CATHODIC PROTECTION FOR CASING STRINGS AND OILFIELD PIPELINES AGAINST CORROSION AND DEVICE FOR METHOD IMPLEMENTATION Russian patent published in 2015 - IPC C23F13/02 E21B41/02 H01R4/00 

FIELD: oil and gas industry.

SUBSTANCE: cathodic protection for casing strings and oilfield pipelines against corrosion includes stages whereat a well is drilled preliminary up to depth bigger per 2.5-3 m than length of anode bed, the well is drilled out within interval of anode bed depth wherein a mat is mounted, upon drilling, directly before running in electrodes to the well clay mud is injected up to the upper level of the mat, anode bed is mounted, protective current is set for initial period of the cathodic protection operation, polarization is performed within 3-7 days; thereafter overall and polarized potentials of the protected structures are measured; when intensity of the protective current changes more than per 20% from the set value then conclusion is made on loss of clay mud and gel is injected up to the upper level of the mat, at that the above gel consists of the following components per 100 l of water: 2 kg of chalk, 2 kg of carboxymethylcellulose glue and 1 kg of salt; the injected gel is withhold until it is jellified per 5-10 hours, then current intensity is measured again, and if it is restored up to the initial value then conclusion is made on complete recovery of conductivity between soil and anode and cathodic protection reaching the well. The cathodic protection for casing strings and oilfield pipelines against corrosion comprises electrode-input lead with a cable, operating electrode, output cable, control and measurement station, perforated polymer gas vent, mat, polyethylene casing tube, capronic wire rope, filling material represented by the gel consisting of the following components per 100 l of water: 2 kg of chalk, 2 kg of carboxymethylcellulose glue and 1 kg of salt.

EFFECT: improved efficiency of protection against corrosion of casing strings and oilfield equipment, improved reliability of their operation, increased life between overhauls.

8 cl, 2 dwg