 The cementation exponent models how much the pore network increases the resistivity, as the rock itself is assumed to be non-conductive.If the pore network were to be modelled as a set of parallel capillary tubes, a cross-section area average of the rock's resistivity would yield porosity dependence equivalent to a cementation exponent of 1.However, the tortuosity of the rock increases this to a higher number than 1.