Patent ID: 7343983

Claim:
An apparatus for isolating a zone in a hydrocarbon formation for testing flow of hydrocarbons, formation fluids and/or drill cuttings during vertical, horizontal or directional reverse circulation drilling of a wellbore using concentric drill string, said concentric drill string comprising an inner tube having an inner conduit and an outer tube, said inner tube being situated inside the outer tube and forming an annular conduit therebetween, comprising: (a) an isolation tool comprising a center tube, an outer casing and an expandable and contractible packer means for sealing off an outside annular passage formed between a wall of said wellbore and an outer surface of said concentric drill string, said isolation tool adapted to be operably connected to said concentric drill string such that the isolation tool is in fluid communication with both conduits; and (b) a downhole flow control means having at least one valve means for controlling the flow of hydrocarbons, formation fluids and drill cuttings through the annular conduit, the inner conduit or both and adapted to be operably connected to said concentric drill string such that the downhole flow control means is in fluid communication with both conduits.