Quantitative Characterization of Deep Shale Gas Reservoir Pressure-Solution and Its Influence on Pore Development in Cases of Luzhou Area in Sichuan Basin

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Overall Assessment

This is a well-designed and scientifically sound study that makes a novel contribution to the understanding of diagenetic processes in deep shale gas reservoirs. The manuscript presents valuable data and introduces a useful quantitative parameter (Qp) for characterizing pressure-solution. It is recommended for publication after minor revisions.

Specific Suggestions for Improvement:

1. Title Refinement:Consider refining the title to be more concise and impactful. Suggested alternatives include:

"Quantitative Characterization of Pressure-Solution and Its Impact on Pore Development in Deep Longmaxi Shale, Sichuan Basin"

"The Role of Pressure-Solution in Pore Evolution of Deep Shale Gas Reservoirs: A Case Study from the Luzhou Area"

2.Abstract Strengthening: Replace tentative phrasing like "We believe that..." with more definitive statements such as "Our results demonstrate that...". Furthermore, explicitly state that the established thresholds (Sw>40%, Quartz>70%) provide a critical criterion for de-risking exploration and sweet-spot identification.

3.Sharpening the Introduction: Formulate a central scientific question in the introduction to heighten the study's intellectual focus. For example: "How does pressure-solution quantitatively control pore system evolution in deep shale reservoirs, and what are its key geological drivers?"

4.Deepening Phenomenological Analysis: In Section 5.1.1, add a concluding sentence that explicitly links the three described microscopic phenomena (particle fusion, sutures, dissolution) to the fundamental processes of dissolution, transport, and precipitation under stress from classic PS theory.

5.Justifying the Qp Parameter: In Section 5.1.2, provide a more robust geological justification for the Q_p formula. Elaborate on how it conceptually captures the increase in quartz proportion (C_q) from mineral transformation and the increase in quartz grain size (D_q) relative to the rock matrix (D_m) from grain coalescence.

6.Elaborating the Evolutionary Model: In Section 5.4, explicitly frame the impact of PS as a two-stage, competing process: a) a constructive phase (Q_p < ~55%) where silica cementation strengthens the framework and preserves porosity, and b) a destructive phase (Q_p > ~55%) where excessive fusion and cementation occlude pores. Clearly state these thresholds in the text and consider marking them in Figure 11.

7.Exploring Quartz Origins: In the discussion on mineral composition (Section 5.3.3), briefly discuss whether different quartz origins (e.g., detrital vs. authigenic) might exhibit different susceptibilities or responses to pressure-solution, adding a layer of detail to the analysis.

8.Language and Terminology Polish: Conduct a thorough proofreading to ensure consistent use of terminology (e.g., standardize on "Pressure-solution (PS)") and replace informal phrases (e.g., "real-drilled core") with standard scientific equivalents ("drilled core" or "core samples").

Author Response

Reviewer 1#

Specific Suggestions for Improvement:

Q1.Title Refinement:Consider refining the title to be more concise and impactful. Suggested alternatives include:

"Quantitative Characterization of Pressure-Solution and Its Impact on Pore Development in Deep Longmaxi Shale, Sichuan Basin"

"The Role of Pressure-Solution in Pore Evolution of Deep Shale Gas Reservoirs: A Case Study from the Luzhou Area"

Reply：it has been revised.

Q2.Abstract Strengthening: Replace tentative phrasing like "We believe that..." with more definitive statements such as "Our results demonstrate that...". Furthermore, explicitly state that the established thresholds (Sw>40%, Quartz>70%) provide a critical criterion for de-risking exploration and sweet-spot identification.

Reply：it has been revised.

Q3.Sharpening the Introduction: Formulate a central scientific question in the introduction to heighten the study's intellectual focus. For example: "How does pressure-solution quantitatively control pore system evolution in deep shale reservoirs, and what are its key geological drivers?"

Reply：We added the following statement to the manuscript.

Therefore, this study is designed to address a central scientific question: How does pressure-solution quantitatively control pore system evolution in deep shale reservoirs, and what are its key geological drivers? To answer this question, we focus on the following specific objectives: (1) to characterize the phenomena of PS and establish a quantitative parameter for its intensity; (2) to identify and quantify the key geological factors controlling PS; (3) to unravel the mechanistic links between PS intensity and the evolution of pore networks.

Q4.Deepening Phenomenological Analysis: In Section 5.1.1, add a concluding sentence that explicitly links the three described microscopic phenomena (particle fusion, sutures, dissolution) to the fundamental processes of dissolution, transport, and precipitation under stress from classic PS theory.

Reply：We added the following statement to the manuscript.

In summary, the disappearance of particle contours and mineral fusion represent the culmination of the PS process, where dissolution at contacts and precipitation in pores leads to textural homogenization. The observed discontinuous sutures and increased grain size are direct evidence of localized dissolution followed by the precipitation of the dissolved phase. Finally, the development of intergranular dissolution pores with subsequent organic matter infill captures an intermediate stage where transport and precipitation have not yet fully occluded the porosity. Collectively, these three microscopic phenomena provide direct visual evidence for the fundamental trilogy of pressure-solution: dissolution at grain contacts, mass transport along grain boundaries, and re-precipitation in adjacent pore spaces.

Q5.Justifying the Qp Parameter: In Section 5.1.2, provide a more robust geological justification for the Qp formula. Elaborate on how it conceptually captures the increase in quartz proportion (Cq) from mineral transformation and the increase in quartz grain size (Dq) relative to the rock matrix (Dm) from grain coalescence.

Reply：We added the following statement to the manuscript.

The Qp parameter physically represents the intensity of fabric modification driven by pressure-solution. It integrates the enrichment of quartz content (Cq) from silica redistribution and the relative coarsening of quartz grains (Dq/Dm), which results from the dissolution of smaller grains and reprecipitation on larger ones. The ratio Dq/Dm specifically isolates the diagenetic coarsening from the detrital background, making Qp a direct metric for the extent of textural equilibration achieved through intergranular dissolution-precipitation creep.

Q6.Elaborating the Evolutionary Model: In Section 5.4, explicitly frame the impact of PS as a two-stage, competing process: a) a constructive phase (Qp < ~55%) where silica cementation strengthens the framework and preserves porosity, and b) a destructive phase (Qp > ~55%) where excessive fusion and cementation occlude pores. Clearly state these thresholds in the text and consider marking them in Figure 11.

Reply：Our decision is based on the fact that the transitional QP value of ~55%, while evident in our dataset (Fig. 11), is interpreted as a characteristic of the specific samples in our study area. We feel that framing it as a universal, two-stage model might over-generalize the findings at this stage. However, to enhance clarity, we have now explicitly stated in the text that the peak in pore volume at Qp ~55% represents a transition from a net preservational to a net destructive regime of pressure-solution, and we have added a vertical dashed line at Qp = 55% in Figure 11 to visually highlight this inflection point.

Q7.Exploring Quartz Origins: In the discussion on mineral composition (Section 5.3.3), briefly discuss whether different quartz origins (e.g., detrital vs. authigenic) might exhibit different susceptibilities or responses to pressure-solution, adding a layer of detail to the analysis.

Reply：We thank the reviewer for raising this interesting point regarding the potential differential behavior of detrital versus authigenic quartz during pressure-solution. In the current study, our methodology and dataset are focused on establishing the net, bulk consequence of pressure-solution on the shale fabric, for which the QP parameter is well-suited. While we agree that distinguishing quartz origins could add a valuable layer of detail, it falls beyond the primary scope of this work, which is to define and calibrate the regional impact of the process. We have therefore incorporated a sentence in the conclusion (or discussion) to acknowledge this complexity and to highlight it as a recommended focus for future research employing more advanced techniques, such as high-resolution cathodoluminescence (CL) imaging.

Q8.Language and Terminology Polish: Conduct a thorough proofreading to ensure consistent use of terminology (e.g., standardize on "Pressure-solution (PS)") and replace informal phrases (e.g., "real-drilled core") with standard scientific equivalents ("drilled core" or "core samples").

Reply：it has been revised and checked.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript provides a detailed quantitative investigation of pressure-solution (PS) processes in deep shale gas reservoirs of the Longmaxi Formation in the Sichuan Basin, with a focus on their influence on pore structure evolution. The authors combine multi-scale experimental techniques, including FE-SEM (Maps), low-pressure nitrogen adsorption, and high-pressure mercury intrusion, to establish a semi-quantitative model (QP parameter) correlating PS intensity with mineralogical and petrophysical properties.

The paper is technically sound and addresses a timely and underexplored aspect of shale diagenesis in deep marine systems: the coupling between PS, mineral composition (particularly quartz content), and pore development. The integration of microscopy, mineral quantification, and petrophysical measurements is commendable, and the dataset is rich. However, several parts of the manuscript would benefit from clearer explanations, structural refinement, and improved English readability. Conceptual discussion of the pressure-solution mechanism and its thermodynamic background remains limited, and some figures and methodological details require clarification to enhance reproducibility and interpretation. Overall, the study offers valuable contributions to understanding diagenetic controls on pore evolution in deep shale gas reservoirs, but major revisions are needed before acceptance.

Major Comments:

• The introduction should better distinguish this study from previous works (e.g., Dong et al., 2019; Gao et al., 2022; Wu et al., 2018) that discussed silica diagenesis and quartz transformation in the Longmaxi Formation.
• Clarify how the newly proposed QP parameter quantitatively improves upon prior semi-empirical diagenetic indices. Include a brief comparison with previous porosity evolution models or quartz cementation indices.
• The QP formula is a useful metric, but the physical meaning and justification are not fully elaborated (line 312).
• Several figures (e.g., Figs. 3, 5, 7, 10, and 11) require higher resolution and clearer labeling. SEM-Maps images should have scale bars and mineral annotation layers visible.
• Figure 11 (pore parameter variation vs. PS) is key to the interpretation—consider including R² values or fitted trendlines.
• A schematic diagram summarizing the conceptual mechanism linking PS → mineral fusion → pore reduction (complementing Fig. 12) would enhance clarity.
• The discussion of how water saturation enhances PS (Section 5.3.2) should include more thermodynamic and kinetic reasoning. For example, describe how increased water film thickness around grains promotes diffusion and mineral re-precipitation.
• The coupling between PS and quartz recrystallization (authigenic quartz growth) could be discussed in the context of chemical potential gradients or dissolution-precipitation creep models.
• While nitrogen adsorption and mercury intrusion cover complementary pore-size ranges, the method of merging datasets (BJH + MIP) needs more clarity. Specify how overlaps were corrected and whether scaling factors were applied.
• It would strengthen the work to present one representative integrated pore-size distribution curve combining all techniques.

Minor Comments:

• In the Keywords: Consider replacing “burial depth” with “burial diagenesis” and adding “pressure-solution intensity” for indexing.
• Add coordinates or scale for the study area map presented in Fig.1.
• Maintain consistent units (e.g., μm vs. um, % vs. wt.%).
• Clarify how average particle size was determined (mean area equivalent diameter?) in Table 1.
• Conclusion point (3) uses “Permeability of Shale (PS)”—please correct, PS here refers to pressure-solution, not permeability.

 

Author Response

Reviewer 2#

Q1.The introduction should better distinguish this study from previous works (e.g., Dong et al., 2019; Gao et al., 2022; Wu et al., 2018) that discussed silica diagenesis and quartz transformation in the Longmaxi Formation.

Reply：it has been revised

Previous researchers have had a deep understanding of the mechanical compaction effect of shale pore spaces [30,31]. The primary minerals in the Longmaxi Formation shale are quartz and clay, with diagenesis inevitably and closely linked to these minerals. Previous studies have extensively documented the sources and diagenetic evolution of quartz in the Longmaxi Formation, including the roles of biogenic silica, clay mineral transformation, and detrital input[32,33,34]. Furthermore, the interplay between quartz cementation, thermal maturity, and pore preservation has been a focus of research[35,36]. However, these studies have primarily focused on silica cementation and its preservational effect, often overlooking the specific process of pressure-solution (PS) and its quantitative impact on mineral fusion and pore destruction, particularly under the high water saturation conditions prevalent in deep reservoirs. Typically, the organic content in shale is positively correlated with quartz[37,38]. A higher quartz content ensures better protection for the development of organic pores within the organic matter due to the quartz particle framework [39,40]. Microcrystalline quartz, resulting from the transformation of clay diagenesis, may have a restricted impact on pore preservation (Xu et al., 2021; Dong et al., 2019). However, some studies have shown that an excessive increase in quartz content and quartz grain size is not conducive to the development of pores, but they do not explain the reasons for the increase in quartz content and quartz grain size [41,42]. It can be seen that people pay more attention to the mutual transformation of quartz and clay in shale reservoirs, while ignoring the PS of shale reservoirs. Concurrently, as deep shale gas exploration and development progress, numerous shale reservoirs with high water saturation have been encountered [43,44]. With the increase in water saturation and pressure, the diagenetic processes of shale become more complex, PS will become more prevalent, affecting the development of pores in the shale reservoir [45]. However, the factors influencing PS in deep shale reservoirs and their control over pore development remain poorly understood. So, unraveling the mechanisms behind high porosity development in deep shale reservoirs proves challenging.

 

 

Q2.Clarify how the newly proposed QP parameter quantitatively improves upon prior semi-empirical diagenetic indices. Include a brief comparison with previous porosity evolution models or quartz cementation indices.

Reply：We added the following statement to the manuscript.

The QP parameter provides a quantitative advancement over previous semi-empirical diagenetic indices by integrating two direct consequences of pressure-solution—the enrichment of quartz content (Cq) and the relative coarsening of quartz grains (Dq/Dm)-into a single metric. This offers an objective measure of diagenetic intensity, moving beyond qualitative descriptions of fabric maturity. In contrast to quartz cementation models that primarily predict porosity loss from authigenic pore-filling, the QP parameter specifically quantifies the fabric reorganization and concomitant porosity destruction attributable to intergranular dissolution and reprecipitation under differential stress. It thus serves as a complementary diagenetic index, uniquely quantifying the extent of textural equilibration driven by PS.

 

Q3.The QP formula is a useful metric, but the physical meaning and justification are not fully elaborated (line 312).

Reply：We added the following statement to the manuscript.

The Qp parameter physically represents the intensity of fabric modification driven by pressure-solution. It integrates the enrichment of quartz content (Cq) from silica redistribution and the relative coarsening of quartz grains (Dq/Dm), which results from the dissolution of smaller grains and reprecipitation on larger ones. The ratio Dq/Dm specifically isolates the diagenetic coarsening from the detrital background, making Qp a direct metric for the extent of textural equilibration achieved through intergranular dissolution-precipitation creep.

Q4.Several figures (e.g., Figs. 3, 5, 7, 10, and 11) require higher resolution and clearer labeling. SEM-Maps images should have scale bars and mineral annotation layers visible.

Reply：it has been revised

 

Q5.Figure 11 (pore parameter variation vs. PS) is key to the interpretation—consider including R² values or fitted trendlines.

Reply：We thank the reviewer for this suggestion. We have considered adding R² values or trendlines to Figure 11. However, after careful evaluation, we found that the relationships are primarily descriptive and illustrative of the proposed two-stage model, rather than being based on a statistically significant curve fit. Therefore, we believe that adding fitted lines might be misleading. Instead, we have opted to enhance the figure caption and the corresponding text in Section 5.4 to more explicitly describe the observed trends and the conceptual transition at the Qp ~55% threshold.

 

Q6.A schematic diagram summarizing the conceptual mechanism linking PS → mineral fusion → pore reduction (complementing Fig. 12) would enhance clarity.

Reply：We thank the reviewer for this constructive suggestion. While we agree that a schematic diagram could be useful, we feel that creating a new, generalized schematic based on the current dataset might be overly speculative. The processes of pressure-solution and mineral fusion are highly heterogeneous and context-dependent. Therefore, we believe that the existing high-resolution FE-SEM images in Figures 3, 5, and 7 already provide direct and compelling visual evidence for the mechanistic chain from pressure-solution to mineral fusion and pore reduction. To enhance clarity as the reviewer suggested, we have instead significantly expanded the textual description in Section 5.4 to explicitly and systematically articulate this conceptual linkage, guiding the reader through the evidence in the existing figures.

 

Q7.The discussion of how water saturation enhances PS (Section 5.3.2) should include more thermodynamic and kinetic reasoning. For example, describe how increased water film thickness around grains promotes diffusion and mineral re-precipitation.

Reply:We added the following statement to the manuscript.

The enhancement of PS by high water saturation is governed by coupled thermodynamic and kinetic effects. Thermodynamically, water lowers the activation energy for stress-induced dissolution at grain contacts. Kinetically, thicker water films around grains, resulting from higher saturation, drastically enhance the diffusion rates of dissolved silica from dissolution sites to precipitation sites. This accelerates the entire dissolution-precipitation creep cycle, intensifying the fabric reorganization and porosity reduction characteristic of PS.

 

Q8.The coupling between PS and quartz recrystallization (authigenic quartz growth) could be discussed in the context of chemical potential gradients or dissolution-precipitation creep models.

Reply:We added the following statement to the manuscript.

The PS process is intrinsically coupled with quartz recrystallization and authigenic growth through a dissolution-precipitation creep mechanism governed by chemical potential gradients [66]. Differential stress establishes a thermodynamic driving force, wherein the chemical potential of silica is elevated at grain-to-grain contacts (high-stress dissolution sites) relative to adjacent pore spaces or free grain surfaces (low-stress precipitation sites). This gradient drives the dissolution of quartz at contacts and the simultaneous diffusion and reprecipitation of silica (as H4SiO4) onto the surfaces of authigenic quartz. Consequently, the observed mineral fusion and the concomitant increase in both quartz content and grain size are direct manifestations of this stress-induced, fluid-mediated mass transfer. This model unifies the phenomena of pressure-solution and quartz cementation, explaining how they operate in concert to reconfigure the shale fabric and reduce porosity.

 

Q9.While nitrogen adsorption and mercury intrusion cover complementary pore-size ranges, the method of merging datasets (BJH + MIP) needs more clarity. Specify how overlaps were corrected and whether scaling factors were applied.

Reply:We added the following statement to the manuscript.And thee was no applied scaling factos.

To comprehensively characterize the full-aperture pore characteristics, a multi-scale integration method was adopted. The nitrogen adsorption data (DFT model) was directly used for micropores (<2 nm). For the mesopore range (2–50 nm), a unified approach was applied: data from the BJH model (derived from N2 adsorption) was given priority, as it more accurately reflects the pore-body size distribution. Mercury intrusion porosimetry (MIP) data, which characterizes pore-throat sizes, was relied upon exclusively for macropores (>50 nm). In the overlapping mesopore range, no scaling factor was applied; instead, the BJH data was preferentially used to avoid the well-known underestimation of pore volume by MIP in this range due to the "ink-bottle" effect and pore-throat access limitations. This approach ensures a more accurate representation of the pore-volume distribution across the entire spectrum.

 

Q10.It would strengthen the work to present one representative integrated pore-size distribution curve combining all techniques.

Reply:We thank the reviewer for this suggestion. We agree that a representative integrated curve could be illustrative. In our study, the full-aperture pore size distribution was reconstructed for each individual sample using the integrated method detailed in Section 4.2. Presenting a single curve for one sample might not fully capture the sample heterogeneity that is central to our findings. Instead, the key results of this integration are effectively presented in Fig. 7, which statistically summarizes the pore volume distribution across the entire sample set with different PS intensities. We believe Fig. 7 more robustly conveys the general trends we wish to highlight. To improve clarity, we have now explicitly stated in the figure caption of Fig. 7 that the data are derived from the integrated BJH+MIP dataset.

 

Q11.In the Keywords: Consider replacing “burial depth” with “burial diagenesis” and adding “pressure-solution intensity” for indexing.

Reply：it has been revised

 

Q12.Add coordinates or scale for the study area map presented in Fig.1.

Reply：it has been revised

 

Q13.Maintain consistent units (e.g., μm vs. um, % vs. wt.%).

Reply：it has been revised

 

Q14.Clarify how average particle size was determined (mean area equivalent diameter?) in Table 1.

Reply:We added the following statement to the manuscript.

The QEMSCAN technique enables the acquisition of both the surface area and particle count of different minerals within the mapping field of view. From this data, the average surface area of each mineral can be derived. By approximating mineral particles as circular shapes, the average particle size for all minerals, as well as for individual mineral types, can be calculated.

Q15.Conclusion point (3) uses “Permeability of Shale (PS)”—please correct, PS here refers to pressure-solution, not permeability.

 Reply：it has been revised

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

my comments are attached.

Best regards

Comments for author File: Comments.pdf

Author Response

Reviewer 3#

Q1.Do you consider the topic original or relevant in the field? Does it address a specific gap in the field? The work is experimental in nature, contains original measurement data, and presents interesting conclusions based on this experimental data.

 Reply：We thank the reviewer for their positive assessment of our work. We firmly believe this study is both original and highly relevant, as it addresses a critical gap in understanding diagenetic processes in deep shale reservoirs. While pressure-solution is a known phenomenon, our work provides the first quantitative framework for characterizing its intensity in deep, high-water-saturation shales through the novel QP parameter. More importantly, we reveal the dual role of pressure-solution in pore evolution—shifting from pore-preserving to pore-destructive beyond specific thresholds of water saturation (~40%) and quartz content (~70%). This finding provides crucial geological criteria for de-risking deep shale gas exploration, where conventional models based on shallow reservoirs prove inadequate. Thus, our study offers both a novel methodological approach and practical insights for predicting reservoir quality in challenging deep shale environments.

Q2.What does it add to the subject area compared with other published material? The authors investigated the characteristics of PS in shale deposits, analyzed the geological factors influencing PS, and described the mechanism by which PS influences pore development in shale deposits.

 Reply：We thank the reviewer for this pertinent question. Our work provides three distinct advances beyond existing literature. First, we introduce the first quantitative parameter (QP) to characterize pressure-solution intensity in shales, enabling systematic comparison of diagenetic degree. Second, we reveal the dual role of pressure-solution in pore evolution - transitioning from pore-preserving to destructive beyond specific thresholds - challenging the conventional wisdom that high quartz content universally benefits reservoir quality. Third, we establish the mechanistic link between water saturation and PS enhancement through dissolution-precipitation creep processes. Collectively, these findings provide crucial predictive criteria for evaluating deep shale reservoir quality in high-fluid-pressure environments.

 

Q3.What specific improvements should the authors consider regarding the methodology? What further controls should be considered? It's good measurement practice to take measurement errors into account. Please, if possible, supplement your work with an estimate of measurement errors.

 Reply：We thank the reviewer for this pertinent question.

 

Q4.Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed? The conclusions are correct.

 Reply：We thank the reviewer for this pertinent question.

 

Q5.Are the references appropriate? The references are appropriate.

 Reply：We thank the reviewer for this pertinent question.

 

Q6.Please include any additional comments on the tables and figures. • Table 1: With what accuracy the values of parameters are given? Please standardize the significant numbers of each parameter. • Figure 2: Unclear - maybe too many curves in one figures. • Figure 9a: Please explain why the slope lines are drawn this way. • Figure 10c: Authors write „… no apparent correlation exists between PS parameters and carbonate mineral content (Fig 10c).” - while the figure shows a weak decreasing relationship.

 Reply：We thank the reviewer for their careful review and valuable comments regarding the tables and figures. We have addressed each point as follows:

 

Regarding Table 1: The reviewer is correct. We have standardized the significant figures for all parameters to ensure consistency. Depths are now reported to one decimal place (e.g., 4137.5), TOC and mineral contents to one decimal place (e.g., 4.1%, 69.3%), water saturation and porosity to one decimal place (e.g., 28.9%, 3.6%), pore volume to four decimal places (e.g., 0.0178 cm³/g), and particle sizes to two decimal places (e.g., 1.19 μm). This standardization improves the table's readability and precision.

 

Regarding Figure 2:it has been revised

 

Regarding Figure 9a: The slope line in Figure 9a represents a segmented linear regression that best fits the data distribution. The breakpoint in the slope was statistically identified near the 40% water saturation threshold discussed in the text. The initial, steeper slope indicates a stronger response of PS to increasing water saturation in the lower range, while the flatter slope beyond ~40% suggests a diminishing effect, likely due to the approach of a physical limit for water film thickness and its impact on diffusion rates. We have added this explanation to the figure caption.

 

Regarding Figure 10c: We thank the reviewer for this astute observation. We have rephrased the text to state: "In the study area, a weak negative correlation exists between PS parameters and carbonate mineral content (Fig 10c), although it is not statistically significant . The relatively dispersed distribution and low contact density of carbonate minerals in the Longmaxi Formation shales render their content a secondary factor influencing PS compared to quartz and clay minerals." This more accurately describes the observed trend while supporting our conclusion about its limited influence.

 

Q7. Other comments: • Editorial errors - for example line 11 • 3. Experiments: what type of X-ray diffraction analyzer was used – there is no information on this in the text. • 3.3. Scanning Electron Microscope…: Authors write: „ …the polished sample was coated…” - there is no information about what layer it is. • 5.3.2. Water saturation: Authors write: „The results revealed a notable positive correlation between PS parameters and water saturation (Fig 9a).” - please explain what does it means.

 Reply：We thank the reviewer for these insightful comments. We have corrected the editorial errors and added the missing methodological details as follows:

 

Editorial errors (e.g., line 11): We have thoroughly proofread the manuscript to correct typographical and grammatical errors.

 

X-ray diffraction analyzer: The analysis was performed using a Rigaku D/max-2550 PC X-ray diffractometer (added to Section 3.2).

 

SEM sample coating: The polished samples were coated with a ~10 nm thick gold-palladium (Au-Pd) conductive layer to prevent charging under the electron beam (added to Section 3.3).

 

Correlation explanation (Fig. 9a): The "notable positive correlation" indicates that the PS parameter (Qp) systematically increases with rising water saturation (Sw), suggesting that higher water content in the shale promotes the pressure-solution process. The trend is not perfectly linear, and we have updated the text to describe it as a positive trend with a threshold effect, which is more accurate.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is accepted as revised. Thank you for thoroughly addressing all comments.

Comments on the Quality of English Language

The quality of the English has noticeably improved in the revised manuscript.