Proppant permeability and mesh size

Proppant used should be permeable or permittive to gas under high pressures; the interstitial space between particles should be sufficiently large, yet have the mechanical strength to withstand closure stresses to hold fractures open after the fracturing pressure is withdrawn. Large mesh proppants have greater permeability than small mesh proppants at low closure stresses, but will mechanically fail and produce very fine particulates at high closure stresses such that smaller-mesh proppants overtake large-mesh hsp proppant in permeability after a certain threshold stress