Water block:
1.A reduction in the permeability of a formation caused by the invasion of water into the pores.
2.
A relative permeability problem usually occurring in a gas zone.
Highest potential formations for water blocks are low pressure gas sands (<0.25 psi/ft pore pressure), with small pore throats (<10 microns), lower permeability (<100 md), and when using water that has a surface tension about 50 dyne/cm.
