Dilation Potential Analysis of Low-Permeability Sandstone Reservoir under Water Injection in the West Oilfield of the South China Sea
Round 1
Reviewer 1 Report
Comments and Suggestions for Authorsž Ensure that all references follow a consistent style and format, adhering to the journal's requirements.
ž Ensure that section headings are clear and consistent throughout the paper.
ž Tables and figures should be properly labeled and referenced in the text. Captions should be descriptive and placed below figures and above tables.
ž Expand the introduction to provide a more comprehensive background, including the importance of the topic and a brief summary of the existing literature.
ž Provide a clear justification for the choice of experimental methods and why they are appropriate for the study.
ž The authors should provide a clear rationale for the choice of experimental conditions, such as the use of hot water (50°C to 80°C) and the decision to perform or not perform pore pressure pretreatment.
ž The true triaxial stress conditions (19 MPa vertical stress, 14 MPa maximum horizontal principal stress, and 8 MPa minimum horizontal principal stress) should be justified based on the target reservoir's depth and in-situ stress gradient. Additionally, it would be beneficial to discuss the implications of these stress conditions on the experimental outcomes.
ž The criteria for determining the maximum injection pressure (up to 16.3 MPa) should be explained, along with the rationale for choosing this specific threshold. This is crucial for understanding the fracture pressure of the target reservoir rock.
ž Ensure that the descriptions of the experimental procedures are concise and to the point, avoiding unnecessary technical details that do not add significant value to the understanding of the results.
ž A few review papers could be helpful in improving the quality of Introduction part. [1] 10.1016/j.compgeo.2021.104482. [2] 10.1016/j.fuel.2023.128754.
Comments on the Quality of English Language- The paper generally uses correct grammar and syntax, but there are occasional issues with sentence structure that may affect clarity. Some sentences are overly complex and could be simplified for better readability.
- Consistency in terminology and style is important. Ensure that terms such as "dilation potential," "micro-fractures," and "low-permeability sandstone" are used consistently throughout the paper.
Author Response
Comments and Suggestions ：
Comments 1: Ensure that all references follow a consistent style and format, adhering to the journal's requirements.
Response 1: Thank you very much for your suggestion, we will further modify the format of the paper.
Comments 2: Ensure that section headings are clear and consistent throughout the paper.
Response 2: Thank you very much for your suggestion, we will further modify the section heading of the paper.
Comments 3: Tables and figures should be properly labeled and referenced in the text. Captions should be descriptive and placed below figures and above tables.
Response 3: Thank you very much for your suggestion, we will modify the position of paper pictures and table notes.
Comments 4: Expand the introduction to provide a more comprehensive background, including the importance of the topic and a brief summary of the existing literature.
Response 4: Thank you very much for your suggestion, we will add background information and improve the content of the paper.
Comments 5: Provide a clear justification for the choice of experimental methods and why they are appropriate for the study.
Response 5: Thank you very much for your suggestion. This experiment is a preliminary exploratory experiment, mainly to explore whether the reservoir is suitable for water injection expansion technology. X-ray diffraction experiment is used to determine whether the mineral composition in the reservoir sample will undergo a hydration reaction. Rock reservoirs prone to hydration reactions are not suitable for water injection expansion technology. The laser particle size analysis experiment is mainly used to judge the particle size sorting, if the sorting is poor, it is not suitable for water injection expansion technology.
Comments 6: The authors should provide a clear rationale for the choice of experimental conditions, such as the use of hot water (50°C to 80°C) and the decision to perform or not perform pore pressure pretreatment.
Response 6: Thank you very much for your suggestion. Pore pressure pretreatment is an experimental exploration. We believe that the transient and rapid fluid injection is not conducive to the development of a reservoir fracture zone. The pressure-retaining pretreatment is when the injected fluid is fully injected into the rock mass to increase the expansion radius. And that's exactly what happened.Hot water injection is because the target interval is deep. The formation conditions are high temperature and high pressure. To better simulate the real formation water injection situation, hot water injection is selected.
Comments 7: The true triaxial stress conditions (19 MPa vertical stress, 14 MPa maximum horizontal principal stress, and 8 MPa minimum horizontal principal stress) should be justified based on the target reservoir's depth and in-situ stress gradient. Additionally, it would be beneficial to discuss the implications of these stress conditions on the experimental outcomes.
Response 7: Thank you very much for your suggestion. The triaxial stress conditions were obtained from field data. Because the maximum horizontal principal stress and the minimum horizontal principal stress have a large difference, the formation is more conducive to the use of water injection expansion technology.
Comments 8: The criteria for determining the maximum injection pressure (up to 16.3 MPa) should be explained, along with the rationale for choosing this specific threshold. This is crucial for understanding the fracture pressure of the target reservoir rock.
Response 8: Thank you very much for your suggestion. We set up a pilot test in the design of true triaxial rock mechanics waterflood physical simulation tests. The first set of experiments in this paper is the first set of experiments, obtained by the first set of pump pressure curves. When the pumping pressure does not rise with the amount of water injected, the rock is broken. The highest pressure is the rupture pressure, which is 16.3MPa.
Comments 9: Ensure that the descriptions of the experimental procedures are concise and to the point, avoiding unnecessary technical details that do not add significant value to the understanding of the results.
Response 9: Thank you very much for your suggestion. We will further optimize the paper language.
Comments 10: A few review papers could be helpful in improving the quality of Introduction part.
Response 10: Thank you very much for your comments and references. We have learned a lot from your comments. We will carefully read your recommended review before revising the paper. I believe this will speed up our revision process.
Comments on the Quality of English Language：
Comments 11: The paper generally uses correct grammar and syntax, but there are occasional issues with sentence structure that may affect clarity. Some sentences are overly complex and could be simplified for better readability.
Response 11: Thanks for your suggestions, I will further optimize the paper language.
Comments 12: Consistency in terminology and style is important. Ensure that terms such as "dilation potential," "micro-fractures," and "low-permeability sandstone" are used consistently throughout the paper.
Response 12: Thanks for your suggestions, I further clarify the unity of the article's professional terms.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper analyzes the feasibility of a new technology, named rock dilation under water injection, for the development of offshore low permeability sandstone reservoirs through a set of experiments, such as X-ray diffraction, laser grain size analysis, and true triaxial physical simulation. The feasibility is evaluated by the brittleness value, sorting coefficient, and water-injection expansion area. In general, the manuscript is attractive for the readers, especially for the engineers in the oil field. I recommend acceptance after minor revisions as follows:
1. In this paper, there are many groups of parameters in the X-ray diffraction experiment, such as X-ray, 1-2, and the definition of the experimental sample is not clear.
2. The symbol of the volume fraction of the sample in formula (4) is different from that in the paper, so it needs to be unified.
3. When describing the standard of selective coefficient, the sentences of the paper are repeated, and the language needs to be refined.
4. In the fourth part of this paper, there are macroscopic observations, electron microscope scanning, and CT scanning, but it is not reflected in the conclusion of the fifth part.
Author Response
Comments and Suggestions：
Comment 1：In this paper, there are many groups of parameters in the X-ray diffraction experiment, such as X-ray, 1-2, and the definition of the experimental sample is not clear.
Thank you for your comments. We'll make sure the names of the samples in the X-ray diffraction experiment are clear.
Comment 2: The symbol of the volume fraction of the sample in formula (4) is different from that in the paper, so it needs to be unified.
Thank you for your comments. We will adjust the volume fraction of the sample in formula (4).
Comment 3: When describing the standard of selective coefficient, the sentences of the paper are repeated, and the language needs to be refined.
Thank you for your comments. We will refine the language of the paper and make it more precise.
Comment 4: In the fourth part of this paper, there are macroscopic observations, electron microscope scanning, and CT scanning, but it is not reflected in the conclusion of the fifth part.
Thank you for your comments. We will present macroscopic observations, electron microscope scanning, and CT scanning results in fifth part.
Thank you very much for your comments and references. We have learned a lot from your comments.
Reviewer 3 Report
Comments and Suggestions for AuthorsFigures:
1. In general, captions of figures should be independent of their in-text explanation. They should tell general information about the content of the figures just by reading the captions. For example, caption of figure 1 could have A, B, and C defining each object in the figure. A good example of this is figure 4.
2. Some images of the figures are deformed when being resized. It is recommended to provide un-deformed images, such as in figure 1, the round objects are not in perfect roundness.
3. It is recommended to include a scale when applicable to visualize the size comparison between objects. For example, the rock samples in figure 9 look bigger than the loading pistons in figure 11. Having scales by the images or providing more in-text explanation assists.
4. Curves in figure 15 should be presented in different line style for better differentiation.
Comments on the Quality of English Language
The overall English writing is acceptable. Even through there are some minor English issues that do not impact the overall reading, however, the following could improve the manuscript quality when adopted:
1. Some sentences are very long (about 10 lines long), breaking them to shorter sentences is recommend. For example: The 3rd last sentence in the abstract.
2. Avoiding word repetition is advisable. For example the work experiment is repeated after each test, where it is mentioned by experiments at the start of the statement as shown in “In order to investigate whether the water injection-induced dilation technology is suitable or not, these experiments are conducted to analyze the dilation potential for offshore low-permeability sandstone reservoirs, including X-ray diffraction experiment, laser particle size analysis experiment, physical simulation experiment, Computed Tomography scan experiment and electron microscope scanning experiment.”
Author Response
Comments and Suggestions：
Comments 1: In general, captions of figures should be independent of their in-text explanation. They should tell general information about the content of the figures just by reading the captions. For example, caption of figure 1 could have A, B, and C defining each object in the figure. A good example of this is figure 4.
Response 1: Thank you very much for your suggestion, we will further improve the picture name. In the picture name, the meaning of different pictures is reflected in detail.
Comments 2: Some images of the figures are deformed when being resized. It is recommended to provide un-deformed images, such as in figure 1, the round objects are not in perfect roundness.
Response 2: Thank you very much for your suggestion. We will further modify the aspect ratio of the image so that it does not affect the final content of the image.
Comments 3: It is recommended to include a scale when applicable to visualize the size comparison between objects. For example, the rock samples in figure 9 look bigger than the loading pistons in figure 11. Having scales by the images or providing more in-text explanation assists.
Response 3: Thank you very much for your suggestion. We are very sorry for the error caused by the picture proportion, which makes the description in the paper inconsistent. We will further address this issue by adjusting the image proportions.
Comments 4: Curves in figure 15 should be presented in different line style for better differentiation.
Response 4: Thank you very much for your suggestion. For Figure 15, we will use two different styles of curves.
Comments on the Quality of English Language:
Comments 1: Some sentences are very long (about 10 lines long), breaking them to shorter sentences is recommend. For example: The 3rd last sentence in the abstract.
Response 1: Thank you very much for your suggestion. We split the long sentences of the paper into multiple simple sentences for readers to read and understand.
Comments 2: Avoiding word repetition is advisable. For example the work experiment is repeated after each test, where it is mentioned by experiments at the start of the statement as shown in “In order to investigate whether the water injection-induced dilation technology is suitable or not, these experiments are conducted to analyze the dilation potential for offshore low-permeability sandstone reservoirs, including X-ray diffraction experiment, laser particle size analysis experiment, physical simulation experiment, Computed Tomography scan experiment and electron microscope scanning experiment.”
Response 2: Thank you very much for your suggestions. We will further improve the logic of the paper, the clarity of the sentences, and reduce the reading amount of readers. Make the paper look more organized
