US Patent 7665545 Pressure controlled downhole operations

A method and apparatus for temporarily increasing fluid pressure at a specific location in a work string to perform an operation in an oil or gas well bore. Apparatus is provided which, in a first position provides fluid flow through the work string; in a second position provides the desired increase in fluid pressure to perform the operation in the well bore by dropping a ball (62) into the apparatus; and, by shearing pins (52) to move a sleeve (50) within the apparatus, provides a third position which returns fluid flow through the work string via bypass channels (26) created in the apparatus around the ball. Operation of a pressure activated near bit reamer in conjunction with the apparatus is also described.