Discussion on paper by Mackie, Volume 46 Number 4, pp 25-34

This writer accepts the findings of the paper that there is reasonable correlation between core permeability, as measured using gas, with geophysical data from wireline logs. The writer also accepts the statistical methodology used by Mackie in achieving the correlations.

However, the writer is concerned with two inferences in the paper, and one explicit statement. The inferences are as follows.

• Firstly, given that the work was done for a project at Ulan Mine, an inference is that core permeability data may be, or is, relevant to the estimate of groundwater flows and pressures, either before or after longwall mining.
• Secondly, regardless of the relevance of core permeability, an inference is that using gas gives a valid measure of such permeability.