Materials Performance

SEP 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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Page 78 of 128

20 SEPTEMBER 2018 W W W.MATERIALSPERFORMANCE.COM C L A S S I C Introduction Corrosion of s oil- s ide s urfa C e of oil well cas ing is rec- ognized as a major production corrosion problem, and considerable attention has been paid to cathodic pro- tection as a means of control. With this in mind, objec- tives of this study were established (1) to determine feasibility of protecting deep wells, (2) to establish a practical method to determine current requirements and (3) to determine the effect of ground bed loca tion on m i n i mu m c u r rent requ i rements a nd c u r rent distribution. Others have published data relating to some of these factors, but many of the questions are not an- swered. The authors of this article aimed at the above objectives as useful in providing data which would permit a more precise appli cation of protection. This article is published as originally appeared in MP, Vol. 1, No. 8 (1962). Current Distribution Distribution of current along casings to a depth of 8000 feet has been stud- ied elsewhere by the po- tential profile method. 1,2,3 In this study, changes of casing-to-soil potentials are measured with a reference electrode placed about one foot below casing bottom to indicate current distribu tion over the entire casing. Current Requirements Current requirements are determined by the polar- ization curve method. This method was se lected be- cause it is theoretically indicative of both localized Feasibility Studies on Cathodic Protection of Deep Well External Casing Surfaces « SUMMARY Describes study designed to examine feasi bility of protecting deep well casings and to validate polarization curve method for de termining minimum protective current val ues. Both laboratory and field studies are de scribed. Changes of casing to soil poten tials measured with reference electrode lo cated immediately below the casing were used to determine the feasibility of protec tion. Variables investigated include location of ground bed, location of reference cell, and time intervals for current integrals. F. E. Blount and P. W. Bolmer Socony Mobil Oil Company, Inc. Dallas, Texas « Revision of a paper titled "Cathodic Protection of External Surfaces of Well Casing" presented at a meeting of the South Central Region Conference, National Association of Corrosion Engineers, October 24-26, 1961, Houston, Texas, and at the Western Division Conference of the NACE Canadian Region, February 7-8, 1962, Calgary, Alberta, Canada.

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