A practical model has been developed to predict internal pitting corrosion of oil and gas pipelines. This model, applicable for both sour and sweet production and transmission pipelines, is based on experiments carried out in the laboratory at high pressure and high temperature under the operating conditions of the oil and gas pipelines and on the actual pit growth rates in six operating fields over a period of four years.

The inputs required to use the model are readily available from the field. The inputs are of two kinds: construction (pipe diameter, pipe wall thickness, and pipe inclination) and operational (production rates of oil, water, gas, and solid, temperature, total pressure, partial pressures of H2S and CO2, and concentrations of sulphate, bicarbonate, and chloride ions).

The model accounts for the statistical nature of the pitting corrosion, predicts the growth of internal corrosion pits based on field operational parameters, considers the variation of the pitting corrosion rate as a function of time, and determines the error in the prediction.

The model was validated using integrity management data obtained from an operating pipeline.

Subject
Pits, Water, Piping, Corrosion rate, Solids, Pipelines, Bicarbonates, Pitting corrosion rates, Partial pressures, Corrosion modeling, Surface layers, Pitting, Oil
Government work published by the Association for Materials Protection and Performance (AMPP) with permission of the author(s). Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2007
GOV
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