Analysis of Water Forms in Lignite and Pore Size Distribution Measurement Utilizing Bound Water as a Molecular Probe

2017 ◽  
Vol 31 (11) ◽  
pp. 11884-11891 ◽  
Author(s):  
Keji Wan ◽  
Pengchao Ji ◽  
Zhenyong Miao ◽  
Zishan Chen ◽  
Yongjiang Wan ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Bound Water ◽  
Molecular Probe ◽  
Distribution Measurement

Determination of T2 cut-off for shale reservoirs: a case study from the Carynginia formation, Perth Basin, Western Australia

2017 ◽  
Vol 57 (2) ◽  
pp. 664 ◽  
Author(s):  
M. Nadia Testamanti ◽  
Reza Rezaee ◽  
Yujie Yuan ◽  
Dawei Pan
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Petroleum Industry ◽  
Bound Water ◽  
Invasive Technique ◽  
Sources Of Information ◽  
Vacuum Oven ◽  
Low Field ◽  
Wide Range

Over recent decades, the low-field Nuclear Magnetic Resonance (NMR) method has been consistently used in the petroleum industry for the petrophysical characterisation of conventional reservoirs. Through this non-invasive technique, the porosity, pore size distribution and fluid properties can be determined from the signal emitted by fluids present in the porous media. Transverse relaxation (T2) data, in particular, are one of the most valuable sources of information in an NMR measurement, as the resulting signal decay can be inverted to obtain the T2 distribution of the rock, which can in turn be correlated with porosity and pore size distribution. The complex pore network of shales, which can have a large portion of pore sizes in the nanopore and mesopore range, restricts the techniques that can be used to investigate their pore structure and porosity. The ability of the NMR technique to detect signals from a wide range of pores has therefore prompted the quest for more standardised interpretation methods suitable for shales. Using low-field NMR, T2 experiments were performed on shale samples from the Carynginia formation, Perth Basin, at different saturation levels. The shale samples were initially saturated with brine and the T2 spectrum for each sample was obtained. Then, they were placed in a vacuum oven and their weight monitored until a constant value was reached. T2 curves were subsequently obtained for each of the oven-dried samples and a cut-off value for clay-bound water was calculated.

scholarly journals The Study of Bound Water Status and Pore Size Distribution of Chinese Fir and Poplar Cell Wall by Low-Field NMR

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Huimin Cao ◽  
Jianxiong Lyu ◽  
Yongdong Zhou ◽  
Xin Gao
Keyword(s):  
Cell Wall ◽  
Low Temperature ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Adsorption Isotherms ◽  
Bound Water ◽  
Chinese Fir ◽  
Fast Growing ◽  
Pore Size Distributions

With the increasing shortage of timber resources and the advancement of environmental protection projects, many artificial fast-growing forests are planted and used as raw materials in China. There are significant differences in the properties of natural forest wood and artificial fast-growing forest wood, and the properties of wood mainly depend on the change in the status of bound water in the cell wall. In this study, the fiber saturation point (FSP) and pore size distributions within the cell wall of six species of fast-growing forest wood were studied by low-temperature nuclear magnetic resonance (NMR) technology. The effects of species, growth rings, and extractives on the FSP and pore structure were analyzed. The water vapor sorption experiments were performed, and the adsorption isotherms of the samples were fitted through the Guggenheim-Anderson-de Boer (GAB) equation. According to the least-square regression of the adsorption isotherms and combined with the low-temperature NMR experiments, the content and proportion of the different types of bound water were analyzed. The results showed that the average FSP of each Chinese fir was about 40% and that of each poplar was about 35%. There is about a 10% difference between the FSP measured by NMR technology and the adsorption bound water content obtained by adsorption isothermal. The pore size distribution results show that in all samples, the proportion of pores larger than 10.5 nm is very low, about 10%; the proportion of 1.92-10.5 nm pores is about 30%; and the proportion of pores smaller than 1.92nm is more than 50%. This work will be helpful to the study of the wood moisture status and provide reference data for wood modification.

scholarly journals Bound Water Content and Pore Size Distribution of Thermally Modified Wood Studied by NMR

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1279
Author(s):  
Chenyang Cai ◽  
Fanding Zhou ◽  
Jiabin Cai
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Water Content ◽  
Size Distribution ◽  
Bound Water ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Thermally Modified Wood ◽  
Bound Water Content ◽  
Modified Wood

The physical and mechanical properties of thermally modified wood (TMW) have been comprehensively studied; however, the quantitative analysis of water states and cell wall pores of TMW is limited. In this work, Douglas fir and Norway spruce were thermally modified at 180, 200 and 220 °C, and then studied by NMR cryoporometry method. The results show that thermally modified samples had lower fiber saturation point and the bound water content than the reference samples at all the experimental temperatures, indicating the reduced hygroscopicity due to thermal modification (TM). In addition, TM decreased number of hygroscopic groups, which can be implied by the decreased proportion of bound water sites, and TM also increased the proportion of small voids for bound water clusters. An increase in TM intensity resulted in lower bound water content and a smaller number of hygroscopic groups. In summary, the NMR method detected the water states and pore size distribution and confirmed that TM decreased the fiber saturation point and hygroscopicity of wood by reducing the bound water content and proportion of bound water sites in wood cell walls.

pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

2019 ◽  
Author(s):  
Paul Iacomi ◽  
Philip L. Llewellyn
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Isosteric Heat ◽  
Material Characterisation ◽  
Mixture Adsorption ◽  
Surface Energetics ◽  
Adsorption Processing ◽  
User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

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