Patent ID: 7712549
Filing Date: 2010-05-11
Classification: E21B

Abstract:
1. A drilling tool comprising: a casing; a central pilot bit extending from a first location of a bottom end of the casing, the bit including a plurality of abrasion-resistant cutting elements; one or more mills extending from at least a second location of the bottom end of the casing and disposed laterally outwardly from the central bit, each of the one or more mills including a plurality of abrasion-resistant cutting elements; and a plurality of motors disposed within the casing, one for each of the one or more mills and the pilot bit, each of the plurality of motors having an output that is coupled directly to separate ones of the pilot or one of the one or more mills without gears or bearings; wherein each of the plurality of motors is a hydraulically powered, positive displacement motor and/or turbine; and wherein the casing includes a plurality of motor or turbine cavities, each of the plurality of motor or turbine cavities receiving one of the of the plurality of motors or turbine, each motor or turbine cavity having an opening in the bottom end of the tool through which the motor or turbine is received in the tool.