Numerical Simulation of Proppant Transport in Transverse Fractures of Horizontal Wells
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
The authors, in this study, describe some numerical simulations made to investigate the proppant transport in transverse fracture of the horizontal well. The idea is to develop a full characterization of this system to have better understanding and to make it helpful for future optimization or design.
This is a good work that can be published in this journal.
However, I have some minor comments that authors should consider:
1. Figure 2 is not very clear and most importantly not well detailed.
2. Figure 3 shows the control unit for hydraulic fracture, it would be more insightful if you design an example of the fracture in the unit cell.
3.In all the equations, dx and dy have been considered. The width is not included in the equation (dz), can you explain?
4. The definition of some terms (density for instance) of the equations are repetitive, better to define it once.
5. Figure 5 is not clear, enhance quality.
Author Response
This is a good work that can be published in this journal.
Response 1: Thank you for your comment.
Figure 2 is not very clear and most importantly not well detailed.
Response 2: Thank you for pointing this out. Fig.2 was replaced by more clear picture. In addition, more explanations were added.
Figure 3 shows the control unit for hydraulic fracture, it would be more insightful if you design an example of the fracture in the unit cell.
Response 3: Agree. This figure was revised.
In all the equations, dx and dy have been considered. The width is not included in the equation (dz), can you explain?
Response 4: We agree with this comment. The detail about the equation (dz) is discussed in the revised paper. In fact, the fracture width w in equation (1) refers to dz.
- The definition of some terms (density for instance) of the equations are repetitive, better to define it once.
Response 5: Sorry for this question. The repetitive equation was deleted.
- Figure 5 is not clear, enhance quality.
Response 6: Thank you for your question. More clear picture was used as the figure 5.
Reviewer 2 Report
Comments and Suggestions for Authors
This article examines the flow path mechanism between the transverse fracture and the horizontal wellbore, which is often neglected in practical design. The fluid continuity equation, the fracturing fluid flow equation and the proppant continuity equation for its transport were determined for the transverse fracture of the horizontal well, and the finite element method was used to solve it, two-dimensional radial flow was taken into account in modeling the proppant transport. The results presented in this article indicate that proppant concentration and the fracture wall effect can slow down the rate of proppant settlement, but also they can block horizontal proppant transport and shorten the effective length of proppant fractures. Increasing fracturing fluid viscosity and build volume, reducing proppant density and particle size, and adopting appropriate sand addition procedures can provide better proppant distribution and therefore better fracturing and rebuilding results.
I have no major objections to the article, my minor comments concern the following issues:
1. The presentation of the current state of the art section 1. Introduction could be more extensive.
2. In conclusions, lines 474-477, the same text is repeated twice.
3. Incomplete bibliographic data is provided for some literature items
Author Response
- The presentation of the current state of the art section 1. Introduction could be more extensive.
Response 1: We agree with this comment. More extensive information was added in the introduction part.
- In conclusions, lines 474-477, the same text is repeated twice.
Response 2: Sorry for this mistake. The repeated part was deleted.
- Incomplete bibliographic data is provided for some literature items
Response 3: Sorry for this mistake. The bibliographic data for some literature items is added.
Reviewer 3 Report
Comments and Suggestions for Authors
This paper seems to be well discussed the proppant transport and distribution in hydraulic fracture by numerical simulations based on case studies. It is however that no descriptions for verification of model application with field data, although it is stated in the last paragraph of introduction. Additionally, the descriptions of models used in the present study are noted in detail, however the reviewer can not understand well how these models or equations have been integrated and used in the numerical simulation. It should be clarified without confusing the readers. It is not easy to read the descriptions of formula since the characters and/or sizes of unit are not uniformed. The authors do not pay attention for reducing the careless mistakes in the current manuscript. It is therefore that the reviewer does not recommend accepting for the journal of Processes, unfortunately.
Author Response
Response 1: Thank you for your comment. We try our best to revise the paper while make the reader more aware of the significance of the equations and the purpose of the research throughout the paper.
