Structure Of Void Space Research Articles

Straightforward fabrication of luminescent-magnetic GdF3:Yb3+, Ho3+@void@SiO2 wire-in-tube structured nanofibers

GdF3:Yb3+,Ho3+@void@SiO2 wire-in-tube structured nanofibers (WITSN) with bifunctional characteristic of up-conversion luminescence and magnetism properties are successfully obtained by self-created technique combining monoaxial electrospinning and single-crucible fluorination technology. The products are pure orthorhombic phase. GdF3:Yb3+,Ho3+@void@SiO2 WITSN exhibit large specific surface area and distinctive void space structure. The unique structure of the prepared nanofibers expands the new field of one-dimensional special morphology nanomaterials. In addition, GdF3:Yb3+,Ho3+@void@SiO2 WITSN have the bifunctionality of excellent up-conversion luminescent and paramagnetic properties. Materials have broad applications prospects in display, lighting, optical imaging, magnetic resonance imaging, and biomedicine. This work presents an innovative and high-efficient approach to construct photoluminescence-magnetism bifunctional GdF3:Yb3+,Ho3+@void@SiO2 WITSN, providing a new idea for the preparation of coated structured nanomaterials with excellent multifunctional characteristics.

High Permeability Streak Identification and Modelling Approach for Carbonate Reef Reservoir

Reef reservoirs are characterised by a complex structure of void space, which is a combination of intergranular porosity, fractures, and vuggy voids distributed chaotically in the carbonate body in different proportions. This causes great uncertainty in the distribution of porosity and permeability properties in the reservoir volume, making field development a complex and unpredictable process associated with many risks. High densities of carbonate secondary alterations can lead to the formation of zones with abnormally high porosity and permeability—high permeability streaks or super-reservoirs. Taking into account super-reservoirs in the bulk of the deposit is necessary in the dynamic modelling of complex-structure reservoirs because it affects the redistribution of filtration flows and is crucial for reservoir management. This paper proposes a method for identifying superreservoirs by identifying enormously high values of porosity and permeability from different-scale study results, followed by the combination and construction of probabilistic curves of superreservoirs. Based on the obtained curves, three probabilistic models of the existence of a superreservoir were identified: P10, P50, and P90, which were further distributed in the volume of the reservoir and on the basis of which new permeability arrays were calculated. Permeability arrays were simulated in a dynamic model of the Alpha field. The P50 probabilistic model showed the best history matching after one iteration.

ВИЗНАЧЕННЯ ЕФЕКТИВНОЇ ПОРИСТОСТІ ПОРІД-КОЛЕКТОРІВ ЗА ДАНИМИ СТРУКТУРИ ЇХ ПУСТОТНОГО ПРОСТОРУ У ВІЗЕЙСЬКИХ І ТУРНЕЙСЬКИХ ВІДКЛАДАХ БЕРЕЗІВСЬКОГО РОДОВИЩА

Background. Currently, it is quite important to track the patterns of the internal structure of reservoirs with their physical properties. The analysis of well-logging data in the well 203 of the Berezivske field of the Dnipro-Donetsk depression is necessary to assess the prospectivity of complexly structured reservoirs. Methods. The methodology for studying the void space structure in complexly structured reservoirs involved several stages: interpretation of well logging data; determination of parameters for the initial mathematical model of the reservoir; inversion of data from acoustic surveys into a curve of the distribution of different void formats; evaluation of reservoir rock types with determination of their effective porosity. Results. Based on the data of compressional and shear wave velocities, as well as density, three distinct rock groups were identified: compacted sandstone, calcareous sandstone and limestone. The initial approximation was obtained for each rock sample, including the set of void formats and their concentration within the reservoir layers. Direct analysis of the resulting data by the authors revealed that the most optimal void formats for the investigated intervals are: for intergranular voids – 0.07 to 0.9; for transitional voids and microcracks – 0.05 to 0.077; for microcracks – 0.007 to 0.0019; for caverns – 4 to 8. Based on the research results, it has been established that granular-cavernous porosity (39,2 %) and fracturedcavernous-granular porosity (29,5 %) are prevailing types of reservoirs. Conclusions. The calculated values of the void formats were used for these formations to quantitatively assess effective porosity based on the obtained data and specific electrical resistivity values at different depths of investigation. The resulting approximation of α = 0.6996 was selected, which reduced the error in calculating the effective porosity of reservoir rocks. The obtained results have demonstrated that the proposed methodologies are essential for understanding and quantitatively assessing the void space structure and filtration-capacitive properties of reservoir rocks, particularly when we are facing with a limited well logging data and restrictive core sampling.

Electrospinning of photoluminescent-magnetic GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons with tunable fluorescence and energy transfer

A novel strategy has been devised to synthesize directly GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons by uniaxial electrospinning technique and subsequent fluorination approach. GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons with sheathed ribbon structure have large specific surface area and unique void space structure between the inner and outer ribbons, which enables materials possess extraordinary applications in cancer therapy, drug delivery, sensors, catalysis, etc. The average widths of the inner and outer layers of the GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons are 1.60 ± 0.03 μm and 1.87 ± 0.02 μm, respectively. Furthermore, GdF3:1%Tb3+,x%Sm3+@SiO2 and GdF3:y%Tb3+,2%Sm3+@SiO2 belt-in-belt structured nanoribbons (x = 0.5, 1, 2, 3, 4, 5; y = 0.1, 0.3, 0.5, 0.7, 1, 2) have also been successfully constructed to observe energy transfer phenomenon and tunable changes in light color. Energy transfer from Tb3+ ions to Sm3+ ions has been proved according to the measured luminescence spectra of the samples. More importantly, Tb3+, Sm3+ co-doped GdF3@SiO2 belt-in-belt structured nanoribbons simultaneously exhibit multicolor luminescent and paramagnetic dual functional performances owing to the natural magnetic moment of Gd3+ ions, making materials have potential applications in flat-panel displays, lasers, biomarkers, and magnetic resonance imaging. In this work, a novel and high-efficient approach is presented to construct photoluminescence-magnetism dual functional GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons, providing theoretical basis and technical guidance for the simple construction of other nanomaterials with special structures.

Анализ зависимости проницаемости от открытой пористости карбонатных пород коллектора в районах Астраханского газоконденсатного месторождения

At the present moment the fields reserves containing viscous and high-viscosity oil account for more than half of all the explored reserves of oil and gas fields. Carbonate deposits, in which oil and gas fluids are concentrated, are characterized by a complex structure of void space containing hydrocarbons. Due to the higher content of part of the oil in unrelated shallow cracks, the development of such reserves is difficult. For this reason, the main task of this study was to establish the dependence of the core-core permeability index on the porosity of carbonate reservoir rocks composing the Astrakhan Gas Condensate field (AGCM). Based on the characteristics of the Astrakhan arch and deposits in the AGCM areas, the paper presents the results of research work to determine the porosity of the rock by hydrostatic weighing based on the available information about the carbonate deposits of the formation, the physical properties of the rocks composing the formation, the characteristics of the geophysical values of porosity and permeability. The obtained values of the mass samples are given by weighing in various saturation states and calculating the permeability of the core samples. The linear dependence of the open porosity of carbonate rocks on permeability is revealed. The analysis of the results of studies on core samples obtained at the wells of the AGCM was carried out. The values of porosity and permeability coefficients are given. Based on the conclusion about the filtration-capacitance properties of the deposit the dependence of the permeability of the rock on the open porosity on the reservoir properties of the deposit was cocluded. The graph obtained on the basis of the calculated data is given, the equation of the “core-core” dependence or a linear regression equation is compiled.

Nanoquartz in Late Cretaceous Deposits in the Lower Berezovskaya Subformation

The Lower Berezovskaya subformation in the Upper Cretaceous is a complex reservoir with unconventional reservoir rocks located in the north of Western Siberia. The clay–siliceous deposits in the Lower Berezovskaya subformation are represented by various types of silicites that have unique petrophysical and mineralogical characteristics that cause significant difficulties in the development of associated productive layers. The aim of the research is to study their mineral composition, the parameters of the void space structure, and the conditions of formation, as well as to determine the sources of silica and perform a detailed study on the structure of nanoquartz. To study the mineral composition, the structure of the void space, and the genesis, special methodological techniques were applied, and a comprehensive analysis of the results using a wide range of laboratory studies, including optical micro- and stereoscopy, scanning electron microscopy, X-ray diffraction analysis, and microtomography, was performed. Silicites in the Lower Berezovskaya subformation are caused by the complex structure of the void space, which includes a wide range of genetic types of voids ranging from micron and submicron dimensions to fractions of a millimeter (voids confined to the burrowing organisms, intraform voids, interform voids, lenticular voids, cellular voids, and voids confined to microstylolite seams). The most widespread type of void is the interaggregate (lenticular and cellular) void, which is formed by clay (montmorillonite) scales, on the surface of which numerous α-quartz nanocrystals ranging in size from 0.05 to 0.5 microns are noted. The content of such quartz reaches up to 80% of the total volume of the rock in individual samples. The source of siliceous material for nanoquartz crystals was most likely volcanic processes, since the revealed mineral paragenesis of montmorillonite, cristobalite, and zeolites indicates the active transformation of ash material that entered the basin from volcanic formations.

Цеолитовая минерализация пород-коллекторов севера Западной Сибири: литолого-геофизические аспекты и особенности разработки

As the hydrocarbon production tends to decline, formations with a complex geological structure and various secondary mineral formation types of reservoir rocks gain a considerable attention. The importance of secondary minerals for formation of pore and void space structure in hydrocarbon reservoirs is extremely high. The physical and chemical properties of these minerals should be considered during exploration works, calculation of reserves, reservoir engineering, wellwork planning. This article highlights the methodological study approach of mountain rocks with zeolitization based on the results of modern lithological, analytical, and laboratory research. The implementation of the approach allowed for recommendations for rapid quantitative assessment of zeolite content in the Lower Cretaceous sediments of the Bolshekhetskaya Depression.

Study of void space structure and its influence on carbonate reservoir properties: X-ray microtomography, electron microscopy, and well testing

Many carbonate reservoirs containing significant hydrocarbon resources are characterized by complex pore structures and, as a result, heterogeneous distributions of fluids in their pore networks. Accurately assessing the microscopic pore structure characteristics of carbonate rocks and their influence on reservoir properties is essential for the successful development of oil fields. In the studied carbonate reservoirs of three oil fields in the Perm Krai, Russia, complex tectonic activity and multi-stage diagenetic modification have resulted in the formation of a heterogeneous pore network spectrum ranging from macropores to nanometer-scale (<1 μm) pores. Thin sections and computed tomography were applied to obtain the petrography of carbonate rocks, 2D images of a wide range of pores, and a 3D representation of the pore network. Well testing was used to study the pore network structure at the macrolevel. Combining well testing and laboratory-based core studies allowed the structural features of the reservoirs of the three fields under consideration to be characterized in high detail. The presence of magnesium in the mineral composition of the studied limestone decreased its capacitive characteristics. We identify three fundamentally different void space scenarios: (i) void spaces formed only by primary intercrystalline pores, (ii) much larger secondary pores are also present, and (iii) primary and secondary voids connected by a network of partially healed fractures. Such variations in the structure of void space contribute to varying reservoir behavior. The presence of larger voids and, accordingly, higher initial permeability contributes to intense deformation of the void space and permeability decreases with decreasing pressure. The established patterns in this work explain the characteristic dynamics of well flow rates during field development.

Study of the reliability of the determination of reservoir characteristics of productive formations in the Stretenskoye field using correlation analysis

Storage properties (porosity) of productive strata at Stretenskoye field were determined using several methods of geophysical studies of wells. The filtration properties (permeability) are determined according to the interpretation of the hydrodynamic study materials under unsteady conditions. At the same time, the methods used in a number of cases showed different results. In order to avoid misinterpretation of the structure of void space and its properties, it is advisable to conduct studies to assess the reliability of all the methods. For this purpose, the paper used the tools of mathematical statistics such as correlation and multivariate regression analysis. As a result of the research, the authors gave the recommendations for the application of methods to determine the filtration and storage properties of reservoirs differentially for terrigenous and carbonate reservoirs of the studied field.

Improved lithium storage performance of (Ni0.1Co0.7Mn0.2)3O4@Void@N-doped carbon via the synergistic effect between void space structure and N-doped carbon layer

Improved lithium storage performance of (Ni0.1Co0.7Mn0.2)3O4@Void@N-doped carbon via the synergistic effect between void space structure and N-doped carbon layer

The structure of void space of complex structured Bashkir carbonate reservoir rocks from the Opishnianske deposit of the DDD

The analysis of materials of well-logging of the wells of the Opishnanske deposit of the DDD was conducted for the purpose of the determination of their reservoir promise. The void structure of Bashkir carbonate reservoir rocks (productive horizon B-10) of 11 wells of the Opishnanske deposit of the DDD was defined for the first time in this article. The quantitative assessment of porosity types of reservoir rocks was done using a method, developed at the Taras Shevchenko University of Kyiv, which basis is a complex of well-logging methods that includes radioactivity and acoustic logging. Using well-logging methods, the potential reservoir rocks were distinguished, the forms of voids were calculated, and the contribution of different void types (intergranular, fracture, vuggy, secondary porosity) in the absolute porosity was assigned. As a result of the study, it was found that the fracture voids are present to a large extent only in layers, presented by water-saturated reservoir rocks, whose fracture porosity ratio acquire values from 0,2 % to 1,5 %. The fracture type of voids is present in layers with gas-saturated reservoirs in rocks with considerably lower concentrations (from 0,05 to 0,29 %). The vugggy voids are distinguished in almost a majority of layers, a vuggy porosity ratios in them reach 9,8 %. Based on the determination of type and concentration of voids in car-bonate reservoir rocks, the promise and predictive discharges of water and gas were determined by authors using a calculated parameter of the unit surface area of voids. The authors have identified the predictive yields higher than 1tonn per day in all wa-ter-saturated reservoir layers, and the highest were in two layers with daily flowrates of 307 and 3200 t/d in the well intervals of: 2816,4—2820 m (№ 12) and 2864—2870,4 m (№ 114). The highest predictive discharge of gas, that is 352 thousand cubic meters per day, is determined in a well 127 (the interval of 2773,8—2775,5 m). The gas discharges in three intervals of the well 127 are calculated within 140 thousand cubic meters per day (2762,4—2764,7, 2788—2790, 2822,8—2824,4 m). Increased discharges correlate with the presence of fracture and increased secondary porosity.

Mathematical modeling of the acoustic and elastic anisotropy of the shale reservoir rocks of the Dnipro-Donetsk depression

The purpose of the work is to analyze the parameters of elastic and acoustic anisotropy in the study of a multicomponent reservoir rock model, which is represented by shale. Research theory To solve this problem, the methods of conditional moment functions using the Mori-Tanaka calculation scheme, as well as the ordinary least squares were used. The technique of effective elastic invariables mathematical modelling of unconventional shale reservoir rocks has been developed. Justification of the mathematical model Eight varieties of mathematical models that characterize the mineral composition, the structure of the void space and elastic properties that are characteristic for shale reservoir rocks of the Dnipro-Donetsk depression in Ukraine were substantiated and developed. The models are based on previous publications by the authors and the results of petrographic studies at the Institute of Geology. Results The authors for the first time carried out an analysis of elastic constant rock models, acoustic tensor components, linearity and shale parameters, isolines stereo projections of index surfaces of nine elastic anisotropy parameters, as well as Thomsen parameters. Acoustic data can be used to trace the change in the structure of the reservoir rock void space, the concentration of rock-forming minerals in the rock. Fracturing has a greater effect on rock structure than granular voids and mineral structure. The orientation of inclusions has the greatest influence on the coefficient of acoustic anisotropy, anisotropy coefficients in rocks, where the voids are oriented in the plane perpendicular to the borehole axis have the largest values (more than 20%). When calculating the Thomsen parameters, the parameters of elastic anisotropy were obtained. They characterize not only the mineral composition of the rocks but also the qualitative structure of the void space, the orientation of minerals and voids in the rocks. Thomsen parameters correlate with acoustic anisotropy parameters for shale reservoir models. The parameters of acoustic and elastic anisotropy are indicators in the studies of similar-type rocks with different types of mineral inclusions and the structure of the void space. The mathematical modelling of elastic and acoustic parameters which characterizes their anisotropy and was carried out by the authors is an important step in substantiating mathematical models of shale reservoir rocks. Such models can be used in the interpretation of geophysical data (seismic surveys and well logging) to make corrections for elastic anisotropy in prospecting and exploration of oil, gas and water saturated unconventional shale reservoir rocks of complex structure, and also to compile a database of mathematical models of reservoir rocks in the given region.

АНАЛІЗ АКУСТИЧНИХ ВЛАСТИВОСТЕЙ ПОРІД-КОЛЕКТОРІВ РУНОВЩИНСЬКОЇ ПЛОЩІ НА ОСНОВІ ПЕТРОФІЗИЧНИХ ДОСЛІДЖЕНЬ У РІЗНИХ БАРИЧНИХ УМОВАХ

The results of rock physics study of 68 core samples from well No. 110 of the Runovshchynska field of the Dnipro-Donets depression in Ukraine are presented. Investigation of the P-waves on samples under different pressure conditions with the use of 'Kern-4' and high pressure VSC-1000 was performed. Analysis of the obtained data and calculated reservoir values of P-waves was performed. The character of the change in velocity of P- and S-waves for atmospheric conditions is considered. It is shown that the predominant amount of water saturated samples has a velocity of P-waves 3200–3500 m/s (dry samples 2100–2550 m/s), and the S-wave velocity for saturated samples is 2100–2550 m/s (dry specimens 1400–1500 m/s). For a collection of samples, which were measured in atmospheric conditions, the correlation dependence between velocities of P-waves and their density with a close correlation was established. Correlation dependences between elastic wave velocities and the connected porosity of saturated samples were investigated. The dependences of type Vð = f (Kð) with high correlation coefficient for three separate picks of the homotypic sandstones were established. During the analysis of the acoustic studies results under conditions of variable pressure for the majority of samples from the studied intervals, the authors obtained the following common factors. The values of the P-wave velocity, measured in atmospheric conditions, are always smaller than the values obtained after the removal of the pressure; however, there are sometimes quite noticeable fluctuations in their difference, which can be explained by a sharp (possibly hopping) closure of microcracks in the rock with increasing pressure and their delayed opening or non-disclosure when it is reduced. The most contrasting changes in the behavior of the P-wave velocities are haracteristic for several samples (Nos. 27, 48, 50, 53/1), which is most likely due to the void space structure in the rocks, possibly with an increased number of microcracks compared with other samples. On the basis of a priori data and the results of researches of samples at variable pressures, the authors calculated the P-wave velocities in reservoir conditions, conducted their comparative analysis with velocities that are characteristic for samples in atmospheric conditions, built a tight (R² = 0,85) correlation dependence of the investigated parameters.

СУЧАСНІ ПІДХОДИ ДО ВИЗНАЧЕННЯ ПРОНИКНОСТІ ПОРІД-КОЛЕКТОРІВ ЗА ДАНИМИ ГЕОФІЗИЧНИХ ДОСЛІДЖЕНЬ

Permeability of rock is its physical property that describes its ability to conduct fluids under the pressure gradient. This paper presents short description and analysis of methods for determination of permeability of oil and gas reservoirs. Permeability is a function of different parameters that leads to difficulties during its estimation. Investigations of the void space structure of rocks, their anisotropy etc.were carried out in order to take into account all factors that have an influence on the permeability. Reservoir conditions could also be modeled for that purpose. Methods for determination of permeability of rocks can be divided into three groups: methods based on the laboratory studies of rocks; methods based on the well logging data; and methods based on the correlations between different parameters of rocks. The first two groups include methods for steady and unsteady fluid flow. Methods for the unsteady flow are usually more precise and rapid, thus prospects of extension of methods for permeability determination are mostly connected with them. Each of the presented methods to determine permeability is characterized by some pros and cons. The most appropriate method for the specific experiment is always chosen according to conditions and requirements and expected results. Further author's investigations will be related to the creation of petrophysical models of permeability of oil and gas reservoir rocks, including reservoirs of complex structure.

Prediction of flow rate of karstic springs using support vector machines

ABSTRACTComplex void space structure and flow patterns in karstic aquifers render behaviour prediction of karstic springs difficult. Four support vector regression-based models are proposed to predict flow rates from two adjacent karstic springs in Greece (Mai Vryssi and Pera Vryssi). Having no accurate estimates of the groundwater flow pattern, we used four kernels: linear, polynomial, Gaussian radial basis function and exponential radial basis function (ERBF). The data used for training and testing included daily and mean monthly precipitation, and spring flow rates. The support vector machine (SVM) performance depends on hyper-parameters, which were optimized using a grid search approach. Model performance was evaluated using root mean square error and correlation coefficient. Polynomial kernel performed better for Mai Vryssi and the ERBF for Pera Vryssi. All models except one performed better for Pera Vryssi. Our models performed better than generalized regression neural network, radial basis function neural network and ARIMA models.

A Feasibility Study of the Pore Topology Method (PTM), A Medial Surface-Based Approach to Multi-phase Flow Simulation in Porous Media

Computationally efficient microscale models designed to simulate multi-phase flow and characterize low-porosity media are challenged in thin, highly porous materials, primarily due to large, irregular pore spaces and inability to satisfy representative elementary volume requirements. In this article, we describe the pore topology method (PTM) and explore its capabilities to characterize a set of isotropic fibrous materials and to simulate multi-phase flow. PTM is a fast, algorithmically simple method that reduces the complexity of the 3-D void space geometry to its topologically consistent medial surface and uses it as a solution domain for single- and multi-phase flow simulations. Our results in permeability calculations, pore size distribution, and quasi-static drainage and imbibition simulations are in very good agreement with other numerical methods and analytical solutions. We expect that incorporating detailed spatial information about the porous media structure into the medial surface will enable a more accurate representation of the void space structure and of physical phenomena involved in multi-phase flow, thus expanding the applicability of PTM to a broader range of porous media, including non-fibrous materials.

Визначення структури пустотного простору складнопобудованих порід за даними петроакустичних досліджень Семиреньківської площі

Визначення структури пустотного простору складнопобудованих порід за даними петроакустичних досліджень Семиреньківської площі

Effect of the Catalytic Pyrolysis Conditions on the Properties of Biological Coke

Abstract An orthogonal experiment was used to investigate the effects of cotton stalk catalytic pyrolysis conditions on the properties of biological coke. The Fourier transform infrared spectroscopy (FTIR) coupled with scanning electron microcopy (SEM) was applied to inquiry the forming mechanism of biological coke. Reaction catalyst, pyrolysis temperature, holding time and sweeping gas flow rate were considered as the key factors. The results indicate that catalyst and pyrolysis temperature are the dominant factors. Decreasing the temperature can improve bio-coke yield and functional groups retention index. Catalysts can not only improve the pyrolysis reaction rate, but also obtain the biological coke with rich void space structure and abundant surface morphology, which can be the high quality raw materials for more products with fairly high added value. Steam atmosphere is conducive to generate relatively high quality biological coke and higher calorific value gas.

Оцінка структури пустотного простору низькопористих порід Зарічної площі за результатами петрофізичних та геофізичних досліджень

Оцінка структури пустотного простору низькопористих порід Зарічної площі за результатами петрофізичних та геофізичних досліджень

Molecular Structure of Corncob‐Derived Biochars and the Mechanism of Atrazine Sorption

This study evaluated the sorption of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] to biochars and thereby explored their potential use as an efficient and low‐cost soil amendment for mitigating and removing agricultural contaminants. Biochars derived from corncobs (Zea mays L.) produced at incremental pyrolysis temperatures (350–650°C in 100°C intervals) were characterized using elemental analysis, specific surface area, scanning electron microscopy, x‐ray diffractometry, and Fourier‐transform infrared spectra to estimate the relationship between the physical and chemical properties of biochars and the treatment temperature. Generally, carbonization, aromatization, and specific surface area increased with the elevation of temperatures, whereas the occurrence of polar functional groups and crystallinity decreased. The sorption isotherms fit the Freundlich equation well. A negative correlation between the logarithm of the concentration‐dependent distribution coefficient Koc and H/C and (O + N)/C ratios suggested that the presence of aromatic C and hydrophobic structures are advantageous for biochars to sorb atrazine in aqueous solutions. Biochar prepared at 650°C has a relatively developed void space structure and therefore a much larger surface area than when prepared at lower pyrolysis temperatures, indicating that pore filling has occurred. These results may provide a reference for biochar design and application in agricultural pollution control.