An alternative for carbon dioxide emission mitigation: In situ methane hydrate conversion

Kvamme, Bjørn; Morrissey, Kathryn Lee

doi:10.1063/1.4771807

Cited by 4 publications

(8 citation statements)

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“…The exchange between CH 4 hydrate and CO 2 hydrate is possible through two primary mechanisms. The first mechanism is a solid-state exchange which has been verified experimentally for temperatures substantially inside the ice region for water [5,6] and also theoretically through molecular dynamics (MD) simulations [7]. For temperatures above freezing the water surrounding the hydrate in the pores is a combination of liquid water and pore bounded water.…”

Section: Introductionmentioning

confidence: 88%

Stages in the Dynamics of Hydrate Formation and Consequences for Design of Experiments for Hydrate Formation in Sediments

et al. 2019

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Natural gas hydrates in sediments can never reach thermodynamic equilibrium. Every section of any hydrate-filled reservoir is unique and resides in a stationary balance that depends on many factors. Fluxes of hydrocarbons from below support formation of new hydrate, and inflow of water through fracture systems leads to hydrate dissociation. Mineral/fluid/hydrate interaction and geochemistry are some of the many other factors that determine local hydrate saturation in the pores. Even when using real sediments from coring it is impossible to reproduce in the laboratory a natural gas hydrate reservoir which has developed over geological time-scales. In this work we discuss the various stages of hydrate formation, with a focus on dynamic rate limiting processes which can lead to trapped pockets of gas and trapped liquid water inside hydrate. Heterogeneous hydrate nucleation on the interface between liquid water and the phase containing the hydrate former rapidly leads to mass transport limiting films of hydrate. These hydrate films can delay the onset of massive, and visible, hydrate growth by several hours. Heat transport in systems of liquid water and hydrate is orders of magnitude faster than mass transport. We demonstrate that a simple mass transport model is able to predict induction times for selective available experimental data for CO2 hydrate formation and CH4 hydrate formation. Another route to hydrate nucleation is towards mineral surfaces. CH4 cannot adsorb directly but can get trapped in water structures as a secondary adsorption. H2S has a significant dipole moment and can adsorb directly on mineral surfaces. The quadropole-moment in CO2 also plays a significant role in adsorption on minerals. Hydrate that nucleates toward minerals cannot stick to the mineral surfaces so the role of these nucleation sites is to produce hydrate cores for further growth elsewhere in the system. Various ways to overcome these obstacles and create realistic hydrate saturation in laboratory sediment are also discussed.

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Section: Introductionmentioning

confidence: 88%

Stages in the Dynamics of Hydrate Formation and Consequences for Design of Experiments for Hydrate Formation in Sediments

et al. 2019

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“…A second mechanism is a substantially slower direct solid-state exchange. 24,25 This hydrate exchange is also feasible with injection of carbon dioxide and nitrogen mixtures, as demonstrated by the Prudhoe Bay field pilot project in the winter of Ref. 26.…”

Section: Introductionmentioning

confidence: 91%

Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO₂ into CH₄ hydrate

2015

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In this work, nonequilibrium thermodynamics and phase field theory (PFT) has been applied to study the kinetics of phase transitions associated with CO 2 injection into systems containing CH 4 hydrate, free CH 4 gas, and varying amounts of liquid water. The CH 4 hydrate was converted into either pure CO 2 or mixed CO 2 ACH 4 hydrate to investigate the impact of two primary mechanisms governing the relevant phase transitions: solid-state mass transport through hydrate and heat transfer away from the newly formed CO 2 hydrate. Experimentally proven dependence of kinetic conversion rate on the amount of available free pore water was investigated and successfully reproduced in our model systems. It was found that rate of conversion was directly proportional to the amount of liquid water initially surrounding the hydrate. When all of the liquid has been converted into either CO 2 or mixed CO 2 ACH 4 hydrate, a much slower solid-state mass transport becomes the dominant mechanism. V C 2015 American Institute of Chemical Engineers AIChE J, 61: [3944][3945][3946][3947][3948][3949][3950][3951][3952][3953][3954][3955][3956][3957] 2015

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“…The solid-state mechanism has also been examined theoretically using molecular dynamics simulations. 36,37 The interesting aspect of Figure 4b is that CO 2 hydrate is thermodynamically more stable than CH 4 hydrate. A substantially faster mechanism involves the formation of a new hydrate from CO 2 , which is injected into in situ CH 4 hydrate-filled sediments.…”

Section: Relative Stabilities Of Hydratesmentioning

confidence: 99%

“…This is also confirmed by simulations with CH 4 slab on mineral but no gas phase outside. 37,38,39 Also, these systems go through a nucleation-like step close to the mineral surface but then the nuclei dissolve again.…”

Section: Primary and Secondary Adsorption Of Hydrate Formers On Miner...mentioning

confidence: 99%

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Consistent Thermodynamic Calculations for Hydrate Properties and Hydrate Phase Transitions

Kvamme¹

2020

J. Chem. Eng. Data

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Natural gas hydrates in natural sediments are dominated by methane. It is a clean source of hydrocarbon energy compared to conventional oil and gas. Most of these hydrates are created from biogenic degradation of organic material in the upper crust and are almost pure methane hydrates. Production of methane from hydrates can also be combined with steam cracking of CH 4 to H 2 and CO 2 . The produced CO 2 can be used for the continued production of CH 4 in a zero-emission cycle for producing hydrogen from CH 4 hydrates. One of the challenges in theoretical evaluation of various concepts for producing hydrates has traditionally been related to limitations in theoretical descriptions and associated thermodynamic calculations. Any theoretical concept for phase transition dynamics based on physical principles is based on the implicit couplings between thermodynamic control, mass transport dynamics, and associated heat transport dynamics. In this work, I apply a simple theory based on extensions of the classical nucleation theory (CNT). This is used as a basis for illustrating the need for a consistent thermodynamic model for free-energy-related quantities and energy quantities. The model is also utilized to address the thermodynamic control of hydrate phase transitions in various hydrate schemes, as well as in associated energy changes. Specifically, it is argued that the pressure reduction method is limited by low temperature. One of the kinetic bottlenecks in hydrate production is the slow transport of molecules across an interface of strong hydrogen bonds between liquid water and hydrate. Free-energy changes are also limited in the pressure reduction method. Using CO 2 with limited amounts of N 2 is thermodynamically feasible, in terms of both free-energy changes and released enthalpy during the formation of hydrate from the injected CO 2 /N 2 mixture. Addition of limited amounts of low-molecular-weight surfactants is needed to keep the water/CO 2 mixture interface open and not blocked by hydrate films.

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An alternative for carbon dioxide emission mitigation: In situ methane hydrate conversion

Cited by 4 publications

References 0 publications

Stages in the Dynamics of Hydrate Formation and Consequences for Design of Experiments for Hydrate Formation in Sediments

Stages in the Dynamics of Hydrate Formation and Consequences for Design of Experiments for Hydrate Formation in Sediments

Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO₂ into CH₄ hydrate

Consistent Thermodynamic Calculations for Hydrate Properties and Hydrate Phase Transitions

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An alternative for carbon dioxide emission mitigation: In situ methane hydrate conversion

Cited by 4 publications

References 0 publications

Stages in the Dynamics of Hydrate Formation and Consequences for Design of Experiments for Hydrate Formation in Sediments

Stages in the Dynamics of Hydrate Formation and Consequences for Design of Experiments for Hydrate Formation in Sediments

Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO2 into CH4 hydrate

Consistent Thermodynamic Calculations for Hydrate Properties and Hydrate Phase Transitions

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Impact of water film thickness on kinetic rate of mixed hydrate formation during injection of CO₂ into CH₄ hydrate