Experimental Study on Particle-Based Temporary Plugging Material Selection and Diversion Law of Shale Gas Reservoirs in WY Area, Sichuan, China
, Longfei Fan 1,2,3 and Panyang Guo 1,2,3Round 1
Reviewer 1 Report
A photo of the used 3D printer is to be added.
The characteristics of the 3D printer are to be mentioned.
The schematics of the Pressure-bearing capacity test experimental device and True three-axis physical simulation system, including the main components and a legend are to be added for a better understanding of the experiments.
The type of sensors used in the measurement are to be mentioned.
An experimental uncertainty study is to be performed.
In figure 5, for the concentration 24 kg/cm3, how can you explain the pressure drop at t = 24 min (approximately)? Is it an experimental error or a physical phenomenon?
In figure 7, why the Pressure curves are limited to only 2 concentrations?
The legend of Fig. 11 is very confusing, it is better to use, case 1, case 2….., and explain each case in the title of the figure and the in the descriptive text. (the same for Figs.13 and 15)
Have you checked the repetitions of the results, by using similar samples at same conditions?
Some quantitative findings are to be added to the conclusion.
The English level is to be improved.
Author Response
Response to Reviewer 1 Comments
Point 1: A photo of the used 3D printer is to be added.The characteristics of the 3D printer are to be mentioned.
Response 1: Thanks for your suggestion. Figure 1 has been modified to 3D scanning of fractured rock slab and real object.
Figure 1. 3D scanning of fractured rock slabs.
Point 2: The schematics of the Pressure-bearing capacity test experimental device and True three-axis physical simulation system, including the main components and a legend are to be added for a better understanding of the experiments.
Response 2: Thanks for your suggestion. In Figure 2 and figure 3, the Pressure-bearing capacity test experimental device and True three-axis physical simulation system are added respectively, and the main components and a legend are added at the same time.
Figure 2. Physical and schematic diagrams of Pressure-bearing capacity test experimental device.
Note :1-Pressure pump ( ISCO single pump ) ;2- Injection pump ( ISCO dual pump ) ; 3-Pressure machine ;4- Diversion chamber ; 5 - Intermediate container ; 6 - Pressure sensor ; 7-Beaker ; 8-Computer
Figure 3. Physical and schematic diagrams of True three-axis physical simulation system.
Note: 1 - Pressure plate ; 2-Natural outcrop ; 3 - Intermediate container ; 4 - Injection pump ( ISCO dual pump ) ; 5 - Pressure sensor ; 6 - Computer
Point 3: The type of sensors used in the measurement are to be mentioned.
Response 3: Thanks for your suggestion. The pressure sensitive sensor is used, and the accuracy is 0.01.
Point 4: An experimental uncertainty study is to be performed.
Response 4: Thanks for your suggestion. The data is transmitted from the sensor to the computer. We have carried out many experiments. The value in this paper is the average value of the experiment, which is more convincing.
Point 5: In figure 5, for the concentration 24 kg/cm3, how can you explain the pressure drop at t = 24 min (approximately)? Is it an experimental error or a physical phenomenon?
Response 5: Thanks for your suggestion. The liquid supply in this experiment was circulated by AB double pumps, and there was a short-term pressure drop in the pump changing process, which was neither an experimental error nor a physical phenomenon.
Point 6: In figure 7, why the Pressure curves are limited to only 2 concentrations?
Response 6: Thanks for your suggestion. Due to the 4mm gap width corresponding to the concentration of 12 kg/cm3 can not achieve temporary plugging effect ( time consuming is too long ), so it is not put into the figure.
Point 7: The legend of Fig. 11 is very confusing, it is better to use, case 1, case 2….., and explain each case in the title of the figure and the in the descriptive text. (the same for Figs.13 and 15)
Response 7: Thanks for your suggestion. The full paper has classified such problems, and the full text paper and figures use the case format.
Point 8: Have you checked the repetitions of the results, by using similar samples at same conditions?
Response 8: We have checked the repetitions of the results, by using similar samples at same conditions. Meanwhile,we got the same result.
Point 9: Some quantitative findings are to be added to the conclusion.
Response 9: Thanks for your suggestion. The conclusion has been rewritten.
Point 10: The English level is to be improved.
Response 10: Thanks for your suggestion. Considering the Reviewer’s suggestion, we will take great effort to modify the sentence to make it more professional. I hope it can meet with requirement.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Authors,
I think that the manuscript (MS) must be improved.
The Authors use a repetitious style, they use the same words in the same phrase. They must improve this point to facilitate the reading.
The abstract exceeds the 200 words.
Lines 18-22: it is not clear, please rewrite.
Line 26: why you put a symbol in the abstract?
Lines 48-111: they contain a long list of other works. This list must be shortened and more focused.
Lines 111-124: could you better explain the link (and the importance of your work) between the lacking of “systematic physical model”, and your experiment?
I have a general discussion about the figure in the MS:
- Figure 1: please describe part a and b.
- Figure 2 and 3 must be joined in one Figure 2a and 2 b. The same for 5 and 6, 7 and 8, 9 and 10, 11 and 12, 13 and 14.
- Line 131-147: please remove the symbols describing the content.
Lines 177-178: five or four ratios?
Please add a table in which you put the different trials.
Please divide all the number from their measuring unit living a space.
Lines 210-212: what is it? A part of template?
Lines 214-216: you could give this information in the introduction because it is important to understand your aim.
Line 244-252: could you add a table to make the reading and comparison more easy to the readers?
Line 410: could you specify how you create the diagrams?
Add the color legends in figures 21 and 22.
Line 444: please add a space between the tests number.
Line 470: Darcy flow is not explained before.
Could you better explain the point 3 of the conclusion?
Line 486: formation of…
Best regards
Author Response
Response to Reviewer #2:
- The Authors use a repetitious style, they use the same words in the same phrase. They must improve this point to facilitate the reading.
Reply: Thanks for your suggestion. We have modified the full paper and such issues have been resolved.
- The abstract exceeds the 200 words.
Reply: Thanks for your suggestion. Abstract has been modified again.
Temporary plugging agent is one of the effective methods for increasing production in old wells. In view of the temporary plugging materials used in the remote WY area, the concentrations ( 12.0, 18.0, 24.0 kg / m3 ) and ratios ( 1:4, 1:2, 1:1, 2:1, 4:1 ) under different fracture width were designed and optimized. Based on this, the fracture diversion under true triaxial stress is studied. The results showed that when the fracture widths are 2.0, 4.0, or 6.0mm, the corresponding optimal plugging scheme is that the concentration of temporary plugging agent are 12.0, 18.0 or 18.0 kg/m3 and the ratio of 20-70 mesh to 200-300 mesh temporary plugging agent are 4:1, 2:1 or 4:1, respectively. When maintaining the same horizontal stress, the greater the axial stress, the greater the fracture pressure; the initial fractures almost propagate along the direction of horizontal maximum principal stress σH, but the shape of turning fractures is quite different. When the axial stress is the same, the greater the horizontal stress difference, the corresponding fracture pressure decreases, and the degree of fracture turning decreases gradually. This study provides a basis for numerical simulation and field application of temporary plugging fracturing at fracture ends.
- Lines 18-22: it is not clear, please rewrite.
Reply: Thanks for your suggestion. The sentence has been modified to “When the axial stress is the same, the greater the horizontal stress difference, the corresponding fracture pressure decreases, and the degree of fracture turning decreases gradually.”
- Line 26: why you put a symbol in the abstract?
Reply: Thanks for your suggestion. That's the article template.
- Lines 48-111: they contain a long list of other works. This list must be shortened and more focused.
Reply：Thanks for your suggestion. This part has been shortened and more concise.
- Lines 111-124: could you better explain the link (and the importance of your work) between the lacking of “systematic physical model”, and your experiment?
Reply: Thanks for your suggestion. Previous studies mostly focused on particles and fibers. We focused on small particles (relatively large mesh). In view of the similarity in principle, we used the same physical model to verify.
- I have a general discussion about the figure in the MS:Figure 1: please describe part a and b.
Reply: Thanks for your suggestion. Originally, a and B in Figure 1 are the rock plate diagrams used in the experiment, which are derived from 3D printing and simulated etching. Figure 1 has been modified to 3D scanning of fractured rock slab and real object.
Figure 1. 3D scanning of fractured rock slabs.
- Figure 2 and 3 must be joined in one Figure 2a and 2 b. The same for 5 and 6, 7 and 8, 9 and 10, 11 and 12, 13 and 14.
Reply:Thanks for your suggestion. All Figures have been modified according to this format.
- Line 131-147: please remove the symbols describing the content.
Reply: Thanks for your suggestion. We have revised such issues in the full paper.
- Lines 177-178: five or four ratios?
Reply: Thanks for your suggestion. With the increase of fracture width, low concentration can not achieve temporary plugging. For example, the concentration of 4mm joint width is 12 kg/m3 and the concentration of 6mm fracture width is 12 and 18 kg/m3, and the pressure rise is too slow, so it is not reflected in the curve.
- Please add a table in which you put the different trials.
Reply: Thanks for your suggestion. Since there are five groups of true triaxial experiments and there are many curves and rock samples, this paper mainly summarizes 1 and 2.
- Please divide all the number from their measuring unit living a space.
Reply: Thanks for your suggestion. All numbers are guaranteed from the units of measurement in which they live in a space.
- Lines 210-212: what is it? A part of template?
Reply: Thanks for your suggestion. It belongs to figure 2.
(a) (b)
Figure 2(a). Physical diagram of Pressure-bearing capacity test experimental device.
Figure 2(b). Schematic diagram of Pressure-bearing capacity test experimental device.
Note :1-Pressure pump ( ISCO single pump ) ;2- Injection pump ( ISCO dual pump ) ; 3-Pressure machine ;4- Diversion chamber ; 5 - Intermediate container ; 6 - Pressure sensor ; 7-Beaker ; 8-Computer
- Lines 214-216: you could give this information in the introduction because it is important to understand your aim.
Reply: Thanks for your suggestion. This part is part of the template and has been deleted.
- Line 244-252: could you add a table to make the reading and comparison more easy to the readers?
Reply: Thanks for your suggestion. Data has been added to Table 1
- Line 410: could you specify how you create the diagrams?
Reply: Thanks for your suggestion. The data comes from the computer output, and the diagrams is drawn by Origin software.
- Add the color legends in figures 21 and 22.
Reply: Thanks for your suggestion. The color legends have been noted under the figure.
- Line 444: please add a space between the tests number.
Reply: Thanks for your suggestion. A space has been added between test numbers.
- Line 470: Darcy flow is not explained before.
Reply: Thanks for your suggestion. This section has been deleted.
- Could you better explain the point 3 of the conclusion?
Reply: Thanks for your suggestion. With the increase of fracture width, low concentration can not achieve temporary plugging. Although the temporary plugging effect of 2 mm fracture width corresponding to the concentration of 18 kg/m3 and 2 4kg/m3 is better than 12 kg/m3, the difference is small. Considering the economic benefits, choose a lower concentration. The fracture width of 4 mm and 6 mm are the same.
Round 2
Reviewer 1 Report
After revision, the paper can be accepted for publication
Author Response
Thanks for your review. Wish you have a good life!
Reviewer 2 Report
Dear Authors,
I think that the manuscript (MS) needs a major revision, because the authors did not address many comments and they left the MS filled with errors.
Lines 201-209 and 218-229: in this way the lists are unreadable.
3) Line 21-22: continues to be unclear.
4) In the abstract it is superfluous to put the symbol of a physical quantity (there are no equations!), so you must delete it.
5) Lines 48-111: they contain a long list of other works. This list must be shortened and more focused.
Reply: Thanks for your suggestion. This part has been shortened and more concise.
I am sorry but this point was not addressed.
6) Lines 111-124: could you better explain the link (and the importance of your work) between the lacking of “systematic physical model”, and your experiment?
Reply: Thanks for your suggestion. Previous studies mostly focused on particles and fibers. We focused on small particles (relatively large mesh). In view of the similarity in principle, we used the same physical model to verify.
You must describe the peculiarity of your study and your aim clearly into the text. It is still not clear the link between the lacking of “systematic physical model”, and your experiment.
7) Figure 1: You are showing 2 images so you need 2 captions: Figure 1a and 1b.
9) Line 131-147: please remove the symbols 1 and 2 inside to a circle.
10) Lines 177-178: five or four ratios?
Reply: Thanks for your suggestion. With the increase of fracture width, low concentration cannot achieve temporary plugging. For example, the concentration of 4mm joint width is 12 kg/m3 and the concentration of 6mm fracture width is 12 and 18 kg/m3, and the pressure rise is too slow, so it is not reflected in the curve.
I am sorry but in the corresponding lines (now 191-192) you show 5 ratios in the brackets.
Line 190: ml is mL.
11) Please add a table in which you put the different trials. It is not a scheme of experiment.
In table 1 RATE? o particles size ratio?
14) Lines 211-214: you could give this information in the introduction because it is important to understand your aim.
15) new Lines 231-240: you must define here the physical quantities related to the symbols. You must add a table for summarizing the 5 different stress states here and not in table 2 (These data aren’t in table 1 as you wrote). Please explain why you select the 1 and 2 states.
20) Could you better explain the point 3 of the conclusion? it continues to be unclear. What is the construction economic efficiency?
Best regards
Author Response
Response to Reviewer 2 Comments
Point 1: I think that the manuscript (MS) needs a major revision, because the authors did not address many comments and they left the MS filled with errors.
Response 1: Thanks for your suggestion. We have made major revisions to the full text, including some syntax errors and comments.
Point 2: Lines 201-209 and 218-229: in this way the lists are unreadable.
Response 2: Thanks for your suggestion. The sentence has been revised to "First, the temporary plugging fluid was configured, and crack slate was installed to adjust the fracture width. The diversion chamber was placed in the press while confining pressure was applied on both sides. Subsequently, the temporary plugging liquid was poured into the intermediate container, the pipeline equipment was connected, the liquid injection pump was turned on, and the liquid volume was recorded. The computer was used to record the fracturing pressure and fluid output in real time. When the pressure reached the turning pressure, it was maintained for 5 min. Finally, the pressure was relieved, the rock plate was disassembled, and the crack plugging effect was recorded." See line 156-164. And “ As illustrated in Figure 4 [22,23], the natural outcrop is drilled and well cemented. The fracturing fluid is prepared and added in the optimal concentration and ratio. Then the direction of in-situ stress is indicated while the natural fracture is replicated in the true triaxial fracturing simulation system. For the first fracturing, a low-viscosity fracturing fluid is used for the simulation at a flow rate of 20.0 ml/min, and tracer marks are used to record the pressure changes during the experiment. The rock sample is then placed down, and the cracks formed after the first fracturing are observed and photographed. Subsequently, the rock sample is reinstalled while the same triaxial stress as the first time is applied. Fracturing fluid containing a temporary plugging agent is then injected into the sample at a constant displacement, simulating secondary fracturing. The pressure change during the experiment is recorded, the rock sample is placed down, and the cracks formed after the second fracturing are observed and photographed.” See line 173-185.
Point 3: Line 21-22: continues to be unclear.
Response 3: Thanks for your suggestion. The sentence has been revised to "When the axial stress was the same, an increase in the horizontal stress difference was accompanied by a decrease in the corresponding fracture pressure and a gradual decrease in the degree of fracture turning." See line 22-24.
Point 4: In the abstract it is superfluous to put the symbol of a physical quantity (there are no equations!), so you must delete it.
Response 4: Thanks for your suggestion. The symbol of the physical quantity has been deleted. The article abstract has been modified to ”Temporary plugging agent is an effective tool for increasing production in old wells. By considering the temporary plugging materials used in the remote WY area, three concentrations and five ratios under different fracture width were designed and optimized. Thus, the fracture diversion under true triaxial stress was studied. The results showed that when the fracture widths were 2.0, 4.0, and 6.0 mm, the corresponding optimal plugging scheme was that the concentration of temporary plugging agent are 12.0, 18.0 and 18.0 kg/m3 and the ratio of 20-70 mesh to 200-300 mesh temporary plugging agent were 4:1, 2:1 and 4:1, respectively. When maintaining the same horizontal stress, an increase in the axial stress was accompanied by an increase in the fracture pressure; the initial fractures almost propagated along the direction of the horizontal maximum principal stress, but the shapes of the turning fractures were different. When the axial stress was the same, an increase in the horizontal stress difference was accompanied by a decrease in the corresponding fracture pressure and a gradual decrease in the degree of fracture turning. This study provides a basis for numerical simulation and field application of temporary plugging fracturing at fracture ends.” See line 12-26.
Point 5: Lines 48-111: they contain a long list of other works. This list must be shortened and more focused.
Reply: Thanks for your suggestion.This part has been shortened and more concise.
I am sorry but this point was not addressed.
Response 5: Thanks for your suggestion. This list has been shortened and more focused. “Key determinants of the effectiveness of the temporary plugging agent are its particle size, applied concentration, dosage, carrying liquid properties, and pump injection parameters. Various experimental methods have been explored in studying the plugging law of the temporary plugging agent. At present, the single-particle and multi-particle bridging models have been proposed to study the influence of particle size and shape on the temporary plugging effect [7–8]. In order to optimize the particle size distribution, Carpenter et al. designed a water injector connected to a rectangular groove with a specific opening, and installed a filter at the end of the groove to simulate the clogging experiment . Xue et al. used foam horizontal steel plate to simulate hydraulic fractures, and studied the effects of plugging agent dosage, particle size, adding speed and adding method on plugging capacity . The physical model test of true triaxial hydraulic fracturing is an important means to study the propagation and steering law of hydraulic fractures [11–12]. Fiber, granular and layered materials, particles and proppant mixture and other materials have been used to simulate temporary plugging steering. Experiments show that it can effectively block the old cracks and turn to open new cracks [13-15,17-18]. Zhou et al. , Liu et al. , Zhang et al. used true triaxial hydraulic fracturing system to study the influence of natural fracture network on hydraulic fracture propagation, mechanical properties and permeability mechanism of carbonate reservoir, which provided basic data and theoretical support for shale gas exploration and development in China.” See line 41-61.
Point 6: Lines 111-124: could you better explain the link (and the importance of your work) between the lacking of “systemgestion. Previous studies mostly focused on particles and fibers. We focused on small particles (relatively large mesh). In view of the similarity in principle, we used the same physical model to verify.
You must describe the peculiarity of your study and your aim clearly into the text. It is still not clear the link between the lacking of “systematic physical model”, and your experiment.
Response 6: Thanks for your suggestion. This part has been revised in introduction. “In view of the differences in the optimal values of the concentration and ratio of temporary plugging materials in different shale blocks, as well as the inter-well interference caused by rolling development in WY area, it is necessary to combine the temporary plugging steering technology in the field to improve the temporary plugging steering to reduce the pressure channeling effect under different working conditions by optimizing the temporary plugging parameters at the fracture end. In this paper, based on the indoor simulation of 3D fracture temporary plugging steering fracturing and temporary plugging belt formation device, the optimal ratio and concentration of temporary plugging agent suitable for different fracture widths are carried out. Combined with the field outcrop simulation, the fracture initiation law and steering after temporary plugging at the fracture end are studied, so as to provide theoretical support and technical guidance for shale gas wells in WY area to achieve efficient temporary plugging steering fracturing.”See line 62-74.
Point 7: Figure 1: You are showing 2 images so you need 2 captions: Figure 1a and 1b.
Response 7: Thanks for your suggestion. The format of Figure 1 has been modified in the text.
(a) (b)
Figure 1（a）. 3D scan of fractured rock slabs.
Figure 1（b）.Real rock plate for experiment
Point 8: Line 131-147: please remove the symbols 1 and 2 inside to a circle.
Response 8: Thanks for your suggestion. Symbols 1 and 2 in the circle have been removed.
Point 9: Lines 177-178: five or four ratios?
Reply: Thanks for your suggestion. With the increase of fracture width, low concentration cannot achieve temporary plugging. For example, the concentration of 4mm joint width is 12 kg/m3 and the concentration of 6mm fracture width is 12 and 18 kg/m3, and the pressure rise is too slow, so it is not reflected in the curve.
I am sorry but in the corresponding lines (now 191-192) you show 5 ratios in the brackets.
Response 9: Thanks for your suggestion. We set five ratios in the experiment and named them in case format. When the fracture width is 2mm, all ratios can achieve temporary plugging. When the fracture width is 4mm, case 1 can not achieve temporary plugging well because the particles with large mesh have certain settlement problems. Similarly, when the fracture width is 6mm, case 1 and case 2 cannot achieve temporary plugging, so they are not shown in Figs. 9 and 10.
Point 10: Line 190: ml is mL.
Response 10: Thanks for your suggestion. This problem has been resolved.
Point 11: Please add a table in which you put the different trials. It is not a scheme of experiment.
In table 1 RATE? o particles size ratio?
Response 11: Thanks for your suggestion. Table 1 has been modified. See line 154.
Point 14:Lines 211-214: you could give this information in the introduction because it is important to understand your aim.
Response 11: Thanks for your suggestion. We have added the important information of this section in the introduction.
Point 15: new Lines 231-240: you must define here the physical quantities related to the symbols. You must add a table for summarizing the 5 different stress states here and not in table 2 (These data aren’t in table 1 as you wrote). Please explain why you select the 1 and 2 states.
Response 15: Thanks for your suggestion. In order to more clearly describe different stress states, the data are summarized in Table 2, and the meanings of physical quantities are marked below the table; Although the stresses of the five groups of experiments are different, the slit widths are similar, and the schemes used are the same. Therefore, Experiments 1 and 2 are selected as the research objects.
Point 20:Could you better explain the point 3 of the conclusion? it continues to be unclear. What is the construction economic efficiency?
Response 20: Thanks for your suggestion. The construction economic efficiency is to use a relatively small amount as far as possible to complete temporary blocking. For example, for two different mass concentrations, the higher the concentration, the higher the amount required. Therefore, for the fracture width of 6mm, when the concentration of 18 and 24kg / m3 can meet the temporary plugging condition, it is better to select a lower concentration as the construction condition.
Author Response File: Author Response.pdf
Round 3
Reviewer 2 Report
Dear Authors,
thanks for the corrections. I think that before publishing you must add in the text the explaination of the construction economic efficiency.
Best regards
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 2 Comments
Point 1: Thanks for the corrections. I think that before publishing you must add in the text the explaination of the construction economic efficiency.
Response 1: Thanks for your suggestion. Conclusion 3 has been revised, mainly to add an explanation of the construction economic efficiency. ”A comparison of the different proportions of sliding water and temporary plugging showed that the maximum sliding water system could temporarily plug 6.0 mm fracture widths. Under the same construction conditions, the volume of fracturing fluid with high concentration is larger than that with low concentration, and the corresponding construction cost is relatively high. Considering the economic efficiency of construction, when the fracture widths are 2.0, 4.0, or 6.0 mm, the corresponding optimal plugging scheme should be temporary plugging agent concentrations of 12.0, 18.0, and 18.0 kg/m3.”
