Google info, "Net pay is the thickness of the porous, permeable...

Google info, "Net pay is the thickness of the porous, permeable interval containing commercial
hydrocarbon saturations. The thickness of net pay compared to the total pay zone
thickness is known as the net-to-gross ratio. This is an important factor in
hydrocarbon volumetric calculations of reserves, and the design of facilities. Net pay
definition is particularly difficult in low permeability gas reservoirs, since sands
which are typically excluded as being tight may, in fact, contribute significantly to
gas movement.
With no net pay cut-off, gas reserves may be over estimated. This might mean
daily contract quantities are not met, with the consequent implication of financial
penalties.
With a net pay cut-off that is too high, gas reserves would be under estimated.
This could lead to the production facilities being designed for too short a lifetime,
with possible consequent loss in gas reserves.
Given the importance of net pay definition, it is still surprisingly arbitrary being
normally defined by a single porosity or permeability value.
GL Tomorrow. DYOR.