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Methane bubbles dynamics in aquatic sediments
Methane bubbles dynamics in aquatic sediments
Gassy aquatic sediments over the world are a source of a major concern due to their contribution to sediment destabilization and global warming. Sediment displacing large methane bubbles ascend toward the seafloor by fracturing the ambient muddy sediment. Modelling and simulations are conducted to analyze dynamics and controlling factors of growing and ascending methane bubbles, and to estimate a possibility of sediment destabilization and methane (greenhouse gas) release to the water column and potentially to atmosphere. Modelling relies on solid/fracture mechanics and solute transport physics.
Current projects:
Methane bubble growth in transversely anisotropic muddy sediment:
The project explores bubble shape evolution under the different anisotropy degrees, and its implications for methane transport and release within muddy sediment.
Solute transport during bubble growth and its controlling factors:
The project explores factors that affect methane supply to the growing bubble, such as mechanical and ambient sediment properties.
Effective gassy media models and acoustic applications:
In this project, bubble’s shapes and sizes are evaluated and along with their distributions, are upscaled to constitute an effective gassy media theory. Results are verified against results of in-situ acoustic application.
Dynamics of gaseous methane in Lake Kinneret, Israel:
The project explores spatial and temporal variability of gas content and bubbles characteristics in the lake sediments are modelled and verified against in-situ remote acoustic measurements conducted in the Lake Kinneret. Controlling factors of the identified temporal and spatial variability are analysed.
Induced earthquakes
Induced earthquakes
Earthquakes are one of the primary geological hazards. Their triggers are usually attributed to tectonic motion. However, observations indicate that fluids can also be responsible for triggering seismic activity. Large part of the explored fluid-induced seismicity has an anthropogenic origin. This kind of seismicity is reported everywhere, counts a bigger number of events with time, and prompts a reconsideration of seismic hazard in regions of formerly negligible seismic concern.
Current projects:
Historic seismicity at the Dead Sea fault and its correlation to the regional water level changes:
Different historic water bodies occupied a tectonic depression of the Dead Sea fault in the middle East. Their significant water level fluctuations could have an effect on the historic seismicity pattern in the region. Modelled poro-elasto-plastic deformations produced by both tectonic motion and water level changes, explain the changing seismic rates in the region and demonstrate their correlation with water level changes of the regional historic lakes.
Seismicity patterns of induced earthquakes:
Seismic cycles of the earthquakes induced by water level changes in contemporary reservoirs are modelled and their differences from the tectonically-induced seismicity are analysed.
Pore-scale flow and processes
Pore-scale flow and processes
Pore scale modelling in CT-imaged rock geometry allows to relate macroscopic rock permeability to basic microscopic rock descriptors and to perform a proper up-scaling. Preferential fluid flow pathways at pore-scale are inherently connected to rock microstructure, formed by depositional sedimentary structures such as pore shapes, their preferential orientation, lamination or connectivity. Digital 3-D microscale core analysis is a necessary technique especially for rocks that are difficult to characterize due to various reasons or for those with inhomogeneous or anisotropic pore space.
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