Study on Quantitative Evaluation Method for Failure Risk Factors of the High-Temperature and High-Pressure Downhole Safety Valve
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript innovatively applies the Bow-tie method to identify the causes and consequences of the failure of high temperature and high pressure downhole safety valves, and analyses and obtains the analysis report of the FMECA of its key components. Moreover, the group decision-making Dematel method is innovatively proposed to quantitatively assess the failure risk factors of high-temperature and high-pressure downhole safety valves, and the influence and importance ranking of 14 failure risk factors are obtained, and the operation and maintenance suggestions are proposed for different risks in the implementation process. The research work as a whole is innovative and complete, but there are still several problems that need to be modified as follows:
1. In the FMECA analysis section, there is no clear role for the study of safety valve failure factors in the resulting FMECA analysis results, and it is recommended that a relevant description be added to highlight the need for the use of the FMECA methodology.
2. It is suggested that the name of Table 5-15 in the text be changed to be more specific in its description and to make it clear what exactly is being done in the figure.
3. Some of the accompanying figures in the manuscript need to be adjusted for clarity and formatting, for example, the size of Figure.3, where the text is not particularly clear. Figure.1 and Figure.2 are not centred in the text, and it is suggested that the formatting be readjusted and the layout of the pictures be modified.
4. Revise the labelling of the FMECA tables in the conclusions of the text to correspond to the content of the text.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
Response to reviewers
Response to Reviewer #1:
Thanks to the reviewer for your evaluation of our work. We will work harder with the very good suggestions you give in this manuscript.
Comment 1: In the FMECA analysis section, there is no clear role for the study of safety valve failure factors in the resulting FMECA analysis results, and it is recommended that a relevant description be added to highlight the need for the use of the FMECA methodology.
Reply 1: Thank you for your comments. We have emphasised the need for FMECA by adding the relevant description earlier in title 3.4.
By performing FMECA on the safety valves, we clarified the consequences caused by each failure mode and the severity of the consequences. Also, based on the repairability of the failure, we categorise the failure modes in order to design improvement measures.
Comment 2: It is suggested that the name of Table 5-15 in the text be changed to be more specific in its description and to make it clear what exactly is being done in the figure.
Reply 2: Thank you for your comments. We have changed the captions of Figures 5 - 13 as requested. We have clarified exactly which part of the part has been analysed using FMECA.
Comment 3: Some of the accompanying figures in the manuscript need to be adjusted for clarity and formatting, for example, the size of Figure.3, where the text is not particularly clear. Figure.1 and Figure.2 are not centred in the text, and it is suggested that the formatting be readjusted and the layout of the pictures be modified.
Reply 3: Thank you for your comments. We have resized and repositioned Figures 1-Figure 3 as requested, please refer to the text for specific changes.
Comment 4: Revise the labelling of the FMECA tables in the conclusions of the text to correspond to the content of the text.
Reply 4: Thank you for your comments. We have made the requested changes to the Conclusion section, please refer to the main text.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe work is aimed at improving the efficiency of oil and gas production safety valves. The work uses methods of system analysis and decision theory.
Notes:
1. Line 76-80. I don't agree. The accuracy and quality of the expert assessment method depends on the volume of factors, their analysis and interrelation. The author needs to add the text “However, there are also positive results from using the expert assessment method, for example in the work [x]”
[x] Ilyushin, Y.V.; Kapostey, E.I. Developing a Comprehensive Mathematical Model for Aluminum Production in a Soderberg Electrolyser. Energies 2023, 16, 6313. https://doi.org/10.3390/en16176313
2. Line 83. Text “aÄ´ention of many scholars [27-29].” maybe there is an error here
3. Line 156. Who introduced this categorization? What is the level criterion?
4. Line 169. Table 3. How does your table differ from the table of ranks of the expert assessment method?
5. Line 178-200. The table must be included in the appendix.
6. Line 237-240. “Relevant literature will be examined” could be studied? If not, please add relevant links. (possibly inaccurate translation)
General comment:
1. I am not a native speaker, but I have never seen an “oil field” called an “oil mine.” There are also some doubts about the terminology. I recommend that authors check the text with a native speaker.
Conclusion . The article is positive. Although the author is critical of alternative solutions to the problem. This point of view also has its place. Overall, I recommend accepting the work with minor modifications.
Author Response
Response to reviewers
Response to Reviewer #2:
Thanks to the reviewer for your evaluation of our work. We will work harder with the very good suggestions you give in this manuscript.
Comment 1: Line 76-80. I don't agree. The accuracy and quality of the expert assessment method depends on the volume of factors, their analysis and interrelation. The author needs to add the text “However, there are also positive results from using the expert assessment method, for example in the work [x]”[x] Ilyushin, Y.V.; Kapostey, E.I. Developing a Comprehensive Mathematical Model for Aluminum Production in a Soderberg Electrolyser. Energies 2023, 16, 6313. https://doi.org/10.3390/en16176313
Reply 1: Thank you for your comments. We have added relevant references to illustrate the benefits of expert assessment methods. “However, expert assessment methods also have a positive effect. The advantage of the expert assessment method is that it allows the combination of different examination methods. Different groups of subjects are studied during the inspection process and different assessment methods are used.”
Comment 2: Line 83. Text “aÄ´ention of many scholars [27-29].” maybe there is an error here.
Reply 2: Thank you for your comments.We have amended and confirmed that there are no grammatical problems with this passage.
Comment 3: Line 156. Who introduced this categorization? What is the level criterion?
Reply 3: Thank you for your comments. Table 1 shows the evaluation metrics that we have introduced in order to perform FMECA on the key components of the safety valve. The criteria for classification are based on the severity of the consequences of component failure.
Comment 4: Line 169. Table 3. How does your table differ from the table of ranks of the expert assessment method?
Reply 4: Thank you for your comments. Table 3 is based on the classification of safety valve critical components based on the severity of failure as a criterion. Unlike the expert assessment methodology, the formulation of Table 3, like the previous tables, is a necessary part of the FMECA procedure and contributes to the FMECA analysis.
Comment 5: Line 178-200. The table must be included in the appendix.
Reply 5: Thank you for your comments. We have added the tables from Figure 5 to Figure 13 to the appendices as requested. The appendices are in the last chapter of the article.
Comment 6: Line 237-240. “Relevant literature will be examined” could be studied? If not, please add relevant links. (possibly inaccurate translation)
Reply 6: Thank you for your comments. When we checked, we found a translation error here. The original text has been corrected.
We have categorised the consequences of downhole safety valve failure through our research into four types: inability to open, failure to close, early closure and disconnection. The original text has been corrected.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript “Quantitative Evaluation Method for Failure Risk Factors of the High Temperature and High Pressure Downhole” contains only a general validation of the risk assessment method described in lines 333 to 357. It is necessary to compare the failure results of the subsurface safety valve taking into account statistical estimators . The authors should explain in the article what is the cause and effect relationship between the described method and the recommendations formulated in section 4.3 of the manuscript.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Response to reviewers
Response to Reviewer #3:
Thanks to the reviewer for your evaluation of our work. We will work harder with the very good suggestions you give in this manuscript.
Comment 1: The manuscript “Quantitative Evaluation Method for Failure Risk Factors of the High Temperature and High Pressure Downhole” contains only a general validation of the risk assessment method described in lines 333 to 357. It is necessary to compare the failure results of the subsurface safety valve taking into account statistical estimators . The authors should explain in the article what is the cause and effect relationship between the described method and the recommendations formulated in section 4.3 of the manuscript.
Reply 1: Thank you for your comments. We have supplemented the content of Chapter 4.3 by adding the process of quantitative analysis of safety valve failure factors in order to correspond to the content of the previous chapters related to the Bow-tie method and the Dematel model.
Analysis of failure factors of downhole safety valves: firstly, the failure modes of key components are obtained through FMECA, and the failure severity level is formulated; maintenance decisions are formulated for subsequent maintenance; then the failure modes of each component are brought into the Bow-tie model to screen out the failure causes with the greatest impact, and finally, the causes of failure are quantitatively evaluated through the DEMATEL method. The results of quantitative evaluation of failure risk are crucial for improving the reliability of downhole safety valves. For the key failure risk factors screened in the previous section, effective measures should be taken to prevent and respond to them in the operation and maintenance management of downhole safety valves. In order to improve the reliability of downhole safety valves, the following aspects should be improved and strengthened:
(1) From the results of the four-degree calculation in the DEMATEL method, it can be seen that the factor that has the greatest influence on the degree of centrality is (spring failure). Existing safety valve design has technical objective defects, resulting in downhole safety valves can not meet the design life indicators. Most of the existing designs rely only on the spring to push the centre tube to open the safety valve, and there is no corresponding redundancy design, once the spring fails, it will directly lead to the failure of the downhole safety valve. Therefore, optimising the structural design of downhole safety valves and improving the manufacturing process have the greatest impact on the service life of safety valves. Design and manufacturing determines the upper limit of the reliability of the downhole safety valve. Underground safety valve design and manufacturing involves mechanical, hydraulic, sealing, fluid, materials and other professional disciplines, the impact of complex factors, need to consider the sealing and reliability of the piston movement part of the high temperature and high pressure, while the need to solve the gate switch part of the hard sealing problem, the joint part of the thread machining accuracy also has a direct impact on the performance indicators of the underground safety valve. At present, there is still a big gap between domestic downhole safety valve design experience and proprietary inspection equipment and foreign countries, and need to further increase research and development efforts.
(2) Based on the analysis results of Bow-tie method, it can be seen that the main failure modes of downhole safety valves are opening failure and closing failure. Set up a high-efficiency field management team, continuously carry out equipment operation and maintenance management training, and establish a field failure response mechanism. In case of failure to open, it is necessary to strictly implement the opening operation procedures, and at the same time ensure the pressure balance between the top and bottom of the safety valve, and if necessary, cooperate with the fracturing pump to balance the oil pressure. For the failure of closure, on the one hand, it is necessary to cancel the operation in the tubing and carry out well risk assessment, and at the same time, it is necessary to formulate monitoring measures, so as to avoid major catastrophic accidents due to the failure of the safety barrier. Field research found that tubing leakage and tubing gas stringing are also two common failure modes in the field. Pipeline cascading is caused by sealing problems in the piston dynamic sealing components, resulting in the leakage of sulphur-containing natural gas in the pipeline through the piston sealing components to the control pipeline, and the sulphur-containing natural gas displacing the hydraulic oil and then to the control cabinet tank or the manual pump on the ground. In view of these failure modes, field management personnel should actively modify the equipment and establish corresponding management countermeasures; at the same time, they should continue to carry out training on downhole safety valves and ancillary systems, and continuously improve the field operation level and emergency response capability.
