Self-adjusted elastic action and its CBM pool-forming effect of the high rank coal reservoir

2005 ◽  
Vol 50 (S1) ◽  
pp. 99-103 ◽  
Author(s):  
Yong Qin ◽  
Xuehai Fu ◽  
Caifang Wu ◽  
Guoyou Fu ◽  
Yingying Bu
Keyword(s):  
High Rank ◽  
Coal Reservoir

scholarly journals Influence of Extreme Temperature on the Pore and Fracture Development of High-Rank Coal

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Ming Yang ◽  
Jingcang Bi
Keyword(s):  
Temperature Stress ◽  
Pore Volume ◽  
Coal Sample ◽  
High Rank ◽  
Research Attention ◽  
Ultralow Temperature ◽  
Distribution Features ◽  
Fracture Development ◽  
Porosity And Permeability ◽  
Coal Reservoir

Pore and fracture structures in coals and their distribution features play an important role in the enrichment and osmosis migration of coalbed methane (CBM). The modification and antireflection of pore and fracture in coal reservoir through ultrahigh and ultralow temperature stress, such as liquid nitrogen frozen-induced cracking and thermal antireflection of coal reservoir, have attracted wide research attention. This study conducted a nuclear magnetic resonance (NMR) experiment of pore and fracture features of coal samples under two extreme temperatures (100°C, −196°C) using the Meso MR23-060H-I low-field NMR and imaging instrument. The influencing law of ultrahigh and ultralow temperature stress on pore and fracture development in high-rank coal was discussed. Results demonstrated that temperature can influence pore and fracture development of high-rank coal samples. The pore volume, porosity, and permeability of the coal sample increase after low-temperature (−196°C) treatment. The proportion of microspores decreases, the proportion of small pores increases, the proportion of mesopores remains the same, and the proportion of macrospores increases to some extent. The pore volume of coal sample decreases after high-temperature (100°C) treatment. Porosity and permeability decrease. The proportion of mesopores declines, the proportion of mesopores remains basically same, and the proportion of macrospores decreases.

scholarly journals Petrophysical characterization of high-rank coal by nuclear magnetic resonance: a case study of the Baijiao coal reservoir, SW China

2018 ◽  
Vol 5 (12) ◽  
pp. 181411 ◽  
Author(s):  
Dongming Zhang ◽  
Yapei Chu ◽  
Shujian Li ◽  
Yushun Yang ◽  
Xin Bai ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Coalbed Methane ◽  
High Rank ◽  
Free Fluid ◽  
Permeability Model ◽  
Cutoff Value ◽  
Coal Reservoir ◽  
Nuclear Magnetic

To better apply nuclear magnetic resonance (NMR) to evaluate the petrophysical characterization of high-rank coal, six anthracite samples from the Baijiao coal reservoir were measured by NMR. The porosity, T 2 cutoff value, permeability and pore type were analysed using the transverse relaxation time ( T 2 ) spectrum before and after centrifugation. The results show that the T 2 spectrum of water-saturated anthracite can be divided into a discontinuous and continuous trimodal distribution. According to the connectivity among pores, three T 2 spectrum peaks were identified at the relaxation times of 0.01–1.7 ms, 1.7–65 ms and greater than 65 ms, which correspond to the micropores (less than 100 nm), mesopores (100–1000 nm) and macropores (greater than 1000 nm), respectively. Based on the T 2 cutoff value, we divided the T 2 spectrum into two parts: bound fluid and free fluid. By comparing two classic permeability models, we proposed a permeability model to calculate the permeability of anthracite. This result demonstrates that NMR has great significance to the exploration of coal reservoirs and to the understanding of the development of coalbed methane.

Control Mechanism of the Effective Stress on Nano-Micro Pores and the Permeability of High-Rank Coals

2021 ◽  
Vol 21 (1) ◽  
pp. 484-494
Author(s):  
Xiaofeng Ji ◽  
Dangyu Song ◽  
Shaokai Yu ◽  
Kaikai He ◽  
Yunbo Li
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Gas Adsorption ◽  
Initial Permeability ◽  
High Rank ◽  
Control Factors ◽  
Reservoir Permeability ◽  
Variation Mechanism ◽  
Coal Reservoir ◽  
The Impact

To study the change and main control factors of the high-rank coal reservoir permeability in deep coal seams, permeability tests under different stresses and gas pressures were carried out in the laboratory. The development and distribution of nano-micro pores and fractures in the coal matrix were analyzed and observed by mercury intrusion porosimetry, gas adsorption, scanning electron microscope and computed tomography to reveal the permeability variation mechanism. The results showed that the initial permeability of the coal samples ranged from 0.0114 mD to 0.2349 mD when the effective stress was 0 MPa, and it clearly varied among different samples. The permeability of all the coal samples was very sensitive to the effective stress and decreased exponentially with the increase of the effective stress. The increase of the pore pressure also led to a decrease of the permeability, whereas the impact of the pore pressure on permeability was less obvious compared with the effective stress. Sub-nanopores, nanopores, micro-fractures and larger fractures are all developed in the coal samples. Connected larger fractures were the main gas migration channels in permeability determination, and the narrowing, disconnection, and closure of the fractures caused by the increase of the effective stress were the most important reasons for significant reduction of permeability.

Triple medium physical model of post fracturing high-rank coal reservoir in southern Qinshui Basin

2014 ◽  
Vol 26 (3) ◽  
pp. 407-415 ◽  
Author(s):  
Shiqi Liu ◽  
Shuxun Sang ◽  
Qipeng Zhu ◽  
Jiefang Zhang ◽  
Hefeng Gao ◽  
...  
Keyword(s):  
Physical Model ◽  
High Rank ◽  
Qinshui Basin ◽  
Southern Qinshui Basin ◽  
Coal Reservoir

Comprehensive analysis of CBM recovery in high rank coal reservoir of Jincheng area

2013 ◽  
Vol 23 (3) ◽  
pp. 447-452 ◽  
Author(s):  
Aihua Liu ◽  
Xuehai Fu ◽  
Bin Luo ◽  
Peipei Luo ◽  
Chunlin Jiao
Keyword(s):  
Comprehensive Analysis ◽  
High Rank ◽  
Coal Reservoir

Permeability dynamic variation under the action of stress in the medium and high rank coal reservoir

2015 ◽  
Vol 26 ◽  
pp. 1030-1041 ◽  
Author(s):  
Junlong Zhao ◽  
Dazhen Tang ◽  
Wenji Lin ◽  
Hao Xu ◽  
Yong Li ◽  
...  
Keyword(s):  
High Rank ◽  
Dynamic Variation ◽  
Coal Reservoir

Temperature-Rising Desorption of CBM

2012 ◽  
Vol 524-527 ◽  
pp. 364-370
Author(s):  
Dong Min Ma ◽  
Ya Bing Lin ◽  
Wei Ma
Keyword(s):  
Gas Production ◽  
High Rank ◽  
Isothermal Adsorption ◽  
Theoretical Support ◽  
Different Temperatures ◽  
Negative Effect ◽  
Higher Rank ◽  
Mining Projects ◽  
Coal Reservoir ◽  
Adsorption Desorption

In order to study the effects of CBM temperature-rising desorption, the isothermal adsorption /desorption experiments on three coal-ranks （anthracite，coking coal and lignite）at different temperatures were designed based on the traditional CBM decompression desorption. The experimental results show that temperature-rising desorption is more effective in high-rank coal and raising the temperature of high-rank coal reservoir can reduce the negative effect of Coal Matrix Shrinkage in the process of production and improve the permeability of coal reservoir. It is also revealed that the technique of temperature-rising desorption used in higher-rank coal reservoir can enhance CBM recovery ratio. This study has provided theoretical support for the application of temperature-rising desorption technique to practical diacharging and mining projects and can effectively solve gas production “bottleneck” problem.

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