Experimental Design, Instrumentation, and Testing of a Laboratory-Scale Test Rig for Torsional Vibrations—The Next Generation

Round 1

Reviewer 1 Report

The authors developed a novel laboratory-scale drilling rig that is capable of simulating drilling operations. The drilling rig can capture detrimental performance such as vibration and stick-slip in drilling, and it can potentially improve the drilling efficiency.

1. The real time monitoring of mechanical specific energy is an important factor to evaluate the drilling efficiency. Is it possible to integrate the specific energy in the control panel?
2. It is common that a drilling operations occurs in different formations. Please discuss more details on the drilling performance on different formations.
3. Please enhance the discussion on how detrimental operations such as stick-slip can be alleviated.
4. Please use a table for the conversions between Lines 235- 240.
5. Please remove commercial brands.

Author Response

Thank you very much for your valuable comments. We hope that we have answerd all your questions.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper addresses the construction of a laboratory-scale test rig. The presented work is of interest to the scientific community. However, the paper in its current status does not provide scientific new conclusions. While the experimental setup is innovative, the authors should provide a clear scientific conclusion. Further comments are below:

In the abstract, you mentioned that downhole vibrations depend on the bit sticking period and frequency. Can you please elaborate on that? The sticking period and frequency of sticking are a result of operating parameters and bit specification etc. if, for example, you increase the applied RPM the sticking frequency will decrease. In other words, it seems like you are saying downhole vibrations depend on downhole vibrations?

 

Section 2.1.2, what is the base of the downscaling? For the downscaling ratio, what’s the operating parameters scale for the downscaling? i.e. if you are applying top drive speed of 100 RPM and WOB of 2500 lb for the model, what’s the prototype parameters?  

 

You mention the major components of the rig are the top drive, drillstring, and the BHA in section 2.1. In your experimental design, you are treating the braking system as your BHA, correct? In that case, the drillstring in the experimental setup is tension or compression?

Is there a critical sampling frequency of the downhole measurements, i.e. encoders, that will change the results dramatically? It will be useful to determine such a limit to be used in the actual drillstring vibration measurements in the field.

Further discussion regarding the experimental limitation and assumption should be provided.

Author Response

Thank you very much for your valuable comments. We hope that we have answerd all your questions.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors has addressed all the reviewer comments and I'm recommending the paper for publication as the quality of the paper has improved. 

Please go over the paper one more time to insure consistency. For example, for the majority of the paper you have used "RPM" but in page 16 line 419 and 422 you used "rpm". 

 

Author Response

thank you for spotting the inconsistency in parameters. We have fixed all as requested.