DOWNHOLE ANODE GROUNDING ELECTRODE Russian patent published in 2003 - IPC

FIELD: cathode protection of underground structures against corrosion. SUBSTANCE: proposed downhole grounding electrode includes current lead located in insulation inside sheath coaxial to it and separated from it by dielectric material, electrodes welded to sheath on outside and to one another numbering 6 and forming protective enclosure and additional enclosure of nonconductive material positioned in upper part of grounding electrode, protruding above ground surface and fitted with perforated cover. Sheath and electrodes are made of steel pipes of same diameter, length of electrodes exceeds length of sheath by three diameters of pipe as minimum. Grounding electrode is equipped with steel plate having thickness exceeding thickness of pipe wall, length equal to length of electrode and width amounting to half-diameter of pipe as minimum installed between two electrodes and welded to sheath and electrodes. Interelectrode welds and welds between plate and electrodes are covered on outside with anticorrosion protective mastic. Employment of reliable grounding electrode with long service period according to proposed invention makes it feasible to raise degree of cathode protection of underground structures, specifically, downhole equipment against corrosion. EFFECT: prolonged service life of grounding electrode thanks to ensured current running-off from electrodes of grounding electrode to ground. 4 dwg