Multi-Sized Granular Suspension Transport Modeling for the Control of Lost Circulation and Formation Damage in Fractured Oil and Gas Reservoirs

Round 1

Reviewer 1 Report

The work presents a mathematical model on particulate suspension transport in fracture network for the prediction of formation damage induced by drill-in fluid loss. Experiments are conducted to validate the analytical model. This is an interesting topic and overall the technical quality of the paper is very good. However, there are a number of technical issues that need to be addressed before consideration for publication.

Here are the major comments for this paper:

1. How can the author get Eq. 8? Please add the original reference of this equation. It is the same for other adopted equations from other papers, such as Eq. 6.

2. How can the author combine Eq.8 with Eq.10 to obtain Eq. 11, please give more detailed derivation?

3. In page #21, "the experimental conditions of particle/particle and particle/grain repulsion are adopted to result in the absence of particle retention by attachment to matrix", I do suggest the authors to give more details about how to control the experimental design to ignore the effects of particle retention.

4. Formation damage can also be induced by particle deposition on the fracture surface. But only particle plugging is considered in this paper. Why?

5. One of the main findings from the modelling work is that the fractures with width closer to the injected particle size disappears faster. More explanations and discussion should be made for this phenomenon. Possible to quantify it?

6. Limitations of the mathematical model need to be explained.

Minor editing of English language required

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript studied the role of transport and retention of multi-sized suspended granules on reservoir permeability and oil/gas productivity. The authors developed stochastic models to simulate multi-sized suspended granule flow and retention in naturally fractured reservoir with consideration of percolation theory. The modelling results were demonstrated by experiments, both indicating that multi-sized suspended granule shows great advantages over the mono-sized suspended granule in the control of permeability damage induced by granule retention and fracture clogging. The retained granule concentration and permeability damage rate decrease with fracture network connectivity improvement.

This paper could be a good supplement to the current understandings on transport and retention of multi-sized suspended granules on reservoir permeability. From my point of view, this manuscript has the potential for publication in Process after minor revisions. A number of suggestions are given, but not limited to the following:

1.     Introduction: The background introduction, knowledge gap, scope of work are well organized and easy to follow. It would be more attractive to have your own schematic rather than referring to others (Figure 1 and 3).

2.     It could be better and more straightforward to compare the results from modelling and experiments in one figure.

3.     The limitations of the modelling and experimental designs were not well discussed.

Minor editing for English language

Author Response

Please see the attachment.

Author Response File: Author Response.pdf