Drill bit and other downhole tools having electro-negative surfaces and sacrificial anodes to reduce mud balling

摘要

Various steel, downhole tools and components of a drill string, including, as examples, a PDC drill bit, a rotary rock bit, a cross-over sub, a stabilizer, a reamer, a hole enlarger and a coring bit, are selectively treated to cause certain of their parts to be electro-negative with respect to steel, and certain other parts to either have the same electro-negativity as steel, or to be treated to be electro-positive with respect to steel.