Permeability and Pore Throat Size

Permeability is conventionally shown cross-plotted with porosity because porosity is an easy variable to obtain and is correlated with other variables that influence or control permeability. The principal variable that exerts greatest influence on permeability in low-permeability rocks is the pore throat size (and pore throat size distribution). The correlation between k and principal pore throat diameter (PPTD) is continuous for all lithofacies including both carbonates and siliciclastics.

Differences in k- relations between different lithofacies reflect changes in the relationship of how mechanical and chemical compaction influence total porosity and pore throats. The existence of a good permeability-porosity correlation, assuming that pore throat size is the dominant control, provides insights into the nature of initial packing and diagenesis and a
measure of the colinearity of pore throat size and porosity.