Currently, high-yield gas reservoirs have been discovered by exploring Lower Paleozoic tight carbonate oil and gas reservoirs in the Changqing area. These reservoirs, however, are impacted by ...subsequent karstification and diagenesis processes, leading to the formation of complex pore spaces with varying pore diameters ranging from microns to millimeters. Conventional well curves, with a resolution at the decimeter level, can only provide an overview of the reservoir porosity, making it challenging to evaluate the pore structure. On the other hand, electrical imaging logging data has a sampling interval of 0.1 inches and a resolution as fine as 5 mm, providing valuable information for pore structure evaluation in tight reservoirs. Since formation resistivity is influenced by factors like porosity, mud filtrate resistivity, and cementation, the cementation index serves as a reflection of the pore structure. Therefore, by calibrating the cementation index using data obtained from experiments at different scales, the pore structure parameters of tight carbonate reservoirs can be evaluated. This study conducted a comparison between numerous core experiments at various scales and both conventional and imaging log data. A method was proposed for extracting pore size distribution characteristics and calculating the pore size spectrum based on electrical imaging logging, ultimately leading to the establishment of a quantitative evaluation model for the pore structure of tight carbonate reservoirs. The results demonstrated improved accuracy and consistency in interpretation, as confirmed by well test data.
Highlights
The functional relationship between the cementation index and pore size is established based on experimental analysis data from cores at various scales.
Taking into consideration the contribution of different pore components to permeability, we have proposed the pore component method for calculating reservoir permeability.
By conducting a comprehensive comparison of numerous core experiments, conventional logging, imaging logging, and other data, this paper presents a method for extracting pore size distribution features and calculating the pore size spectrum based on electrical imaging logging.
The coal wall breakage deflection formula is constructed.
Bracket horizontal force has an effect on coal wall breakage.
The regression equation between the bracket support parameter and the index of plasticity zone occupancy is established.
Adjusting support parameters can prevent coal wall rib spalling to a certain extent.
Increasing support resistance at the working face is beneficial to the stability control of coal wall.
The microstructure and corrosion characteristics of 316L stainless steel specimens fabricated by spark plasma sintering (SPS) and selective laser melting (SLM) techniques were investigated. SPS ...specimens have a relatively low density compared with SLM specimens. Microstructural analysis showed that SPS specimens consisted of fully and partially sintered regions and contained initial pores, which are located at the powder boundaries (PBs). SPS specimens have relatively low density and high kernel average misorientation (KAM) values near the interface of the pores and the matrix. In the case of SLM specimens, the scanning strategy did not affect the spatial distribution of the KAM, while it affected the extent of surface defects. Electrochemical analysis revealed that the corrosion behavior of SPS specimens was similar to localized corrosion, and weak levels of passive protection were observed in the anodic response curves due to the initial surface pores. SLM specimens with well-connected scan tracks showed passivation behavior similar to that of as-rolled specimens. Moreover, due to a homogeneous microstructure distribution and lower porosity, in NaCl solutions the SLM specimens showed corrosion performance that was significantly enhanced compared with that of SPS specimens. Cross-sectional analysis of corroded SPS specimens revealed that the configuration and connectivity of pores (or small cavity) affected the morphology of open spaces under the corroded surface.
•Microstructure and corrosion characteristics of 316L SS fabricated by SPS and SLM techniques were investigated.•SPS specimens had relatively high KAM values in the regions near pores.•The higher corrosion current density of SPS was due to the pores on the surface.•SLM specimens with well-connected scan tracks showed passivation behaviors that were similar to those of as-rolled specimens.•Corroded SPS specimens contained the single and dual jar-shaped open structures.
Organic matter serves as the hydrocarbon-generating parent material for shale reservoirs, in which organic pores are also important reservoir spaces. Different types of organic matter have wide ...differences in hydrocarbon generation and pore-forming ability. Based on the occurrence state of organic matter, in the over-mature Marine shale organic matter mainly includes in situ and migrated organic matter. It has been extensively studied on in situ organic matter and organic matter migrating into inorganic pores, while there are few reports of organic matter migrating into microfractures. In this study, the over-mature Marine shale reservoir in the first sub-member of the Silurian Longmaxi Formation in the Luzhou area of the Sichuan Basin is taken as an example. Core observation, optical microscope, high-precision large-view scanning (MAPS, modular automated processing system) and mineral analysis scanning (QEMSCAN, quantitative evaluation of minerals by scanning electron microscopy) were conducted to observe the morphological characteristics of organic matter veins, and then analyze the genesis and pore-forming characteristics of such organic matter. The results show that: ① Organic matter veins (OM veins) are soluble organic matter with fractures as an effective channel, and OM veins in the study section is easy to form under the condition of micro-fractures in the shale sweet segment after organic matter generating oil and before gas generation ② Organic matter in the OM veins are less efficient in pore-forming, with sparse pores and smaller pore sizes. The occurrence of fractures varies greatly, including horizontal fractures, oblique fractures and high-angle fractures, which are mostly developed in the Long111 and Long112 layers. ③ The development of OM veins can indicate better reservoir conditions, that is, the layers have strong hydrocarbon generation intensity (strong pore-forming ability of organic matter) and high brittle mineral content (strong reservoir compressibility). The new findings in this paper reveal that OM veins are instructive for the determination of geological–engineering sweet spots in the Longmaxi Formation in the Sichuan Basin, and also provide guidance for future research on occurrence form and geological significance of different types of organic matter.
Flexible supercapacitors have recently attracted intense interest. However, achieving high energy density via practical materials and synthetic techniques is a major challenge. Here, we develop a ...hetero-structured material made of black phosphorous that is chemically bridged with carbon nanotubes. Using a microfluidic-spinning technique, the hybrid black phosphorous-carbon nanotubes are further assembled into non-woven fibre fabrics that deliver high performance as supercapacitor electrodes. The flexible supercapacitor exhibits high energy density (96.5 mW h cm
), large volumetric capacitance (308.7 F cm
), long cycle stability and durability upon deformation. The key to performance lies in the open two-dimensional structure of the black phosphorous/carbon nanotubes, plentiful channels (pores <1 nm), enhanced conduction, and mechanical stability as well as fast ion transport and ion flooding. Benefiting from this design, high-energy flexible supercapacitors can power various electronics (e.g., light emitting diodes, smart watches and displays). Such designs may guide the development of next-generation wearable electronics.
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The excessive CO2 emission has gained global attentions due to its potential effects on climate change, plant nutrition deterioration, and human health and safety. Metal-organic ...frameworks (MOFs) featured with high specific surface area, adjustable pore size, and tailorable morphology have been widely applied for CO2 capture. However, some drawbacks of poor mechanical stability and uneven distribution of mesopores limit their further applications. Herein, we demonstrate a one-step synthesis of bimetallic center framework (OSSBCF) and pore reconstruction (PRC) strategy to prepare the hierarchical porous Zn/Co-ZIF@ANF aerogels. This unique design achieves the construction of efficient gas transfer channels and creates massive micropores with abundant Lewis basic adsorption sites. Benefiting from theses merits, the bimetallic Zn/Co-ZIF@ANF aerogels demonstrate high MOFs loading mass of 47.51 wt%, high specific surface area of 686.39 m2g−1, and large porosity of 99.31 %. Moreover, the bimetallic Zn/Co-ZIF@ANF aerogels exhibit an enhanced CO2 adsorption capacity of 5.99 mmol/g and CO2/N2 adsorption selectivity of 35 at 25 °C and 1 bar. The CO2 capacity of bimetallic Zn/Co-ZIF@ANF aerogels keep up to 95.19 % after ten cycles of CO2 adsorption, indicating the excellent long-term recycle stability. Therefore, this study provides a promising strategy to engineer hierarchical porous bimetallic MOF aerogels toward practical CO2 capture.
Soil carbon sequestration arises from the interplay of carbon input and stabilization, which vary in space and time. Assessing the resulting microscale carbon distribution in an intact pore space, ...however, has so far eluded methodological accessibility. Here, we explore the role of soil moisture regimes in shaping microscale carbon gradients by a novel mapping protocol for particulate organic matter and carbon in the soil matrix based on a combination of Osmium staining, X-ray computed tomography, and machine learning. With three different soil types we show that the moisture regime governs C losses from particulate organic matter and the microscale carbon redistribution and stabilization patterns in the soil matrix. Carbon depletion around pores (aperture > 10 µm) occurs in a much larger soil volume (19-74%) than carbon enrichment around particulate organic matter (1%). Thus, interacting microscale processes shaped by the moisture regime are a decisive factor for overall soil carbon persistence.
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Electrochemical impedance spectroscopy (EIS) constitutes a useful tool in membrane science and technology because it provides valuable structural and functional information. The ...different arcs observed in the impedance spectra permit to decouple and understand distinct physico-chemical phenomena occurring under operating conditions. By using EIS techniques, we have characterized here multipore asymmetric membranes with conical pores that exhibit a broad range of ionic conduction properties, including current rectification. These properties can be modulated by tuning the electrical interaction between the charges functionalized on the pore surface and the nanoconfined ionic solution. In particular, the membrane electrical response is studied as a function of the amplitude and frequency of the external voltage signal, the electrolyte type and concentration, and the solution pH. Remarkably, significant chemical inductance effects are observed. The scalability and biocompatibility of these pores suggest good potential for use in hybrid biodevices and interfaces.
This work describes a simple and novel biosensor for the quantitative determination of Staphylococcus aureus (S. aureus) based on target-induced release of signal molecules from aptamer-gated ...aminated mesoporous silica nanoparticles (MSNs) coupled with surface-enhanced Raman scattering (SERS) technology. MSNs were synthesized and then modified with amino groups by (3-aminopropyl) triethoxysilane to make them positively charged. Next, signal molecules (4-aminothiophenol, 4-ATP) were loaded into the pores of MSNs. Then, negatively charged aptamers of S. aureus were assembled on the surface of MSNs through electrostatic interactions. Upon the addition of S. aureus, the assembled aptamers were specifically bound to the bacteria. Consequently, the “gates” were opened, resulting in the release of 4-ATP from the pores of MSNs. The released molecules were measured by a Raman spectrometer, and the intensity of 4-ATP at 1071 cm–1 was linearly related to the S. aureus concentration. A silver nanoflower silica core–shell structure (Ag NFs@SiO2) was prepared and it served as a SERS substrate. Under optimized experimental conditions, a good linear relationship (y = 2107.93 + 1536.30x, R 2 = 0.9956) in the range from 4.7 × 10 to 4.7 × 108 cfu/mL was observed with a limit of detection of 17 cfu/mL. The method was successfully applied for the analysis of S. aureus in fish samples and the recovery rate was 91.3–109%.
•With the aggregate size increases, the permeability coefficient of pervious concrete increases significantly.•With the increase of aggregate size, the 2D/3D pores size increases, while the total ...pore surface area decreases.•The permeability increases with the increase of 2D/3D pores size and decreases with the increase of total pore surface area.•Permeability is most sensitive to the content of small pores, followed by large pores content, and is less sensitive to the content of medium pores.
The pores characteristics such as pores size, distribution and specific surface areas play a dominant role in the permeability of pervious concrete. The aim of this research was to identify the pores characteristics in pervious concrete by 2D/3D CT images and investigate the relationship between pores characteristics and permeability. Eight groups of pervious concrete specimens with almost the same porosity but different aggregate size were prepared. Based on CT imaging technology, the 2D/3D pores characteristics were extracted and analyzed. It was found that the pores in pervious concrete were usually surrounded by three to seven aggregates. Most of pores were close to an ellipse with the ratio between major axis and minor axis varied from 1 to 6. According to the influence of pores size on permeability, pores were artificially classified into three groups, small (<20 mm2), medium (20 mm2–50 mm2) and large pores (>50 mm2). With the aggregate size increased, the content of small pores decreased and the proportion of large pores increased, while the content of medium pores had no significant change. Whatever the aggregate size was, lots of (>14%) “small pores (<2 mm2)” existed in pervious concrete. Subsequently, the absolute permeability experiment simulation of pervious concrete was conducted by the software of Avizo. The results of permeability simulations showed the permeability increased with the increase of 2D/3D pores size and decreased with the increase of the total pore surface area. Permeability is more sensitive to the content of small pores compared to large pores and medium pores. With aggregate size increases, the number of seepage flow lines increases and the seepage flow paths become thicker, which contribute to water permeation. The permeability simulations results corresponded to the laboratory results.
Permeability in reactive porous media evolves in complex ways that are hard to predict. Macroscopic empirical equations are often used to estimate permeability evolution but fail to reflect the ...impact of pore scale reactions on permeability. This work aims to understand the evolution of permeability in systems where mineral dissolution and precipitation occur simultaneously. Pore network models are used for permeability simulation of a Paluxy sandstone using pore and pore‐throat size distributions from the analysis of X‐ray CT images. Pore and pore‐throat radii are increased and decreased to reflect the effects of dissolution and precipitation reactions. Varying spatial distributions of reactions are simulated and the resulting porosity and permeability values compared with commonly used macroscopic equations. It is observed that when dissolution occurs at the inlet and precipitation at the outlet, porosity increases while permeability decreases. Similar results are also observed in the respective opposite scenario where precipitation occurs at the inlet and dissolution at the outlet. When dissolution and precipitation reactions are randomly distributed throughout the network, porosity increases with little change in permeability that is not captured by the empirical equations. When reactions are controlled by pore and pore‐throat sizes, such as dissolution occurring in pores and pore‐throats of small size and precipitation in pores and pore‐throats of larger size, porosity and permeability decrease. When precipitation occurs in pores and pore‐throats of smaller size and dissolution in pores and pore‐throats of larger size, porosity and permeability increase and is described relatively well by the Verma‐Pruess porosity‐permeability equation.
Key Points
The spatial distribution of dissolution and precipitation reactions controls permeability evolution
Simultaneous mineral reactions can increase, decrease, or result in little change in permeability
Porosity‐permeability relationships have limited predictive capability
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