Fluid flow that deviates from Darcy's law, which assumes laminar flow in the formation. Non-Darcy flow is typically observed in high-rate gas wells when the flow converging to the wellbore reaches flow velocities exceeding the Reynolds number for laminar or Darcy flow, and results in turbulent flow. Since most of the turbulent flow takes place near the wellbore in producing formations, the effect of non-Darcy flow is a rate-dependent skin effect.