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Yongchen Song - One of the best experts on this subject based on the ideXlab platform.
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The Study of Flow Characteristics During the Decomposition Process in Hydrate-Bearing Porous Media Using Magnetic Resonance Imaging
MDPI AG, 2019Co-Authors: Kaihua Xue, Yongchen Song, Lei Yang, Jiafei Zhao, Shan YaoAbstract:The flow characteristics during decomposition of hydrate-bearing sediments are the most critical parameters for the gas recovery potential from natural gas hydrate reservoirs. The Absolute and relative Permeability and the flow field distribution during the decomposition process of hydrate-bearing porous media synthetically created by glass beads are in-situ measured by using magnetic resonance imaging. The Absolute Permeability value increased slowly, then became stable after the decomposition amount was 50%. The relative Permeability change curve is a typical X-shaped cross curve. As the hydrate decomposed, the relative Permeability values of the two phases increased, the range of the two-phase co-infiltration zone increased with the increase of relative Permeability at the endpoint, and the coexistence water saturation decreased. At the beginning of the decomposition, (hydrate content 100% to 70%), the relative Permeability of methane and water rose rapidly from 22% to 51% and from 58% to 70%, respectively. When the amount of the remaining hydrate was less than 50%, the relative Permeability curve of the hydrate-bearing glass beads almost kept unchanged. During the hydrate decomposition process, the velocity distribution was very uneven and coincided with the porous media structure
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analysis of the effect of particle size on Permeability in hydrate bearing porous media using pore network models combined with ct
Fuel, 2016Co-Authors: Jiaqi Wang, Jiafei Zhao, Yi Zhang, Dayong Wang, Yanghui Li, Yongchen SongAbstract:Abstract Because of the clean burning and minimal pollution generation of natural gas hydrates, they are viewed as premium fuel energy. The gas and water flow is highly dependent on the seepage properties of the hydrate sediments; therefore, the Permeability is a key parameter for estimating the gas production of hydrate reservoirs. Pore network models combined with X-ray computed tomography (CT) were proposed to analyze the index properties and percolation characteristics of porous media containing hydrates in our previous study. This study extends our previous investigation into the influences of particle size and porosity on Permeability. The results suggest the porosities of hydrate-bearing porous media formed by different-size particles, as calculated by both the pore network models and the volumetric method, are in agreement. Moreover, the hydrate-bearing porous media formed by larger-size particles has larger porosity, smaller capillary pressure, and larger Absolute Permeability. In addition, under the same degree of water saturation, larger porosity induced a larger water-phase relative Permeability, but a smaller gas-phase relative Permeability.
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Numerical simulation for laboratory-scale methane hydrate dissociation by depressurization
Energy Conversion and Management, 2010Co-Authors: Haifeng Liang, Yongchen Song, Yongjun ChenAbstract:Abstract In this study, a 2-D axisymmetric simulator is developed to model methane hydrate dissociation in porous media by depressurization. Mass transport, intrinsic kinetic reaction and energy conservation are included in the governing equations, which are discretized using the finite difference method and are solved in the implicit pressure-explicit saturation (IMPES) method. A series of simulations are performed to study the effect of several parameters, including initial gas saturation, outlet pressure, surrounding temperature, and Absolute Permeability, on the behavior of hydrate dissociation in the laboratory-scale system. The results show that a fast hydrate dissociation rate can be induced by the factors including high initial gas saturation, low outlet pressure, high surrounding temperature and high Absolute Permeability. On the other hand, it can be found that a lower outlet pressure and higher initial gas saturation can result in a higher amount of final cumulative gas production; however, final cumulative gas production can not be affected by the change of overburden heat transfer and Absolute Permeability. The depressurization is proved to be more effective than other techniques in the exploitation of the hydrate reservoir with higher initial gas saturation.
Yoshihiro Konno - One of the best experts on this subject based on the ideXlab platform.
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Permeability of sediment cores from methane hydrate deposit in the eastern nankai trough
Marine and Petroleum Geology, 2015Co-Authors: Yoshihiro Konno, Jun Yoneda, Masato Kida, Kosuke Egawa, Kiyofumi Suzuki, Tetsuya Fujii, Jiro NagaoAbstract:Abstract Effective and Absolute Permeability are among the most important factors affecting the productivity of hydrate-bearing sediments during gas recovery operations. In this study, effective and Absolute Permeability have been measured using natural sediment cores obtained from a methane hydrate reservoir in the Eastern Nankai Trough off the shore of Japan. The cores were recovered under pressure and shaped cylindrically with liquid nitrogen spray after rapid pressure release. The cylindrical core was inserted into a core holder for flooding tests in order to apply a near in situ effective stress. The effective Permeability of water in the hydrate-bearing sandy sediment was 47 millidarcies (md) with a hydrate saturation of 70%. After hydrate dissociation, the Absolute Permeability was estimated to be 840 md. Other test results showed that the Absolute Permeability of the hydrate-free sediments was estimated to be tens of microdarcies for clayey sediments, tens of md for silty sediments, and up to 1.5 darcy for sandy sediments. Absolute Permeability showed a strong correlation with sediment grain size in log–log plots. In addition, the effective Permeability of hydrate-bearing sandy sediments and the Absolute Permeability of hydrate-free sandy sediments correlated with the effective porosity. We compared measured data to other experimental data using pressure cores recovered from the same well and wireline pressure tests from a well near the coring well. The results are consistent with each other. At this location, we found that the effective Permeability for hydrate-bearing sandy sediments was in the range of 1–100 md, which was 2–3 orders of magnitude higher than conventional estimates. Finally, the change of Permeability, potentially caused by depressurization-induced gas production, was analyzed. It was found that the high effective stress owing to depressurization and freshwater generation originating from hydrate dissociation caused reduction in Absolute Permeability.
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key factors for depressurization induced gas production from oceanic methane hydrates
Energy & Fuels, 2010Co-Authors: Yoshihiro Konno, Yoshihiro Masuda, Yosuke Hariguchi, Masanori Kurihara, Hisanao OuchiAbstract:Oceanic methane hydrate (MH) deposits have been found at high saturations within reservoir-quality sands in the Eastern Nankai Trough and the Gulf of Mexico. This study investigates the key factors for the success of depressurization-induced gas production from such oceanic MH deposits. A numerical simulator (MH21-HYDRES: MH21 Hydrate Reservoir Simulator) was used to study the performance of gas production from MH deposits. We calculated the hydrate dissociation behavior and gas/water production performance during depressurization for a hypothetical MH well. Simulation runs were conducted under various initial reservoir conditions of MH saturation, temperature, and Absolute Permeability. A productivity function (PF) was introduced as an indicator of gas productivity, which is a function of gas production rate, water production rate, and discount rate. The simulations showed that recovery factors over 36% and maximum gas production rates over 450 000 Sm3/d were expected for the most suitable conditions of ...
Shahab Ayatollahi - One of the best experts on this subject based on the ideXlab platform.
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estimation of carbonates Permeability using pore network parameters extracted from thin section images and comparison with experimental data
Journal of Natural Gas Science and Engineering, 2017Co-Authors: Arash Rabbani, Riyaz Kharrat, Nader Dashti, Ali Assadi, Shahab AyatollahiAbstract:Abstract Petrography and image analysis have been widely used to identify and quantify porous characteristics in carbonate reservoirs. This paper uses the thin section images of 200 carbonate rock samples to predict the Absolute Permeability using intelligent and empirical methods. For each thin section, several pore network parameters are extracted from thin section images of rocks including the average pore size, average throat size, average throat length and average 2-D coordination number of pore network. A neural-based model successfully predicts the Permeability of samples using pore network parameters as the inputs. Second neural network is applied for predicting Absolute Permeability considering lithology, pore type and fabric of the rock samples. Finally, an empirical formula containing porosity and average coordination number as inputs is proposed to predict the Permeability. It has been found that the porosity and coordination number can directly describe the Permeability of carbonates while pore and throat sizes extracted from a single 2-D cross section of rock cannot explain the Permeability of carbonates very well. The results of this study indicate the better performance of pore network extraction method compared to the simple regression analysis for prediction of the Permeability.
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estimation of 3 d pore network coordination number of rocks from watershed segmentation of a single 2 d image
Advances in Water Resources, 2016Co-Authors: Arash Rabbani, Shahab Ayatollahi, Riyaz Kharrat, Nader DashtiAbstract:Abstract In this study, we have utilized 3-D micro-tomography images of real and synthetic rocks to introduce two mathematical correlations which estimate the distribution parameters of 3-D coordination number using a single 2-D cross-sectional image. By applying a watershed segmentation algorithm, it is found that the distribution of 3-D coordination number is acceptably predictable by statistical analysis of the network extracted from 2-D images. In this study, we have utilized 25 volumetric images of rocks in order to propose two mathematical formulas. These formulas aim to approximate the average and standard deviation of coordination number in 3-D pore networks. Then, the formulas are applied for five independent test samples to evaluate the reliability. Finally, pore network flow modeling is used to find the error of Absolute Permeability prediction using estimated and measured coordination numbers. Results show that the 2-D images are considerably informative about the 3-D network of the rocks and can be utilized to approximate the 3-D connectivity of the porous spaces with determination coefficient of about 0.85 that seems to be acceptable considering the variety of the studied samples.
Jingchun Feng - One of the best experts on this subject based on the ideXlab platform.
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measurements of water Permeability in unconsolidated porous media with methane hydrate formation
Energies, 2013Co-Authors: Bo Li, Xiaosen Li, Gang Li, Jingchun FengAbstract:Permeability is one of the key factors that determine the fluids flow capacity and production potential of hydrate deposits. In this study, an experimental setup is developed to investigate the flow properties of the porous media, and the permeabilities to water are measured in the unconsolidated porous media with or without hydrate deposition in the pores. A specialized method of precisely controlling the amount of injected methane gas is employed to form methane hydrate in the core sample, and the hydrate formation process is described by the change characteristics of the gas and hydrate saturations. It is found that the residual gas plays an obstructive role in the water flow and it tends to slightly reduce the water Permeability in the porous media, especially under high pressure conditions. After hydrate formation in the core sample, relatively steady flow state can be obtained under suitable water injection rate Q at which hydrate dissociation rate is very slow. The Absolute Permeability of the porous sample is reduced from 49.2 to 1.2 Darcies when the hydrate saturation increases from 0 to 9.3% in this study, indicating a strong dependence of k on the hydrate saturation.
Arash Rabbani - One of the best experts on this subject based on the ideXlab platform.
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estimation of carbonates Permeability using pore network parameters extracted from thin section images and comparison with experimental data
Journal of Natural Gas Science and Engineering, 2017Co-Authors: Arash Rabbani, Riyaz Kharrat, Nader Dashti, Ali Assadi, Shahab AyatollahiAbstract:Abstract Petrography and image analysis have been widely used to identify and quantify porous characteristics in carbonate reservoirs. This paper uses the thin section images of 200 carbonate rock samples to predict the Absolute Permeability using intelligent and empirical methods. For each thin section, several pore network parameters are extracted from thin section images of rocks including the average pore size, average throat size, average throat length and average 2-D coordination number of pore network. A neural-based model successfully predicts the Permeability of samples using pore network parameters as the inputs. Second neural network is applied for predicting Absolute Permeability considering lithology, pore type and fabric of the rock samples. Finally, an empirical formula containing porosity and average coordination number as inputs is proposed to predict the Permeability. It has been found that the porosity and coordination number can directly describe the Permeability of carbonates while pore and throat sizes extracted from a single 2-D cross section of rock cannot explain the Permeability of carbonates very well. The results of this study indicate the better performance of pore network extraction method compared to the simple regression analysis for prediction of the Permeability.
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estimation of 3 d pore network coordination number of rocks from watershed segmentation of a single 2 d image
Advances in Water Resources, 2016Co-Authors: Arash Rabbani, Shahab Ayatollahi, Riyaz Kharrat, Nader DashtiAbstract:Abstract In this study, we have utilized 3-D micro-tomography images of real and synthetic rocks to introduce two mathematical correlations which estimate the distribution parameters of 3-D coordination number using a single 2-D cross-sectional image. By applying a watershed segmentation algorithm, it is found that the distribution of 3-D coordination number is acceptably predictable by statistical analysis of the network extracted from 2-D images. In this study, we have utilized 25 volumetric images of rocks in order to propose two mathematical formulas. These formulas aim to approximate the average and standard deviation of coordination number in 3-D pore networks. Then, the formulas are applied for five independent test samples to evaluate the reliability. Finally, pore network flow modeling is used to find the error of Absolute Permeability prediction using estimated and measured coordination numbers. Results show that the 2-D images are considerably informative about the 3-D network of the rocks and can be utilized to approximate the 3-D connectivity of the porous spaces with determination coefficient of about 0.85 that seems to be acceptable considering the variety of the studied samples.