Fig. 17

Comparison of porosity measured by HEP and WIP methods. a\(\phi_{\text{eff}}^{\text{w}}\) is directly plotted against \(\phi_{\text{eff}}^{\text{He}}\). Data were separated to control lithology dependency. Density plots show a positively skewed distribution and a high variance of porosity. B: Histogram and cumulative frequency of porosity deviation between both methods (bin width = 0.25%). Red dotted lines show 10% and 90% percentiles between which most deviation values were found. Blue dashed line indicates that 50% of all samples have a deviation of less than—0.9% p.u. and 50% more than—0.9% p.u