Definition - What does Fracture Porosity mean?
Fracture Porosity is a kind of secondary porosity by the tectonic fracturing of rocks. The fractures do not typically have great volume themselves, but their permeability can be enhanced significantly by joining the preexisting pores. If enough fracturing takes place, non-reservoir rocks like granite can turn into reservoir rocks, and rough surfaces can separate the two faces causing Fracture Porosity. The infilling of minerals can cover each surface. These minerals can fill entire fracture and convert the open fractures to sealed or healed fractures.
Petropedia explains Fracture Porosity
Fracture Porosity is generally very small, that is, about 0.0001 and 0.001 of the total rock volume. The porosity related to fractures like solution porosity in a carbonate reservoir or granite may obtain larger values but in actual fractures it is still very small. It can be found accurately by processing the curves of formation micro-scanner for fracture intensity and fracture apertures. The reservoir matrix permeability and porosity including those attributed to fracture porosity can be found by the methods of normal porosity calculation.