Corrosion Study of 80S Steel under the Coexistence of CO2 and H2S
Round 1
Reviewer 1 Report
The Figure 1. Pendant size. not clear re drawn this figure
Figure 4 and 5. Microstructure of material. the caption need more details
Add more References and as well add some ref about co2 applications
10.1016/j.mset.2022.08.002 and 10.22059/POLL.2021.328835.1161
Author Response
Response to Reviewer 1 Comments
Point 1: The Figure 1. Pendant size. not clear re drawn this figure.
Response 1: Thank you very much for your advice. The Figure 1 has been redrawn in the manuscript. The edited Figure 1 in section 2.1.
Point 2: Figure 4 and 5. Microstructure of material. the caption need more details
Response 2: Thank you very much for your advice. The titles of Figures 4 and 5 have been modified and the corresponding experimental conditions have been added.
Point 3: Add more References and as well add some ref about CO2 applications
Response 3: Thank you very much for your advice. I have added more references.
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
As the demand for energy continues to increase, the extraction environment in oil and gas fields has gradually shifted to a more hostile environment, leading to increased corrosion of extraction and transmission facilities, for which the most effective solution is the use of corrosion-resistant metals. In this paper, the corrosion behaviour of 80S steel in use in an oilfield underground gathering pipeline was investigated at different temperatures and different partial pressures of H2S and CO2 using an autoclave supplemented by a loss-in-weight method to simulate the corrosive environment in the oilfield. Electrochemical studies were then carried out to investigate the corrosion mechanism. The results show that:
(1) temperature and the partial pressure ratio of H2S to CO2 are important factors affecting the corrosion of the metal.
(2) The corrosion potential decreases with increasing temperature and sulphur
concentration, and its corrosion current density increases.
(3) Under different experimental conditions, the cathodic reaction is controlled by the combined effect of activation and diffusion; at high temperatures and high sulphur concentration, the anodic curve shows a clear passivation zone.
(4) The impedance radius also decreases with increasing temperature, decreasing with increasing sulphur content at low temperatures and increasing with increasing sulphur content at high temperatures. This also reflects the fact that higher temperatures and higher sulphur concentrations produce a more protective iron sulphide product, which inhibits the corrosion of the metal.
This paper is well-organized and needs the following comments to be
answered before publication.
1. What is the novelty and research gap in this study that is missing in the
Introduction?
2. In section 2: add the metal images used for the study.
3. To support the values in Table 1, can the authors authenticate by
means of an XRD graph?
4. Redraw Fig. 1 for better clarity for the readers.
5. In section 2.2, authors must add the experimental set-up figures with
the arrangement used to measure the parameters.
6. The authors are advised to add a separate section 2.3, which will
describe the SEM analysis conducted with their results.
7. Section 2.3 should explain the specimen sizes and all the key
parameters necessary before the samples are placed for the SEM
analysis.
8. The titles for Fig. 3-5 are the same. Change the titles for the Figs and
each represents which material and arrange them in the same format
(30 0 , 60 0 and 100 0 )
9. In the results and discussion explained well, add a few works of
literature to support the results.
10. In conclusion section number is wrong and should change to 4.
11. Conclusion points are too lengthy, and concise and provide (5-6) key
points.
12. The grammatical errors in the entire manuscript need to be corrected.
13. Refer to the following paper and add in the references “Synergistic
corrosion inhibition effect of quinoline quaternary ammonium salt and
Gemini surfactant in H 2 S and CO 2 saturated brine solution”.
and
Effects of corrosion on the strength of self-drilling screw connections in cold-formed steel structures-experiments and finite element modeling
K Roy, HH Lau, Z Fang, R Masood, TCH Ting, JBP Lim, VCC Lee Structures 36, 1080-109614. Authors are advised to check the chemical notations with their suffix
etc. properly.
Author Response
Response to Reviewer 2 Comments
Point 1: What is the novelty and research gap in this study that is missing in the Introduction?
Response 1: Firstly, thank you very much for these suggestions. The starting point of my research was mainly to simulate corrosion at oil and gas field sites, and the medium used was produced water from oil and gas field sites, and the medium used in most articles was standard simulated water. Secondly, there are relatively few research articles on the corrosion of carbon steel in a mixture of CO2 and H2S, and most of the research is on a single gas. In the articles, I used a combination of simulation and electrochemical experiments to study the corrosion behavior of 80S steel, and there are relatively few articles on 80S steel, which is commonly used in oil and gas fields. The shortcomings of the article mainly lie in the fact that the study of the partial pressure of the two gases is not covered in the electrochemical study, and the temperature nodes set are relatively few. However, I would still like to receive your support, and thank you again for your suggestions on this manuscript.
Point 2: In section 2: add the metal images used for the study.
Response 2: Thanks for your suggestion. The metal image has been added in the section 2.1 .
Point 3: To support the values in Table 1, can the authors authenticate by means of an XRD graph?
Response 3: Thanks for your suggestion. For the content of some of the metals in the specimens, we commissioned an institute to carry out the tests using an inductively coupled plasma emission spectrometer.
Point 4: Redraw Fig. 1 for better clarity for the readers.
Response 4: Thanks for your suggestion. The Figure 1 has been redrawn in the manuscript.
Point 5: In section 2.2, authors must add the experimental set-up figures with the arrangement used to measure the parameters.
Response 5: Thanks for your suggestion.I have described the function of the individual electrodes at the end of section 2.2.
Point 6: The authors are advised to add a separate section 2.3, which will describe the SEM analysis conducted with their results.
Response 6: Thanks for your suggestion. The SEM scan results is in section 3.1.1 of this manuscript.
Point 7: Section 2.3 should explain the specimen sizes and all the key parameters necessary before the samples are placed for the SEM analysis.
Response 7: Thanks for your suggestion.In this manuscript I have added section 2.3, and in section 2.3 I have added all the key parameters required for the SEM analysis.Regarding sample dimensions, I describe them in section 2.1 of this manuscript.
Point 8: The titles for Fig. 3-5 are the same. Change the titles for the Figs and each represents which material and arrange them in the same format (30 0 , 60 0 and 100 0 ).
Response 8: Thanks for your suggestion.The titles of Fig. 3-5 have been modified and the corresponding experimental conditions have been added.
Point 9: In the results and discussion explained well, add a few works of literature to support the results.
Response 9: Thanks for your suggestion. I have added some literature works to support these results in sections 3.2.1 and 3.2.2.
Point 10: In conclusion section number is wrong and should change to 4.
Response 10: Thanks for your suggestion. I have revised the chapter numbering throughout the manuscript.
Point 11: Conclusion points are too lengthy, and concise and provide (5-6) key points.
Response 11: Thanks for your suggestion. I have revised the conclusion section.
Point 12: The grammatical errors in the entire manuscript need to be corrected.
Response 12: Thanks for your suggestion. I have asked native English editors to polish and modify the manuscript.
Point 13: Refer to the following paper and add in the references “Synergistic corrosion inhibition effect of quinoline quaternary ammonium salt and Gemini surfactant in H 2 S and CO 2 saturated brine solution”.and Effects of corrosion on the strength of self-drilling screw connections in cold-formed steel structures-experiments and finite element modeling K Roy, HH Lau, Z Fang, R Masood, TCH Ting, JBP Lim, VCC Lee Structures 36, 1080-1096.
Response 13: Thanks for your suggestion. The two references you mention, which I have cited, are references 12 and 22.
Point 14: Authors are advised to check the chemical notations with their suffix etc. Properly.
Response 14:Thank you very much for discovering this error. I have modified the chemical symbols and suffixes in this manuscript.
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
A major important point should be addressed:
- The impedance spectra Fig.9 should be fitted with the proposed equivalent circuit Fig.20 and the fitting should appear in the impedance spectra. Also the results of fitting should be presented in a table containing values for solution resistance Rs, charge transfer resistance RCT, Warburg impedance W, Capacitance Cdl, and the %inhibition %IE
- Blank should be tested and provided with the potentiodynamic data and impedance data , in both cases the blank results to be included in the corresponding Tables and Figures.
- Table 7 The values of corrosion rate should be included.
- % inhibition IE% can be calculated if measurement of blank is done in impedance and Tafel experiments.
Author Response
Response to Reviewer 3 Comments
Point 1: The impedance spectra Fig.9 should be fitted with the proposed equivalent circuit Fig.20 and the fitting should appear in the impedance spectra. Also the results of fitting should be presented in a table containing values for solution resistance Rs, charge transfer resistance RCT,Warburg impedance W, Capacitance Cdl, and the %inhibition %IE
Response 1: Thanks for your suggestion. I have plotted a fit to the impedance spectrum, which is included in Figure 9. And I have added the data you suggested for the parameters of the fitted impedance spectrum.
Point 2: Blank should be tested and provided with the potentiodynamic data and impedance data , in both cases the blank results to be included in the corresponding Tables and Figures.% inhibition IE% can be calculated if measurement of blank is done in impedance and Tafel experiments.
Response 2: Thanks for your suggestion. I would like to clarify that my research focuses on simulating the corrosive environment in oil and gas field sites. After evaluating the blank experiment setup, I believe that it is not very meaningful and the results so far can support the view I will add the suggestions you have made in a subsequent paper.
Point 3: Table 7 The values of corrosion rate should be included.
Response 3: Thanks for your suggestion. I have added the corrosion rate to Table 7.
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
The manuscript is low in scientific depth and content. It is also poorly communicated and I will not recommend publication.
Author Response
Response to Reviewer 4 Comments
Point 1: The manuscript is low in scientific depth and content. It is also poorly communicated and I will not recommend publication.
Response 1: Thanks for your suggestion. Since we did not express it clearly, we are sorry for your misunderstanding. We have asked native English editors to polish and modify the manuscript.We hope we can count on your support.
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
All my comments have been addressed. The paper is ready for publication.
Reviewer 3 Report
The paper can be accepted the author incorporated the changes requested.
