Deliverable Wellhead Temperature—A Feasibility Study of Converting Abandoned Oil/Gas Wells to Geothermal Energy Wells

Round 1

Reviewer 1 Report

I read the manuscript. Its well written

 

1. the subject is not that much interesting

2. In the results the commercial issue must be considered

3. the discussion must reflect the original finding

4. the authors must report some other studies and compare their results with them

5. the references format should be adjusted according to the format of the journal

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The paper presents an interesting topic with well-defined literature and empirical results. Following are some observations,

1. Rescale Figure 1. Also, try to redraw it as a line diagram if possible for more clarity.

2. The mathematical model presented in eq 1-9 are to be discussed in detail to improve the quality of the paper. Authors are advised to give additional descriptive support to these equations.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The authors present a mathematical model for modeling heat transfer from the ground (earth) through layered abandoned oil/gas wells, in order to predict the outlet temperature of heat transfer fluid and possibilities for its application.

The results show relatively high otulet temperatures, which is aperent from the analysed borehole depth of the oil/gas wells.

The problem is covered by literature review, according to good academic standard. The literature review, could include references including research results about heat pump borehole heat transfer, with a focus on ground probe applications (although the typical borehole debths aremuch lower compared to the oil and gas boreholes, but the physical phenomena and therefore mathematical models should be the same, or similar at least).

In rows 63 to 74, the authors refere to ORC applications with relatively low temperature heat. However, fluid pressures are not included in the analysis, and this should be adressed in the paper. The presssure level need to be high enough to enable expansion of the fluid, and perform mechanical work (i.e. power the generator).

An analytical model is decelloped for the purpose of the study, which describes both pipe and annular insulations, with a goal of predicting surface fluid temperatures. The phisical phenomena behind the mathematical model is not documented well, and therefore the mathematical model applied should also be explained better (eq 1 to 9). The mathematical model is not a typical engineering mathematical approach.

The concrate bedding of the borehole presented in fig. 1. seems inpracticable.

The sensitivity analysis is done properly, and the results are logical.

The authors should check the "Nomenclature", and ensure that all the symbols are present and there are no typing errors.

 

Author Response

See attachment.

Author Response File: Author Response.pdf