Abstract

Cost effective management of Well Integrity is crucial for maintaining O&G production economics particularly in mature fields. Optimization of Workover resources, cost, time and associated production outage is the key for maximizing productivity. Monitoring wellbore completion through multi-tubular corrosion scanning provides the ability to operators in making this critical decision. Objective of this field trial conducted in the SNOC Sajaa field, onshore Sharjah, United Arab Emirates; was to determine thru-tubing high resolution metal loss across multiple barriers for well integrity assurance in single completion wells.

Wells operating in a low pressure envelope during later life cycle are susceptible to collapse against the original pore pressure due to the loss in wall thickness from corrosion, particularly in the case of legacy packerless completions. Quantitative measurement of thickness in the tubing and casing strings independently was addressed by a real time Magnetic Impulse Defectoscope tool. Scanning metal thickness by measuring magnetic impulse decay including the qualitative detection of the fourth barrier was achieved in the downhole gas-condensate environment. The results were interpreted to classify the average wall loss profile in this pilot project. The results analyzed and presented in this paper demonstrate the effectiveness of continuous corrosion inhibitor using ¼″ capillary strings and direct annulus injection. In addition, a deterioration comparison of tubular integrity over 10+ years of production in a high temperature low pressure corrosive (H2S & CO2) system is presented. Effectiveness and limitations of the Electromagnetic survey against Multi-Finger Caliper is compared and the importance of repeatability in well integrity testing is also demonstrated.

An insight into the metal detection accuracy through multiple tubulars and the fundamentals of well integrity assurance in mature assets is presented. Finally, evaluating the true need for intervention- method and timing, resulting in the reduction of mature well life cycle costs in the current low oil price environment.

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