A wellbore roller-reamer comprises a mandrel rotatable about a mandrel axis, and a first roller mounted around the mandrel and having an outer reaming surface for engaging a wall of a wellbore. The first roller is rotatable relative to the mandrel about a first roller axis which is offset from the mandrel axis such that, during use, rotation of the mandrel with the outer reaming surface engaged with a wall of the wellbore causes the first roller to be driven to rotate relative to the mandrel and ream the wall of the wellbore.

A wellbore roller-reamer comprises a mandrel rotatable about a mandrel axis, and a first roller mounted around the mandrel and having an outer reaming surface for engaging a wall of a wellbore. The first roller is rotatable relative to the mandrel about a first roller axis which is offset from the mandrel axis such that, during use, rotation of the mandrel with the outer reaming surface engaged with a wall of the wellbore causes the first roller to be driven to rotate relative to the mandrel and ream the wall of the wellbore.

Bearing assemblies, apparatuses, systems, and methods include bearing assemblies where one of the bearing assemblies may include bearing surfaces defining an at least partially conical inner surface.

Bearing assemblies, apparatuses, systems, and methods include bearing assemblies where one of the bearing assemblies may include bearing surfaces defining an at least partially conical inner surface.

Bearing assemblies, apparatuses, systems, and methods include bearing assemblies where one of the bearing assemblies may include bearing surfaces defining an at least partially conical surface.

Bearing assemblies, apparatuses, systems, and methods include bearing assemblies where one of the bearing assemblies may include bearing surfaces defining an at least partially conical surface.

A radial bearing having a wear surface with improved wear characteristics comprises a steel support, to which is bonded a metal carbide composite wear surface made by first arranging, within a cavity defined between a steel mold and the steel support, tiles made of microwave sintered, cemented metal carbide, closely packing the voids between the tiles with metal carbide powder, and infiltrating the mold cavity with a metal brazing alloy by subjecting the filled mold to rapid heating. The brazing alloy fills voids between the metal carbide particles, the microwave sintered metal carbide tiles, and the metal support, thereby relatively rapidly consolidating the carbide into a wear layer bonded with the steel support without substantially damaging the properties of the microwave-sintered metal carbide tiles.

A roller reamer for downhole operations in boreholes, such as are drilled for oil and/or natural gas production, or as injection wells. An elongated main body has preferably three circumferentially spaced pockets. A roller assembly is preferably disposed in each pockets, the roller rotating in roller blocks at each end of the roller disposed within the roller blocks. Mating locking profiles, such as dovetails, lock the roller blocks within the pockets, as the roller blocks are moved longitudinally into the locking profiles, preventing any radially outward movement of the roller assembly. The roller assembly is prevented from longitudinal movement within the pockets by lock blocks also positioned within the pockets.

A roller reamer for downhole operations in boreholes, such as are drilled for oil and/or natural gas production, or as injection wells. An elongated main body has preferably three circumferentially spaced pockets. A roller assembly is preferably disposed in each pockets, the roller rotating in roller blocks at each end of the roller disposed within the roller blocks. Mating locking profiles, such as dovetails, lock the roller blocks within the pockets, as the roller blocks are moved longitudinally into the locking profiles, preventing any radially outward movement of the roller assembly. The roller assembly is prevented from longitudinal movement within the pockets by lock blocks also positioned within the pockets.

A hybrid bit includes a fixed cutting structure and a rolling cutting structure. The fixed cutting structure includes a plurality of fixed cutting elements. The rolling cutting structure is coupled to the fixed cutting structure and includes a journal bore extending through the rolling cutting structure from a leading face to a trailing face, and a radially outer surface. The rolling cutting structure also includes a plurality of cutting elements extending from the radially outer surface of the rolling cutting structure.