Leak Location in CCUS Wellbores Using Autocorrelation Delay Features: Method and Field Application

Stable leak localization in CCUS injection wellbores remains difficult under strong background noise. This study proposes a leak localization method based on autocorrelation time delay features of leakage acoustic signals. Considering the generation of confined leakage noise and its waveguide propagation in the wellbore, a time delay relationship between the direct acoustic component and the bottom-reflected echo is established, and an integrated workflow is developed for signal preprocessing, normalized autocorrelation analysis, feature extraction, and location inversion. Experimental results show that the dominant autocorrelation time delay feature remains stable under varying leakage conditions, while leak position changes produce distinguishable peak–valley patterns. The proposed method achieves high localization accuracy, with absolute errors of 0.018–0.046 m and relative errors of 0.76–1.93% under the tested conditions. A field application in a CO2 injection well further demonstrates its practical feasibility. Overall, the method provides a stable and effective approach for leak localization in CCUS injection wellbores and shows potential for engineering applications in noisy environments.