{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T09:37:06Z","timestamp":1786700226314,"version":"build-2736575974"},"reference-count":18,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T00:00:00Z","timestamp":1786665600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The detection of microleaks in subsea gas pipelines remains challenging in shallow-water environments because weak bubble-plume echoes are often obscured by seabed reverberation, ambient noise, and platform-induced interference. This study develops a custom multibeam forward-looking sonar system and a dual-domain framework for acoustic detection and localization of underwater gas microleakage. Local statistical enhancement suppresses stable background interference and strengthens anomalous bubble echoes. Blind deconvolution, adaptive grid-based thresholding, and spatial clustering then improve target sharpness, extract candidate bubble-plume regions, and reduce localized false detections. This unsupervised framework requires no pre-collected training data. It was evaluated in 30 independent sea-trial groups conducted in Bohai Bay using air to simulate leakage. Six orifice diameters from 0.5 to 3.0 mm were tested under different compressor-indicated pressures. The plume-observation distances (defined as the sonar-to-leak-device distance at the first confirmed plume response in the sonar image) ranged from 32 to 66 m across the tested conditions. Under the minimum tested condition of a 0.5 mm orifice and a compressor-indicated pressure of 0.5 MPa, the plume was observed at a distance of 32 m. The results demonstrate the feasibility of the proposed system for ROV-assisted detection and localization of subsea gas microleakage in low-visibility shallow-water environments.<\/jats:p>","DOI":"10.3390\/s26165142","type":"journal-article","created":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T09:04:01Z","timestamp":1786698241000},"page":"5142","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Echo- and Image-Domain Fusion for Micro-Leak Detection and Localization in Subsea Gas Pipelines"],"prefix":"10.3390","volume":"26","author":[{"given":"Haichao","family":"Liu","sequence":"first","affiliation":[{"name":"School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"},{"name":"CNOOC (Tianjin) Pipeline Engineering Technology Co., Ltd., Tianjin 300450, China"},{"name":"Tianjin Key Laboratory of Subsea Pipeline, Tianjin 300450, China"},{"name":"CNOOC Energy Technology & Service Limited Key Laboratory for Intelligent Manufacturing and O&M of Offshore Equipment, Tianjin 300450, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian","family":"Li","sequence":"additional","affiliation":[{"name":"School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaobin","family":"Jiang","sequence":"additional","affiliation":[{"name":"CNOOC (Tianjin) Pipeline Engineering Technology Co., Ltd., Tianjin 300450, China"},{"name":"Tianjin Key Laboratory of Subsea Pipeline, Tianjin 300450, China"},{"name":"CNOOC Energy Technology & Service Limited Key Laboratory for Intelligent Manufacturing and O&M of Offshore Equipment, Tianjin 300450, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi","family":"Luo","sequence":"additional","affiliation":[{"name":"CNOOC (Tianjin) Pipeline Engineering Technology Co., Ltd., Tianjin 300450, China"},{"name":"Tianjin Key Laboratory of Subsea Pipeline, Tianjin 300450, China"},{"name":"CNOOC Energy Technology & Service Limited Key Laboratory for Intelligent Manufacturing and O&M of Offshore Equipment, Tianjin 300450, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Leighton, T.G. 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