Assessment of Local Corrosion Based on Data Obtained From Electrical Resistance Sensors

   Complications related to the corrosive environment, according to Rosneft, are among the prevailing ones at oil and gas production facilities and occupy the 4th place among other factors complicating production – 12 % of the complicated mechanized well stock. Therefore, diagnostics and monitoring of the condition of oilfield equipment for corrosion wear is an urgent direction for improving the reliability of the technological process of oil production and transportation. The «electrical resistance» (ES) method is one of methods of corrosion monitoring in the oil and gas industry. The disadvantage of the ES method is that the devices currently used do not allow to assess the unevenness of corrosion losses on the surface of the material, that is, they cannot identify the process of local corrosion development. Nevertheless, it is local corrosion that causes failures of oilfield equipment. The article proposes a physical model of the development of corrosion, reflecting the relationship of changes in the resistance of a corroding element with the rate of corrosion consumption. The corrosion process is described through special cases of uniform and local corrosion having different rates of corrosion flow. Based on
the results of the analysis of the physical model of local corrosion, methods for interpreting data obtained from electrical resistance sensors are proposed, which allows detecting the manifestation of ulcerative corrosion. A marker of developing local corrosion is a change in the dynamic of sensing element resistance growth.

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