Proactive Corrosion Assessment and Mitigation Strategies for Enhanced Oil Recovery Operations: A Case Study from an Offshore Water Alternating Gas (WAG) Injection Well

Abstract The Water-Alternating Gas (WAG) injection in crude oil recovery poses unique challenges to well integrity due to potential corrosion events. This study assesses the historical corrosion damage and predicts future corrosion risks for an offshore water injection well. The corrosion assessment encompassed modeling of three stages: water injection, shut-in, and gas injection periods, utilizing the in-house corrosion model. During the Water Injection, the presence of dissolved oxygen was found to be the primary corrosion factor, with predicted corrosion rates ranging from 1.9 mpy (with oxygen scavengers) to 17.8 mpy (with untreated seawater). During shut-in periods, the predicted peak pitting corrosion rates ranged from 8.1 mpy and 73.0 mpy. During gas Injection, the predicted internal corrosion rates were minimal for dry gas injection. Corrosion rates for the injection well are heavily influenced by the differential liberation of CO2 during shut-in periods, with severe internal corrosion potentially occurring at certain depths. The model was able to predict specific locations for potential failure along the well, corroborated by data from similar well failures. To mitigate the corrosion risks, it was recommended to consider options such as limiting shut-in durations, employing batch corrosion inhibition prior to shut-in, or considering alternative metallurgy.