Downhole fluid resistivity sensor systems and methods

摘要

Disclosed is a downhole fluid resistivity sensor that includes a ceramic cylinder having a fluid -contacting surface, and at least four metal pins that penetrate a wall of the ceramic cylinder at axially-spaced locations. The pins are bonded to the ceramic to form a pressure seal. The sensor may include a circuit that injects current into a fluid via an outer two of the pins, and measures a resulting voltage via an inner two of the pins. The circuit may also provide an indication of fluid resistivity based at least in part on the resulting voltage. At each of the axially-spaced locations, a set of multiple pins may penetrate the wall to contact the fluid at circumferentially-spaced positions. The fluid- contacting surface may be an inner surface or an outer surface of the ceramic cylinder. A downhole fluid resistivity measurement method is also described.