Fig. 18

Dependency of porosity deviation between HEP and WIP methods related to different factors. a Porosity deviation becomes increasingly negative with increasing porosity. A positive deviation was mainly found for samples with low porosity. b Correlation of the porosity deviation with grain density suggests a dependency on lithology. c The porosity deviation seems not to be related to bulk volume (i.e., dimensions) of the sample. d The matrix shows the Pearson correlation coefficients of different parameters. Blue color represents a positive correlation, whereas red represents a negative correlation. (\(\phi_{\text{eff}}^{\text{He}}\) = effective porosity (HEP), \(\phi_{\text{eff}}^{\text{w}}\) = effective porosity (WIP), \(\rho_{\text{B}}\) = bulk density, \(\rho_{\text{T}}\) = grain density, \(V_{\text{B}}\) = bulk volume, \(V_{\text{T}}\) = helium grain volume, \(V_{\text{P}}\) = pore volume)