Acoustic methane seepage quantification model design, experiments and deep-sea application

Nikolovska, Aneta; Schanze, J.J.

doi:10.1109/oceanse.2007.4302285

Cited by 6 publications

(9 citation statements)

References 16 publications

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“…The question may be addressed, what the upper and lower limit of gas flux might be that can be estimated on the basis of the acoustical backscatter method. As we have not encountered fluxes in access of 5.5 l/min at Batumi seep, we may refer to earlier experiments in a water tank [ Nikolovska and Schanze , 2007]. During these experiments that were conducted with a different sonar system, it was observed that the maximum measurable gas flux is in the range of 20 l/min.…”

Section: Resultsmentioning

confidence: 98%

Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Nikolovska

Sahling

Bohrmann

2008

Geochem Geophys Geosyst

113

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[1] Detailed acoustic investigation of bubble streams rising from the seafloor were conducted during R/V Meteor cruise M72/3a at a deep submarine hydrocarbon seep environment. The area is located offshore Georgia (eastern part of the Black Sea) at a water depth between 840 m and 870 m. The sediment echosounder Parasound DS-3/P70 was used for detecting bubbles in the water column that causes strong backscatter in the echographs (''flares''). Employing the swath echsounder Kongsberg EM710 flares in the water column were mapped along the entire swath width of approximately 1000 m at high spatial resolution. The exact location of the flares could be extracted manually. Subsequently, the horizontally looking sonar Kongsberg digital telemetry MS1000 mounted on a remotely operated vehicle (ROV) was utilized to quantify the flux of bubbles. A model was developed that is based on the principle of finding the ''acoustic mass'' in order to quantify the bubble flux at various seeps. The acoustic approach from the backscatter data of the ROV sonar resulted in bubble fluxes in the range of 0.01 to 5.5 L/min (corresponding to 0.037 to 20.5 mol CH 4 /min) at in situ conditions ($850 m water depth, $9°C). Independent flux estimations using a funnel-shaped device showed that the acoustic model consistently produced lower values but the offset is less than 12%. Furthermore, the deviation decreased with increasing flux rates. A field of bubble streams was scanned three times from different directions in order to reveal the reproducibility of the method. Flux estimations yielded consistent fluxes of about 2 l/min (7.4 mol CH 4 /min) with variations of less than 10%. Although gas emissions have been found at many sites at the seafloor in a range of geological settings, the amount of escaping gas is still largely unknown. With this study presenting a novel method of quantifying bubble fluxes employing a horizontally looking sonar system, it is intended to contribute to the global effort of better constraining bubble fluxes at deep-sea settings.

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Section: Resultsmentioning

confidence: 98%

Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Nikolovska

Sahling

Bohrmann

2008

Geochem Geophys Geosyst

113

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“…Geochemical analyses (Planke et al, 2003) suggest that the water-dominated salsas represent expulsions of shallow waters, whereas deep-seated waters percolate slowly to the surface and are expelled as mud-water mixtures in gryphons and springs. Mazzini et al (2009) suggest that a mixing of meteoric water with a deep originated brine could justify some peculiar characteristics (low Boron content) of one of the Dashgil's salsas (Salsa A). However, the studied area is in the BSh Köppen-Geiger climate area (Peel et al, 2007) and a water surplus able to recharge a phreatic aquifer is almost impossible.…”

Section: The Dashgil Mud Volcanomentioning

confidence: 97%

“…1) presents the typical structure of a mud volcano summit caldera (Evans et al, 2008). Gas, mud and water seepage occur at a number of different structures (Hovland et al, 1997;Mazzini et al, 2009), and their distribution is probably controlled by structural features (Roberts et al, 2011). In the southwestern sector of the summit area, a north-south oriented field of active gryphons and mud cones exist.…”

Section: The Dashgil Mud Volcanomentioning

confidence: 99%

Monitoring methane emission of mud volcanoes by seismic tremor measurements: a pilot study

Albarello

Palo

Martinelli

2012

Nat. Hazards Earth Syst. Sci.

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Abstract.A new approach for estimating methane emission at mud volcanoes is here proposed based on measurements of the seismic tremor on their surface. Data obtained at the Dashgil mud volcano in Azerbaijan reveal the presence of energy bursts characterized by well-determined features (i.e. waveforms, spectra and polarization properties) that can be associated with bubbling at depth. Counting such events provides a possible tool for monitoring gas production in the reservoir, thus minimizing logistic troubles and representing a cheap and effective alternative to more complex approaches. Specifically, we model the energy bursts as the effect of resonant gas bubbles at depth. This modelling allows to estimate the dimension of the bubbles and, consequently, the gas outflow from the main conduit in the assumption that all emissions from depth occur by bubble uprising. The application of this model to seismic events detected at the Dashgil mud volcano during three sessions of measurements carried out in 2006 and 2007 provides gas flux estimates that are in line with those provided by independent measurements at the same structure. This encouraging result suggests that the one here proposed could be considered a new promising, cheap and easy to apply tool for gas flux measurements in bubbling gas seepage areas.

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“…Previous at-sea investigations have used active acoustics to locate gas seeps (Nikolovska and Schanze, 2007;Schneider von Deimling et al, 2010;Westbrook et al, 2009;Nikolovska et al, 2008). It has been shown that quantification can also be performed using such systems (Caudron et al, 2012;Ostrovsky et al, 2008;Shakhova et al, 2014;Leblond et al, 2014;Bayrakci et al, 2014).…”

Section: Resultsmentioning

confidence: 99%

“…In addition, sonar systems (e.g. scientific echosounders) hold the potential to produce quantification of gas flux (Hornafius et al, 1999;Caudron et al, 2012;Greinert and Nutzel, 2004;Schneider von Deimling et al, 2010;Ostrovsky, 2003;Ostrovsky et al, 2008;Nikolovska and Schanze, 2007;Shakhova et al, 2014). For the purpose of long term monitoring (e.g.…”

Section: Introductionmentioning

confidence: 99%

Passive acoustic quantification of gas fluxes during controlled gas release experiments

Bergès

Leighton

White

2015

International Journal of Greenhouse Gas Control

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Acoustic methane seepage quantification model design, experiments and deep-sea application

Cited by 6 publications

References 16 publications

Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Monitoring methane emission of mud volcanoes by seismic tremor measurements: a pilot study

Passive acoustic quantification of gas fluxes during controlled gas release experiments

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