Coal permeability prediction method based on the microscopic pore-fracture dual-porosity structure

2022 ◽  
pp. 110107
Author(s):  
Hongyang Ni ◽  
Jiangfeng Liu ◽  
Tao Chen ◽  
Shaojie Chen ◽  
Qingbin Meng
Keyword(s):  
Prediction Method ◽  
Dual Porosity ◽  
Coal Permeability ◽  
Porosity Structure ◽  
Permeability Prediction

scholarly journals Model development and analysis of coal permeability based on the equivalent characteristics of dual-porosity structure

2019 ◽  
Vol 17 (2) ◽  
pp. 313-327
Author(s):  
Haijun Guo ◽  
Kai Wang ◽  
Yuanping Cheng ◽  
Liang Yuan ◽  
Chao Xu
Keyword(s):  
Coalbed Methane ◽  
Model Development ◽  
Gas Pressure ◽  
Dual Porosity ◽  
Permeability Evolution ◽  
Evolution Law ◽  
Fracture Width ◽  
Coal Permeability ◽  
Porosity Structure ◽  
Gas Seepage

Abstract Mining is a dynamic fracture process of coal and/or rock. The structural failure of coal bodies will change the coal matrix-fracture characteristics and then affect the distribution characteristics of the coalbed methane (CBM). Because of the structural complexity of coal, the coal matrices and fractures will be assumed to the geometries with rule shapes when the gas seepage characteristics in coals are analyzed. The size of the simplified geometries is the equivalent scale of dual-porosity coal structures (i.e. the equivalent fracture width and equivalent matrix scale). In this paper, according to the reasonable assumptions with regarding to dual-porosity coal structures, a new coal permeability evolution model based on the equivalent characteristics of dual-porosity structure (ECDP model) was built and the effect of the equivalent characteristics of dual-porosity structure on the coal permeability evolution law was analyzed. It is observed that if the initial fracture porosity is constant and the equivalent matrix scale increases, the range in which the permeability of coal rises with rising gas pressure increases; if the equivalent fracture width decreases and the equivalent matrix scale is constant, the range in which the permeability of coal rises with rising gas pressure decreases. The ECDP model is more suitable for revealing the evolution law of the coal permeability when large deformations occur in the coal bodies and/or the coal structure is damaged irreversibly, especially during enhancing CBM recovery.

A New Coal Permeability Prediction Method Based on Experiment and Dimension Analysis

SPE Journal ◽  
2013 ◽  
Vol 19 (03) ◽  
pp. 356-360 ◽  
Author(s):  
Wang Zhiming ◽  
Yang Gang ◽  
Zhang Jian
Keyword(s):  
Regression Analysis ◽  
Effective Stress ◽  
Prediction Method ◽  
Effect Of Temperature ◽  
Permeability Model ◽  
Coal Permeability ◽  
Permeability Prediction ◽  
Dimension Analysis ◽  
Permeability Increase ◽  
Core Permeability

Summary This paper aims to investigate the effect of temperature and effective stress on coal permeability. Through the experiment, we find a reversal phenomenon in which the coal permeability presents different change trends as temperature increases at two sides of the reverse point. The term “critical effective stress” refers to the effective stress at the reverse point. When effective stress is lower than the critical effective stress, the outward expansion effect of the coal block caused by grain and gas swell is greater than compaction effect as temperature increases under low effective stress condition. Therefore, the coal expands primarily outward, which results in fissure opening and permeability increase. When effective stress is higher than the critical effective stress, high effective stress limits the coal's outward expansion. The coal expands inward with increasing temperature, thus causing fissure closure and permeability decrease. On the basis of dimension analysis and regression analysis, combined with experimental data, this paper develops a high-precision semitheoretical coal permeability model of Qinshui basin in China. Simultaneously, what this paper presents is a permeability prediction method: measuring coal core permeability and performing dimension analysis and regression analysis. With this work done, we can establish a similar permeability model suitable for other target zones. Thus, the analytical method presented in this paper provides a basis for coal permeability prediction.

scholarly journals Permeability Prediction in Deep Coal Seam: A Case Study on the No. 3 Coal Seam of the Southern Qinshui Basin in China

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Pinkun Guo ◽  
Yuanping Cheng
Keyword(s):  
Coal Seam ◽  
Effective Stress ◽  
Axial Stress ◽  
Gas Pressure ◽  
Coal Bed ◽  
Stress And Strain ◽  
Qinshui Basin ◽  
Coal Permeability ◽  
Permeability Prediction ◽  
Southern Qinshui Basin

The coal permeability is an important parameter in mine methane control and coal bed methane (CBM) exploitation, which determines the practicability of methane extraction. Permeability prediction in deep coal seam plays a significant role in evaluating the practicability of CBM exploitation. The coal permeability depends on the coal fractures controlled by strata stress, gas pressure, and strata temperature which change with depth. The effect of the strata stress, gas pressure, and strata temperature on the coal (the coal matrix and fracture) under triaxial stress and strain conditions was studied. Then we got the change of coal porosity with strata stress, gas pressure, and strata temperature and established a coal permeability model under tri-axial stress and strain conditions. The permeability of the No. 3 coal seam of the Southern Qinshui Basin in China was predicted, which is consistent with that tested in the field. The effect of the sorption swelling on porosity (permeability) firstly increases rapidly and then slowly with the increase of depth. However, the effect of thermal expansion and effective stress compression on porosity (permeability) increases linearly with the increase of depth. The most effective way to improve the permeability in exploiting CBM or extracting methane is to reduce the effective stress.

Electrospun dual-porosity structure and biodegradation morphology of Montmorillonite reinforced PLLA nanocomposite scaffolds

Biomaterials ◽  
2005 ◽  
Vol 26 (16) ◽  
pp. 3165-3172 ◽  
Author(s):  
Yun Hui Lee ◽  
Jong Hoon Lee ◽  
In-Gu An ◽  
Chan Kim ◽  
Doo Sung Lee ◽  
...  
Keyword(s):  
Dual Porosity ◽  
Porosity Structure ◽  
Nanocomposite Scaffolds

Characterization of dual-structure pore-size distribution of soil

2009 ◽  
Vol 46 (2) ◽  
pp. 129-141 ◽  
Author(s):  
X. Li ◽  
L. M. Zhang
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Void Ratio ◽  
Experimental Results ◽  
Dual Porosity ◽  
Porosity Structure ◽  
The Relationship ◽  
Comprehensive Study

The microporosity structure of soil provides important information in understanding the shear strength, compressibility, water-retention ability, and hydraulic conductivity of soils. It is a soil characteristic that depends on sample preparation method and wetting–drying history. A comprehensive study of the microporosity structure of a lean clay with sand was conducted in this research to investigate variations of the microporosity structure during compaction, saturation, and drying processes. Scanning electron microscopy was used to observe the microporosity structure of soil sample surfaces. Mercury intrusion porosimetry was used to measure the microporosity structure quantitatively by showing the relationship between cumulative pore volumes and pore radius. The experimental results show that a dual-porosity structure (i.e., interaggregate pores and intra-aggregate pores) forms during the compaction process. The interaggregate pores are compressible and the associated volume is closely related to the final void ratio of the compacted sample. Changes to interaggregate pores is dominant during compaction, but changes to intra-aggregate pores is dominant during saturation and drying. Based on the experimental results, a dual-porosity structure model was developed by relating the pore-size distribution to the void ratio. Consequently, the pore-size distribution at any void ratio can be predicted.

scholarly journals A permeability prediction method based on pore structure and lithofacies

2019 ◽  
Vol 46 (5) ◽  
pp. 935-942 ◽  
Author(s):  
Lideng GAN ◽  
Yaojun WANG ◽  
Xianzhe LUO ◽  
Ming ZHANG ◽  
Xianbin LI ◽  
...  
Keyword(s):  
Pore Structure ◽  
Prediction Method ◽  
Permeability Prediction

Benchmark assessment of coal permeability models on the accuracy of permeability prediction

Fuel ◽  
2014 ◽  
Vol 132 ◽  
pp. 194-203 ◽  
Author(s):  
Yan Peng ◽  
Jishan Liu ◽  
Wancheng Zhu ◽  
Zhejun Pan ◽  
Luke Connell
Keyword(s):  
Coal Permeability ◽  
Benchmark Assessment ◽  
Permeability Prediction
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