As the number of aging wells grows in the oil and gas industry, there is a recurrent need for monitoring the health of these wells over their productive life and providing assurance of the integrity of the well barriers that isolate them from uncontrolled formation pressure and fluids. Tubing and casing condition evaluation is a crucial aspect of this evaluation. The industry utilizes a number of conventional technologies for evaluation of tubing and casing integrity, such as internal mechanical calipers, electromagnetic and ultrasonic thickness (UT) tools, which are generally quite satisfactory for the evaluation of the inner casing but are often affected by internal tubular diameters in terms of their application. Most conventional tubular evaluation tools are unable to evaluate multiple concentric barriers. When combined with the low diameter production tubing completions the options for evaluating the production and outer casings become very limited, necessitating the need to pull the inner casing by performing a workover at a considerable expense and inspect the outer casing with conventional technology. A new electromagnetic casing corrosion evaluation technology was applied in a group of critical wells completed with small diameter tubing. The technology utilizes electromagnetic pulsed transient eddy currents to simultaneously inspect tubing and the casing behind it and provide quantifiably segregated measurements of thickness in the tubing and the first concentric casing as well as qualitatively characterized by a third casing string. This slim tool with a diameter of 1-11/16” allows measurements through slim production tubing. The objective of the study was to assess the integrity of a group of mature wells completed with small diameter restrictions, near populated areas and associated with high H2S environment. This study includes the candidate generation, field application, results evaluation and general recommendations for the well integrity program. The results exhibited that the data obtained from the tool is reliable. A quantifiable assessment of the metal loss of casing behind the tubing could be made, which made a mitigation strategy possible to prevent casing leaks, which in these wells are critical due to their population sensitive location.


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