Abstract: A downhole rotary drive apparatus (10) for driving a bit (12) used to drill or ream a borehole (B) comprises a body (14) configured for coupling to, or forming part of, a tubular string (S1:S2:S3) for running into the borehole (B) and an output shaft (16) at least partially disposed within and rotatably mounted to the body (14). A plurality of rotary drives (32) are disposed around the body (14), each having a rotor (36). The apparatus (10) further comprises a transmission arrangement (46) comprising a drive component mounted on at least one of the rotors (36) of the rotary drives (32) and a driven component mounted on the output shaft (16). The driven component is disposed radially inwards of the drive component such that an inner surface of the drive component engages an outer surface of the driven component, rotation of the driven component by the drive component driving rotation of the output shaft (16).

Abstract: An apparatus for driving a drillable drill bit of a drilling assembly and a method of manufacturing of the apparatus for driving the drillable drill bit is provided. The apparatus employs a drilling assembly that includes one of a casing string or a tubular string suspendable in a borehole and a drill pipe housed within one of the casing string or the tubular string. The drillable drill bit is fixed at the bottom of the drill pipe. The drilling assembly further includes a plurality of motors mounted circumferentially on the one of casing string or tubular string, wherein the plurality of motors is attached to wall of the one of casing string or tubular string and are partially outside the one of casing string or tubular string in the borehole, and the plurality of motors are configured to drive the drillable drill bit.

Abstract: An apparatus for driving a drillable drill bit of a drilling assembly and a method of manufacturing of the apparatus for driving the drillable drill bit is provided. The apparatus employs a drilling assembly that includes one of a casing string or a tubular string suspendable in a borehole and a drill pipe housed within one of the casing string or the tubular string. The drillable drill bit is fixed at the bottom of the drill pipe. The drilling assembly further includes a plurality of motors mounted circumferentially on the one of casing string or tubular string, wherein the plurality of motors is attached to wall of the one of casing string or tubular string and are partially outside the one of casing string or tubular string in the borehole, and the plurality of motors are configured to drive the drillable drill bit.