Isolation packer and methods of cementing from a floating vessel

Abstract

The extended length isolation packer of the present invention comprises upper and lower tubular body assemblies which are interconnected by a middle body. The upper tubular body assembly has an upper packer assembly and a closing positioner attached to its outer surface. The lower tubular body assembly has a lower packer assembly attached to its outer surface. An upper inner mandrel is concentrically disposed within said upper tubular body assembly and has a port disposed therein for communicating an inner cavity of said upper inner mandrel with the annular cavity between the isolation packer and an oil well casing. A lower inner mandrel is concentrically disposed within said lower tubular body assembly and communicates with said upper inner mandrel through said middle body. A fluid bypass is provided through annular cavities between the inner mandrels and the tubular body assemblies. The extended length provided by the lower tubular body assembly effectively doubles the distance between upper and lower packer assemblies providing for much greater allowable error in positioning the isolation packer within an oil well casing. Additionally, attached to a drill string, with the extended length isolation packer, is an anchor means which may be set against the casing to provide the necessary resistance between the drill string and the casing to operate a motion compensator system on a floating vessel. The motion compensator system then adjusts the effective length of the drill string as needed to compensate for wave induced vertical motion. This prevents movement of the isolation packer during cementing procedures. Additionally, methods are disclosed for cementing or treating a selected zone within an oil well borehole, from a floating vessel.