Reservoir Turbulence

Reservoir Turbulence (Non-Darcy Skin)

Darcy’s law assumes laminar flow in the reservoir as the gas approaches the wellbore.  In high rate gas wells it is possible to see flow velocities converging at the wellbore that exceed laminar flow, resulting in turbulent flow as defined by a high Reynolds number.  This is commonly referred to as a “rate dependent skin effect” because the effect is reduced or completely eliminated if rates are lowered sufficiently whereby flow returns to laminar or a non-turbulent state.  To test for rate dependent skin you would normally perform a 3-4 rate test or a modified isochronal test.