Maximizing MFL ILI Sizing Confidence and Accuracy Using High-Resolution Field Measurement Data

Abstract

Magnetic Flux Leakage inspection tools are generally calibrated on a series of manufactured defects. This has been shown to give good results on a wide range of defects in varying wall thicknesses, velocities and pipeline conditions. Significant improvements in sizing performance can be achieved if sizing algorithms can be optimized on high resolution field data with low uncertainty that more closely reflects the actual line specific corrosion dimensions and profiles. The effects of defect profile can be significant to the MFL signal response. In order to achieve this goal, very high resolution and accurate field measurement techniques are needed to map the combined profile of a significant number of corrosion defects. This paper discusses a process for developing high performance sizing algorithms that consistently better industry standards for MFL sizing performance in areas of high density or complex corrosion in both oil and gas pipelines through the incorporation of high resolution laser scan technology. Complex corrosion may be considered as an area wherein individual corrosions interact together such that they no longer behave as a single corrosion and the MFL response experiences a superposition of leakage signals. A review of the methodology will be discussed and the results demonstrated through case studies from both Enbridge Pipelines Inc. and TransCanada Pipelines Ltd. where high-resolution field data was used as the basis for sizing model optimization.