the many errors. It is hard to follow your thoughts in most cases. Therefore, I strongly recommend that you give your manuscript to someone else who is proficient in the English language to correct the paper before you resubmit it.
Another point I wish to draw your attention is your figure 5. It is not clear to me how you obtained the best prediction angle for porosity, volume of shale, and water saturation (refer to my comments in the attached pdf file). In addition, it seems to me that your figure 6 does not show what you were referring to in the text; rather, it shows the design of the algorithm. Therefore, you need to cite the correct figure here (see page 13, first paragraph). I also suggest you enlarge figure 10 for better visualization. One last point. I suggest you cut down on the theory, focus more on the results, show only necessary equations and present Discussion section.
Regards,
Osareni Ogiesoba
Comments for author File: 
Comments.pdf
Author Response
Dear Osareni Ogiesoba,
First of all, thank you so much for your appreciation, valuable comment and suggestion, and also helpful correction.. It’s very motivating and provide us deeper insight about the article we were submitted. .
Authors realize so many mistakes in the article and I agree to improve the article as your suggestion and correction.
- Authorsagree to improve the theory and methodology by applying subheading and explain the necessary of every step and how it was applied.
- Authors also agree to rewrite most of entire manuscript according to your correction and suggestions.
- Authors will try to re-explain how to obtain the best prediction angle for porosity, volume of shale, and water saturation.
- Authors realized that I made mistake in citing the figure 6. I will make correction accordingly.
- Authors will try to enlarge figure 10 for better visualization.
- Authors agree to cut down the thery and add Discussion section to the manuscript
Once again thanks so much.
Best Regards,
Eko Widi Purnomo
Reviewer 3 Report
The entire manuscript may be edited to reduce its overall length and improve its technical content. The exercise will definitely improve the impact of the research work.
Author Response
Dear Reviewer
Thank you so much for your appreciation and valuable comment and suggestions.
Authors agree to reduce the overall length of the manuscript and try to improve the technical content.
Once again thanks so much.
Best Regards,
Eko Widi Purnomo
Reviewer 4 Report
I would like to suggest the authors to shorten the manuscipt in the revision, especially the abstract and conclusion parts. The Appendix are unnecessary - they can be easily found in the original papers. Please check the formats of equations and text thoroughly.
Author Response
Dear Reviewer
Thank you so much for your appreciation and valuable suggestions.
Authors agree to shorten the manuscript, check the equation format and text.
Once again thanks so much.
Best Regards,
Eko Widi Purnomo
Reviewer 5 Report
1. The abstract does a good job of clearly stating the research question and approach taken in the paper, but it could benefit from more specific details about the results and conclusions reached.
2. The introduction part could be benefited by including more possible applications of the EEI inversion and framework in unconventional shale reservoirs the article below is suggested to be consulted. Investigations of CO2 storage capacity and flow behavior in shale formation. Journal of Petroleum Science and Engineering 2022
3. The methodology section could be more detailed, specifically regarding the implementation of the Extended Elastic Impedance (EEI) inversion and the Bayesian-Markov Chain Monte Carlo framework.
4. The paper could benefit from more discussion on the limitations and potential future directions of the research.
5. The figures and tables used in the paper are informative and well-labeled, but they could be more clearly explained in the text.
6. The authors should consider discussing the implications of their findings in the context of other similar studies in the field.
7. The conclusion could be more explicit and detailed, and it could include implications of the study and recommendations for future research.
8. The paper should be proofread to correct any grammatical or spelling errors.
Based on the comments, minor revision is suggested at this stage final decision is up to the editor.
Author Response
Dear Reviewer,
Dear Reviewer
First of all, thank you so much for your appreciation and valuable comment and suggestions.
- Thank you for appreciation. Authors agree and try to improve the abstract accordingly.
- Authors agree to include the possibility of EEI inversion application for unconventional reservoirs into the article introduction.
- Authors agree, and will try to improve the methodology section by detailing the implementation of the Extended Elastic Impedance (EEI) inversion and the Bayesian-Markov Chain Monte Carlo framework.
- Authors agree, and will add discussion section that includes the discussion about the limitations and potential future directions of the research.
- Thanks for your appreciation. Authors agree, and will try to explain more clearly the the figures in the text.
- Authors agree, and will try to cite and discuss the previous studies in the field.
- Authors agree, and try to improve the conclusion to be more explicit and detail, include the implications of the study and recommendations for future research.
- Authors agree and try to proofread the article to correct it’s grammatical or spelling errors.
Once again thanks so much.
Best Regards,
Eko Widi Purnomo
Reviewer 6 Report
The study by Eko Widi Purnomo et al. is ordinary but has many applications. The study deserve publication if revise it properly and adequately. Since there are many flaws which makes this study poor. I am highlighting those aspects. Kindly improve it so that it can accessed again whether further improvements are needed or not. Mention the continuous line numbering for the next submission.
My suggestions and recommendations are as follows;
1. Abstract contains 360+ words which is not standard and confusing. Abstract needs to be modified. A concise abstract is needed incorporating problem statement, advanced method and brief results. Remove extra results discussion and some initial lines which are useless.
2. English is poor and need extensive modifications. Authors have wrongly written the uppercase and lowercase letters at many instances. There are many issues with the grammar and structure of the English language.
3. Authors have not followed the MDPI style formatting for the sections, equations, and references.
4. The references are not correctly cited. There is no need to write e.g. with the references.
5. The research gap and research contribution is not clear. The last paragraph of the introduction is good and acknowledgeable. However, before that, the literature presented is not consistent. For the literature review, other methods of inversion should also be discussed briefly so that the pro and cons of EEI can better be highlighted in terms of advantages over other inversion techniques. For those, I am highlighting some studies that should be discussed are as follows;
a) Li, L., Zhang, J. J., Pan, X. P., & Zhang, G. Z. (2020). Azimuthal elastic impedance-based Fourier coefficient variation with angle inversion for fracture weakness. Petroleum Science, 17, 86-104.
b) Ashraf, U., Zhang, H., Anees, A., Ali, M., Zhang, X., Shakeel Abbasi, S., & Nasir Mangi, H. (2020b). Controls on reservoir heterogeneity of a shallow-marine reservoir in Sawan gas field, SE Pakistan: Implications for reservoir quality prediction using acoustic impedance inversion. Water, 12(11), 2972.
c) Adesanya, O. Y., Adeoti, L., Oyedele, K. F., Afinotan, I. P., Oyeniran, T., & Alli, S. (2021). Hydrocarbon reservoir delineation using simultaneous and elastic impedance inversions in a Niger Delta field. Journal of Petroleum Exploration and Production Technology, 11(7), 2891-2904.
d) Anees, A., Zhang, H., Ashraf, U., Wang, R., Thanh, H. V., Radwan, A. E., ... & Tan, S. (2022). Sand-ratio distribution in an unconventional tight sandstone reservoir of Hangjinqi area, Ordos Basin: Acoustic Impedance Inversion-Based Reservoir Quality Prediction. Frontiers in Earth Science, 1791.
e) Sharifi, J., Hafezi Moghaddas, N., Lashkaripour, G. R., Javaherian, A., & Mirzakhanian, M. (2019). Application of extended elastic impedance in seismic geomechanics. Geophysics, 84(3), R429-R446.
6. Authors have ignored geology section. A proper adequate geological section incorporating regional stratigraphy and tectonics should also be discussed along with petroleum play.
7. Theory and Method section (should be written as Data and Methods) currently goes upto 8 pages. 8 pages of methods section for a research paper is not standard and it reduced the impact of the study. 1-2 pages of theories and methods are adequate providing the methods applied are novel enough. Since EEI is not new and authors are working on the application of elastic impedance inversion from last 2 decades, therefore, remove extra explanations which have no worth.
8. The equations written in the Theory and Method section contain mistakes. Follow the required pattern of MDPI. Also, take care of italics, lower and upper case, super and subscripts and check whether is it compulsory to include all the literature in your papers.
9. Data used in the study should also be explained. Wells used and the grid incorporated should also be incorporated in the study.
10. Figure 1 flowchart is confusing since some loops are not understandable. Abbreviations used needs to be written at the end of the flowchart. The output should also be clearly written that what sort of petrophysical volume can be generated. Use same font color, size, and shape. Also revise the caption since there is no need to write the whole term after the abbreviation.
11. Sections should be clear. Results section, and discussion section should be clearly mentioned.
12. Figure 3. The overlay log should also be written on the seismic sections. Also, the filters applied, if any, should be mentioned in the caption.
13. Figure 4. Field location map is not understandable and need to be zoomed with improved resolution. DEPTHS? Depths are not written. The depth of the reservoir in every well should be written clearly.
14. Authors have written “seismic-to-well ties are reasonably good and allows for identification of the key seismic events”. KINDLY SHOW THE SEISMIC-TO-WELL TIE.
15. Below Figure 6, authors have explained the methods and equations are written. It is hard to understand the results. The methods and results should be presented in separate sections.
16. Figure 11. Improve the resolution.
17. Figure 10. highlight the conventional and possible unconventional reservoirs on the regional inverted porosity section.
18. Figure 12. R2 should be written as R2. 2 should be written in superscript.
19. Figures 12 and 15, the R values are average and needs to be excellent for good results. Justify the results. A clarification and careful explanation is needed.
20. Figure 17: Authors have concluded the research on the geobody interpretation. Therefore, I would suggest the authors to revise the title, workflow, and study according to the geobody interpretation. Authors should go through some recent studies to have a better view of the geobody interpretation. Also, compare and highlight the comparative analysis of the study on a regional scale (national or international).
a) Ashraf, U., Zhang, H., Anees, A., Mangi, H. N., Ali, M., Zhang, X., ... & Tan, S. (2021). A core logging, machine learning and geostatistical modeling interactive approach for subsurface imaging of lenticular geobodies in a clastic depositional system, SE Pakistan. Natural Resources Research, 30, 2807-2830.
b) Olaniyi, A., Miguel, M. G. I., Anindya, D., & Kefe, A. (2019, August). Geobody Interpretation and Its Application for Field Development. In SPE Nigeria Annual International Conference and Exhibition. OnePetro.
21. Figures 16 and 17, more explanations are needed since these pictures are the pure results of the study.
22. Limitations of the proposed workflow should be discussed.
23. A nomenclature section should be added at the end.
24. Conclusions should be revised. Conclusion section is extremely poor. Bullet concise points are recommended.
25. Revise the reference section. Improve the literature and follow the MDPI style pattern.
Author Response
Dear Reviewer,
First of all, thank you very much for invaluable critical comment and recommendations. It is very insightful.
- Authors agree to modify the abstract by incorporating problem statement, advanced method and brief results, and remove extra results discussion and useless initial lines.
- Authors agree to improve the English of the manuscript.
- Authors will revise the manuscript to follow the MDPI style formatting for the sections, equations, and references.
- Authors will correct the references citation by deleting the ‘e.g.’
- Authors I will try to modify the introduction section by making clear the research gap and research contribution and discuss other methods of inversion so that highlighted the pro and cons of EEI and the advantages of EEI over other inversion techniques.
- Authors will add additional explanation and discussion about the regional stratigraphy and tectonics of the study field to the manuscript.
- Authors agree and will replace the section header Theory and Method to be Data and Methods and shortened the section.
- Authors will correct any equations writing to follow the required pattern of MDPI.
- Authors will explain the data used in the study.
- Authors will modify the flowchart as suggested, to make it clear and understandable.
- Authors will modify the manuscript Sections to make it clear.
- Authors will try to overlay log on the seismic sections and mention the applied filters in the caption.
- Authors will try to improve the field location map and add the DEPTH for every well.
- Authors try to add the seismic-to well tie to the manuscript.
- Authors realized, there was citation mistake for Figure 6, and will make correction.
- Authors will try to improve the Figure 11 resolution.
- Authors will try to highlight the conventional and possible unconventional reservoirs on the regional inverted porosity section in Figure 10.
- Authors will replace R2 in Figure 12 with R2.
- Author will clarify and explain the R values in Figures 12 and 15 for result justification.
- Author will try to revise the title, workflow, and study according to the geobody interpretation including the regional comparative study.
- Author will try to reexplain Figures 16 and 17.
- Authors will add discussion about the limitations of the proposed workflow.
- Authors will try to add nomenclature section at the end of manuscript.
- Authors will revise the conclusion as suggested.
- Authors will revise and improve the reference section to follow the MDPI style pattern.
Once again, thank you so much.
Best Regards,
Eko Widi Purnomo
Round 2
Reviewer 6 Report
The authors have ignored my comments and awkwardly and unprofessionally gave responses to my comments. The responses are not standard with poor English. Authors have replied a single line comment for each of my 25 comments by saying "WILL" everytime. Perhaps authors dont have the experience of replying to the responses.
In addition, authors have highlighted almost half of the paper by yellow color instead of changing the text and figures. I am not able to figure out where authors have made changes. Introduction and English is still poor and significant changes were needed to ensure publication however no changes have been made.
Therefore, i would suggest the authors to show a serious behavior and act responsibly towards my comments. My comments are same from the last review, which were as follows;
The study by Eko Widi Purnomo et al. is ordinary but has many applications. The study deserve publication if revise it properly and adequately. Since there are many flaws which makes this study poor. I am highlighting those aspects. Kindly improve it so that it can accessed again whether further improvements are needed or not. Mention the continuous line numbering for the next submission.
My suggestions and recommendations are as follows;
1. Abstract contains 360+ words which is not standard and confusing. Abstract needs to be modified. A concise abstract is needed incorporating problem statement, advanced method and brief results. Remove extra results discussion and some initial lines which are useless.
2. English is poor and need extensive modifications. Authors have wrongly written the uppercase and lowercase letters at many instances. There are many issues with the grammar and structure of the English language.
3. Authors have not followed the MDPI style formatting for the sections, equations, and references.
4. The references are not correctly cited. There is no need to write e.g. with the references.
5. The research gap and research contribution is not clear. The last paragraph of the introduction is good and acknowledgeable. However, before that, the literature presented is not consistent. For the literature review, other methods of inversion should also be discussed briefly so that the pro and cons of EEI can better be highlighted in terms of advantages over other inversion techniques. For those, I am highlighting some studies that should be discussed are as follows;
a) Li, L., Zhang, J. J., Pan, X. P., & Zhang, G. Z. (2020). Azimuthal elastic impedance-based Fourier coefficient variation with angle inversion for fracture weakness. Petroleum Science, 17, 86-104.
b) Ashraf, U., Zhang, H., Anees, A., Ali, M., Zhang, X., Shakeel Abbasi, S., & Nasir Mangi, H. (2020b). Controls on reservoir heterogeneity of a shallow-marine reservoir in Sawan gas field, SE Pakistan: Implications for reservoir quality prediction using acoustic impedance inversion. Water, 12(11), 2972.
c) Adesanya, O. Y., Adeoti, L., Oyedele, K. F., Afinotan, I. P., Oyeniran, T., & Alli, S. (2021). Hydrocarbon reservoir delineation using simultaneous and elastic impedance inversions in a Niger Delta field. Journal of Petroleum Exploration and Production Technology, 11(7), 2891-2904.
d) Anees, A., Zhang, H., Ashraf, U., Wang, R., Thanh, H. V., Radwan, A. E., ... & Tan, S. (2022). Sand-ratio distribution in an unconventional tight sandstone reservoir of Hangjinqi area, Ordos Basin: Acoustic Impedance Inversion-Based Reservoir Quality Prediction. Frontiers in Earth Science, 1791.
e) Sharifi, J., Hafezi Moghaddas, N., Lashkaripour, G. R., Javaherian, A., & Mirzakhanian, M. (2019). Application of extended elastic impedance in seismic geomechanics. Geophysics, 84(3), R429-R446.
6. Authors have ignored geology section. A proper adequate geological section incorporating regional stratigraphy and tectonics should also be discussed along with petroleum play.
7. Theory and Method section (should be written as Data and Methods) currently goes upto 8 pages. 8 pages of methods section for a research paper is not standard and it reduced the impact of the study. 1-2 pages of theories and methods are adequate providing the methods applied are novel enough. Since EEI is not new and authors are working on the application of elastic impedance inversion from last 2 decades, therefore, remove extra explanations which have no worth.
8. The equations written in the Theory and Method section contain mistakes. Follow the required pattern of MDPI. Also, take care of italics, lower and upper case, super and subscripts and check whether is it compulsory to include all the literature in your papers.
9. Data used in the study should also be explained. Wells used and the grid incorporated should also be incorporated in the study.
10. Figure 1 flowchart is confusing since some loops are not understandable. Abbreviations used needs to be written at the end of the flowchart. The output should also be clearly written that what sort of petrophysical volume can be generated. Use same font color, size, and shape. Also revise the caption since there is no need to write the whole term after the abbreviation.
11. Sections should be clear. Results section, and discussion section should be clearly mentioned.
12. Figure 3. The overlay log should also be written on the seismic sections. Also, the filters applied, if any, should be mentioned in the caption.
13. Figure 4. Field location map is not understandable and need to be zoomed with improved resolution. DEPTHS? Depths are not written. The depth of the reservoir in every well should be written clearly.
14. Authors have written “seismic-to-well ties are reasonably good and allows for identification of the key seismic events”. KINDLY SHOW THE SEISMIC-TO-WELL TIE.
15. Below Figure 6, authors have explained the methods and equations are written. It is hard to understand the results. The methods and results should be presented in separate sections.
16. Figure 11. Improve the resolution.
17. Figure 10. highlight the conventional and possible unconventional reservoirs on the regional inverted porosity section.
18. Figure 12. R2 should be written as R2. 2 should be written in superscript.
19. Figures 12 and 15, the R values are average and needs to be excellent for good results. Justify the results. A clarification and careful explanation is needed.
20. Figure 17: Authors have concluded the research on the geobody interpretation. Therefore, I would suggest the authors to revise the title, workflow, and study according to the geobody interpretation. Authors should go through some recent studies to have a better view of the geobody interpretation. Also, compare and highlight the comparative analysis of the study on a regional scale (national or international).
a) Ashraf, U., Zhang, H., Anees, A., Mangi, H. N., Ali, M., Zhang, X., ... & Tan, S. (2021). A core logging, machine learning and geostatistical modeling interactive approach for subsurface imaging of lenticular geobodies in a clastic depositional system, SE Pakistan. Natural Resources Research, 30, 2807-2830.
b) Olaniyi, A., Miguel, M. G. I., Anindya, D., & Kefe, A. (2019, August). Geobody Interpretation and Its Application for Field Development. In SPE Nigeria Annual International Conference and Exhibition. OnePetro.
21. Figures 16 and 17, more explanations are needed since these pictures are the pure results of the study.
22. Limitations of the proposed workflow should be discussed.
23. A nomenclature section should be added at the end.
24. Conclusions should be revised. Conclusion section is extremely poor. Bullet concise points are recommended.
25. Revise the reference section. Improve the literature and follow the MDPI style pattern.
Author Response
Dear Reviewer,
First of all, authors thanks so much for the critical and invaluable review.
The following are our response:
- The abstract of the article has been modified according to Review suggestion. It has been reduced to 205 words, incorporating problem statement, advanced method and brief results (page 1, line 23-38).
- The English of the article has been tried to improve. Thanks to one Reviewer who spent time to give the English corrections for the article.
- The article has been reformatted in term of sections, equation and references, to follow MDPI style.
- The citation of the article has been check corrected. All e.g. term in references have been removed
- The research gap and research contribution of the article has been tried to pointed out by discussing other recommended inversion methods to better see the pro and cons of EEI (page 1 line 58 to page 3 line 46)
- Geological section discussing regional stratigraphy, tectonics and petroleum play in the study field has been added in the article (page 4 line 7 to page 6 line 9).
- The Theory and Method section has been written as Data and Methods and reduced in page (page 7 line 24 to page 10 line 29) and extra explanation about EEI has been removed.
- The equations writing have been corrected to follow MDPI pattern (page 8 line 12, page 8 line 44, page 9 line 17, page 9 line 35, page 9 line 41)
- Data used explanation, including wells used and survey grid, has been added in the article (page 4 Figure 1, page 6 Figure 3, page 7 Figure 4)
- The Flowchart has been simplified (page 7 Figure 5).
- Sections in the article have been rearranged. Results section and discussion section have been added and mentioned (page 10 line 31 and page 18 line 8)
- The overlay log (gamma ray log) on the seismic section has been written in the figure caption (page 6 Figure 3a and b).
- The location map has been redrawn in Figure 1a page 4. Whereas, the depth of the reservoir has been written in well used display Figure 4 page 7.
- The seismic-to-well tie has been shown in Figure 3c page 6.
- Figure 6 (GRNN diagram) has been re-explained (page 13 line 8 to page 14 line 6). Figure 8 (previously Figure 6) is GRNN diagram that describe the GRNN training had been conducted to optimize the model. Authors prefer to consider this diagram as a result of training process, however it is secondary. Additional figure (Figure 9) was added to illustrate the result of training. Figure 9 supports the training summary Figure 10 (page 10), from where the GRNN model is optimized.
- Porosity estimation display has been improved in resolution (Figure 12, page 16).
- A paragraph has been added to highligth the existing thin beds reservoir (considered as unconventional) encountered by three available wells (page 19 line 21 to 29), extend the Figure 16 (previously Figure 10) explanation.
- R2 in Figure 12 (now is Figure 13 page 16) has been replaced by R2 .
Author referred to : “Maurya S. P. and N. P. Singh, 2018, , Estimating reservoir zone from seismic reflection data using maximum-likelihood sparse spike inversion technique: a case study from the Blackfoot field (Alberta, Canada), Journal of Petroleum Ex-ploration and Production Technology, https://doi.org/10.1007/s13202-018-0600-y” and “Fernando J., 2021, R-Squared Formula, Regression, and Interpretation, Investopedia, https://www.investopedia.com/ terms/r/r-squared.asp” to justify the inversion result.
The explanation is in page 14 line 14 to 15, and page 16 line 27 to 30
- The geobody interpretation has been more highlighted. The title of the article (page line 2 to 3) and the workflow (page 7 Figure 5) has been revised accordingly. Recommended recent study regarding geobody interpretation have also been discussed in methodology section (page 10 line 10 to 29)
- Figure 16 and 17 (now is Figure 17 and 18) have been more explained to more highlighted the inversion result (page 19 line 31 to page 21 line 16)
- Limitations of the proposed workflow has been added in conclusion section (page 22 line 17 to 21).
- A nomenclature section has been added at the end of article (page 22 line 41).
- Conclusions have been revised with bullet point format (page 21 line 30 to page 22 line 32
- The reference section has been revised to follow MDPI style pattern (page 23 line 27 to page 24 line 40)
Thus the revision we have done, that may be still far from perfect.
Again we thanks so much for the consideration, revision and support.
Best Regards,
Eko Widi Purnomo
Round 3
Reviewer 6 Report
The authors have provided responses to all of my queries and acted accordingly as per my suggestions and recommendations. The revised manuscript is an improved version in all aspects and I recommend it for publication.
