دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

adj: preventing the passage of fluid. A formation may be porous yet impermeable if there is an absence of connecting passages between the voids within it. See permeability.

adj: preventing the passage of the fluid through the pores of the rock.

Rock with passages so small that no effective flow can take place. Note: all manmade and natural substances have some permeability, given high pressure, time, enough surface area and a low permeability fluid.