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.

Abstract: A bendable sub for use in the drilling string includes an elongated tubular mandrel with a threaded top end for mounting the mandrel at the bottom end of a drilling string, a lock nut threaded onto the body of the mandrel between the ends thereof for vertical movement, a coupler slidably mounted on the mandrel beneath the lock nut for movement between a release position and a locking position, the coupler being non-rotatable on the mandrel, a sleeve on the mandrel beneath the coupler with a tapering passage extending therethrough, a latch between the coupler and the sleeve for releasably connecting the coupler to the sleeve, and a retaining nut on the bottom end of the mandrel beneath the sleeve for retaining the latter on the mandrel, at least the bottom end of the coupler and the top end of the sleeve being inclined with respect to the longitudinal axis of the mandrel, whereby the sleeve can be tilted or inclined with respect to the mandrel to form a bend in the drilling sub.