US Patent 7578343 Viscous oil inflow control device for equalizing screen flow

A flow balancing system for long screen sections particularly useful in high viscosity hydrocarbon production features an annular flow path whose height and length can be varied to provide a predetermined resistance to a given flow rate of a material of a given viscosity. In assembling a long length of screen sections, greater resistance configurations are placed closer to the wellhead end of the screen section with the more remote sections having progressively less restriction until the furthest section of the screen string where low or no resistance to flow internally to the screen section is offered.