We should keep in mind that the sidewall core tests only represent point values of porosity and permeability at a particular depth from the near wellbore region. In one of Scott Macmillan's video presentations he discussed some of the geologic uncertainties, such as the areal variation (stratigraphic) in rock properties within a layer. It maybe that some of the sidewall core plugs were taken from inferior quality rock at the edge of a fluvial deposit (river based sand bar) or the edge of a lacustrine (lake) deposit, which have reduced porosity and permeability because of a larger clay content. Kiwigeo has also mentioned that the thinner the layer, the more clay content there is.
Hopefully, next year there will be an opportunity to run 3D seismic, which will help Invictus pick the best well locations because 3D seismic can generate an areal map of the sweet spots containing the best porosities, which for a sandstone should have the best permeabilities.
The most reliable method for estimating permeability is well testing- larger depth of investigation into a reservoir and over a greater depth interval compared to the singular core plugs depths. Hope this helps.
IVZ Price at posting:
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