Permeability analysis of hydrate-bearing sediments considering the effect of phase transition during the hydrate dissociation process

2021 ◽  
pp. 104337
Author(s):  
Min Li ◽  
Shanshan Zhou ◽  
Peng Wu ◽  
Lunxiang Zhang ◽  
Lei Yang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Dissociation Process ◽  
Hydrate Dissociation ◽  
Hydrate Bearing Sediments

Geomechanical Responses During Gas Hydrate Production Induced by Depressurization

2016 ◽  
Author(s):  
Ah-Ram Kim ◽  
Gye-Chun Cho ◽  
Joo-Yong Lee ◽  
Se-Joon Kim
Keyword(s):  
Methane Hydrate ◽  
Fossil Fuel ◽  
Gas Production ◽  
Field Scale ◽  
Production Well ◽  
Physical Processes ◽  
Hydrate Dissociation ◽  
Thermal Changes ◽  
New Energy ◽  
Hydrate Bearing Sediments

Methane hydrate has been received large attention as a new energy source instead of oil and fossil fuel. However, there is high potential for geomechanical stability problems such as marine landslides, seafloor subsidence, and large volume contraction in the hydrate-bearing sediment during gas production induced by depressurization. In this study, a thermal-hydraulic-mechanical coupled numerical analysis is conducted to simulate methane gas production from the hydrate deposits in the Ulleung basin, East Sea, Korea. The field-scale axisymmetric model incorporates the physical processes of hydrate dissociation, pore fluid flow, thermal changes (i.e., latent heat, conduction and advection), and geomechanical behaviors of the hydrate-bearing sediment. During depressurization, deformation of sediments around the production well is generated by the effective stress transformed from the pore pressure difference in the depressurized region. This tendency becomes more pronounced due to the stiffness decrease of hydrate-bearing sediments which is caused by hydrate dissociation.

Molecular Dynamics Simulation Study of Lecithin Inhibiting Hydrate-Dissociation

2017 ◽  
Vol 890 ◽  
pp. 252-259
Author(s):  
Le Wang ◽  
Guan Cheng Jiang ◽  
Xin Lin ◽  
Xian Min Zhang ◽  
Qi Hui Jiang
Keyword(s):  
Molecular Dynamics ◽  
Water Movement ◽  
Simulation Analysis ◽  
Mass Density ◽  
Dynamics Simulation ◽  
Dissociation Process ◽  
Hydrate Dissociation ◽  
Hydrocarbon Chains ◽  
Dynamics Simulations ◽  
Mass Density Profile

Molecular dynamics simulations are used to study the dissociation inhibiting mechanism of lecithin for structure I hydrates. Adsorption characteristics of lecithin and PVP (poly (N-vinylpyrrolidine)) on the hydrate surfaces were performed in the NVT ensemble at temperatures of 277K and the hydrate dissociation process were simulated in the NPT ensemble at same temperature. The results show that hydrate surfaces with lecithin is more stable than the ones with PVP for the lower potential energy. The conformation of lecithin changes constantly after the balanced state is reached while the PVP molecular dose not. Lecithin molecule has interaction with lecithin nearby and hydrocarbon-chains of lecithin molecules will form a network to prevent the diffusion of water and methane molecules, which will narrow the available space for hydrate methane and water movement. Compared with PVP-hydrate simulation, analysis results (snapshots and mass density profile) of the dissociation simulations show that lecithin-hydrate dissociates more slowly.

scholarly journals Tri-Axial Shear Tests on Hydrate-Bearing Sediments during Hydrate Dissociation with Depressurization

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1819 ◽  
Author(s):  
Dongliang Li ◽  
Qi Wu ◽  
Zhe Wang ◽  
Jingsheng Lu ◽  
Deqing Liang ◽  
...  
Keyword(s):  
Shear Tests ◽  
Hydrate Dissociation ◽  
Axial Shear ◽  
Hydrate Bearing Sediments

scholarly journals Heat-Induced Evolution of Phase Transformations in Tetrahydrofuran Hydrate-Bearing Sediment

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
X. H. Zhang ◽  
X. B. Lu ◽  
Z. M. Zheng ◽  
L. M. Zhang
Keyword(s):  
Phase Transformations ◽  
Hydrate Dissociation ◽  
Three Phase ◽  
Deformation Processes ◽  
Strata Deformation ◽  
Series Of Experiments ◽  
Similar Solutions ◽  
Hydrate Bearing Sediments ◽  
And Control ◽  
Kinetics Of

Heat conduction and phase transformations are basic physical-chemical process and control the kinetics of dissociation, fluid flow and strata deformation during hydrate dissociation in sediments. This paper presents a simplified analysis of the thermal process by assuming that the heat-induced evolution can be decoupled from flow and deformation processes. Self-similar solutions for one-, two- and three-phase transformation fronts are obtained. A series of experiments on THF-hydrate-bearing sediments was conducted to test the theory. The theoretical, numerical and experimental results on the evolution of hydrate dissociation front in the sediment are in good agreement.

scholarly journals Enthalpies of Hydrate Formation and Dissociation from Residual Thermodynamics

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4726 ◽  
Author(s):  
Solomon Aforkoghene Aromada ◽  
Bjørn Kvamme ◽  
Na Wei ◽  
Navid Saeidi
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Gas Hydrate ◽  
Hydration Number ◽  
Hydrate Formation ◽  
Formation Enthalpy ◽  
Hydrate Dissociation ◽  
Enthalpy Changes ◽  
Hydrate Phase ◽  
Temperature Equilibrium

We have proposed a consistent thermodynamic scheme for evaluation of enthalpy changes of hydrate phase transitions based on residual thermodynamics. This entails obtaining every hydrate property such as gas hydrate pressure-temperature equilibrium curves, change in free energy which is the thermodynamic driving force in kinetic theories, and of course, enthalpy changes of hydrate dissociation and formation. Enthalpy change of a hydrate phase transition is a vital property of gas hydrate. However, experimental data in literature lacks vital information required for proper understanding and interpretation, and indirect methods of obtaining this important hydrate property based on the Clapeyron and Clausius-Clapeyron equations also have some limitations. The Clausius-Clapeyron approach for example involves oversimplifications that make results obtained from it to be inconsistent and unreliable. We have used our proposed approach to evaluate consistent enthalpy changes of hydrate phase transitions as a function of temperature and pressure, and hydration number for CH4 and CO2. Several results in the literature of enthalpy changes of hydrate dissociation and formation from experiment, and Clapeyron and Clausius-Clapeyron approaches have been studied which show a considerable disagreement. We also present the implication of these enthalpy changes of hydrate phase transitions to environmentally friendly production of energy from naturally existing CH4 hydrate and simultaneously storing CO2 on a long-term basis as CO2 hydrate. We estimated enthalpy changes of hydrate phase transition for CO2 to be 10–11 kJ/mol of guest molecule greater than that of CH4 within a temperature range of 273–280 K. Therefore, the exothermic heat liberated when a CO2 hydrate is formed is greater or more than the endothermic heat needed for dissociation of the in-situ methane hydrate.

Experimental Study on Gas Production from Methane Hydrate Bearing Sand by Depressurization

2013 ◽  
Vol 310 ◽  
pp. 28-32
Author(s):  
Jian Ye Sun ◽  
Yu Guang Ye ◽  
Chang Ling Liu ◽  
Jian Zhang
Keyword(s):  
Experimental Study ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Gas Production ◽  
Decomposition Kinetics ◽  
Dissociation Process ◽  
Hydrate Dissociation ◽  
Gas Hydrate Formation ◽  
Experimental Apparatus ◽  
Hydrate Saturation

The simulate experiments of gas production from methane hydrates reservoirs was proceeded with an experimental apparatus. Especially, TDR technique was applied to represent the change of hydrate saturation in real time during gas hydrate formation and dissociation. In this paper, we discussed and explained material transformation during hydrate formation and dissociation. The hydrates form and grow on the top of the sediments where the sediments and gas connect firstly. During hydrates dissociation by depressurization, the temperatures and hydrate saturation presented variously in different locations of sediments, which shows that hydrates dissociate earlier on the surface and outer layer of the sediments than those of in inner. The regulation of hydrates dissociation is consistent with the law of decomposition kinetics. Furthermore, we investigated the depressurizing range influence on hydrate dissociation process.

Numerical Simulations of Drilling Mud Invasion into the Marine Gas Hydrate-Bearing Sediments

2011 ◽  
Vol 366 ◽  
pp. 378-387 ◽  
Author(s):  
Fu Long Ning ◽  
Yi Bing Yu ◽  
Guo Sheng Jiang ◽  
Xiang Wu ◽  
Ke Ni Zhang ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Gas Hydrate ◽  
Wellbore Stability ◽  
Drilling Mud ◽  
Hydrate Dissociation ◽  
Hydrate Saturation ◽  
Drilling Condition ◽  
Hydrate Bearing Sediments ◽  
Invasion Behavior ◽  
Hydrate Stability

When drilling through the oceanic gas hydrate-bearing sediments, the water-based mud under overbalanced drilling condition will invade into the borehole sediments. The invasion behavior can influence the hydrate stability, wellbore stability and well logging evaluation. In this work, we performed the numerical simulations to study the effects of density (i.e., corresponding pressure), temperature and salinity of mud on the mud invasion and hydrate stability around borehole. The results show that the mud invasion will promote greatly the hydrate dissociation near wellbore sediments if the temperature of mud is higher than that of hydrate stability. Under certain conditions, the higher mud density, temperature and salinity, the greater degree of mud invasion and heat transfer, and the more hydrate dissociation. The gas produced from hydrate dissociation can reform hydrates again in the sediments, and even the hydrate saturation is higher than that in situ sediments due to the displacing effect of the mud invasion, which forms a high-saturation hydrate girdle band around the borehole.

Study on the spatial differences of methane hydrate dissociation process by depressurization using an L-shape simulator

Energy ◽  
2021 ◽  
Vol 228 ◽  
pp. 120635
Author(s):  
Jin-Long Cui ◽  
Li-Wei Cheng ◽  
Jing-Yu Kan ◽  
Wei-Xin Pang ◽  
Jun-Nan Gu ◽  
...  
Keyword(s):  
Methane Hydrate ◽  
Dissociation Process ◽  
Hydrate Dissociation ◽  
Spatial Differences

scholarly journals Investigating the Interaction Effects between Reservoir Deformation and Hydrate Dissociation in Hydrate-Bearing Sediment by Depressurization Method

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 548
Author(s):  
Lijia Li ◽  
Xiaosen Li ◽  
Yi Wang ◽  
Chaozhong Qin ◽  
Bo Li ◽  
...  
Keyword(s):  
Production Process ◽  
Coupling Model ◽  
Effective Porosity ◽  
Gas Production ◽  
Water Production ◽  
Reservoir Temperature ◽  
Hydrate Dissociation ◽  
Mechanical Coupling ◽  
Hydrate Decomposition ◽  
Hydrate Bearing Sediments

Natural gas hydrate (NGH) has been widely focused on having great potential for alternative energy. Numerous studies on gas production from hydrate-bearing sediments have been conducted in both laboratory and field. Since the strength of hydrate-bearing sediments depends on the saturation of NGH, the decomposition of NGH may cause the failure of sediments, then leading to reservoir deformation and other geological hazards. Plenty of research has shown that the reservoir deformation caused by hydrate decomposition is considerable. In order to investigate this, the influence of sediment deformation on the production of NGH, a fully coupled thermo-hydro-chemo-mechanical (THMC) model is established in this study. The interaction effects between reservoir deformation and hydrate dissociation are discussed by comparing the simulation results of the mechanical coupling and uncoupled models on the laboratory scale. Results show that obvious differences in behaviors between gas and water production are observed among these two models. Compared to the mechanical uncoupled model, the mechanical coupling model shows a significant compaction process when given a load equal to the initial pore pressure, which leads to a remarkable decrease of effective porosity and reservoir permeability, then delays the pore pressure drop rate and reduces the maximum gas production rate. It takes a longer time for gas production in the mechanical coupling model. Since the reservoir temperature is impacted by the comprehensive effects of the heat transfer from the boundary and the heat consumption of hydrate decomposition, the reduced maximum gas production rate and extended gas production process for the mechanical coupling model lead to the minimum reservoir temperature in the mechanical coupling model larger than that of the mechanical uncoupled model. The reduction of the effective porosity for the mechanical coupling model causes a larger cumulative water production. The results of this paper indicate that the reservoir deformation in the gas production process should be taken into account by laboratory and numerical methods to accurately predict the behaviors of gas production on the field scale.

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