Surface adjustable adjustable bent housing

Abstract

An adjustable bent housing for use in downhole drilling which includes a housing, mandrel, ring and locking mechanism. The housing has a housing central axis, a downward facing end face defining a plane whose normal is offset from the housing central axis, and an inner shoulder parallel to the downward facing end face. The mandrel has a mandrel central axis, a first end dimensioned to fit inside the housing and having a downward facing outer shoulder defining a plane whose normal is offset from the mandrel central axis. The ring is axially slidable on the mandrel, with a ring central axis and an upward facing end face defining a plane whose normal is offset from the ring central axis. A locking mechanism, a mandrel head threaded onto the mandrel, engages and disengages the upward facing end face of the ring with the downward facing end face of the housing and simultaneously engages and disengages the inner shoulder of the housing with the outer shoulder of the mandrel. Keys or like means are used to control the position of the ring on the mandrel in selected circumferential positions only. One of the keys may be differently sized from other keys. Preferably markings on the ring and housing are used indicate relative degrees of rotation of the housing in relation to the ring.