scholarly journals Dependency of continuum model parameters on the spatially correlated pore structure studied by pore-network drying simulations

2018 ◽  
Author(s):  
Abdolreza Kharaghani ◽  
Xiang Lu ◽  
Evangelos Tsotsas
Keyword(s):  
Vapor Pressure ◽  
Pore Structure ◽  
Moisture Transport ◽  
Transport Coefficient ◽  
Continuum Model ◽  
Pore Network ◽  
Partial Vapor Pressure ◽  
Spatially Correlated ◽  
Pore Structures ◽  
Network Simulations

Pore-network simulations are carried out for monomodal and bimodal pore structures with spatially correlated pore-size distributions. The internal and surface relationships between the partial vapor pressure and saturation as well as the moisture transport coefficient for these model porous structures are identified from the post-processing of the corresponding pore-network model solutions. The simulation results show that the deviation of the partial vapor pressure from the saturation vapor pressure in the presence of liquid – which is referred to as non-local equilibrium effect – in the bimodal pore structures is less pronounced than in the monomodal pore structures. For the monomodal pore structures the moisture transport coefficient profile is not unique over the entire drying process, whereas this profile depends marginally on the drying history of the bimodal pore structures. Finally the ability of the continuum model to predict the results of the pore-network simulations for multiple realizations of the pore space is assessed. Keywords: Scale transition, Moisture transport coefficient, Pore structure, Discrete model, Continuum model  

scholarly journals Deformation of Ordered Mesoporous Silica Structures on Exposure to High Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
John B. Lowe ◽  
Richard T. Baker
Keyword(s):  
Mesoporous Silica ◽  
Pore Structure ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Ordered Mesoporous Silica ◽  
Large Cage ◽  
Pore Structures ◽  
Ordered Mesoporous ◽  
Pore Size Distributions ◽  
Wide Range

Ordered mesoporous silica materials are of interest for a wide range of applications. In many of these, elevated temperatures are used either in the preparation of the material or during its use. Therefore, an understanding of the effect of high temperature treatments on these materials is desirable. In this work, a detailed structural study is performed on silicas with three representative pore structures: a 2-D hexagonal pore arrangement (SBA-15), a continuous 3D cubic bimodal pore structure (KIT-6), and a 3D large cage pore structure (FDU-12). Each silica is studied as prepared and after treatment at a series of temperatures between 300 and 900°C. Pore structures are imaged using Transmission Electron Microscopy. This technique is used in conjunction with Small-Angle X-ray Diffraction, gas physisorption, and29Si solid state Nuclear Magnetic Resonance. Using these techniques, the pore size distributions, the unit cell dimensions of the mesoporous structures, and the relative occupancy of the distinct chemical environments of Si within them are cross correlated for the three silicas and their evolution with treatment temperature is elucidated. The physical and chemical properties before, during, and after collapse of these structures at high temperatures are described as are the differences in behavior between the three silica structures.

Characterization of Micro-Pore Structure in Novel Cement Matrices

2014 ◽  
Vol 1712 ◽  
Author(s):  
Seyoon Yoon ◽  
Isabel Galan ◽  
Kemal Celik ◽  
Fredrik P. Glasser ◽  
Mohammed S. Imbabi
Keyword(s):  
Portland Cement ◽  
Pore Structure ◽  
Engineering Properties ◽  
Calcium Sulfoaluminate ◽  
Pore Structures ◽  
Porosity And Permeability ◽  
Experimental Protocols ◽  
Novel Processing ◽  
Main Component

ABSTRACTCalcium sulfoaluminate (CSA) cements are being developed using a novel processing method having as its objective lowering specific CO2 emissions by ∼50% relative to a Portland cement benchmark. We need to be able to measure the properties of the products. Porosity and permeability measurements help define the engineering properties but their quantification is influenced by the choice of experimental protocols. In the present study we used ordinary Portland cement (PC) paste as a benchmark and hydrated ye’elimite, which is a main component of CSA cements, to understand its pore structure. We report on the use of synchrotron-sourced radiation for µCT (Computerized Tomography) and 3D image re-construction of the internal micro-pore structure of PC and ye’elimite-gypsum pastes. As a comparison, porosity and permeability measurements were traditionally obtained using Mercury Intrusion Porosimetry (MIP). The Mori-Tanaka method and the polynomial statistical model were used to analyze the effects of different 3-D micro-pore structures on mechanical properties. The results show that e micro-pore structures differ considerably between PC and ye’elimite pastes and their bulk modulus is significantly affected by the shapes of their micro-pore structures.

Solvolysis of isopropyl bromide in ethanol–water mixtures. Dissection into initial state and transition state contributions

1976 ◽  
Vol 54 (24) ◽  
pp. 3944-3948 ◽  
Author(s):  
Wiendelt Drenth ◽  
Michael Cocivera
Keyword(s):  
Vapor Pressure ◽  
Transition State ◽  
Thermodynamic Parameters ◽  
Activation Parameters ◽  
Solvent Composition ◽  
Initial State ◽  
Partial Vapor Pressure ◽  
State Variation

Rates were determined for the solvolysis of isopropyl bromide in ethanol–water mixtures (20 to 80% by volume of ethanol) at 50 and 75 °C and the corresponding activation parameters calculated. From the partial vapor pressure of isopropyl bromide over the various solutions at 50 and 75 °C, the variations in its initial state thermodynamic parameters were calculated. Thus, the variation in the activation parameters with solvent composition could be analyzed in terms of initial and transition state contributions. The initial state variation dominates according to a unimolecular as well as to a bimolecular treatment of data.

scholarly journals Identification of Oil Reservoir Meeting Atypical Archie Phenomenon

2015 ◽  
Vol 8 (1) ◽  
pp. 354-357
Author(s):  
Shixiong Yuan ◽  
Haimin Guo ◽  
Yu Ding ◽  
Rui Deng
Keyword(s):  
Pore Structure ◽  
Water Saturation ◽  
Saturation Index ◽  
Oil Reservoir ◽  
Formation Water ◽  
Core Data ◽  
Hydrocarbon Reservoir ◽  
Pore Structures ◽  
Structure Index ◽  
Very High

According to core data, this paper studies variation of resistivity in different pore structures and wettability conditions. The results show that with the increase of pore structure index m, the resistivity will increase significantly when the saturation is constant. Similarly, with increasing saturation index n, the resistivity will also increase even with the same saturation. With fixed m and n, the calculated formation water saturation will be very high, resulting in hydrocarbon reservoir being ignored. This variation characteristic is significant for the identification of hidden reservoir with atypical Archie formula.

scholarly journals A Complex Network Approach for Quantitative Characterization and Robustness Analysis of Sandstone Pore Network Structure

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yuhao Hu ◽  
Guannan Liu ◽  
Feng Gao ◽  
Fengtian Yue ◽  
Tao Gao
Keyword(s):  
Pore Structure ◽  
Complex Network ◽  
Degree Distribution ◽  
Path Length ◽  
Robustness Analysis ◽  
Pore Network ◽  
Average Path Length ◽  
Clustering Coefficient ◽  
Random Disturbance ◽  
Pagerank Algorithm

The rational characterization and quantitative analysis of the complex internal pore structure of rock is the foundation to solve many underground engineering problems. In this paper, CT imaging technology is used to directly characterize the three-dimensional pore network topology of sandstone with different porosity. Then, in view of the problem, which is difficult to quantify the detailed topological structure of the sandstone pore networks in the previous study, the new complex network theory is used to characterize the pore structure. PageRank algorithm is based on the number of connections between targets as a measure index to rank the targets, so the network degree distribution, average path length, clustering coefficient, and robustness based on PageRank algorithm and permeability-related topological parameters are studied. The research shows that the degree distribution of sandstone pore network satisfies power law distribution, and it can be characterized by scale-free network model. The permeability of rock is inversely proportional to the average path length of sandstone network. The sandstone pore network has strong robustness to random disturbance, while a small number of pores with special topological properties play a key role in the macroscopic permeability of sandstone. This study attempts to provide a new perspective of quantifying the microstructure of the pore network of sandstone and revealing the microscopic structure mechanism of macroscopic permeability of pore rocks.

scholarly journals Different Formation Routes of Pore Structure in Aluminum Powder Metallurgy Alloy

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3724 ◽  
Author(s):  
Jana Bidulská ◽  
Róbert Bidulský ◽  
Marco Actis Grande ◽  
Tibor Kvačkaj
Keyword(s):  
Plastic Deformation ◽  
Powder Metallurgy ◽  
Pore Structure ◽  
Structure Parameters ◽  
Technological Solution ◽  
Porosity Evolution ◽  
Angular Pressing ◽  
Pore Structures ◽  
Powder Metallurgy Alloy ◽  
Size And Morphology

In powder metallurgy (PM), severe plastic deformation (SPD) is a well-known technological solution to achieve interesting properties. However, the occurrence of pores in the final product may limit these properties. Also, for a given type of microstructure, the stereometric parameters of the pore structures, such as shape (represented by Aspect and Dcircle) and distribution (fshape, and fcircle), decisively affect the final properties. The influence of different processing routes (pressing, sintering and equal channel angular pressing (ECAP)) on pore structures in an aluminum PM alloy is discussed. The nature of porosity, porosity evolution and its behavior is explored. The correlation between pore size and morphology is also considered. The final pore structure parameters (Aspect, Dcircle, fshape, and fcircle) of studied aluminum alloys produced by different processing routes depends on the different formation routes.

Multiscale characterization of pore structure in carbonate formations: Application to the Scurry Area Canyon Reef Operators Committee Unit

2016 ◽  
Vol 4 (2) ◽  
pp. SF165-SF177 ◽  
Author(s):  
Emmanuel Oyewole ◽  
Mehrnoosh Saneifar ◽  
Zoya Heidari
Keyword(s):  
Pore Structure ◽  
Pore Network ◽  
Effective Porosity ◽  
Well Log ◽  
Porosity And Permeability ◽  
Network Properties ◽  
Log Domain ◽  
Carbonate Formations ◽  
Pore Types

Carbonate formations consist of a wide range of pore types with different shapes, pore-throat sizes, and varying levels of pore-network connectivity. Such heterogeneous pore-network properties affect the fluid flow in the formation. However, characterizing pore-network properties (e.g., effective porosity and permeability) in carbonate formations is challenging due to the heterogeneity at different scales and complex pore structure of carbonate rocks. We have developed an integrated technique for multiscale characterization of carbonate pore structure based on mercury injection capillary pressure (MICP) measurements, X-ray micro-computed tomography (micro-CT) 3D rock images, and well logs. We have determined pore types based on the pore-throat radius distributions obtained from MICP measurements. We developed a new method for improved assessment of effective porosity and permeability in the well-log domain using pore-scale numerical simulations of fluid flow and electric current flow in 3D micro-CT core images obtained in each pore type. Finally, we conducted petrophysical rock classification based on the depth-by-depth estimates of effective porosity, permeability, volumetric concentrations of minerals, and pore types using an unsupervised artificial neural network. We have successfully applied the proposed technique to three wells in the Scurry Area Canyon Reef Operators Committee (SACROC ) Unit. Our results find that electrical resistivity measurements can be used for reliable characterization of pore structure and assessment of effective porosity and permeability in carbonate formations. The estimates of permeability in the well-log domain were cross-validated using the available core measurements. We have observed a 34% improvement in relative errors in well-log-based estimates of permeability, as compared with the core-based porosity-permeability models.

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