Theory and simulation analysis of FSM used in internal corrosion monitoring for oil&gas pipeline

Field signature method (FSM) is used today by many of the world´s major oil companies in a wide range of monitoring applications, with advantages of high degree of reliability and accuracy, non-intrusive, reflecting wall thickness visually. In this paper, the theory of FSM used in inner corrosion monitoring was analyzed and the expression of defects evaluation parameter (Fc) was deduced based on the corresponding relation between wall thickness (Tt) and potential drop (Et) of plate model. Numerical simulations with a finite element (FE) model were used for current conduction analysis, the models with defect of various depths were simulated, the relation between Fc and defects was summarized, and the validity of model formula was verified. The correction formulas was given by data fitting and proved to be effective by examples.