An apparatus and method for protecting against the problems associated
with heave of a floating drilling rig are disclosed. The disclosed
invention is a unique inline compensator in which a plurality of
cylinders housed within a tubular housing and a plurality of low pressure
and high pressure accumulators function together to provide a system for
compensating for heave in the event a primary heave compensation system
fails or becomes inoperative. The typical inline compensator of the
present invention utilizes a plurality of hydraulic cylinders that act in
opposite directions and that have different piston areas such that the
piston rods of the cylinders are extended or retracted at different
pressure levels to account for heave. The typical inline compensator of
the present invention is self-contained and compact enough to fit in the
limited space available on a floating drilling structure. Further, a pair
of inline compensators of the present invention can be utilized with
coiled tubing operations. In such a case, the inline compensators will
not interfere with the tooling necessary to conduct the coiled tubing
operations.