Application of NMR in Coal Reservoir Characterization

2013 ◽  
Vol 765-767 ◽  
pp. 2168-2171 ◽  
Author(s):  
Zi Yang ◽  
Xiao Hua Pan ◽  
Sheng Qiang Yuan ◽  
Zhi Feng Ji
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Reservoir Characterization ◽  
High Rank ◽  
Low Rank ◽  
Main Peak ◽  
Low Rank Coal ◽  
Trimodal Distribution ◽  
Porosity And Permeability ◽  
Coal Reservoir ◽  
Low Rank Coals

Nuclear Magnetic Resonance (NMR) can provide information about pore and fracture structures, porosity and permeability of reservoirs. It can deep into materials without destroying samples, with advantages such as rapid, accurate and high resolution. This paper introduced the experimental principles and carried out a series of NMR experiments based on high rank coal and low rank coal samples. Results show that: the T2 spectra of high rank coal samples have an independent trimodal distribution with the main peak located at the low T2 value section, indicating that high rank coal is dominated by micropores and transition pores; while the T2 spectrum of low rank coal samples show a continuous trimodal distribution with the main peak located at the high T2 value section, demonstrating the dominance of macropores, mesopores and fractures. The pore and fracture structures of low rank coals are significantly favorable than those of high rank coals.

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.

Mineral Characteristics of Low-Rank Coal and the Effects on the Micro- and Nanoscale Pore-Fractures: A Case Study from the Zhundong Coalfield, Northwest China

2021 ◽  
Vol 21 (1) ◽  
pp. 460-471 ◽  
Author(s):  
Sandong Zhou ◽  
Dameng Liu ◽  
Yidong Cai ◽  
Yingjin Wang ◽  
Detian Yan
Keyword(s):  
Adsorption Capacity ◽  
Coalbed Methane ◽  
Mineral Content ◽  
Northwest China ◽  
Low Rank ◽  
Low Rank Coal ◽  
Mineral Characteristics ◽  
Type D ◽  
Coal Reservoir ◽  
Nuclear Magnetic

The mineral characteristics (occurrence, type, and content) of low-rank coal and their influence on coalbed methane (CBM) reservoirs are investigated at the micro- and nanoscales. Six coal samples of three representative coalmines were used to demonstrate the uniform tectonization from the Zhundong coalfield, NW China. Based on optical microscopy and scanning electron microscopyenergy dispersive spectrum (SEM-EDS) analysis, the mineral composition and occurrence characteristics were discussed. The micro- and nanoscale reservoir characteristics in low-rank coal (pore size distribution and adsorption capability) were studied by diverse methods, including lowtemperature N2 adsorption/desorption, mercury intrusion porosimetry and CH4 isotherm adsorption analysis. The coal reservoir nuclear magnetic T2 spectra of porosity and movable fluid were obtained by combining low-field nuclear magnetic resonance (NMR) analysis, which has an advantage of determining pore fluid technology. The mineral content is highly variable (4˜16 vol.%) in the Xi Heishan prospecting area of the Qitai region. Kaolinite, goyazite, ankerite and anorthosite were microscopically observed to be filling in coal pores and microfractures, and the minerals are given priority to silicate minerals. There is a greater content of mesopores (100–1000 nm) and transition pores (10–100 nm), and they are well connected. The micropores (0–10 nm) are dominated by parallel plate, closed or wedge-shaped pores. Furthermore, the microfractures are mainly observed for types B (width ≥ 5 μm and length≤ 10 mm) and D (width<5 μm and length<300 μm). The results show that microfractures B and C (width< 5 μm and length ≥ 300 μm) are better connected, but the orientation and connectivity of type D are worse. The Langmuir volume and mesopore content decreased with increasing mineral content, which shows that the low-rank coal minerals filled some adsorption space; the reduced CBM adsorption capacity and cellular pore and intergranular pore filled with minerals affect the mesopore content. Therefore, mineral characterization significantly influences methane adsorption capacity and pore structure.

Biological Anaerobic Treatment for Low-Rank Coal Preparation

2011 ◽  
Vol 361-363 ◽  
pp. 328-331
Author(s):  
Li Mei Sun ◽  
Jiang Wu
Keyword(s):  
Biological Treatment ◽  
Culture Medium ◽  
Flow Reactor ◽  
Coal Ash ◽  
Anaerobic Treatment ◽  
Low Rank ◽  
Low Rank Coal ◽  
Higher Rank ◽  
Iron Manganese ◽  
Low Rank Coals

The effect of microbiological treatment of low-rank coal with an anaerobic microbial consortium on theirs characteristics and composition has been inwestigated. A large amount of pyrite sulfur is removed and coal ash is decreased with anaerobic conditions in closed flask. After biological treatment of these low-rank coals in a continuously operationg flow reactor without air blowiong and with everyday aeration, coal ash reduction is found to be more significant under conditions of reactor aeration due to activation of facultative microorganisems. In some time, some metals are removed from two kinds of low-rank coals, includiing iron, manganese, potassium, lithium, toxic and trace metals. The exchange of elements between coal and mineral culture medium depends on coal rank. Metal leaching is higher for higher rank coal.

scholarly journals Pore size distributions and pore multifractal characteristics of medium and low-rank coals

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bin Sun ◽  
Qing Yang ◽  
Jie Zhu ◽  
Tangsha Shao ◽  
Yuhang Yang ◽  
...  
Keyword(s):  
Pore Size ◽  
Pore Volume ◽  
Nitrogen Adsorption ◽  
Low Rank ◽  
Size Distributions ◽  
Confining Stress ◽  
Mercury Intrusion ◽  
Pore Size Distributions ◽  
Porosity And Permeability ◽  
Low Rank Coals

AbstractIt is of great significance to study the porosity and permeability properties of medium and low-rank coal. The porosity and permeability in confining stress experiments were used to simulate the porosity and permeability variations of coal samples under different depth conditions. The pore structure of Baoqing coal samples is greatly affected by the confining pressure, and the pores and micro cracks are more easily compressed. Based on the experimental data of mercury intrusion porosimetry (MIP) and nitrogen adsorption (NA), the pore size distributions (PSDs) of medium and low-rank coals were studied. High mercury intrusion pressure would lead to coal matrix compression. Therefore, the pore volume calculated by MIP data was corrected by NA data. The PSDs characteristics of Jixi (JX) coal and Baoqing (BQ) coal samples are obtained from the revised pore volume, and the dominant pores of medium and low-rank coals are obtained. The results show that JX coal has higher spatial heterogeneity, connectivity and pore autocorrelation. Micro fractures have an influence on the autocorrelation and heterogeneity of coal samples, especially for BQ coal samples.

scholarly journals The influence of steam drying process on combustion behavior of Indonesian low-rank coals

2020 ◽  
Vol 23 (2) ◽  
pp. 105-115
Author(s):  
Datin Umar ◽  
◽  
Suganal Suganal ◽  
Ika Monika ◽  
Gandhi Hudaya ◽  
...  
Keyword(s):  
Ignition Temperature ◽  
Calorific Value ◽  
High Rank ◽  
Low Rank ◽  
Drying Process ◽  
Combustion Behavior ◽  
East Kalimantan ◽  
Steam Drying ◽  
Low Rank Coals

Steam drying process of the Low Rank Coals (LRCs) has been conducted to produce coal which is comparable with the High Rank Coal (HRC). Characterization of the raw and dried coals was carried out through proximate, ultimate, calorific value, Fourier Transform Infrared (FTIR) spectroscopy and Thermo Gravimetry-Differential Thermal Analysis (TG-DTA) to study the combustion behavior of the coals. This study used Indonesian low rank coals coming from Tabang (TKK coal) and Samurangau (SP coal), East Kalimantan. The results indicate that the calorific value of the dried coals increases significantly due to the decrease in moisture content of the coal. The FTIR spectrums show that the methylene-ethylene (RCH3/CH2) and aromaticity-aliphaticity ratios (Rar/al) of the dried coals increased while the ratio of RCO/ar decreased which reflect that the rank of the coals increased equivalent to the high rank coal (bituminous). Meanwhile, the TG-DTA indicates that the ignition temperature (Tig) and combustion rate (Rmax) of the dried coals increased. This analysis expresses that the dried coals produced by steam drying process have better combustion behavior due to the higher calorific value than those of the raw coals.

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