The seepage flow characteristics of hydrophobically associated polymers with different aggregation behaviours in porous media

The polymer solution for oil displacement is subjected to strong shear action in practical application, and this action will affect its percolation characteristics in porous media. The effects of mechanical shearing on the solution properties and seepage characteristics of modified hydrophobically associated polymers and dendrimers with two different aggregation behaviours were studied. The results showed that mechanical shearing did not affect hydrophobic microzones. Polymers can re-associate to restore part of the network structure, thereby improving shear resistance (dendritic hydrophobically associating polymers > hydrophobically modified partially hydrolysed polyacrylamide). Polymers with ‘cluster’ aggregation behaviour enhanced solution performance, enabling them to establish higher resistance coefficient (RF) and residual resistance factor (RRF) in porous media but also bringing about injection difficulties. Increasing the injection rate would increase the injection pressure, but the established RF and RRF showed a downward trend. Mechanical shear pretreatment effectively improved the injectability of the polymer. To achieve polymer injection and flow control, pre-shearing polymer solution and low-speed injection can be used in field applications.


Review form: Reviewer 2
Is the manuscript scientifically sound in its present form? Yes Are the interpretations and conclusions justified by the results? Yes P2 Abstract "Mechanical shear pretreatment effectively improves the injection conductivity of the polymer." Please explain "injection conductivity".
P3 "Although the bulk viscosity is irreversibly damaged, the structural viscosity is reconnected to form part of the spatial structure under the association effect, and the solution viscosity is restored." This sentence it confusing. Please rewrite this sentence to clarify what the authors mean.

P4 Experiment
Past tense should be used in describing the experiment procedure.
P4 "Experimental drugs": change to "Chemicals". P4 "Experimental equipment:": change to "Instruments". P4 "Experimental process device for core displacement". Please explain what it is. P4 "the other is DHAP…" Please include the full name of DHAP here.
P4 "Then, 20.16 g and 8.09 g of two methylene sulfoxide are added…" By methylene sulfoxide, I assume the authors mean dimethyl sulfoxide.
P4 Fig.2 The molecular structure of the HMPAM Please redo this scheme (using ChemDraw, etc.) to make it better. P5 "0.26 g solvent urea…" What is solvent urea? P9 3.1.2 Analysis of Microstructure Characteristics by AFM The AFM sample was prepared with evaporating the solvent with nitrogen flow. However, the structure of the polymer aggregates are very likely to change during the solvent loss process. Therefore the images can not be used as morphology representation for polymers in solution. I suggest the authors remove Fig. 8  P11 "As shear stress increases, the Ie/Im of 2000 mg/L HMPAM solution…" Please define Ie and Im here. P11-12 "Based on the effect of shear action on the hydrophobic microregion, we think the shear mainly destroys the polymer molecular chains." It is weird. It was likely not molecular chains but intermolecular packing that broke. You can never observe molecular chain breaking with SEM.
P12 "The shear action causes the breakage of some polymer chains and aggregates, …" The experiment was static adsorption, so why authors believe the polymers were sheared? The editor assigned to your manuscript has now received comments from reviewers. We would like you to revise your paper in accordance with the referee and Subject Editor suggestions which can be found below (not including confidential reports to the Editor). Please note this decision does not guarantee eventual acceptance.
Please submit your revised paper before 16-Oct-2019. Please note that the revision deadline will expire at 00.00am on this date. If we do not hear from you within this time then it will be assumed that the paper has been withdrawn. In exceptional circumstances, extensions may be possible if agreed with the Editorial Office in advance. We do not allow multiple rounds of revision so we urge you to make every effort to fully address all of the comments at this stage. If deemed necessary by the Editors, your manuscript will be sent back to one or more of the original reviewers for assessment. If the original reviewers are not available we may invite new reviewers.
To revise your manuscript, log into http://mc.manuscriptcentral.com/rsos and enter your Author Centre, where you will find your manuscript title listed under "Manuscripts with Decisions." Under "Actions," click on "Create a Revision." Your manuscript number has been appended to denote a revision. Revise your manuscript and upload a new version through your Author Centre.
When submitting your revised manuscript, you must respond to the comments made by the referees and upload a file "Response to Referees" in "Section 6 -File Upload". Please use this to document how you have responded to the comments, and the adjustments you have made. In order to expedite the processing of the revised manuscript, please be as specific as possible in your response.
Once again, thank you for submitting your manuscript to Royal Society Open Science and I look forward to receiving your revision. If you have any questions at all, please do not hesitate to get in touch. ********************************************** RSC Subject Editor: Comments to the Author: (There are no comments.) RSC Associate Editor: Comments to the Author: (There are no comments.) ********************************************** Reviewers' Comments to Author: Reviewer: 1 Comments to the Author(s) This manuscript describes the aggregation behaviour characteristics of hydrophobically modified partially hydrolysed polyacrylamide and branched hydrophobically associated polymer; reports the influence of shearing on the viscosity enhancement, aggregation behaviour, microstructure and static adsorption properties of polymer solutions and describes the percolation characteristics of polymers before and after mechanical shearing in porous media at different velocities. It has not been written carefully and not checked by the authors before submission. The organization of the manuscript is not good. The manuscript is not suitable for publication in the present form; it may be resubmitted after careful revision.
Some of my opinions and comments about this manuscript are as follows: 1) Page 2, lines 19-28: Please use past tenses in these sentences.

19) Pages 35 and 36:
• What are the titles of these tables? • These tables should be re-organized. • Please use subscript for "1" and "3" in "I1", "I3" and "I1/I3". Comments to the Author(s) This paper lays the groundwork for the application of polymer flooding technology in oilfield, studies the performance of polymer solutions with different aggregation behavior and their percolation characteristics in porous media. The correlation between polymer micro-aggregation behavior and macro-percolation is established to guide polymer synthesis according to the actual needs of oilfields. The whole content, structure and basic data of the paper are relatively perfect, which has certain application guiding value. Here are some suggestions and questions: 1) Whether mechanical shear action and mechanical degradation are meaningful, and whether the effect of mechanical shear action is consistent with that of polymer. Mechanical degradation is used more frequently in terminology. 2) Figures 8 and 9, which have two patterns, are best described in subheadings, such as (a) ……. and (b) . 3) For the first time in the abstract, HMPAM and DHAP should be introduced in full and then coded. 4) The format of papers must conform to the periodical norms 5) The introduction of synthetic drugs in this article is not perfect, including name, manufacturer and so on, so as to facilitate the experimental repeatability of other scholars.

Reviewer: 3
Comments to the Author(s) Overall, there are a number of serious flaws and the authors should address the following issues before it might possibly be published.
P2 Abstract "Mechanical shear pretreatment effectively improves the injection conductivity of the polymer." Please explain "injection conductivity".
P3 "Although the bulk viscosity is irreversibly damaged, the structural viscosity is reconnected to form part of the spatial structure under the association effect, and the solution viscosity is restored." This sentence it confusing. Please rewrite this sentence to clarify what the authors mean.

P4 Experiment
Past tense should be used in describing the experiment procedure.
P4 "Experimental drugs": change to "Chemicals". P4 "Experimental equipment:": change to "Instruments". P4 "Experimental process device for core displacement". Please explain what it is. P4 "the other is DHAP…" Please include the full name of DHAP here.
P4 "Then, 20.16 g and 8.09 g of two methylene sulfoxide are added…" By methylene sulfoxide, I assume the authors mean dimethyl sulfoxide.
P4 Fig.2 The molecular structure of the HMPAM Please redo this scheme (using ChemDraw, etc.) to make it better. P5 "0.26 g solvent urea…" What is solvent urea? P9 3.1.2 Analysis of Microstructure Characteristics by AFM The AFM sample was prepared with evaporating the solvent with nitrogen flow. However, the structure of the polymer aggregates are very likely to change during the solvent loss process. Therefore the images can not be used as morphology representation for polymers in solution. I suggest the authors remove Fig. 8  P10 "Compared with DHAP (molecular weight 600)" Please correct the number.

P11 Tab.3 Effect of different shear strengths on the number of hydrophobic microregions in polymer solution
Can the authors please elaborate on the Shear mode? P11 "As shear stress increases, the Ie/Im of 2000 mg/L HMPAM solution…" Please define Ie and Im here. P11-12 "Based on the effect of shear action on the hydrophobic microregion, we think the shear mainly destroys the polymer molecular chains." It is weird. It was likely not molecular chains but intermolecular packing that broke. You can never observe molecular chain breaking with SEM.
P12 "The shear action causes the breakage of some polymer chains and aggregates, …" The experiment was static adsorption, so why authors believe the polymers were sheared?
P19-P67 This part should be rewritten into some form of Supporting Information.

Author's Response to Decision Letter for (RSOS-191270.R0)
See Appendix A.

Do you have any ethical concerns with this paper? No
Have you any concerns about statistical analyses in this paper? No

Recommendation?
Accept with minor revision (please list in comments)

Comments to the Author(s)
The authors addressed most of my questions and I appreciate it. A minor request: Original question: 9) P11 "As shear stress increases, the Ie/Im of 2000 mg/L HMPAM solution…". Please define Ie and Im here. Thank you for submitting the above manuscript to Royal Society Open Science. On behalf of the Editors and the Royal Society of Chemistry, I am pleased to inform you that your manuscript will be accepted for publication in Royal Society Open Science subject to minor revision in accordance with the referee suggestions. Please find the reviewers' comments at the end of this email.
The reviewers and handling editors have recommended publication, but also suggest some minor revisions to your manuscript. Therefore, I invite you to respond to the comments and revise your manuscript.
Because the schedule for publication is very tight, it is a condition of publication that you submit the revised version of your manuscript before 14-Nov-2019. Please note that the revision deadline will expire at 00.00am on this date. If you do not think you will be able to meet this date please let me know immediately.
To revise your manuscript, log into https://mc.manuscriptcentral.com/rsos and enter your Author Centre, where you will find your manuscript title listed under "Manuscripts with Decisions". Under "Actions," click on "Create a Revision." You will be unable to make your revisions on the originally submitted version of the manuscript. Instead, revise your manuscript and upload a new version through your Author Centre.
When submitting your revised manuscript, you will be able to respond to the comments made by the referees and upload a file "Response to Referees" in "Section 6 -File Upload". You can use this to document any changes you make to the original manuscript. In order to expedite the processing of the revised manuscript, please be as specific as possible in your response to the referees.
When uploading your revised files please make sure that you have: 1) A text file of the manuscript (tex, txt, rtf, docx or doc), references, tables (including captions) and figure captions. Do not upload a PDF as your "Main Document". 2) A separate electronic file of each figure (EPS or print-quality PDF preferred (either format should be produced directly from original creation package), or original software format) 3) Included a 100 word media summary of your paper when requested at submission. Please ensure you have entered correct contact details (email, institution and telephone) in your user account 4) Included the raw data to support the claims made in your paper. You can either include your data as electronic supplementary material or upload to a repository and include the relevant doi within your manuscript 5) All supplementary materials accompanying an accepted article will be treated as in their final form. Note that the Royal Society will neither edit nor typeset supplementary material and it will be hosted as provided. Please ensure that the supplementary material includes the paper details where possible (authors, article title, journal name).
Supplementary files will be published alongside the paper on the journal website and posted on the online figshare repository (https://figshare.com). The heading and legend provided for each supplementary file during the submission process will be used to create the figshare page, so please ensure these are accurate and informative so that your files can be found in searches. Files on figshare will be made available approximately one week before the accompanying article so that the supplementary material can be attributed a unique DOI.
Once again, thank you for submitting your manuscript to Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry. I look forward to receiving your revision. If you have any questions at all, please do not hesitate to get in touch.  Thank you very much for your attention and the referees' valuable comments on our paper. We have revised the manuscript according to reviewers' comments. Enclosed please find the revised manuscript, responses to the referees as well as a list of changes. We sincerely hope this manuscript will be finally acceptable to be published on Royal Society Open Science. We look forward to hearing from you soon. Best regards Dr. zhu Reviewers' Comments to Author:

Reviewer: 1
Comments to the Author(s): This manuscript describes the aggregation behaviour characteristics of hydrophobically modified partially hydrolysed polyacrylamide and branched hydrophobically associated polymer; reports the influence of shearing on the viscosity enhancement, aggregation behaviour, microstructure and static adsorption properties of polymer solutions and describes the percolation characteristics of polymers before and after mechanical shearing in porous media at different velocities. It has not been written carefully and not checked by the authors before submission. The organization of the manuscript is not good. The manuscript is not suitable for publication in the present form; it may be resubmitted after careful revision.

Some of my opinions and comments about this manuscript are as follows:
1) Page 2, lines 19-28: Please use past tenses in these sentences.

Response:
According to experts'opinions, the contents of 19-28 are written in the past tense. The revises are as follows: "The results were showed that mechanical shearing did not affect hydrophobic microzones. Polymers can re-associate to restore part of the network structure, thereby improving shear resistance (dendritic hydrophobically associating polymers > hydrophobically modified partially hydrolysed polyacrylamide). Polymers with "cluster" aggregation behaviour enhanced solution performance, enabling them to establish higher resistance coefficient (RF) and residual resistance factor (RRF) in porous media but also bringing about injection difficulties. Increasing the injection rate would increase the injection pressure, but the established RF and RRF showed a downward trend. Mechanical shear pretreatment effectively improved the injectivity of the polymer. " 2) Page 2, lines 22 and 23: Abbreviations "DHAP" and "HMPAM" should be defined at first mention. Response: The revises are as follows: "DHAP" change to "dendritic hydrophobically associating polymers" "HMPAM" change to "hydrophobically modified partially hydrolysed polyacrylamide".
3) Page 3, line 9: After this sentence, I suggest the authors that the following sentence  Response: The problem in the diagram was revised. "Volum" change to "Volume".

Response:
The format was revised according to the periodical requirements.

18) Pages 20-34:
• What are the titles of these tables? • Furthermore, they should be given in Supplementary Materials.

Response:
The original data in Figures 5 and 6.