In mature onshore wells, near surface casing and wellhead landing base corrosion was identified as a critical concern that can compromise well integrity. Multiple field studies were conducted to identify the root causes for this corrosion growth, such as water presence (rain, shallow aquifers, etc.) or the absence of adequate cathodic protection. Consequently, a comprehensive surface casing and landing base inspection and repair program was established to proactively take the required corrective measures and ensure the integrity of all wells. The current inspection techniques involve cellar excavation, visual inspection for metal loss, ultrasonic (UT) inspection, or even cement chipping if required. Therefore, optimization of candidate selection and the use of alternative equivalent tools to detect near surface corrosion issues is imperative to enhance well integrity management.

As part of its well integrity management program, Saudi Aramco has put more focus on using eddy current tools (EDCs) to assess the integrity of downhole tubulars and identify downhole leaks. The limitations of the first generation tools were related to the total measured thickness and radius of investigation. However, with technology advancement, progressive tools were introduced with much higher thickness measurement capabilities and deeper radius of investigation that can reach up to the 30-in conductor casing. These added features enabled nonintrusive inspection of near surface casing integrity as well as downhole corrosion profiling.

This paper presents a field application of a nonintrusive approach to inspect shallow surface casing using electromagnetic EDC technology. The methodology allowed for early detection of surface casing corrosion growth, and, accordingly, proactive measures were implemented to enhance the well integrity program and save time, manpower, and operational costs. The paper also recaps multiple case studies of severely corroded near surface casing profiles identified by EDCs.

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