EXPANDING OPEN WELL BORE REAMER Russian patent published in 2007 - IPC E21B7/28 

FIELD: drilling equipment, particularly enlarging drilled holes, for instance by counterboring.

SUBSTANCE: well bore reamer comprises body with sub, pipe, expanding movable members pivotally arranged in longitudinal slots of the body and provided with limiting ledges, piston connected to sliding hollow rod and provided with blocking widened end part formed on outer surface thereof and jet nozzle. The body is provided with lower guiding pipe adapted to receive jet nozzle. Piston with longitudinal channels is installed in cylindrical bore of lower guiding pipe. The piston is provided with longitudinal channels made around piston outline and adapted to receive additional jet nozzles. The rod is spring-loaded with respect to sub. Blocking widened end part of the rod is made as a cone corresponding to mating inner surfaces of expanding movable members.

EFFECT: increased efficiency and reliability of reamer due to improved well bottom cleaning during well drilling and prevention of expanding member jamming during reamer shifting in transport position.

2 dwg