The seepage characteristics of methane hydrate-bearing clayey sediments under various pressure gradients

Liu, Weiguo; Wu, Zhiying; Li, Jiajie; Zheng, Jia‐nan; Li, Yanghui

doi:10.1016/j.energy.2019.116507

Cited by 63 publications

(34 citation statements)

References 34 publications

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“…Natural gas hydrate (NGH) is considered as a promising strategic natural gas energy resource for the future due to its high energy density and large reserves (Koh et al, 2012; Liu, Li, et al, 2019; Liu, Wu, et al, 2019; Malagar et al, 2019). NGH exploitation can be a great help to meet the growing energy demand and reduce carbon dioxide emissions (Li et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution of Hydrate‐Bearing Sands During Thermal Dissociation and Ensued Impacts on the Mechanical and Seepage Characteristics

Liu

et al. 2020

JGR Solid Earth

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102

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In this study, a microfocus X‐ray computed tomography‐based triaxial testing apparatus was used to observe and quantify the microstructure evolution of hydrate‐bearing sands during thermal dissociation of hydrate. Three triaxial shear tests with X‐ray computed tomography were conducted to study the influence of hydrate dissociation on the mechanical behavior of hydrate‐bearing sands. The results show that hydrate covering the sand particle surface dissociates first and then at the menisci between sand particles. The secondary hydrate formation mainly occurs on the menisci between sand particles and the surfaces of the hydrate shells where hydrates already exist. Hydrate dissociation could cause fabric changes in hydrate‐bearing sands, resulting in a more isotropic orientation distribution of sand particles. The failure behavior of the hydrate‐free sand specimen is similar to that of the specimen after hydrate dissociation, which shows an obvious drum‐shaped failure pattern with X‐shaped shear bands. However, the hydrate‐bearing sand specimen exhibits a shear band with a determined thickness and inclination angle. Hydrate dissociation could cause a significant loss of supporting cementation, resulting in a decline in the stiffness and failure strength. The failure strength of hydrate‐free sand specimen is slightly higher than that of the specimen after hydrate dissociation; this may due to that the homogeneous orientation frequency distribution can enhance the stability of the force chain between sand particles. The secondary hydrate formation causes sediment deformation resulting in a decrease in absolute permeability due to pore blockage.

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Section: Introductionmentioning

confidence: 99%

Microstructure Evolution of Hydrate‐Bearing Sands During Thermal Dissociation and Ensued Impacts on the Mechanical and Seepage Characteristics

Liu

et al. 2020

JGR Solid Earth

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102

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“…Seol and Kneafsey (2011) captured the hydrate distribution evolution and potential discrete flow pathways variation in HBS specimens using X‐ray CT. Some experimental permeability measurements have also been compiled according to different matrixes from reservoirs (Johnson et al, 2011; Liu et al, 2020; Wu et al, 2018; Wu, Liu, et al, 2020). The thermal conductivity of HBS is complex because the formation of hydrate between sediment grains enhances the heat transfer between solid particles, and it is related to many parameters, including hydrate saturation, hydrate occurrence, and grain distribution (Dai et al, 2015; Waite et al, 2002, 2005; Wang et al, 2017; Yang et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Pore‐Scale 3D Morphological Modeling and Physical Characterization of Hydrate‐Bearing Sediment Based on Computed Tomography

Sun

et al. 2020

JGR Solid Earth

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Natural gas hydrate is considered to be a promising future energy resource; therefore, obtaining its physical properties is crucial for evaluating gas production efficiency and developing reasonable exploitation strategies. In this study, we present a novel pore-scale 3D morphological modeling algorithm considering various saturation and occurrences (cementing and pore-filling) of hydrate in sediments. To evaluate the performance of the presented algorithm, 14 hydrate-bearing sediment models were constructed based on X-ray computed tomographic images of a consolidated sandy specimen under an effective stress of 3 MPa. Morphologically, the new algorithm generated pore-scale hydrate occurrences coincide with published morphological behaviors of hydrate observed via computed tomography. The tortuosity and fractal dimension of pore spaces of these models were then characterized. The pore networks are also extracted, based on which the evolution of the pore characteristics including the distributions of pore radius, throat radius, throat length, and the coordination number were investigated. Using these generated models, simulations of permeability, thermal conductivity, and electrical conductivity were conducted to evaluate the influences of hydrate saturation and occurrence. These results are validated against published data, demonstrating that this algorithm could be an effective way to construct digital hydrate-bearing sediment models using a single set of computed tomographic images of a hydrate-free specimen. This new method can also be significant for the physical evaluation of natural cores in which hydrate has dissociated during core recovering and transferring.

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“…The characteristics of non-Darcy seepage flow are typically nonlinear, that is, the flow velocity is obviously lower than Darcy flow or the nonlinear section appears when the pressure gradient is small. Furthermore, there is a threshold pressure gradient (TPG), which is the intersection between the nonlinear part and the pressure gradient axis [18][19][20]. When the pressure gradient is lower than TPG, the fluid cannot flow.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the thickness of the boundary layer decreases with the increase of pressure gradient and increases with the increase of fluid viscosity. The characteristics of non-Darcy flow are more serious while boundary layer thickness is bigger [17][18][19]35].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, many investigations indicate that TPG has a significant impact on the determination of development scheme, productivity prediction of fractured wells, and distribution of remaining oil [15][16][17][18][19][34][35][36][37][38][39]. Pascal studied the effect of TPG on oil in non-steady flow by means of analysis, numerical, and integral methods [29].…”

Section: Introductionmentioning

confidence: 99%

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Study on Variation Laws of Fluid Threshold Pressure Gradient in Low Permeable Reservoir

Zhao

Cao

et al. 2020

Energies

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A study on the seepage characteristics and laws of nano-micron pore throat in a low permeable reservoir matrix is of great significance for promoting high efficacy of low permeable reservoirs. Threshold pressure gradient (TPG) is an essential factor to reflect the seepage law. Here, variation laws of TPG and its influencing factors of low reservoir fluid are analyzed systematically through physical simulation experiment. Throat diameter distribution of cores was measured by a mercury injection method, and it was found that with the decrease of pore throat median diameter, TPG increase appeared slowly first and fast afterwards. The patterns of the TPG with permeability in water and oil were compared. Results showed that the TPG versus permeability gave power functions in a form and the TPG in oil was more than two times larger than that of water. Besides, TPG in two-phase flow was investigated by the stabilization method. Tests revealed that the higher the oil saturation, the greater the TPG value, and the TPG in two-phase flow is always higher than that of single-phase flow under the same conditions, which function as the combined action of the capillary force. In addition, the effects of core length, fluid type, and core wettability on the TPG were studied systematically, which has guiding significance for the development of a low permeability reservoir.

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The seepage characteristics of methane hydrate-bearing clayey sediments under various pressure gradients

Cited by 63 publications

References 34 publications

Microstructure Evolution of Hydrate‐Bearing Sands During Thermal Dissociation and Ensued Impacts on the Mechanical and Seepage Characteristics

Microstructure Evolution of Hydrate‐Bearing Sands During Thermal Dissociation and Ensued Impacts on the Mechanical and Seepage Characteristics

Pore‐Scale 3D Morphological Modeling and Physical Characterization of Hydrate‐Bearing Sediment Based on Computed Tomography

Study on Variation Laws of Fluid Threshold Pressure Gradient in Low Permeable Reservoir

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