In petrophysics there are a number of subtle differences when discussing porosity. Porosity is defined as the void or space in the material being observed. In context of hydrocarbon exploration and development we concern ourselves with how much of the rock has the capacity for storage. Once the storage capacity is determined we then attempt to understand the fluids contained within.

As almost all of the wireline tools are designed to measure things that when combined can infer an analysis (ie Resistivity, Bulk Density, Hydrogen Index) then it becomes increasingly important to understand what each piece actual measures.

NuTech ties the calculated porosity to core and lithology (as the density is lithology dependent). This allows us a constant to tie everything to. Below is an image that shows that definition in our logs.