Unraveling Concentric Casing Failures: Insights from Two Decades of Investigative Endeavors

Abstract

Abstract Structural well integrity of concentric casing strings set across shallow aquifers, or indeed other corrosive formations is a critical aspect of life cycle well integrity assurance efforts. Regardless of the region (Middle East, North Sea, Gulf of Mexico, West Coast of Africa, or Asia Pacific), wells in these different regions with and without corrosion protection systems, have shown varying degrees of damage profiles due to corrosion impact. For instance, corrosion damage particularly due to shallow aquifer activity has been observed to be the result of different modes of longline corrosion cells set up on the casing strings. Irrespective of the mechanism, a loss of casing integrity due to corrosion results in a loss of primary containment which may impact on well life cycle, environmental protection, loss of production avails or wells asset, and requiring significant resources for remediation. The paper aims to identify the corrosion mechanism behind some example failures using an integrated data approach consisting of downhole wireline corrosion logs, drilling, completion and production data to minimize such future occurrence in the field. The approach highlights the significance of continuously evolving investigative methods to uncover previously unforeseen integrity issues. Cutting-edge technologies, including electromagnetic testing, ultrasonic imaging, and advanced potential profile tools were deployed to enhance the ability to conduct further thorough assessments of well integrity. Dynamic and static potential profile measurements, along with electromagnetic time domain tools, were utilized to assess corrosion trends and understand the underlying mechanisms affecting the assurance of well integrity from a corrosion perspective.