Abstract: Devices and methods for well logging using a wear-resistant electrode are provided. A downhole device may include a drill collar and a first electrode mounted on the drill collar. Further, the first electrode may include a wear-resistant face. The first electrode may be movably coupled within the drill collar, and the first electrode may be configured to extend and retract into a wellbore to maintain contact with a wall of the wellbore. Furthermore, the first electrode may be configured to measure impedance of a geological formation.

Abstract: Devices and methods for well logging using a wear resistant electrode are provided. A downhole device may include a drill bit, a gauge pad mounted on the drill bit, and a first electrode mounted in the gauge pad. An insulating polycrystalline diamond (PCD) material may surround at least a portion of the first electrode. Additionally, the first electrode may include an electrically conductive wear resistant contact point that maintains constant contact with a wall of a wellbore. Additionally, the first electrode may measure an impedance of a geological formation during a drilling operation.

Abstract: A downhole tool may be used to enlarge and widen a wellbore. The downhole tool may include a reamer with a mandrel that includes a rib extending radially outward from a cylindrical body of the mandrel. The rib may define one or more grooves. A cutter block or other expandable member may be positioned adjacent the rib and may include one or more extensions that mate with the grooves. The rib and cutter block may be positioned within a slot of a housing. The housing may also include one or more grooves on a surface along the slot. The grooves along the slot and the grooves on rib may mate with extensions on opposing sides of the expandable member to define a path by which the expandable member moves between expanded and retracted positions.