Evolution of the Percolation Threshold in Muds and Mudrocks During Burial

Daigle, Hugh; Reece, Julia S.; Flemings, P. B.

doi:10.1029/2019gl083723

Cited by 11 publications

(6 citation statements)

References 106 publications

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“…Marine sediments can also function as a physical sink for CH 4 released from gas hydrate dissociation. There exists a percolation threshold, which is the threshold of gas saturation to show percolation behavior. − Thus, large amounts of gas will be trapped and cannot flow freely in the sediments.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Methane Leakage during Marine Gas Hydrate Production by Depressurization and Hot Water Injection

Shang

Zhan

et al. 2023

Energy Fuels

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Methane hydrate, a potential clean fuel with vast resources, has attracted significant global attention for its exploitation. However, concerns about methane leakage during the hydrate production process persist. This study aims to investigate the possibility of methane leakage during hydrate exploitation using the depressurization and hot water injection methods, as assessed through numerical simulation. Simulation results indicate that, when the depressurization method is employed, dissociated methane remains confined within the hydrate-bearing layer as a result of the pressure differential between this layer and the adjacent layers. Conversely, during hot water injection, the dissociated methane gas migrates into the overlying layer, driven by the increased reservoir pressure. Consequently, the depressurization method proves to be more environmentally friendly than the hot water injection method in terms of mitigating methane leakage.

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Section: Discussionmentioning

confidence: 99%

Evaluation of Methane Leakage during Marine Gas Hydrate Production by Depressurization and Hot Water Injection

Shang

Zhan

et al. 2023

Energy Fuels

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“…We used the Brooks‐Corey parameterization of the capillary drainage curve:

P_{normalc} (S_{w}) = P_{normale} {(\frac{S_{normalw} - S_{wi}}{1 - S_{wi}})}^{- \frac{1}{λ}},

where S w is the wetting phase saturation (assumed to be water), S w i is the irreducible wetting phase saturation, P e is the capillary entry pressure, and λ is the pore‐size parameter (Brooks & Corey, 1964). To constrain the Brooks‐Corey parameters ( P e , S w i , and λ ), we used previously published MICP measurements performed on natural and resedimented samples of marine muds from various locations around the world (Daigle & Dugan, 2014; Daigle et al., 2019; Reece et al., 2013; Sawyer et al., 2008; Schneider, 2011). The Brooks‐Corey parameters are expected to vary with grain size and porosity.…”

Section: Methodsmentioning

confidence: 99%

“…This would be more likely in sediments with lower permeability, but understanding this process completely requires detailed models of multiphase flow, which are beyond the scope of the present work. Note that using a 10% mobility threshold will give more conservative estimates of fracturing behavior than using the percolation threshold, which is considerably larger than 10% in shallow marine muds (Daigle et al., 2019). Future research should investigate gas mobility thresholds specific to marine muds, and how this threshold varies during burial.…”

Section: Methodsmentioning

confidence: 99%

“…Note that using a 10% mobility threshold will give more conservative estimates of fracturing behavior than using the percolation threshold, which is considerably larger than 10% in shallow marine muds (Daigle et al, 2019). Future research should investigate gas mobility thresholds specific to marine muds, and how this threshold varies during burial.…”

Section: Gasmentioning

confidence: 99%

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Gas‐Driven Tensile Fracturing in Shallow Marine Sediments

et al. 2020

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The flow of gas through shallow marine sediments is an important component of the global carbon cycle and affects methane release to the ocean and atmosphere as well as submarine slope stability. Seafloor methane venting is often linked to dissociating hydrates or gas migration from a deep source, and subsurface evidence of gas‐driven tensile fracturing is abundant. However, the physical links among hydrate dissociation, gas flow, and fracturing have not been rigorously investigated. We used mercury intrusion data to model the capillary drainage curves of shallow marine muds as a function of clay content and porosity. We combined these with estimates of in situ tensile strength to determine the critical gas saturation at which the pressure of the gas phase would exceed the pressure required to generate tensile fractures. Our work showed that fracturing is favored in the shallowest 38 m of sediment when the clay‐sized fraction is 0.2, but fracturing may be possible to a depth of 132 m below seafloor (mbsf) with a clay‐sized fraction of 0.5 and to a depth of nearly 500 mbsf with a clay‐sized fraction of 0.7. Dissociating hydrate may supply sufficient quantities of gas to cause fracturing, but this is only likely near the updip limit of the hydrate stability zone. Gas‐driven tensile fracturing is probably a common occurrence in the upper 10–20 mbsf regardless of clay‐sized fraction, does not require much gas (far less than 10% gas saturation), and is not necessarily an indication of hydrate dissociation.

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“…However, we have a poor understanding of critical gas saturation in shallow sediment. Daigle et al (2019) suggested that critical gas saturation varies with porosity and is high (10-60%) in shallow marine muds. However, they also pointed out that the shallow sediment is the weakest and most prone to tensile fracturing (Boudreau, 2012), which would allow gas escape at lower saturations (Daigle et al, 2019).…”

Section: Lithologymentioning

confidence: 99%

Methane Hydrate Formation and Evolution During Sedimentation

You

Flemings

2021

JGR Solid Earth

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We explored methane hydrate formation with sedimentation with a newly developed one‐dimensional, multiphase flow, multicomponent transport numerical model. Our model couples methane hydrate formation from in situ microbial methane generation within the hydrate stability zone (HSZ), methane recycling, and microbial methane generation below the base of the hydrate stability zone (BHSZ). Both recycled methane and deeply generated methane are transported into the HSZ by buoyancy‐driven free gas flow. Free gas flows through the HSZ by both the processes of capillary‐dependent pore fillings and by salt exclusion during hydrate formation, with the former being the dominant mechanism. We quantitively illustrated the formation of enriched hydrate in muddy sediments above, and interconnected free gas below, the BHSZ, which are common features along the world's continental margin. In addition, we showed two ways to form concentrated methane hydrate above the BHSZ. The first mechanism is local free gas flow during methane recycling. This happens at sites with sufficient methane generation above the BHSZ. The second mechanism is deep microbial methane generation which is transported into the HSZ by free gas flow. This mechanism plays a more important role at sites with high sedimentation rates. This study provides new insights into methane hydrate formation and distribution below the seafloor. It is important for understanding the carbon cycle and carbon storage below the seafloor and for resource evaluation and exploitation.

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Evolution of the Percolation Threshold in Muds and Mudrocks During Burial

Cited by 11 publications

References 106 publications

Evaluation of Methane Leakage during Marine Gas Hydrate Production by Depressurization and Hot Water Injection

Evaluation of Methane Leakage during Marine Gas Hydrate Production by Depressurization and Hot Water Injection

Gas‐Driven Tensile Fracturing in Shallow Marine Sediments

Methane Hydrate Formation and Evolution During Sedimentation

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