Optical Flow-Based Detection of Gas Leaks from Pipelines Using Multibeam Water Column Images

Abstract

In recent years, most multibeam echo sounders (MBESs) have been able to collect water column image (WCI) data while performing seabed topography measurements, providing effective data sources for gas-leakage detection. However, there can be systematic (e.g., sidelobe interference) or natural disturbances in the images, which may introduce challenges for automatic detection of gas leaks. In this paper, we design two data-processing schemes to estimate motion velocities based on the Farneback optical flow principle according to types of WCIs, including time-angle and depth-across track images. Moreover, by combining the estimated motion velocities with the amplitudes of the image pixels, several decision thresholds are used to eliminate interferences, such as the seabed, non-gas backscatters in the water column, etc. To verify the effectiveness of the proposed method, we simulated the scenarios of pipeline leakage in a pool and the Songhua Lake, Jilin Province, China, and used a HT300 PA MBES (it was developed by Harbin Engineering University and its operating frequency is 300 kHz) to collect acoustic data in static and dynamic conditions. The results show that the proposed method can automatically detect underwater leaking gases, and both data-processing schemes have similar detection performance.

Semi-Automated Data Processing and Semi-Supervised Machine Learning for the Detection and Classification of Water-Column Fish Schools and Gas Seeps with a Multibeam Echosounder

“…On the other hand, gas seeps are scattered and extend from the seabed to the surface, with their Top-Bottom dimension bigger than the others (N-S or E-W). Fish schools and gas seeps also differ in terms of velocity: the first class is characterized by a low 3D velocity (lesser than 5 m/s [ 49 ]) with the bigger component of this vector parallel to the seabed, whereas the second can also reach speeds over 10 m/s [ 17 ] with the orthogonal component overwhelmingly bigger. Moreover, as the spatial distribution of gas plumes is scattered, the volume of slices is larger for fish schools than gas seeps.…”

“…Indeed, the wide area insonified with a single swath (typically covering about 120°) differentiates MBESs from SBES whose main beam widens less than 20° and therefore requires far more survey time to achieve equivalent coverage. Novel and compelling applications of WCI from MBES range from qualitative descriptions of fish school behavior and morphological characteristics [ 11 , 12 , 13 , 14 ], oil and gas leakage detection [ 15 , 16 , 17 , 18 ], kelp ecosystem mapping [ 19 , 20 ] and aquaculture monitoring [ 21 ], to assessing the mean abundance of marine macro-litter [ 22 , 23 ] and providing other valuable insights to marine systems [ 24 , 25 , 26 , 27 ].…”

Radar and Sonar Imaging and Processing

“…Xu at al. [20] work not with bottom data but with water column data, showing a very interesting case of the use of multi-beam measurements. The goal of this research was to propose an effective method for detecting gas leaks from bottom pipelines based on an analysis of water column images (WCI).…”

Broadband Acoustic Inversion for Gas Flux Quantification—Application to a Methane Plume at Scanner Pockmark, Central North Sea

“…Active acoustics, specifically the use of multibeam echo sounders, has been commonly used for seep detection in the last decades (Greinert, Lewis, et al., 2010; Xu et al., 2020) and has been used to map both natural and anthropogenic ebullition sites worldwide (Greinert, Lewis, et al., 2010; Greinert et al., 2006; Leblond et al., 2014; Nikolovska et al., 2008; Ostrovsky, 2003; Ostrovsky et al., 2008; Urban et al., 2017; von Deimling et al., 2015; Westbrook et al., 2009). Echo sounders also have the advantage of being able to work in any body of water regardless of visibility unlike optical techniques.…”