formation factor [fȯr`mā·shǝn ´fak·tǝr] GEOCHEMISTRY The ratio between the conductivity of an electrolyte and that of a rock saturated with the same electrolyte. Also known as resistivity factor. GEOLOGY A function of the porosity and internal geometry of a reservoir rock system, expressed as F = ϕ-m, where ϕ is the fractional porosity of the rock, and m is the cementation factor (pore- opening reduction). |