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The modification of petroleum resin (PR) by catalytic hydrogenation is an upgrading technology for producing high-value-added hydrogenated petroleum resin (HPR) from of pyrolysis petroleum by-product. This research employed alumina supports with different pore size distributions to prepare supported Mo-Ni type catalysts and investigated their catalytic hydrogenation performance on C9 petroleum resin. Catalysts prepared with bimodal pore alumina (BPA) supports effectively overcome the limitations of internal diffusion and increase the quantity of active sites, thus increasing the catalytic activity for hydrogenation. The experimental results demonstrated that MoNi/BPA achieved a hydrogenation degree of 99.94% for HC9PR, with the hydrogenated product having a Pt–Co colour of 2.37 Hazen. After 140 h of reaction, the hydrogenation degree of HC9PR remained at 96.51%, and the Pt–Co colour value was lower than 40 Hazen. This investigation confirms that solving the mass transfer issues of petroleum resin molecules in the pores of supported catalysts is key to designing efficient hydrogenation catalysts for petroleum resin. [ABSTRACT FROM AUTHOR]

The use of construction waste in creating concrete and mortar is an important process that not only offers economic benefits but also helps protect the environment by reducing waste in rural and urban areas. This experimental study aims to investigate the effect of adding crushed ceramic waste (CCW) and crushed brick waste (CBW) on the bulk density, workability, compressive and flexural strengths, water absorption and microstructural properties of dune sand mortar. To determine changes in porosity, the study uses the mercury intrusion porosimetry technique to measure porosity and pore size distribution. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses are conducted to examine the microstructure and size of the voids using an electron microscope, and photographs of voids in the mortar matrix are taken. By replacing 15% of the sand with CCW and CBW, the compactness and mechanical strength of the dune sand mortar are enhanced, increasing the dynamic modulus of elasticity by around 29 and 26%, respectively. This is due to the pozzolanic activity of these residues, which mainly occur in the form of medium and small capillaries in all the mortars studied, reducing the diameter of the pores. [ABSTRACT FROM AUTHOR]

In-situ thermal upgrading is used to tune the pore system in low-maturity oil shales. We introduce fractal dimension (D), form factor (ff) and stochastic entropy (H) to quantify the heating-induced evolution of pore morphological complexity and azimuthal disorder and develop a model to estimate the impact on seepage capacity via permeability. Experiments are conducted under recreated in-situ temperatures and consider anisotropic properties-both parallel and perpendicular to bedding. Results indicate that azimuthal distribution of pores in the bedding-parallel direction are dispersed, while those in the bedding-perpendicular direction are concentrated. D values indicate that higher temperatures reduce the uniformity of the pore size distribution (PSD) in the bedding-parallel direction but narrow the PSD in the bedding-perpendicular direction. The greater ff (> 0.7) values in the bedding-parallel direction account for a large proportion, while the dominated in the bedding-perpendicular direction locates within 0.2e0.7, for all temperatures. The H value of the bedding-parallel sample remains stable at ~0.925 during heating, but gradually increases from 0.808 at 25 ℃ to 0.879 at 500 ℃ for the beddingperpendicular sample. Congruent with a mechanistic model, the permeability at 500 ℃ is elevated ~1.83 times (bedding-parallel) and ~6.08 times (bedding-perpendicular) relative to that at 25 -Cdconfirming the effectiveness of thermal treatment in potentially enhancing production from lowmaturity oil shales. [ABSTRACT FROM AUTHOR]

Shale gas is a prospective cleaner energy resource and the exploration and development of shale gas has made breakthroughs in many countries. Structure deformation is one of the main controlling factors of shale gas accumulation and enrichment in complex tectonic areas in southern China. In order to estimate the shale gas capacity of structurally deformed shale reservoirs, it is necessary to understand the systematic evolution of organic pores in the process of structural deformation. In particular, as the main storage space of high-over-mature marine shale reservoirs, the organic matter pore system directly affects the occurrence and migration of shale gas; however, there is a lack of systematic research on the fractal characteristics and deformation mechanism of organic pores under the background of different tectonic stresses. Therefore, to clarify the above issues, modular automated processing system (MAPS) scanning, low-pressure gas adsorption, quantitative evaluation of minerals by scanning (QEMSCAN), and focused ion beam scanning electron microscopy (FIB-SEM) were performed and interpreted with fractal and morphology analyses to investigate the deformation mechanisms and structure of organic pores from different tectonic units in Silurian Longmaxi shale. Results showed that in stress concentration areas such as around veins or high-angle fractures, the organic pore length-width ratio and the fractal dimension are higher, indicating that the pore is more obviously modified by stress. Under different tectonic backgrounds, the shale reservoir in Weiyuan suffered severe denudation and stronger tectonic compression during burial, which means that the organic pores are dominated by long strip pores and slit-shaped pores with high fractal dimension, while the pressure coefficient in Luzhou is high and the structural compression is weak, resulting in suborbicular pores and ink bottle pores with low fractal dimension. The porosity and permeability of different forms of organic pores are also obviously different; the connectivity of honeycomb pores with the smallest fractal dimension is the worst, that of suborbicular organic pores is medium, and that of long strip organic pores with the highest fractal dimension is the best. This study provides more mechanism discussion and case analysis for the microscopic heterogeneity of organic pores in shale reservoirs and also provides a new analysis perspective for the mechanism of shale gas productivity differences in different stress–strain environments. [ABSTRACT FROM AUTHOR]

Fly ash (FA) contents and water-binder ratio (w/b) are the important factors influencing the mechanical characteristics of cement-based materials, meanwhile the porous structure of material plays a vital role. The compressive strength and water permeability of cement-based samples with high-volume FA contents (0%, 30%, 40%) and different w/b (0.3, 0.4, 0.5) were measured. The results demonstrated that higher FA contents or greater w/b led to lower compressive strength and higher water permeability at an early stage. The pore structure features of samples were obtained using mercury intrusion porosimetry and low-temperature nitrogen gas adsorption (LT-NGA). The pore size distributions (PSDs) and the matrix compressibility in cementitious materials were also analyzed, with the compression coefficient KC ranging from 11.919 to 1.249 × 10−4 MPa−1. Increasing the FA content and reducing the w/b resulted in an optimized pore structure of the samples, characterized by changing the main pore type from mesopores (10–50 nm) to micropores (< 10 nm). The pores and fractures in the samples also had distinct multifractal characteristics. The strongest negative correlation between the compressive strength and the width of the multifractal generalized spectrum was proved by Pearson correlation analysis, and the correlation coefficient (ρ) was − 0.93. Furthermore, the water permeability had the strongest positive correlation with porosity, with ρ of 0.91. The content of macropores (50–10 μm) had greater influence on its macroscopic properties. The dense structure accompanied by homogeneous PSDs is advantageous for enhancing the strength and anti-permeability properties of cement-based materials. [ABSTRACT FROM AUTHOR]

Mercury intrusion porosimetry (MIP) is widely used for coal pore structure characterization, however, the matrix compressibility (MC) can lead to overestimated measurement results. Determination of MC is crucial for revealing the influence of pore structure on coalbed methane (CBM) flow behavior. In this study, MIP and low temperature N2 adsorption (LT-N2A) were conducted on 15 coal samples from major coal-producing regions in Northern China. The MIP data were corrected using MC theory, and the effects of coal rank and pore structure on coal MC were analyzed. The influence of MC on fractal dimension was elucidated, and the sensitivity of three fractal models to MC was effectively evaluated. Finally, the impact of MC on the coalbed methane (CBM) exploitation was discussed. The results show that low-rank coals have higher MC than medium/high-rank coals, and the MC coefficient follows a cubic polynomial relationship with coal rank, with two inflection points located at 1.4–2.5%, respectively. Micropores and transition pores are the main contributors to MC, for corrected data, the pore volume of both types of pores decreases significantly. The corrected pore size distribution exhibits better agreement with the LT-N2A measurement results, particularly in peak position and size for pores between 5 and 50 nm. This suggests the potential of corrected MIP data to supersede the combined use of MIP and LT-N2A data. MC can lead to overestimation of the fractal dimension, with the thermodynamic model showing the lowest sensitivity to MC. After the microfractures in medium/high-rank coal are greatly compressed, the compressional deformation of micropores and transition pores begins to have a significant impact on the CBM transport. The research results are of great significance for deeply understanding the mechanism of CBM transport. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Permian Fengcheng Formation (P1f.) in the Hashan area, situated on the southwestern margin of the Junggar Basin, has witnessed a remarkable breakthrough in shale oil exploration in recent years with nearly 789 million tons of shale oil resources. As a unique set of mixed sedimentary shales, the Fengcheng Formation in the Hashan area is characterized by mixed sedimentation of terrigenous siliciclastic sediments, authigenic minerals, and tuffaceous materials. However, the understanding of pore characteristics in the mixed sedimentary reservoir still remains limited, prohibiting accurate estimation of the oil content and insights into oil mobility. Scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), X-Ray Computer Tomography (X-CT), and geochemical analysis were performed to investigate the pore size distribution and main controlling factors of the mixed sedimentary reservoir. Results showed that the main pore types in the mixed sedimentary reservoir are intergranular pores and dissolution pores. The pores of the P1f. mixed shales in the Hashan area were classified into II-micropores (< 25 nm), I-micropores (25–100 nm), mesopores (100–1000 nm) and macropores (> 1000 nm). In general, the mixed sedimentary rocks of P1f. formation feature few macropores but a large number of micropores and mesopores. The CS exhibits the most favourable physical properties among all lithofacies. It is concluded that the abundance and maturity of organic matter, mineral composition, sedimentary structure, and diagenesis of reservoir together impact the pore structure in the mixed sedimentary reservoirs. The maturity of organic matter and the content of tuffaceous minerals are the most significant in influencing the pore structure of P1f. shales. Overall, the pore structure of complex lithologic reservoir formed by mixed deposition and its influence on physical properties are studied, and the characteristics of the microscopic pore-throat system of the dominant lithofacies in the Hashan area are clarified, which is of great significance as a guide for the exploration and development of mixed sedimentary reservoirs in continental shale oil in China. [ABSTRACT FROM AUTHOR]

The pore structure has a significant impact on the capability of coal seams to adsorb methane. But there is currently limited research on the features of adsorption pore structure in high-rank coal and its influence on methane adsorption capability. Taking the high-rank coal samples from Nuodong Coal Mine of Guizhou Xing'an Coal Industry Co., Ltd. as the research object, low-temperature N2 adsorption and low-temperature CO2 adsorption experiments are conducted. Combined with fractal theory, this paper studies the pore structure features of high-rank coal adsorption pores. Through high-pressure isothermal methane adsorption experiments, the influence of coal reservoir properties, pore structure features, and fractal dimension on methane adsorption capability is analyzed. The results show the following points. ① The pore morphology of high-rank coal reservoirs is relatively simple, mostly consisting of parallel plate pores and narrow slit pores with open ends. Micro pores dominate the pore structure of coal, with pore volume and pore specific surface area accounting for more than 98%, providing space for gas enrichment. ② The method calculates the comprehensive fractal dimension of high-rank coal pores based on the proportion of pore volume in different aperture segments, with micropore fractal dimension dominating the comprehensive fractal dimension. The pore structure of coal samples has obvious fractal features and strong heterogeneity of pores. ③ The Langmuir model can describe the adsorption behavior of high-rank coal. The physical properties, pore structure, and fractal dimension of coal reservoirs have a significant impact on methane adsorption capability. Langmuir volume is linearly positively correlated with maximum vitrinite reflectance, vitrinite content, ash content, and moisture content. It is linearly negatively correlated with inertinite content. The Langmuir volume is linearly positively correlated with the pore specific surface area and pore volume of the adsorption pores. The Langmuir volume is weakly linearly correlated with the fractal dimension. The research results can provide theoretical guidance for the exploration and development of high-rank coalbed methane and the prevention and control of coal mine methane disasters in southwestern Guizhou.

In order to explore the micro‐pore structure improvement mechanism of multi‐walled carbon nanotubes (MWCNT) on the frost resistance of concrete, five kinds of MWCNT concrete with different contents were prepared and the frost resistance test and mercury intrusion test were carried out. The results show that when the content of MWCNT is 0.1 wt%, the mass loss rate and compressive strength loss rate of concrete after freezing and thawing are 15.97% and 23.85% lower than that of ordinary concrete, respectively, indicating that this content is best amount to improve the frost resistance of concrete in this study. Moreover, 0.1 wt% MWCNT can significantly optimize the internal pore structure of concrete, and the average pore diameter growth rate and harmful pore ratio are 30.1% and 64.45%, respectively, after 200 freeze–thaw cycles. The proportion of more harmful pores has the greatest influence on compressive strength and relative elastic modulus, and the gray correlation degree is more than 0.8. Finally, the mathematical models of compressive strength‐pore parameters and relative dynamic elastic modulus‐pore parameters of MWCNT concrete after freeze–thaw cycle are established considering pore structure parameters and pore size distribution. [ABSTRACT FROM AUTHOR]

The efficient pyrolysis and conversion of organic matter in organic-rich shale, as well as the effective recovery of pyrolysis shale oil and gas, play a vital role in alleviating energy pressure. The state of carbon dioxide (CO2) in the pyrolysis environment of shale reservoirs is the supercritical state. Its unique supercritical fluid properties not only effectively heat organic matter, displace pyrolysis products and change shale pore structure, but also achieve carbon storage to a certain extent. Shale samples were made into powder and three sizes of cores, and nitrogen (N2) and supercritical carbon dioxide (ScCO2) pyrolysis experiments were performed at different final pyrolysis temperatures. The properties and mineral characteristics of the pyrolysis products were studied based on gas chromatography analysis, Xray diffraction tests, and mass spectrometry analysis. Besides, the pore structure characteristics at different regions of cores before and after pyrolysis were analyzed using N2 adsorption tests to clarify the impact of fracturing degree on the pyrolysis effect. The results indicate that the optimal pyrolysis temperature of Longkou shale is about 430 °C. Compared with N2, the oil yield of ScCO2 pyrolysis is higher. The pyrolysis oil obtained by ScCO2 extraction has more intermediate fractions and higher relative molecular weight. The ScCO2 can effectively improve the pore diameter of shale and its effect is better than that of N2. The micropores are produced in shale after pyrolysis, and the macropores only are generated in ScCO2 pyrolysis environments with temperatures greater than 430 °C. The pore structure has different development characteristics at different pyrolysis temperatures, which are mainly affected by the pressure holding of volatile matter and products blocking. Compared to the surface of the core, the pore development effect inside the core is better. With the decrease in core size, the pore diameter, specific surface area, and pore volume of cores all increase after pyrolysis. [ABSTRACT FROM AUTHOR]

Vibrations caused by downhole operations often induce coal and gas outburst accidents in tectonic zone coal seams. To clarify how vibration affects the pore structure, gas desorption, and diffusion capacity of tectonic coal, isothermal adsorption-desorption experiments under different vibration frequencies were carried out. In this study, high-pressure mercury intrusion experiments and low-pressure liquid nitrogen adsorption experiments were conducted to determine the pore structures of tectonic coal before and after vibration. The pore distribution of vibration-affected tectonic coal, including local concentration, heterogeneity, and connectivity, was analyzed using multifractal theory. Further, a correlation analysis was performed between the desorption diffusion characteristic parameters and the pore fractal characteristic parameters to derive the intrinsic relationship between the pore fractal evolution characteristics and the desorption diffusion characteristics. The results showed that the vibration increased the pore volume of the tectonic coal, and the pore volume increased as the vibration frequency increased in the 50 Hz range. The pore structure of the vibration-affected tectonic coal showed multifractal characteristics, and the multifractal parameters affected the gas desorption and diffusion capacity by reflecting the density, uniformity, and connectivity of the pore distribution in the coal. The increases in the desorption amount (Q), initial desorption velocity (V0), initial diffusion coefficient (D0), and initial effective diffusion coefficient (De) of the tectonic coal due to vibration indicated that the gas desorption and diffusion capacity of the tectonic coal were improved at the initial desorption stage. Q, V0, D0, and De had significant positive correlations with pore volume and the Hurst index, and V0, D0, and De had negative correlations with the Hausdorff dimension. To a certain extent, vibration reduced the local density regarding the pore distribution in the coal. As a result, the pore size distribution was more uniform, and the pore connectivity was improved, thereby enhancing the gas desorption and diffusion capacity of the coal. [ABSTRACT FROM AUTHOR]

In this study, an absorbent composite of carbon-fibre-reinforced Mn–Zn ferrite foam concrete was fabricated. The influence of carbon fibre (CF) concentration on the mechanical and electromagnetic wave (EMW) absorption characteristics of Mn–Zn ferrite foam concrete within the 0.2–5GHz were investigated. Key performance indicators, such as compressive and flexural strengths, electromagnetic parameters, reflection loss, and absorption bandwidth were thoroughly analysed. The pore size and distribution were examined by X-ray computed tomography (CT) to reveal the EMW absorption mechanism. The findings indicate that CF effectively mitigates agglomeration in Mn–Zn ferrites, enhancing dielectric and magnetic losses synergistically, which improves not only the mechanical properties but also the EMW absorption capacity of Mn–Zn ferrite foam concrete. The optimal wave absorption performance was observed at a CF content of 0.3 wt%, yielding an impressive absorption bandwidth of 1.46 GHz and a minimum reflection loss (RL min) of −28.75 dB. A noteworthy observation was the inverse correlation between the CF doping level and resistivity. The attenuation constant peaked at 108.13. When the CF content reached 1.2 wt %, the composite attained its percolation threshold, manifesting a resistivity of 145.4 Ω·m. [ABSTRACT FROM AUTHOR]

Organisms alter the primary texture of sediments, leading to alteration in petrophysical properties mediated by a textural and mineralogical contrast between burrow-fill and sediment host, which affects reservoir properties and fluid flow characteristics. In this article, in order to understand the microscopic pore structure and flow state of fluids in microscopic pores of bioturbated reservoirs, Ophiomorpha-bearing bioturbated reservoirs in the Neogene Sanya Formation of the Qiongdongnan Basin in the northern South China Sea were selected to research. Micro-CT was applied to scan selected core plugs, and a 3D pore structure model was established. The geometric characteristics of the microscopic pore structure were quantitatively and visually characterized by a modified maximal ball algorithm, and connectivity analysis of the pore structure was carried out. Numerical simulations of the percolation characteristics of the analyzed bioturbated reservoir samples were performed using digital core software (Avizo) and multi-physics field simulation software (Comsol). The results show that: (1) 3D pore structures reveal that pore volume, pore area, pore equivalent radius, throat area, throat equivalent radius and throat length have a large distribution range; among them, the pore volume has the largest distribution range, which can vary by six orders of magnitude, indicating that the pore size distribution of the bioturbated reservoir is uneven and has strong heterogeneous characteristics; (2) the connected pore structure is very complex, and as the equivalent radius of connected pore increases, the coordination number also gradually increases, the better the connectivity. Numerical percolation simulation results also suggested that larger connected pore space plays a key role in the effective permeability of the reservoir. This study has important implications for analyzing the modification effect of bioturbation on oil and gas reservoirs, and enhancing production and recovery in the study area. [ABSTRACT FROM AUTHOR]

To quantitatively characterize the complexity of shale pore structures and their controlling factors in the Longmaxi Formation of Western Hubei, our study focused on the organic‐rich shale outcrops of the Longmaxi Formation in the Yidu‐Hefeng compound anticline. We conducted tests for shale organic content, maturity, and whole‐rock mineral composition, along with employing high‐pressure mercury injection and low‐temperature gas adsorption experiments. Utilizing the V‐S, FHH, and sponge models, we calculated the fractal dimensions of micro‐, meso‐, and macropores. In the Yidu‐Hefeng region, the Longmaxi Formation is characterized by calcium‐rich shales that are abundant in organic matter. Our analysis of samples revealed a total organic carbon (TOC) ranging between 1.04% and 4.24%, with an average of 2.5%. The Ro values fluctuate between 2.98% and 3.57%, with a mean value of 2.845%, indicating an over‐mature stage from early to late thermogenesis. Constituents such as quartz span from 39.8% to 51.3%, with a median of 44.3%, while feldspar oscillates between 3.8% and 12.4%, averaging at 8.48%. Clay minerals constitute 24.3% to 41.7% of the samples, with a mean of 34.16%. Shale porosity exhibits a segmented fractal nature. For instance, D1 varies from 2.1278 to 2.4056, with a mean of 2.2767; D2 fluctuates between 2.4995 and 2.7492, averaging at 2.6309; and D3 ranges from 2.6835 to 2.9427, centering around 2.8111. These variations indicate the intricacies of the macropore structure. Positive correlations between TOC and maturity with D1 and D2 are evident, whereas a negative association is observed with D3. The collaborative interplay between siliceous minerals and organics mirrors the relationship between the siliceous mineral content and its fractal dimensions, akin to TOC. Clay mineral transformations, due to accumulation and dehydration, predominantly contribute to macro‐porosity, weakly aligning negatively with D1 and D2 but positively with D3. Variations in carbonate and siliceous minerals and their role in primarily yielding dissolution macropores manifest a subtle negative link with D1 and D2 while enhancing D3. Pore volume correlates positively with D1 and D2, exhibits no conspicuous association with D3, and trends negatively. The compaction and transformation processes of clay minerals seem to favor the generation of macropores, mildly aligning positively with D3. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To improve their permeability,porous Si3N4 ceramics were prepared using Si powder as the raw material,Y2O3 and CaF2 as sintering aids,and polymethyl methacrylate microspheres (5 and 20 μm) as pore-forming agents, gel-casting, binder-removing, and finally reaction sintering at 1 650 °C for 3 h in a nitrogen atmosphere. The effects of the particle sizes and additions (volume fractions of 0,15%, 30%, 45%, and 60%) of the pore-forming agents on the apparent porosity,pore size distribution,pore structure and permeability coefficient of the porous Si3N4 ceramics were studied. The results show that: (1) the samples with pore agents exhibit dual pore structures, which are composed of stacking-derived pores and spherical evolution pores, with bimodal pore size distribution; (2) with the same particle size,as the pore-forming agent addition increases,the apparent porosity and permeability coefficient of the samples increase,while the bulk density, bending strength, and fracture toughness decrease; (3) at the same addition, the samples with the smaller-sized agents (5 μm) have higher apparent porosity,permeability coefficient,and bending strength;using smaller-sized pore-forming agents can reduce the thickness of the pore walls and enlarge the pore sizes of the stacking-derived pores within the pore walls,thus enhancing the permeability of the pore walls; (4) the sample with 60% pore-forming agents of 5 μm has the best comprehensive performance,with the apparent porosity of 55.1%,permeability coefficient of 11.62x10-14 m² and bending strength of 35.3 MPa. [ABSTRACT FROM AUTHOR]

The purpose of this study is to prepare monodisperse silica mesoporous microspheres with narrow pore size distribution to promote their application in the field of liquid chromatography. An improved emulsion method was used to prepare silica mesoporous microspheres, and the rotary evaporation temperature, emulsification speed, dosage of porogen DMF, and dosage of the catalyst NH3·H2O were optimized. Subsequently, these microspheres were respectively treated by alkali–heating, calcination, and sieving. The D50 (particle size at the cumulative particle size distribution percentage of 50%) of as–prepared silica mesoporous microspheres is 26.3 μm, and the D90/D10 (the ratio of particle size at a cumulative particle size distribution percentage of 90% to a cumulative particle size distribution percentage of 10%) is 1.94. The resultant silica mesoporous microspheres have distinctive pore structures, with a pore volume of more than 1.0 cm3/g, an average pore size of 11.35 nm, and a median pore size of 13.4 nm. The silica mesoporous microspheres with a large particle size, uniform particle size distribution, large average pore size and pore volume, and narrow mesopore size distribution can basically meet the requirements of preparative liquid chromatographic columns. [ABSTRACT FROM AUTHOR]

Marine–continental transitional shale has become a new field for shale gas exploration and development in recent years. Its reservoir characteristics analysis lags significantly behind that of marine shale, which restricts the theoretical research on the accumulation of marine–continental transitional shale and the progress of exploration and development. The shale pore system is complex and has strong heterogeneity, which restricts the fine evaluation and optimization of the reservoir. Based on nitrogen adsorption–desorption experiments, the morphology and structural characteristics of coal-bearing shale pores were analyzed, and then the micro-pore structure heterogeneity was quantitatively characterized based on fractal theory and nitrogen adsorption–desorption data, and the relationship between pore structure parameters and their influence on fractal characteristics were discussed. The hysteresis loop of nitrogen desorption isotherm mainly belongs to type B, indicating ink bottle, flat plate, and slit are the main pore shapes. The pore size distribution curves are left unimodal or multimodal, with the main peak around 4 nm and 20–60 nm. Smaller pores develop a larger specific surface area, resulting in a high value of fractal dimension (2.564 to 2.677). The rougher the pore surface and the larger the specific surface area provide an adequate adsorption site for shale gas adsorption and aggregation. Thus, fractal characteristics conduced to understand the pore structure, heterogeneity, and gas-bearing property of coal-bearing shale. [ABSTRACT FROM AUTHOR]

Shale matrix permeability is vital to the evaluation of shale petrophysical property. In this study, an analytical model that considers pore size distribution, tortuosity, adsorption, and slippage effects is developed, to calculate the permeability of shale samples. Specifically, field emission scanning electron microscope (FE-SEM), the ImageJ software, and the MATLAB programming and numeric computing environment are employed to experimentally characterize the pore structure and to fit and optimize the pore size distribution. The discrete pore size distributions of organic matter and inorganic matter pores for Longmaxi and Qiongzhusi shale samples are determined based on FE-SEM images. According to the sum of squares error (SSE), coefficient of determination (R2), root-mean-square error (RMSE), and outcome of the fit, the Gaussian 2 correlation function is optimized to fit the continuous pore size distribution. Finally, the permeabilities of five shale rock samples are calculated and compared with the measured results from the Longmaxi and Qiongzhusi Formations. The results illustrate that the multi-term Gaussian fit is more suitable for calculating the permeability of samples with multimodal pore size distributions than the multi-segment Gaussian fit. The calculated results from the pore size distribution are more accuracy than those from the representative mean pore radius. The influence of pore size distribution on permeability and how seepage mechanisms in different pore sizes work together to represent permeability changes at the core scale will be investigated in the future. The study provides a more reliable calculation of the shale matrix permeability compared to previous methods. [ABSTRACT FROM AUTHOR]

Coalbed methane (CBM) mining has always been plagued by low mining efficiency. CBM-rich areas have high mining efficiency, but their formation is affected by CBM seepage. Through on-site mining, it is found that gas seepage in low-permeability areas presents nonlinear characteristics. In this paper, the causes and rules of nonlinear seepage are analyzed. The pore structure characteristic parameters such as pore size distribution, pore proportion and fractal dimension were obtained by nuclear magnetic resonance technology, and the pore structure characteristics of low permeability coal are analyzed. The results showed that the proportion of porosity was 6.30–11.02% and the proportion of percolation pores was 7.52–19.59%. Both total porosity and percolation pores had fractal characteristics. Aiming at the nonlinear problem of gas seepage law in low permeability coal, the permeability and gas flow data of coal samples under different gas pressures were measured by the self-designed coal core permeability automatic tester, and the gas seepage characteristics of low permeability coal samples are studied. The experiment showed that there was a starting pressure gradient in gas seepage in coal samples, and the relationship between gas permeability and gas pressure turned over at 1.25 MPa, indicating that there is a slip effect in coal pores. Considering the influence of pore structure parameters on the nonlinear seepage characteristics of CBM, the relationships between porosity, tortuosity, pore proportion, and fractal dimension and Kirschner permeability, slippage factor, and starting pressure gradient were fitted. The analysis showed that the pore size distribution characteristics with large proportion of micro-pores in low permeability coal made the pressure gradient required for the internal gas seepage larger, the influence of the slippage effect was enhanced, and the seepage of gas was nonlinear. To conclude, the influence of micro-pores developed in low permeability coal on nonlinear gas seepage was significant. [ABSTRACT FROM AUTHOR]

The marine shale within the Sichuan Basin constitutes China's significant shale gas production, featuring old formation age, high degree of thermal evolution, multiple tectonic movements, and complex structural conditions. However, there are significant differences in the shale gas preservation conditions and reservoir quality in different areas, limiting future large-scale exploration and development. Pore structure significantly influences shale reservoir quality, gas content, and exploration of shale gas occurrence, migration, and enrichment mechanisms. The influence of structural-dominated preservation conditions on shale pore structures is essential to comprehend for effective shale gas exploitation. This study employs field-emission scanning electron microscopy in conjunction with other techniques (low-temperature N2 adsorption, low-temperature CO2 adsorption, and nuclear magnetic resonance) for detailed analyses of the pore structure across varied structural zones, revealing the influence of structural attributes, fault systems, depth of burial, and formation pressure on pore architecture, and examining the relationship between pore structure and shale gas preservation conditions. The results show that stable structural condition is conducive to the development and preservation of shale pores. Structural compression causes inorganic and organic pores to become narrow and elongated due to shrinkage, with a significant increase in microfractures. The porosity of shale with stable structural conditions exhibits markedly increased porosity compared to samples under structural compressions. Under conditions of similar TOC and mineral composition, the pore size distribution (PSD), pore volume (PV), and specific surface area (SSA) of shale after structural compression are significantly lower than those of samples with stable structural conditions. As the burial depth increases, the shale porosity shows a decreasing trend, but the decrease is limited. Burial depth significantly impacts the SSA and PV of high-TOC samples (3%-6%). As the burial depth increases, both SSA and PV show a significant decreasing trend. When the burial depth reaches 4000 m, SSA and PV tend to concentrate. The formation pressure coefficient is an important factor for the development and preservation of shale pores, and porosity is positively correlated with the formation pressure coefficient. Increased formation pressure coefficient indicates superior preservation conditions and enhanced pore development. [ABSTRACT FROM AUTHOR]

With the increase of coal mining depth, coal seam has the characteristics of complex pore structure and low porosity under the influence of ground stress, which limits the effect of coal seam water injection. Alternating hydraulic intrusion is an effective method to improve the permeability of low permeability coal seam. By applying low water pressure circulation, it can force the pore structure of coal to be damaged, which is helpful to change its pore structure. However, there is limited research on the evolution of the multi-sacale pore structure in coal under alternating hydraulic pressure using low-field nuclear magnetic resonance (LF-NMR) technology. In this study, we investigate the evolution of coal pore structure under alternating hydraulic pressure using LF-NMR. The pore size distribution (PSD), porosity, fractal dimension, and sensitivity of pores to alternating hydraulic pressure were analyzed. The results indicate that the pore volume of coal exhibits an increasing trend initially and then decreases with the increase of cycle times. An appropriate number of alternating cycles contribute to the development of the coal pore structure. Fractal dimension analysis reveals that the pore fractal dimension decreases first and then increases during the test, indicating a significant effect of alternating hydraulic pressure on the development of pores. Analysis of the sensitivity of pores to alternating hydraulic pressure shows a decreasing trend overall with an increasing cycle time, although the rate of decrease gradually slows non-significant with continued cycling. Mechanism analysis suggests that during the alternating hydraulic intrusion process, the development of new pores and the compaction of pores occur simultaneously under the hydraulic pressure. With the continuous loading of alternating hydraulic pressure, the development rate of new pores gradually becomes lower than the compaction rate of pores, which leads to the phenomenon that the pore structure of coal expands first and then compacts. This study provides theoretical support for the application of alternating water injection in coal reservoir engineering. [ABSTRACT FROM AUTHOR]

In the deep Longmaxi Formation shale gas reservoirs of the southern Sichuan Basin, strong overpressure is universally developed to varying degrees. However, there is currently a lack of in-depth research on the formation mechanisms, evolutionary patterns, and the controlling effects on reservoir pore characteristics of strong overpressure. This limitation significantly restricts the evaluation of deep shale gas reservoirs. This study selected typical overpressured shale gas wells in Yongchuan, Luzhou, and Dazu areas as research subjects. Through comprehensive methods such as log analysis, fluid inclusion analysis, and numerical simulation, the dominant mechanisms of strong overpressure formation were determined, and the pressure evolution from early burial to late strong uplift was characterized. Additionally, the impact of varying degrees of overpressure on reservoir pore characteristics was studied using techniques such as scanning electron microscopy, gas adsorption-mercury intrusion, and helium porosity testing. The research findings indicate that hydrocarbon generation expansion is the primary mechanism for strong overpressure formation. The pressure evolution in the early burial phase is controlled by the processes of kerogen oil generation and residual oil cracking into gas. The reservoir experienced three stages: normal pressure (Ordovician to Early Triassic), overpressure (Early Triassic to Early Jurassic), and strong overpressure (Early Jurassic to Late Cretaceous), with pressure coefficients of approximately 1.08, 1.56, and 2.09, respectively. During the late strong uplift phase, the adjustment of early overpressure occurred due to temperature decrease and gas escape, leading to a decrease in formation pressure from 140.55 MPa to 81.63 MPa, while still maintaining a state of strong overpressure. Different degrees of strong overpressure exert a significant control on the physical properties of shale reservoirs and the composition of organic matter pores. Variations exist in the organic matter pore morphology, structure, and connectivity within the deep Wufeng-Longmaxi shale. Higher overpressure favors the preservation of organic large pores and reservoir porosity. Under conditions of strong overpressure development, deep siliceous shales and organically rich clay shales exhibit favorable reservoir properties. By determining the dominant mechanisms of strong overpressure in the Wufeng-Longmaxi Formation and studying pore characteristics, this research not only deepens the understanding of the geological features of deep shale gas reservoirs but also provides a new perspective for understanding the overpressure mechanisms and reservoir properties of deep shale gas reservoirs. Moreover, it is of significant importance for guiding the exploration and development of deep Longmaxi shale and provides valuable references for further research in related fields. [ABSTRACT FROM AUTHOR]

Marine shales from the Niutitang Formation and marine–continental transitional shales from the Longtan Formation are two sets of extremely important hydrocarbon source rocks in South China. In order to quantitatively compare the pore complexity characteristics between marine and marine–continental transitional shales, the shale and kerogen of the Niutitang Formation and the Longtan Formation are taken as our research subjects. Based on organic petrology, geochemistry, and low-temperature gas adsorption analyses, the fractal dimension of their pores is calculated by the Frenkel–Halsey–Hill (FHH) and Sierpinski models, and the influences of total organic carbon (TOC), vitrinite reflectance (Ro), and mineral composition on the pore fractals of the shale and kerogen are discussed. Our results show the following: (1) Marine shale predominantly has wedge-shaped and slit pores, while marine–continental transitional shale has inkpot-shaped and slit pores. (2) Cylindrical pores are common in organic matter of both shale types, with marine shale having a greater gas storage space (CRV) from organic matter pores, while marine–continental transitional shale relies more on inorganic pores, especially interlayer clay mineral pores, for gas storage due to their large specific surface area and high adsorption capacity (CRA). (3) The fractal characteristics of marine and marine–continental transitional shale pores are influenced differently. In marine shale, TOC positively correlates with fractal dimensions, while in marine–continental shale, Ro and clay minerals have a stronger influence. Ro is the primary factor affecting organic matter pore complexity. (4) Our two pore fractal models show that the complexity of the shale in the Longtan Formation surpasses that of the shale in the Niutitang Formation, and type I kerogen has more complex organic matter pores than type III, aiding in evaluating pore connectivity and flow effectiveness in shale reservoirs. [ABSTRACT FROM AUTHOR]

The low-permeability argillaceous rock mass is an unfavorable geological body commonly found in the construction process of underground engineering conditions such as roadways and tunnels. Due to the compact structure and low permeability of the rock mass, grouting with conventional materials cannot effectively seal the micro-cracks of the rock mass. Based on the low efficiency of high-pressure grouting of nano-silica sol, this paper preliminarily explores the regularities and mechanism of grouting and pore sealing of low-permeability rock mass under the action of silica sol imbibition from the aspects of gelling properties of silica sol, core pore structure, imbibition law, and pore sealing characteristics. The results show the following: (1) The increase in particle size during the gel process reduced the injectability and wettability of the silica sol. The imbibition properties of silica sol were time-varying, and the deterioration inflection points of injectability and wettability appeared at 10 h and 9 h, respectively. (2) Catalyst, temperature, gel process, and rock mass permeability will affect the law of core imbibition, and the injectability and capillary force of the grouting material and rock mass will jointly affect the imbibition process of silica sol. (3) Silica sol imbibition changed the pore size distribution of the core, the pore volume above 50 nm decreased, and the pore volume below 50 nm increased. Silica sol has multiple effects such as filling, adsorption, and percolation in the imbibition process of the micro-pores of rock mass, and the adsorption and percolation of silica are related to the nano micro-pores. [ABSTRACT FROM AUTHOR]

BACKGROUND: In order to investigate the correlation between the pore size distribution of biomass activated carbon adsorbents (BACAs) and VOCs (volatile organic compounds) adsorption/desorption performance. Four BACAs with same specific surface area but different pore size distribution were prepared under different experimental conditions and processes. RESULTS: The impact of the pore size distribution of BACAs on the adsorption/desorption performance of benzene, toluene and xylene was investigated. The results indicated that the adsorption ability of the prepared BACAs for benzene, toluene and xylene was mostly affected by the pore sizes distributed in the 2.60 ~ 3.25, 2.68 ~ 3.35and 4.20 ~ 4.90 nm ranges, respectively, when the studied BACAs had similar specific surface area (SBET ≈ 1080 m2 g−1). However, the desorption amount of adsorbed benzene molecules mainly relied on the pore structures of BACAs having pore sizes in the 3.95 ~ 4.60 nm range. CONCLUSION: The pore structures of BACAs distributed in different pore size ranges have various effects on the phenyl VOCs adsorption capacity. Benzene adsorption on the BACAs was mainly affected by the microporous structures. The pore structure with larger pore size was more favorable for the desorption of the adsorbed toluene and xylene molecules compared to the adsorbed benzene molecules. Benzene, toluene and xylene had low residual rates in the studied activated carbon adsorbents attesting to their superior regenerative properties. This work could provide an important reference for the design, preparation, and selection of activated carbon adsorbents for the adsorption capacity of benzene, toluene and xylene. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

A systematic study of the pore structure characteristics of Lower Cambrian shales in the southeastern Upper Yangtze Platform, was conducted using organic geochemistry, mineralogy, nitrogen adsorption, physical property analysis, and scanning electron microscopy. The results indicate that: 1) The Total organic carbon (TOC) content shows a strong correlation with quartz and clay minerals. Shales with low TOC content and rich in clay minerals primarily exhibit slit-shaped and narrow slit-like inter-clay particle pores with pore size distribution is dominated by mesopores and macropores. Shales with high TOC content predominantly feature narrow slit-like and ink bottle-shaped pores with pore size distribution dominated by micropores and mesopores. 2) Shale pore structures vary significantly under different gas content and preservation conditions. Shales under favorable preservation conditions exhibit a relatively "high porosity, low permeability, and high gas content" pattern, with well-developed organic pores and a strong pore-permeability correlation. In contrast, shales under unfavorable preservation conditions appear dense, with excessively developed fractures increasing both average pore size and local permeability. The pore-permeability correlation is weak, presenting a relatively "low porosity, high permeability, and low gas content" pattern. 3) TOC content plays a crucial role in controlling pore structure, showing overall positive correlations with pore volume, specific surface area, and porosity, and negative correlations with pore size. High TOC content enhances shale plasticity, resulting in lower pore diameters. Factors such as compaction and unfavorable preservation conditions lead to the shrinkage, collapse, and closure of some narrow pore throats, negatively impacting pore volume, specific surface area, brittleness, and fractal dimension, exhibiting a negative correlation with TOC content. 4) The pore structure of Lower Cambrian shales is complex, with fractal dimensions D1 and D2 exhibiting negative correlations with average pore size and positive correlations with TOC, specific surface area, and total pore volume. A high D1 value indicates well-preserved nanoscale pore surface structures with low complexity, suggesting minimal alteration by external fluids and better shale gas preservation. D1 serves as an indicator for shale gas content and preservation conditions. D2 shows better correlations with various pore structure parameters, making it suitable for characterizing pore structures. [ABSTRACT FROM AUTHOR]

Long-term irrigation promotes the infiltration of water in the thick, stratified loess layer, significantly raising the groundwater table and triggering a series of landslides in loess platform areas. The soil–water characteristic curve (SWCC) of loess buried at different depths affects the unsaturated infiltration process and is intricately connected to the soil's microstructure. The SWCCs, scanning electron microscope (SEMs), and pore size distributions (PSDs) for five sets of undisturbed loess samples at depths ranging from 3.4 to 51.9 m are shown in this paper. The results indicate that the fitting parameter air entry value (AEV) of the SWCC rises from 13.67 kPa to 40.19 kPa as the depth increases from 3.4 to 51.9 m. And the saturated volumetric water content drops by 10.9%, with a notable SWCC shape difference between the transition and residual zones observed. Additionally, the total porosity of undisturbed loess falls by 12% when the depth increases from 3.4 to 51.9 m, while the macropores and mesopores reduce by 3.6% and 12.1%, respectively. These findings highlight the control of the pore structure on the SWCC and emphasize the correspondence between the SWCC and PSD. The conclusions also illustrate that the compaction effect changes the microstructure characteristics of loess, thereby affecting the soil's water retention behavior. [ABSTRACT FROM AUTHOR]

The tight tuff reservoir is an unusual type of unconventional reservoir with strong heterogeneity. However, there is a lack of research on the microscopic pore structure that causes the heterogeneity of tuff reservoirs. Using the Chang 7 Formation in Ordos Basin, China as a case study, carbon-dioxide gas adsorption, nitrogen gas adsorption and high-pressure mercury injection are integrated to investigate the multi-scale pore structure characteristics of tuff reservoirs. Meanwhile, the fractal dimension is introduced to characterize the complexity of pore structure in tuff reservoirs. By this multi-experimental method, the quantitative characterizations of the full-range pore size distribution of four tuff types were obtained and compared in the size ranges of micropores, mesopores and macropores. Fractal dimension curves derived from full-range pores are divided into six segments as D1, D2, D3, D4, D5 and D6 corresponding to fractal characteristics of micropores, smaller mesopores, larger mesopores, smaller macropores, medium macropores and larger macropores, respectively. The macropore volume, average macropore radius and fractal dimension D5 significantly control petrophysical properties. The larger macropore volume, average macropore radius and D5 correspond to favorable pore structure and good reservoir quality, which provides new indexes for the tuff reservoir evaluation. This study enriches the understanding of the heterogeneity of pore structures and contributes to unconventional oil and gas exploration and development. [ABSTRACT FROM AUTHOR]

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Superficial weathering in the form of granular disaggregation, powdering and flaking on stone surface is one of the most serious damages to stone heritages, since the surface carries most of the artistic, historical information. The determination of the thickness of the superficially weathered layer of historical stones is critical to their conservation. However, the methodology for quantitative analyses of such thickness remains very limited. In this study, we carefully study the vapor absorption and pore structure evolution of historical sandstones from Guanzhong area with respect to their weathering. We find out that the thickness of superficial weathered layer of Guanzhong sandstones can be derived by following the changes in vapor absorption or pore structure. Such data achieved from various methods developed in this work are consistent with each other and in good agreement with the results obtained by using current techniques such as drilling resistance measurement, the Ruxton method and ultrasonic testing. Among all methods used, pore size distribution analysis requires less sample preparation and measures the thickness of superficial weathered layer of Guanzhong sandstones around 7 mm. [ABSTRACT FROM AUTHOR]

A microscopic experimental study was conducted on the rice husk ash cement paste under freeze-thaw cycles using mercury intrusion porosimetry. The study mainly focused on the influence of rice husk ash on the pore structure of the cement paste through analyses of porosity, pore size distribution, most probable pore size, pore size gradation, and critical pore size under freeze-thaw cycles. The results showed that with an increase in the rice husk ash content under the same freeze-thaw cycles, the porosity of the cement paste decreased, and both the pore size distribution and the most probable pore size decreased. This indicates that the addition of rice husk ash improves the pore structure of the concrete and enhances its frost resistance. Furthermore, as the rice husk ash content increased, the number of harmful and deleterious pores in the cement paste decreased, and the critical pore size decreased, demonstrating the improved durability performance of the concrete with the addition of rice husk ash. [ABSTRACT FROM AUTHOR]

Shale pore structure characterization is key to shale reservoir evaluation, sweet spot selection, and economic exploitation. It remains a challenge to accurately characterize shale micro-nano pores. Common experimental characterization methods for shale pore systems are listed, and advantages and weaknesses of each method are analyzed. An improved pore structure characterization method for shale is proposed by combining Helium and NMR. The new method does not affect shale samples and has a higher accuracy. The affecting factors for shale pore evolution for shale are also discussed, showing that organic matter content and maturity are key factors in total porosity development. Furthermore, a shale porosity–TOC maturity relationship chart is developed based on the experimental data of shale samples selected from six shale reservoirs. The application of this chart in Well X in the Gulong field of Songliao Basin proves its utility in evaluating shale reservoirs. [ABSTRACT FROM AUTHOR]

The pore size distributions of an expansive soil under different simulated rainfall conditions were studied using nuclear magnetic resonance (NMR) techniques. Four sets of treatments with different rainfall intensities (light, moderate, heavy, and rainstorm) and durations (0.5 d, 1 d, 2 d, and 3 d) were designed to analyze the effects of rainfall on the microstructure of the expansive soil. Results show that with increasing rainfall duration, micropores gradually form and develop, enlarge, and interconnect in the soil, eventually forming stable seepage channels. Under light and moderate rain conditions, the proportion of micropores gradually decreases, while the proportions of mesopores and macropores gradually increase. Under heavy and rainstorm conditions, the proportion of micropores sharply decreases and then stabilizes, while the proportions of mesopores and macropores increase. With increasing rainfall intensity, the dominant pore size and porosity both initially increase and then stabilize. A quantitative relationship model between pore size, porosity, and rainfall conditions is established and the fitting effect is good. This study shows that rainfall alters the microstructure of expansive soils, which stabilizes after dynamic equilibrium. This provides a theoretical basis for predicting and controlling the engineering behavior of expansive soils under different rainfall conditions. [ABSTRACT FROM AUTHOR]

Heat-assisted development of shale oil and gas is recognized as a vital technique for the efficient extraction of shale gas; however, there is a need for comprehensive investigation regarding radon release during the extraction process. The aim of this study was to investigate the pore structure and radon release characteristics of heat-treated black shale using low-temperature nitrogen adsorption (LTNA) and radon (Rn-222) measurement equipment. The findings reveal that temperature initially enhances radon release, which subsequently decreases. The maximum radon release occurs at 500 °C, reaching 1.46 times the initial stage. The radon release rate is positively correlated with the volume of micropores (< 2 nm) in the shale. Organic pores within the shale serve as the primary storage spaces for radon, and the intricate pore structure of organic matter provides an optimal environment for radon gas retention. These results contribute to elucidating the mechanisms behind the impact of thermal treatment on shale's radon release rate, which is crucial for guiding radon radiation evaluation in thermal treatment processes. [ABSTRACT FROM AUTHOR]

Hydrochar is an urban soil amender that supports plant growth on slopes. It is a biomass-derived carbon-rich material produced by the hydrothermal carbonation process; thus, it has a different pore structure from biochar produced by pyrolysis. The effects of hydrochar on the hydraulic properties of unsaturated compacted soils and the underlying pore-level soil-hydrochar interaction mechanisms are unclear. In this study, silty-clay sand was amended by grass-derived hydrochars produced at two hydrothermal carbonisation temperatures (180 and 240 °C, denoted as H-180 and H-240, respectively) with different mass proportions ( f H ). The pore and throat size distributions, water retention curves (WRCs) and hydraulic conductivity functions (HCFs) of the soils with and without amendment were measured. The results showed that hydrochar improved the soil water retention capability as the smaller hydrochar particles filled the soil pores with diameters larger than 290 μm. Compared with the increase in air-entry value made by H-180, the one made by H-240 was more substantial as this type of hydrochar altered the soil pores to be smaller in size. Hydrochar also increased the hydraulic conductivity of the soil by half to one order of magnitude due to the increase in the throat frequency and the presence of hydrochar intra-pores. One exception was the amendment by H-180 at f H of 2.5%, wherein the HCF was reduced due to pore clogging at throat diameters less than 90 μm and more than 250 μm. Finally, amending the soil with either H-180 or H-240 at f H of 5% always improved the WRC and HCF, thereby benefiting plant water uptake. [ABSTRACT FROM AUTHOR]

The deep shale of the Wufeng–Longmaxi Formation in the southern Sichuan Basin has high gas potential. The development characteristics of lamination could significantly impact reservoir property. Samples were investigated using microscopic observation, element analysis, organic petrology analysis, mineralogy analysis, and pore structure analysis to determine the types of laminae and laminasets, clarify the formation conditions of argillaceous lamina and silty lamina as well as their relationships with the sedimentary environment, and explore the influence of laminae on shale reservoir property. Results indicate that the Wufeng Formation shale exhibits weak development of laminae due to bioturbation, while the Longmaxi Formation shale develops continuous, parallel, and plate-like laminae. Compared with light silty lamina-rich shale, dark argillaceous lamina-rich shale usually develops in an anoxic reduction environment, with higher total organic carbon content, porosity, pore volume, specific surface area, and more developed organic matter pores, which can provide greater space for shale gas adsorption and storage. Shales in the middle section of the Longmaxi Formation are characterized by the development of silty-argillaceous interbedded type laminaset, which have good reservoir performance, making them the primary target for deep shale gas exploration and development. [ABSTRACT FROM AUTHOR]

When the thermal maturity of the Longmaxi Formation in the southern Sichuan Basin is too high, the pore structure of shale becomes poor. Therefore, to investigate the effect of organic matter thermal maturity on shale pore structure, a study was conducted. Using the Longmaxi Formation shale in the southern Sichuan Basin as an example, the intrinsic relationship between shale porosity, pore structure parameters, organic matter laser Raman maturity, and organic matter graphitization degree was examined using X-ray photoelectron spectroscopy, particle helium porosity measurement, organic matter micro-laser Raman spectroscopy, and gas adsorption experiments. The results indicate that thermal maturity is the macroscopic manifestation of the graphitization degree of organic matter, and the correlation coefficient between the two is 0.85. A thermal maturity of 3.5% (with a corresponding organic matter graphitization degree of 17%) aligns with the highest values of shale porosity, pore volume, and pore-specific surface area across all pore size conditions. The evolution model of shale pore structure can be divided into two stages. The first stage is characterized by a thermal maturity between 2.0% and 3.5% (with a corresponding degree of graphitization of organic matter between 0% and 17%). During this stage, the number and connectivity of micro-macropores increase with increasing thermal maturity. The second stage is marked by a thermal maturity between 3.5% and 4.3% (with a corresponding degree of graphitization of organic matter between 17% and 47.32%). Basement faults are present, leading to abnormally high thermal maturity, poor preservation conditions, continuous generation of micropores, better connectivity, and a reduced number of pores. Medium macropores with good connectivity suffer from gas loss in the fracture network, leading to the collapse and disappearance of pores. The results mentioned in the statement have an important guiding role in the efficient exploration of shale gas in the Longmaxi Formation in the southern Sichuan Basin. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates pore distribution and permeability behavior of tar-rich coal following high-temperature pyrolysis at 500°C using X-ray computed tomography (CT) scanning. Coal samples post-pyrolysis were CT scanned, generating 1755 cross-sectional slices for three-dimensional reconstruction. An axial algorithm extracted pore distribution features, and geometric parameters were computed. An Equivalent Pore Network Model analyzed permeability characteristics. The results show that Post-pyrolysis pore distribution in tar-rich coal exhibited nonuniformity with a significant range in pore size distribution. Pores displayed concentrated spatial patterns. Total porosity was 14.24%, with 12.34% being connected. Most pores in Representative Elementary Volume (REV) regions fell within 10-50 μιτι in width and 20-60 pm in length, constituting over 40% of the total. Pore surface area peaked between 200-100 pm2, also comprising over 40% of the total. The Pore Network Model showed distinct characteristics in two REV regions: REV-1 demonstrated an early stage of development with poor connectivity, while REV-2 displayed a well-developed network with a bimodal coordination number histogram. The study highlights nonuniform post-pyrolysis pore distribution and significant pore size variations in tar-rich coal. This study is crucial for understanding permeability behavior in tar-rich coal after high-temperature pyrolysis. [ABSTRACT FROM AUTHOR]

The Middle and Upper Permian Dalong and Gufeng Formations in South China have recently been considered as potential gas-producing shales. However, their pore structure characteristics remain poorly understood. To investigate the pore structure and fractal characteristics of the pores in these two formations, a suite of shale samples from the Dalong and Gufeng Formations in the western Hubei Province, South China were analyzed by multiple techniques, namely, TOC content, X-ray diffraction (XRD) mineralogy analysis, optical microscopy observations, major elemental analysis, field emission-scanning electron microscopy (FE-SEM), and low-pressure gas adsorption measurements (N2 and CO2). The identified major shale lithofacies include siliceous mudstone, carbonaceous mudstone, argillaceous-siliceous mixed mudstone, and calcareous-siliceous mixed mudstone. SEM images show that the dominant pore types include the pores between brittle minerals, slit-shaped pores between clay sheets, and secondary organic matter (OM) pores within solid bitumen. The pore size distribution is dominated by micropores and mesopores (<30 nm), which are the major contributors to total pore volume and surface area for the Dalong and Gufeng Formations. Based on the Frenkel–Halsey–Hill (FHH) method, fractal dimensions (D1, D2) calculated from the nitrogen adsorption data have a range of from 2.489 to 2.772 (D1) and from 2.658 to 2.963 (D2), and are higher in the Gufeng Formation (average TOC = 8.3 wt.%) due to a higher TOC content comparing to the Dalong Formation (average TOC = 6.2 wt.%). The pore development and fractal characteristics are primarily controlled by organic matter (OM), carbonate minerals, and clay minerals for both the Dalong and Gufeng Formations. Shale samples with high TOC content, low carbonate content, and high clay content tend to develop more heterogeneous micropores and mesopores, which is ascribed to the generation of clay-related and OM-hosted pores, along with the destruction of primary pores by pore-filling carbonate cements. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The stability of the dump is related to the safe operation and economic benefit of the mine, and the mechanical properties of its constituent soils are important basic data to evaluate its stability, while the changes in the mechanical properties are influenced by its internal structure. Nuclear magnetic resonance and scanning electron microscope techniques are used to obtain the pore size distribution and microscopic image characteristics of coarse-grained soil samples under the influence of freeze–thaw, respectively. Based on the fractal theory, the variation law of fractal dimension and box dimension of different apertures is analyzed and studied. In order to select reasonable pore structure parameters, linear fitting correlation analysis was used to determine the large pore ratio and medium pore fractal dimension as the model construction parameters. The correlation model between the dual pore structure parameters and uniaxial compressive strength (UCS) of coarse-grained soils was established. The results show that, with the increase of freeze–thaw cycles, the distance among the particles in the coarse-grained soil samples is increased, the connectivity among the pores is enhanced, the proportion of large pore, surface porosity, and box dimension are all increasing gradually. The proportion of macropores in the samples increased gradually, the medium and large pores showed good fractal characteristics. At the same time, the strength correlation model based on pore structure parameters can also achieve a good prediction of coarse-grained soil UCS. [ABSTRACT FROM AUTHOR]

The formation and evolution mechanisms of complex types and scales of marine–continental transitional shale pores are still indefinite, restricting the accurate evaluation of shale reservoir and the effective evaluation of coal-bearing marine–continental transitional shale gas resource quantity. Considering the Shanxi shale in Ordos basin of China as the research object, combining the FE-SEM images and petrophysical analysis, high-pressure mercury intrusion porosimetry, and CO2 and N2 adsorption–desorption experiments, the structure characteristics and differential evolution mechanisms of multiscale and multitype of coal-bearing shale pores were discussed. The results show that coal-bearing marine–continental transitional shales are rich in clay minerals and organic matters (OMs). Pores developed within organic matters, clay, and brittle minerals of coal-bearing shale have decreasing porosity values. OM pores are directly related to micro- and mesopores, with high specific surface areas, while the porosity of inorganic pores increases with the increasing pore diameter. The porosity of all pores shows a positive relationship with permeability, which changes periodically with the increase in maturity. Coal-bearing shale pores are mainly plate- and ink bottle-shaped, with multimodal pore size distributions. Controlled by both diagenesis and hydrocarbon generation, the evolution of coal-bearing shale pores could be mainly divided into four stages. Furthermore, the pore evolution model of coal-bearing marine–continental transitional shale was preliminarily constructed. This study would enhance the understanding of reservoir evolution of the coal-bearing shale and provide useful information for the assessment and evaluation of reservoir capacity. [ABSTRACT FROM AUTHOR]

Shale gas resource is heterogeneously distributed in Permian Gufeng Formation in the Xuancheng area, Anhui Province. This research aims to investigate the pore size distribution of the Permian Gufeng shales via 16 core samples analyses, combined with x‐ray diffraction, low‐pressure nitrogen gas adsorption (N2‐GA), CO2 gas adsorption (CO2‐GA) and scanning electron microscopy (SEM). N2‐GA shows that the nanopores (diameter < 10 nm) are dominated and developed in the samples. The Brunauer–Emmett–Teller (BET) specific surface area (SSA) of the samples ranges from 6.7051 to 29.4384 m2/g, with a mean of 16.0931 m2/g. CO2‐GA results illustrate that micropore is well developed, especially the pores with a diameter of 0.5–0.6 and 0.8 nm. The total organic carbon (TOC) content of the Gufeng shale ranges from 0.42% to 12.82% with an average content of 6.44%, which has both positive correlation with pore SSA and pore volume, while carbonate mineral content has a positive correlation with pore SSA and the volume of macropore and mesopore. Clay mineral content is a negative correlation with pore SSA and micropore volume. Therefore, the high‐maturity Permian Gufeng shale could be more preferential high‐quality gas shale reservoir for further exploration and development in the Xuancheng area, which has more than 4% TOC content, relatively higher carbonate mineral content and relatively lower clay mineral content. [ABSTRACT FROM AUTHOR]

The capillary pressure curve is a crucial basis for studying the pore structure and multiphase flow characteristics in oil and gas reservoirs. Due to the loose and unconsolidated nature of the clayey-silt sediment of natural gas hydrate reservoirs in the South China Sea, conventional methods such as mercury intrusion and centrifugation struggle to obtain capillary pressure curves for these sediments. In this study, X-ray diffraction analysis, scanning electron microscopy, nitrogen adsorption, and water-gas contact angle measurements are utilized to characterize the mineral composition, pore structure, pore size distribution, and wettability of the clayey-silt sediment. Subsequently, the filter paper method from soil mechanics is employed to determine the capillary pressure curve for the clayey-silt samples. The results indicate that the capillary pressure curve obtained through the filter paper method exhibits a saturation range of 18.39%-80.31% and a capillary pressure range of 19.04 to 46,481.42 kPa. It exhibits a distinct two-stage characteristic, where capillary pressure changes rapidly with water saturation below 61.05% and slowly above 61.05%. The pore radius calculated from the capillary pressure curve ranges from 2.41 nm to 5.91 µm. This alignment with the pore ranges obtains from nitrogen adsorption and Scanning Electron Microscopy confirms the accuracy of the obtained capillary pressure curve. Furthermore, in comparison with a literature capillary pressure curve obtained through centrifugation, the paper filtration method covers a broader range, providing better representation of capillary pressure in the multiscale pores of clayey-silt samples. [ABSTRACT FROM AUTHOR]

The control of rheological properties is gaining in importance to meet the special requirements for cementitious materials in novel technologies such as 3D‐printing. A deeper understanding of the underlying mechanisms of cement hydration is necessary to customize the mix design to the specific application. The hydration of OPC is mainly characterized by the silicate and aluminate reaction. The aluminate reaction is especially relevant for the early rheological development, whereas the formation of C‐S‐H (silicate reaction) is responsible for the later hardening of the hydrating paste. A hydration control agent is used to delay the initial aluminate reaction to a defined point in time. When no additional mixing occurs during this period of rapid ettringite precipitation, the cement paste stiffens to a solid cement stone. However, when the sample is mixed during this period, the workability of the paste is retained. The rheological changes can be correlated directly to the magnitude of ettringite formation. Additionally, the compressive strength and pore size distribution of all systems (reference, HCA, HCA with additional mixing) are investigated to analyze the long‐term properties. These results predict future customized mix designs in various application fields. [ABSTRACT FROM AUTHOR]