Patent ID: 8408337

Claim:
A downhole flow control device for use during reverse circulation drilling with a concentric drill string, the concentric drill string comprising an inner pipe or tube having an inner passage therethrough and an outer pipe or tube surrounding the inner pipe or tube and forming an annular passage therebetween, the device adapted to be connected to the concentric drill string for well control, the device comprising: (a) a first passage therethrough, the first passage being in fluid communication with the inner passage of the concentric drill string; (b) a second passage therethrough, the second passage being in fluid communication with the annular passage of the concentric drill string; (c) a full opening first valve assembly located in the first passage of the device adapted to be moved from a closed position to an open position, whereby, when the first valve assembly is in the open position, flow through the first passage of the device and the inner passage of the concentric drill string is substantially unrestricted; and (d) a second valve assembly located in the second passage of the device adapted to be moved from a closed position to an open position, whereby, when the second valve assembly is in the open position, material can flow through the second passage and the annular passage of the concentric drill string.