Abstract

Metal casing corrosion evaluation using electromagnetic (EM) measurements supports environmentally friendly and efficient hydrocarbon production and regulation-compliant well abandonment at the end of the productive well life. The innermost production tubing can be located inside up to six nested metallic casings. In addition to the uncertainty in casing properties, reduced sensitivity and vertical resolution to outer casing corrosion, the EM responses are further complicated by casing eccentering and metallic profile heterogeneities. The EM multi-barrier evaluation can be based on continuous wave (CW) and pulsed eddy current (PEC) measurements. While advanced processing enables quantitative evaluation of multiple nested casings from multi-spacing and multi-frequency CW, PEC methods rely primarily on time-to-depth mapping for interpreting individual casing thicknesses. In this work, we present a first systematic sensitivity study and information content analysis for evaluation of four or more barriers using PEC sensors of varied lengths. The data resolution concept is used in the study. Three-dimensional finite element modeling is performed for casing eccentering and nearby casing heterogeneities (collars and defects) to demonstrate additional challenges in interpreting outer barriers.

How to Cite:

Omar, S. & Omeragic, D., (2019) “Information content in pulsed eddy current measurements for evaluation of four and more metallic barriers in oil and gas wells”, Review of Progress in Quantitative Nondestructive Evaluation .