Supercritical Fluid Application in the Oil and Gas Industry: A Comprehensive Review
Round 1
Reviewer 1 Report
The manuscript needs significant revision. Part 1 and 2 of the manuscript contain a good review of the literature. However, all subsequent parts (3, 4, 5, and 6) describing Supercritical Fluid applications in the oil and gas industry include minor literature review and references to data older than 5 years.
A review of the present literature is required. References have 62% of studies conducted more than 5 years ago.
Reference [15] is an electronic link to the SciVal online platform.
Figure 2 does not have a vertical axis caption.
Figure 5 has an incomplete legend, no axis signatures, but only units of measurement and poorly described in the text of the manuscript.
Author Response
Dear Colleague,
Thank you for your comments, remarks and valuable opinion about our paper. We have taken into account your remarks. I hope that the manuscript has become better. Below I respond to your comments in consecutive order.
The manuscript needs significant revision. Part 1 and 2 of the manuscript contain a good review of the literature. However, all subsequent parts (3, 4, 5, and 6) describing Supercritical Fluid applications in the oil and gas industry include minor literature review and references to data older than 5 years.
A review of the present literature is required. References have 62% of studies conducted more than 5 years ago.
Answer. We have added new articles for parts 3,4,5 and 6.
Reference [15] is an electronic link to the SciVal online platform.
Answer. Reference [15] is removed.
Figure 2 does not have a vertical axis caption.
Answer. The vertical axis caption is added in Figure 2.
Figure 5 has an incomplete legend, no axis signatures, but only units of measurement and poorly described in the text of the manuscript.
Answer. Corrected and added a description to Figure 5.
Thank you again and best regards,
Praskovya L. Pavlova.
Author Response File: 
Author Response.docx
Reviewer 2 Report
I recommend this work to be published after major revision. As some improvements of the paper please consider following issues/suggestions:
- The text requires a proofreading and editing, there are some sentences to rewrite like “ecologically-friendly in terms of the environment”,
- Please add a punctuation where advantages of SCF are listed.
- I do not agree with the sentence “(SCF) are just beginning to be used in the oil and gas industry” Line 59. For example the SACROC Unit initiated C02 injection in 1972 for oil assisted recovery (SPE 11162 Ten Years of Handling CO2 for SACROC Unit, T. E. Gill).
- How the searching in the SciVal database was conducted? What searching terms were used? For the term “supercritical CO2 for crude oil recovery” in the ScienceDirect database 188 papers only in 2021 are reported.
- Please avoid cumulated citations like [46–58]. The Authors should discuss the findings of each work separately.
- There is no need to compress CO2 to 1000 bar (100 MPa) – see the critical pressure for CO2.
- Table 2 can be presented in the appendix, all symbols in the formulas need to be explained. Please add some examples of the solubility of certain substances in a supercritical CO2 (e.g. some essential oils).
- The MMP abbreviation means the minimum miscibility pressure (not mixing). Please provide some MMP values for different types of oil (here you can refer to https://doi.org/10.1016/j.petlm.2016.11.011 or https://doi.org/10.3390/en13236456). “The earliest carbon dioxide injection projects are those started in 2014 at the Slaughter” – it is not right, the Weyburn-Midale Carbon Dioxide Projectbegan in 2000 and is, probably, the world's largest carbon capture and storage project.
- I do not agree with the sentence “The injection of supercritical carbon dioxide into the reservoir is the most promising and at the same time poorly studied technology”. In most cases CO2 is supercritical at MPP conditions and this kind of displacement is very often studied.
- The system of units should be uniform (MPa or psi, K or oC).
- I do not agree with the sentence “HOD has many valuable components in its composition that can be used as additives to fuel oil, and lubricating composites” – asphaltenes and resins should not be present in fuels or lubricants.
- CO2 cannot lead to the formation of asphaltenes – Line 418, but during the extraction with CO2 asphaltenes naturally occurred in the oil are precipitated.
- How to “shorten the contact time of CO2 with transport and injection systems”? Those systems should operate for 20-30 years. “For an oil-producing system, it is recommended to increase the water entrainment velocity” – water?
- In general, the application of SCF in refining industry should be deeper discussed.
Author Response
Dear Colleague,
Thank you for your comments, remarks and valuable opinion about our paper. We have taken into account your remarks. I hope that the manuscript has become better. Below I respond to your comments in consecutive order.
1. The text requires a proofreading and editing, there are some sentences to rewrite like “ecologically-friendly in terms of the environment”,
Answer. The article was reviewed and proofread by a native English speaker
2. Please add a punctuation where advantages of SCF are listed.
Answer. Punctuation is added and corrected.
3. I do not agree with the sentence “(SCF) are just beginning to be used in the oil and gas industry” Line 59. For example the SACROC Unit initiated C02 injection in 1972 for oil assisted recovery (SPE 11162 Ten Years of Handling CO2 for SACROC Unit, T. E. Gill).
Answer. Of course, we agree with you. Now there are projects for the injection of carbon dioxide. We meant that supercritical fluid technologies are beginning to be introduced in the oil and gas industry. We rephrased this sentence.
4. How the searching in the SciVal database was conducted? What searching terms were used? For the term “supercritical CO2 for crude oil recovery” in the ScienceDirect database 188 papers only in 2021 are reported.
Answer. Yes, in the database ScienceDirect have 188 papers for the term “supercritical CO2 for crude oil recovery”. But we used the online platform SciVal (an online platform for monitoring and analyzing international scientific research using visualization tools and modern citation metrics, economic and social efficiency) which searches for articles by clusters. We considered the cluster "Supercritical Carbon Dioxide; Fracturing Fluids; Thickeners " because other clusters included articles on the extraction of vegetable oils.
5. Please avoid cumulated citations like [46–58]. The Authors should discuss the findings of each work separately.
Answer. Corrected.
6. There is no need to compress CO2 to 1000 bar (100 MPa) – see the critical pressure for CO2.
Answer. Corrected.
7. Table 2 can be presented in the appendix, all symbols in the formulas need to be explained. Please add some examples of the solubility of certain substances in a supercritical CO2 (e.g. some essential oils).
Answer. Added explanations in symbols formulas and examples of solubility of substances
8. The MMP abbreviation means the minimum miscibility pressure (not mixing). Please provide some MMP values for different types of oil (here you can refer to https://doi.org/10.1016/j.petlm.2016.11.011 or https://doi.org/10.3390/en13236456). “The earliest carbon dioxide injection projects are those started in 2014 at the Slaughter” – it is not right, the Weyburn-Midale Carbon Dioxide Projectbegan in 2000 and is, probably, the world's largest carbon capture and storage project.
Answer. Thanks for the comment. Added this information and corrected.
"The Webern-Medel CO2 Monitoring Project is the world's first and largest initiative to measure, monitor and verify CO2 injection and was conducted alongside EOR operations between 2000 and 2011 [135]. The resent (youngest) carbon carbon dioxide injection projects are those started in 2014 at the Slaughter (Smith Igoe) which is located in Texas, USA, and is serviced by a large American oil company named Occidental"
9. I do not agree with the sentence “The injection of supercritical carbon dioxide into the reservoir is the most promising and at the same time poorly studied technology”. In most cases CO2 is supercritical at MPP conditions and this kind of displacement is very often studied.
Answer. We agree with you. The sentence has been corrected.
"The injection of supercritical carbon dioxide into the reservoir is the most promising and studied technology in the laboratory".
10. The system of units should be uniform (MPa or psi, K or oC).
Answer. Corrected on MPa and oC
11. I do not agree with the sentence “HOD has many valuable components in its composition that can be used as additives to fuel oil, and lubricating composites” – asphaltenes and resins should not be present in fuels or lubricants.
Answer. Of course, asphaltenes and resins should not be present in fuel or lubricants. We mean that asphaltenes can be additionally treated with SCF and receive valuable substances that can be further used as additives.
12. CO2 cannot lead to the formation of asphaltenes – Line 418, but during the extraction with CO2 asphaltenes naturally occurred in the oil are precipitated.
Answer. Yes, we agree with you. . The sentence has been corrected.
13. How to “shorten the contact time of CO2 with transport and injection systems”? Those systems should operate for 20-30 years.
Answer. The authors of the work (Wang Z.M., Song G.L. and Zhang J. (2019) Corrosion control with increased oil recovery of CO2 reservoirs From the point of view of multiphase liquids. Before. Mater. 6:272. DOI:10.3389/fmats.2019.00272) recommend coatings and liners, develop new electrochemical and analytical methods in conditions of poor conductivity and aggressive media, such as water containing SC-CO2 and oil-water mixtures to reduce the time of CO2 contact with transportation and injection systems.
“For an oil-producing system, it is recommended to increase the water entrainment velocity” – water?
Answer. This is information for carbon dioxide is injected with alternating water. The sentence in the text was rephrased.
14. In general, the application of SCF in refining industry should be deeper discussed.
Answer. The work has been substantially improved. New scientific articles have been added.
Thank you again and best regards,
Praskovya L. Pavlova
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Accept in present form.
Author Response
Dear Colleague,
Thank you for your comments, remarks and valuable opinion about our paper.
Best regards,
Praskovya L. Pavlova.
Reviewer 2 Report
The paper requires a further modification. I recommend the following issues to be considered/added:
- The review is biased highlighting only advantages of supercritical fluids. In the Introduction section also disadvantages like being expansive or non-compatible with materials (like rubber) should be given.
- The references should be numbered in the order in which they appear. The items in the main text are not numbered consecutively – reference [49] precedes [46-48]. Why the last position [139] appears in the middle of paper (and not at the end)? Some references from the bibliography like [137] are not included in the main text.
- I still recommend to move Table 2 into an appendix and still some symbols are not clear – S is an entropy or a solubility? No explanations are given to the last formula in the table. Some symbols repeat but may have different meanings. Add units in which these parameters should be given.
- Please use the exact names and use more recent data. “The Webern-Medel” is actually Weyburn-Midale. The CO2 injection at the Slaughter field is not the latest (most recent) project, for example the Petra Nova project started in 2017. Please refer to the latest reports on CCS-EOR status like https://sgp.fas.org/crs/misc/R44902.pdf
- Please ensure that are no writing mistakes like in lines 325, 280, 465-466, 782; punctuation in the first line of table 3. The text should be carefully polished.
- Line 473 – what are extraction temperature and separation temperature? Why they differ?
- Line 495 - supercritical oxidation does not lead to the oil extraction but to its destruction.
Author Response
Dear Colleague,
Thank you for your comments, remarks and valuable opinion about our paper. We have taken into account your remarks. I hope that the manuscript has become better. Below I respond to your comments in consecutive order.
1. The review is biased highlighting only advantages of supercritical fluids. In the Introduction section also disadvantages like being expansive or non-compatible with materials (like rubber) should be given.
Answer. In this review we have considered only the Supercritical Fluid Application in the Oil and Gas Industry. In addition to the advantages of SCF, we have considered disadvantages such as corrosion, cost of equipment, loss of asphaltenes which is not always an advantage. We believe that these problems need to be considered comprehensively. In the Introduction we added the disadvantages of supercritical technology.
2. The references should be numbered in the order in which they appear. The items in the main text are not numbered consecutively – reference [49] precedes [46-48]. Why the last position [139] appears in the middle of paper (and not at the end)? Some references from the bibliography like [137] are not included in the main text.
Answer. The references are corrected.
3. I still recommend to move Table 2 into an appendix and still some symbols are not clear – S is an entropy or a solubility? No explanations are given to the last formula in the table. Some symbols repeat but may have different meanings. Add units in which these parameters should be given.
Answer. Table 2 is moved into an appendix A. S is solubility. Н is entropy. Symbols are corrected. Units are added.
4. Please use the exact names and use more recent data. “The Webern-Medel” is actually Weyburn-Midale. The CO2 injection at the Slaughter field is not the latest (most recent) project, for example the Petra Nova project started in 2017. Please refer to the latest reports on CCS-EOR status like https://sgp.fas.org/crs/misc/R44902.pdf
Answer. Suggestions are added and corrected.
5. Please ensure that are no writing mistakes like in lines 325, 280, 465-466, 782; punctuation in the first line of table 3. The text should be carefully polished.
Answer. Suggestions are added and corrected.
6. Line 473 – what are extraction temperature and separation temperature? Why they differ?
Answer. The authors of the work «WEI Hua, HE Huanjie, ZHANG Yi. Optimization of oil based drilling cuttings treatment process by supercritical CO2 fluid using response surface methodology [J]. Chinese Journal of Environmental Engineering, 2017, 11(11): 6050-6055. doi: 10.12030/j.cjee.201701080» introduced the concepts of extraction temperature and separation temperature. Extraction is a procedure used to expel an ideal compound from a solid or a liquid blend utilizing an appropriate solvent. Separation is a procedure that changes the general measures of substances in a blend.
7. Line 495 - supercritical oxidation does not lead to the oil extraction but to its destruction.
Answer. Suggestion is corrected.
Thank you again and best regards,
Praskovya L. Pavlova.
Author Response File: Author Response.docx
