Simulation of Hydraulic Fracturing Using Different Mesh Types Based on Zero Thickness Cohesive Element

Round 1

Reviewer 1 Report

General comments:

The manuscript focus on the hydraulic fracturing simulation and, in particular, on the effects of different mesh types (triangle, quadrangle and deformed quadrangle mesh) on the numerical results. The authors conclude that for large toughness problem, numerical results make little differences, whereas for zero toughness regime, the pore pressure computed by triangle mesh is lower than any other mesh type at the early injection time. In addition the authors state that infinite boundary elements should be utilized in solving hydraulic fracturing problem to avoid border effects that can decrease the accuracy of the numerical solution. 

Specific comments: 1.  I suggest to replace "zero height cohesive element" with  "zero thickness cohesive element" everywhere
2. There is a problem with a reference source in the lines 138, 163, 171, 184. 3. The UEL subroutine used for the simulations (together to the Abaqus input files) should be attached in a the "Supplementary material". This is necessary to reproduce the results. 4. line 377-378. Please merge the sentences.

Author Response

1.The terms "Zero height" are all replaced by "Zero thickness".

2.The problems about the reference source are all corrected in the new file.

3.The supplementary material has been already uploaded.

4.The two line sentences are merged as well in the article.

Please see the attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

Title: Simulation of hydraulic fracturing using different mesh type based on zero height cohesive element

The authors have investigated two hydraulic fraction models based on the element of the PPCZ. They used three types of meshes in their investigation, namely the triangle, quadrangle, and deformed quadrangle meshes. Their simulation results have shown that the triangle type of meshes had lower pore pressure, at zero toughness regime, than the other two types. They have also indicated that PPCZ element can provide accurate large and zero toughness. I believe that the results presented in their article are very promising and would aid the oil industry. In my personal opinion, the presented manuscript is worth publishing after properly reviewing the English grammar (especially in the introduction section) and taking into account the minor points that are highlighted in the attached document. 

All the best.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf