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Purposes In the in-situ mining of oil shale, poor heat transfer efficiency and pronounced anisotropic differences present challenges. Methods In this study, standard samples from Xinjiang's Barikun oil shale are adopted to explore heat transfer variations in horizontal and vertical bedding at different temperatures through indoor experiments, and in-situ mining simulation was conducted. Findings The experimental results show that: 1) With the increase of temperature, the heat conduction coefficient of each bedding direction shows a "decreasing" trend, but the heat conduction coefficient of parallel bedding direction is greater than that of vertical bedding direction; 2) With the increase of temperature, the specific heat capacity first increases and then decreases. When the temperature is 400 ℃, the specific heat capacity is the maximum; 3) Combined with the micro-CT image, with the increase of temperature, the influence of increasing cracks on the heat conduction in the vertical bedding direction is greater than that in the parallel bedding direction. On the basis of the above experimental parameters, the "heat-solid" coupling model of in-situ electric heating of oil shale reservoir is established by COMSOL software. The simulation results show that: With the increase of heating time, anisotropic heat transfer difference gradually appears. When heating duration reaches 600 d, the heat transfer area in parallel bedding direction is obviously larger than that in vertical bedding direction, showing an "ellipse" shape. When heating duration reaches 1 440 d, the heat transfer area increases slightly, and the pyrolysis of the shale in the heating well control area is basically completed.

The characteristics of shale reservoirs play a crucial role in the enrichment and exploitation of shale gas. The Upper Permian Dalong Formation in the northern Sichuan Basin is a significant marine-derived high-quality hydrocarbon source rock that requires further detailed investigation. This study conducted qualitative and quantitative analyses on the pore structure of deep shale reservoirs within the Permian Dalong Formation in northeastern Sichuan. Various methods such as high-resolution field emission scanning electron microscopy, CO2 adsorption, N2 adsorption, and high-pressure Hg injection measurements were employed. Fractal fitting using the V-S model based on CO2 adsorption, the FHH model based on N2 adsorption, and the fractal geometry model based on high-pressure Hg injection was utilized to characterize the pore structure of deep shale. The findings revealed that deep shale reservoirs in the Dalong Formation in northeastern Sichuan Basin contain abundant nano-scale organic pores and limited inorganic pores. The development of organic pores exhibits strong heterogeneity influenced by maceral differences and organic matter distribution. Similar to Longmaxi Formation shale, the pores in the Dalong Formation are predominantly micropores and mesopores, comprising over 90% of the total pore volume and primarily influenced by organic matter abundance. The research on fractal dimension characteristics suggests that macropores in deep shale exhibit stronger heterogeneity compared to mesopores and micropores. Due to their smaller size and minimal diagenetic impact, micropores and mesopores have simpler structures with lower fractal dimensions. On the other hand, macropores display significant heterogeneity due to their larger size, wide distribution range, diverse genesis, and susceptibility to diagenesis. Due to their abundant reservoir space and strong self-similarity, micropores and mesopores in deep shale are conducive to the occurrence, seepage and exploitation of shale gas.

In order to accelerate the exploration and development of shale gas, this paper elaborates on the micro mechanism of shale gas preservation based on shale self-sealing. The self-sealing capacity of shale formations is mainly related to the low connectivity of nano-throats, low speed diffusion caused by bound water occurrence, capillary force sealing, and breakthrough pressure along the layer direction under burial conditions. Results of analysis based on shale pore morphology and connectivity show that the organic pores in shale are mainly composed of nano-throats with poor connectivity and significant retention effects. At the same time, the stacking of multiple relatively dense sealing layers within the top, bottom, and shale layers is conducive to self-sealing in longitudinal direction. Based on experimental and molecular dynamics simulation analysis of the influence of bound water on the diffusion and breakthrough pressure of the shale matrix, it is revealed that the bound water occurrence significantly reduces the effective diffusion capacity of shale matrix pores and could cause high capillary forces, leading to effective sealing of the gas stored in organic pores. In the study, the permeability-breakthrough pressure evolution relationship was constructed, revealing that under deep burial conditions, the effective closure of shale bedding fractures along the layer direction can form high breakthrough pressure sealing. During the uplift stage, under relatively weak tectonic compression, the shale could still maintain a high sealing capacity along the layer direction, which is conducive to shale gas preservation. However, under strong tectonic compression, the shale bedding fractures open and communicate with open fault surface, causing the failure of preservation capacity and large-scale loss of shale gas. This study elucidates the microscopic mechanism of shale gas preservation through experiments and molecular dynamics simulations, which could provide useful guidance for marine shale gas exploration in complex structural areas.

The underwater sound absorption material for submarines should fulfill the demand for remarkable performance in medium-low frequency sound absorption at low thicknesses. Hence, in this paper, the innovative “filled-microperforated plate-like” (F-MPPL) structure was introduced to the hollow microballoons filled underwater sound absorption composite (HBF composite) using the tailor-made 3D spacer fabric. The test results show remarkable mechanical properties with a compression strength and compression modulus of 2256 KPa and 14.6 MPa for the new type of F-MPPL composite, respectively. In addition, the peak sound absorption coefficient of the F-MPPL composite reaches 0.77 at just 7.5 mm thickness based on the resonant sound absorption characteristic introduced by the F-MPPL structure. Moreover, the study investigated the effects of seawater aging on the F-MPPL composite and found that while there was a decrease in compression strength and average sound absorption coefficient, the degradation of the F-MPPL composite was significantly smaller than the HBF composite due to the inhibitory effect of spacer yarns on pore expansion. Finally, this study proposed the method of using compression strength to predict the long-term life of the F-MPPL composite under seawater aging, and a 60% retention rate after 20 months was displayed.

Overpressure is commonly existed in shale gas pools of Jiaoshiba and Dingshan structures in the southeastern part of Sichuan and Huangjinba structure in Changning area of the southern region of Sichuan. From the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation, there are two abnormally pressured compartments of shale gas separated by three sealing layers. The lower compartment is in accordance with the superior shale layer in the Wufeng-Longmaxi formations, sealed by tight marl-bearing limestone and nodular limestone in the Upper Ordovician Linxiang and Baota formations at the bottom and the interbeds of volcanic ash-altered clay rock, thin carbonate rock and mudstone in the central segment of the first sub-member of the first member of Longmaxi Formation on the top, which also works as the sealing layer at the bottom of the upper compartment. Between the first and second members of the Longmaxi Formation, sealing layer for the top of the upper compartment exitsed, which is mainly composed of mudstone or mudstone interbedded with thin carbonate rocks.Researches show that the sealing layers have better sealing ability when they contain tight carbonate rock or thin carbonate rock and are interbedded with mudstone. There are differences in logging curves such as acoustic wave, resistivity, natural gamma, etc. between the top and bottom sealing layers and the compartments. In the upper compartment, the microstructure of shale shows strong anisotropy with low quartz content, high clay content, low organic matter content, poor organic pore connectivity, low total hydrocarbon content, and low porosity. In the lower compartment, the microstructure of shale shows isotropy, with high quartz content, low clay content, high organic matter content, interconnected organic matter, interconnected organic pores, good connectivity, high total hydrocarbon content, and high porosity. These compartments have experienced the early stage of rapid burial, the embryonic stage in which organic matter is immature or low-mature and is dominated by normal fluid pressure system, the formation stage in which a large quantity of hydrocarbon is generated after fast and deep burial and is dominated by overpressure system, the formation stage in which a large quantity of gas is generated after deep burial and high-degree thermal evolution and is dominated by overpressure system, and finally the late stage of the formation of abnormally pressured compartments for shale gas, resulting in two isolated and abnormally pressured compartments for shale gas with three sealing layers on the top or at the bottom, lateral dipping of formation, and lateral sealing of reverse fault. The lower compartment with high porosity, high organic matter content, good connectivity and high pressure coefficient is the priority target for the efficient development of shale gas.

Crowded living conditions and increasingly severe noise problems necessitate the development of a low-thickness sound absorption material with remarkable sound absorption performance. Here, simple materials such as sodium alginate aerogel (SA) and polyurethane (PU) foam are used to combine with special 3D spacer fabric to design an innovative highly-efficient acoustic absorber composite (B&M−L composite). It integrates a “backing cavity-like” (BC-L) structure and “filled-microperforated plate-like” (MPP-L) structure. Thereby, it realizes porous and resonant sound absorption at a small thickness. The superior structure design combining strong resonance with porous structure endows the new type of composite with a remarkable absorption performance. Specifically, the peak absorption coefficient is 0.98, the average absorption coefficient at a thickness of 10 mm is 0.71, and the noise reduction coefficient per unit thickness of B&M−L composites exceeds those of most of the reported sound absorption materials. Based on its remarkable acoustic performance, good mechanical properties, heat insulation performance, and thermal stability, the B&M−L composite provides a convenient and inexpensive method to improve the overall performance of porous sound absorption materials, and displays significant potential for use in the fields of construction, transportation, and large mechanical equipment.

In this paper, the co-occurring characteristics of pore gas and water in the Longmaxi Formation shales in the Sichuan Basin, South China were investigated. Water vapor and methane adsorption by the means of gravimetric methods were carried out to quantitatively determine the behavior of gas and bounding water in micro-nano pores. The impact of the shale compositions and pore structures on the occurring characteristics were discussed. Results showed that the storage capacity of bound water in different types of shales varied dramatically, and the characteristics of bound water could be described by the water vapor adsorption curve and the GAB model. There is an apaprent positive correlation between the maximum monolayer water molecule adsorption capacity and the clay mineral content in shales, indicating that clay minerals provide the main active adsorption sites for water molecules. The adsorption capacity of shale to water molecule is higher than that of methane molecule overall, and methane molecule mainly exist in pores with the form of monolayer adsorption. Bound water, adsorbed gas and free gas could be stored in different pore ranges of different shales. Pores with diameters lower than 2 nm are occupied by bounding water and adsorbed gas. For shales with TOC < 2.5%, free gas would be stored in pores with diameters larger than 5 nm approximately, while for the shales with TOC>2.5%, free gas would be stored in pores with diameters larger than 3 nm approximately. The higher the TOC content, the higher the proportion of the free-gas storage space.

The characteristics and influencing factors of pore development in organic matters of shale are of great significance for shale gas exploration and production in China. The pore development in organic matters of shale has been found to be heterogeneous with SEM observation. However, due to the lack of effective approach for micro-scale research, the influencing factors of pore development of organic matter are still controversial. Black shale samples of the Longmaxi Formation of Pingqiao area of the Sichuan Basin were selected by this study and the heterogeneity of development and distribution of pores in organic matters were analyzed in detail from two-dimensional and three-dimensional levels by the means of Ar ion polishing SEM and FIB-SEM observation. The organic matters with different pore development degrees were divided into three levels, and the area occupancy and contribution to the pores of these three levels of organic matter were studied by MAPS. In this paper, the Raman spectrum of three levels of organic matter with different pore development were obtained by SEM-Raman. The main factors affecting the heterogeneity of pore development of organic matter were discussed in view of the differences of Raman parameters. The results showed that the intensity ratio of D peak to G peak of organic matter was different, which indicated that the order degree of aromatic structure of different organic matter was significantly different, proving that the main factor affecting the pore development in organic matter could be the composition of original organic matter. This method can be used to observe the pores of organic matter in micro area and analyze the molecular structure characteristics of organic matter macerals in-situ, and further clarifies the main influencing factors of pore development of organic matter.

In view of strong heterogeneity and complex formation and evolution of organic pores, field emission scanning electron microscopy (FESEM), Raman spectrum and fluid injection + CT/SEM imaging technology were used to study the macerals, organic pores and connectivity of organic pores in the lower Paleozoic organic-rich shale samples from Southern China. Combined with the mechanism of hydrocarbon generation and expulsion and pore forming mechanism of organic matter-based activated carbon, the relationships between organic pore development and the organic matter type, hydrocarbon generation process, diagenesis and pore pressure were explored to reveal the controlling factors of the formation, preservation and connectivity of organic pores in shale. (1) The generation of organic pores goes on through the whole hydrocarbon generation process, and is controlled by the type, maturity and decomposition of organic matter; the different hydrocarbon generation components and differential hydrocarbon-generation evolution of kerogen and solid asphalt lead to different pore development characteristics; organic pores mainly develop in solid bitumen and hydrogen-rich kerogen. (2) The preservation of organic pores is controlled by maturity and diagenesis, including the steric hindrance effect of in-situ hydrocarbon retention, rigid mineral framework formed by recrystallization, the coupling mechanism of pore-fluid pressure and shale brittleness- ductility transition. (3) The Ro of 4.0% is the maturity threshold of organic pore extinction, the shale layers with Ro larger than 3.5% have high risk for shale gas exploration, these shale layers have low gas contents, as they were in an open state before uplift, and had high hydrocarbon expulsion efficiency and strong aromatization, thus having the “congenital deficiency” of high maturity and pore densification. (4) The pores in the same organic matter particle have good connectivity; and the effective connectivity between different organic matter pores and inorganic pores and fractures depends on the abundance and distribution of organic matter, and development degree of pores and fractures in the shale; the accumulation, preservation and laminar distribution of different types of organic matter in high abundance is the prerequisite for the development and connection of organic pores, grain margin fractures and bedding fractures in reservoir.

The Upper Triassic Xujiahe Formation in the Sichuan Basin is a tight sandstone reservoir with developed dissolution pores, but its formation mechanism is still unclear. In this paper, three samples, including feldspathic lithic, lithic arkose and feldspathic quartz sandstones of the Xujiahe Formation, were taken as examples. Some reaction fluid similar to the organic acid component of the formation was prepared. Five kinds of temperature and pressure conditions were applied in the corrosion simulation experiments, and four understandings were obtained. Firstly, with the increase of temperature and pressure, the concentrations of K+ and Na+ ions in the reaction solution increased, the concentrations of Ca2+ and Mg2+ ions remained stable, but the concentration of Al3+ ions decreased significantly. Secondly, the reaction produced a small amount of quartz and a large number of kaolinite and other new minerals, and the dissolution of feldspar particles and carbonate cement produced a large number of dissolution pores, the porosity was increased and the pore structure was then improved. Thirdly, with the same temperature and pressure, the dissolution rate of feldspathic lithic sandstone was relatively higher than that of feldspathic quartz sandstone. With higher temperature and pressure (e.g. 180℃, 53 MPa), the dissolution rate of sandstone samples were significantly increased. Lastly, the results of dissolution experiments provided a reference for the reconstructing of burial sequence, diagenesis as well as pore evolution of the Xujiahe Formation and the distribution of favorable reservoirs can be predicted. The rapid dissolution of feldspar under higher temperature pressure is one of the genetic mechanisms of effective reservoir of deep clastic rock.

Opaline siliceous shale from the Nenjiang Formation in the Songliao Basin and siliceous shale from the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation in the eastern Sichuan Basin were selected to study the diagenetic evolution of biogenic siliceous shale and the characteristics of shale physical properties and pore structure changes during this process. X-ray diffraction, helium porosity, nitrogen adsorption, and high-pressure mercury intrusion were used to analyze mineral composition, total porosity, and pore structure characteristics. The dehydration and recrystallization of the biogenic opal occurred early, and the transition to quasi-crystalline opal CT and crystalline quartz was completed at the early diagenetic stage. During the conversion of opal-A to opal-CT, the total shale porosity decreased rapidly from more than 75% to around 30%. During the conversion to quartz, the rate of pore loss decreased rapidly, and the decrease was only about 5%, showing two stages. At the same time, the pore volume distribution of different types of pores also changed significantly. The loss of macropores was larger than the loss of micropores. The composition of pores gradually changed from macropores and mesopores to mesopores and micropores. In the early diagenetic stage of siliceous shale, the mechanical compaction and pressure solution occurred synchronously and had a strong effect on shale transformation, which reduced shale porosity, increased hardness, and enhanced the support and resistance to compaction, reducing the transformation and destruction of the early to middle and subsequent diagenesis. The characteristics of rapid diagenesis of siliceous shale in the early stage of biogenesis are the important controls for maintaining high porosity in the middle and late stages of diagenesis.

A method for analyzing the pore connectivity of shale based on a suction experiment of tracer fluid is presented. Sodium chloraurate solution is absorbed into shale pores which have been previously evacuated, and then the solute in the pores is converted to gold by heating. After the suction experiment, the sample surface is polished and analyzed with scanning electron microscopy, in order to get the characteristics of connected pores at the nano-scale. The results of two core samples from the Wufeng-Longmaxi formations in the Sichuan Basin show the connected network in shale could be divided into three parts. The interior connectivity of pores in organic matter is related to the density of pores, and organic matter normally has low flow efficiency because of narrow throat radius. Fractures distributed at grain boundaries such as minerals, organic matter and clay sheets are advantageous pathways, and organic pores are connected by grain boundaries. The development of micro-cracks/fractures, which have high permeability, could significantly improve shale connectivity. Shale pore connectivity has great anisotropy, which means connectivity parallel to bedding is much better than that vertical to bedding.

Thin section analysis, X-ray diffraction, conventional scanning electron microscopy (SEM), high-resolution Ar+ ion polishing SEM, mercury intrusion, nitrogen adsorption, total organic carbon (TOC) content and porosity analyses were used to determine the mineral composition, microstructure and micro-pore volume of shale reservoirs from different depths in the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation in southeastern Sichuan Basin. There are slight differences in the content of siliceous, clay, carbonate and other minerals in shale reservoirs of well D1 in the deep layer and well J1 in the shallow layer, and the longitudinal changes are similar. Only high-quality shale layers with a silica content greater than 40% have different thicknesses. The shale reservoirs of the Wufeng-Longmaxi formations in the deep and shallow layers are dominated by micro-pores in organic matter disseminated in the shale matrix, and the microfractures around the boundaries of silt particles or organic grains and micro-foliation seams parallel to bedding plane are also common, while and intergranular pores are not developed. The high quality shale reservoir at the bottom is structurally isotropic, and the vertical and horizontal structural anisotropy becomes stronger upwards, with thinner micro-lamina and more foliation seams. The TOC content is high at the bottom, and diminishes upwards. The porosity at the bottom shows the same changing trend, indicating a large contribution of organic pores; however, the decrease in porosity is significantly smaller than that of TOC, which is inferred to be related to the existence of more inorganic pores in the shale. The mineral composition, microstructure, TOC and porosity of the Wufeng-Longmaxi shales in the deep and shallow layers have similar changes with depth. Compared with well J1 in the shallow layer, the high-quality reservoir in well D1 in the deep layer has a larger number of micro-pores, meso-pores, macro-pores and total pore volume, which might be explained by more inorganic pores such as grain boundary pores.The shale reservoirs of the Wufeng-Longmaxi formations in the southeastern Sichuan Basin maintain a good porosity under deep burial conditions and have good storage space.

Many pressure wound protection products, such as pressure redistribution supports and exuding wound dressings, are made of polyurethane sponge. However, polyurethane sponge does not possess a desirable combination of air permeability, moisture management and mechanical properties required by pressure redistribution supports and exuding wound dressings. This study explores the optimization of a 3D warp-knitted spacer fabric (WKSF) structure for pressure ulcer protection. The influence of construction and material parameters on the compression performance and air permeability of WKSFs was investigated by numerical simulation and then validated with experiments. The moisture transport and wetting properties of WKSFs were characterized by a moisture management tester. The numerical simulation and experimental results indicate that the WKSF structure can be tuned to achieve compressional properties, air permeability, and moisture management performance that are more suitable for pressure ulcer protection than polyurethane sponge. WKSFs constructed with a low-density surface layer, coarser spacer yarns, and larger spacer yarn inclination-angle are more suitable for pressure redistribution support surfaces, while WKSFs constructed with dense surface layers and coarse spacer yarn can better meet the performance requirements of exuding wound dressings.

Establishing an accurate objective evaluation metric of image sharpness is crucial for image analysis, recognition and quality measurement. In this review, we highlight recent advances in no-reference image quality assessment research, divide the reported algorithms into four groups (spatial domain-based methods, spectral domain-based methods, learning-based methods and combination methods) and outline the advantages and disadvantages of each method group. Furthermore, we conduct a brief bibliometric study with which to provide an overview of the current trends from 2013 to 2021 and compare the performance of representative algorithms on public datasets. Finally, we describe the shortcomings and future challenges in the current studies.

As a type of fiber system, nonwoven fabric is ideal for solid–liquid separation and air filtration. With the wide application of nonwoven filter materials, it is crucial to explore the complex relationship between its meso structure and filtration performance. In this paper, we proposed a novel method for constructing the real meso-structure of spun-bonded nonwoven fabric using computer image processing technology based on the idea of a “point-line-body”. Furthermore, the finite element method was adopted to predict filtration efficiencies based on the built 3D model. To verify the effectiveness of the constructed meso-structure and simulation model, filtration experiments were carried out on the fabric samples under different pollution particle sizes and inlet velocities. The experimental results show that the trends observed in the simulation results are consistent with those of the experimental results, with a relative error smaller than 10% for any individual datum.

Pore connectivity is crucial for shale gas production. However, the three-dimensional (3D) characteristics and distribution of pore networks and, more fundamentally, the underlying role of different pore types on pore connectivity in shales are inadequately understood. By comparing the 3D pore connectivity derived from direct microstructural imaging of pores filled with Wood’s metal at a pressure corresponding to the finest accessible pore throat in the resolution ranges that may be achieved by X-ray micro-CT and SEM, it is possible to evaluate pore connectivity of different types of shales. The pore connectivity of three shales including a mixed mudstone, siliceous shale, and argillaceous shale from the Silurian Longmaxi Formations is investigated via combined broad ion beam (BIB) polishing, and SEM and X-ray micro-CT imaging after Wood’s metal injection at a pressure up to 380 MPa. The three shales show significant differences in pore connectivity. The mixed mudstone shows excellent pore connectivity in the matrix; the siliceous shale shows an overall poor connectivity with only a small amount of OM (organic matter) pores immediately adjacent to microfractures displaying interconnectivity, while the pores in the argillaceous shale, dominated by plate-like clay pores, are largely not interconnected.

As an important branch in the field of image fusion, the multi-focus image fusion technique can effectively solve the problem of optical lens depth of field, making two or more partially focused images fuse into a fully focused image. In this paper, the methods based on boundary segmentation was put forward as a group of image fusion method. Thus, a novel classification method of image fusion algorithms is proposed: transform domain methods, boundary segmentation methods, deep learning methods, and combination fusion methods. In addition, the subjective and objective evaluation standards are listed, and eight common objective evaluation indicators are described in detail. On the basis of lots of literature, this paper compares and summarizes various representative methods. At the end of this paper, some main limitations in current research are discussed, and the future development of multi-focus image fusion is prospected.

In this work, a triple-porosity, two-phase flow model was established to fill the knowledge gap of previous models focusing on gas production characteristics while ignoring the impacts of water injection. The proposed model considers the water flow in the fracture systems and clay minerals and the gas flow in the organic matter, inorganic pore, and fracture systems. The proposed model is solved using a finite element approach with COMSOL Multiphysics (Version 5.6) and verified with field data. Then, the evolutions of the intrinsic and relative permeabilities during water injection and gas production are examined. Furthermore, the impacts of water injection time and pressure are investigated. Good verification results are obtained; the goodness-of-fit value is 0.92, indicating that the proposed model can replicate both the water stimulation and the gas production stages. The relative gas permeability declines during water injection but recovers in the gas depletion stage. Furthermore, the intrinsic permeability increases during the water injection stage but decreases during the gas production stage. A higher water injection pressure and longer injection time would enlarge the intrinsic permeability, thus improving flow capacity. However, it would reduce gas relative permeability, thereby hindering gas flow. The shale gas production characteristic is controlled by the two abovementioned competing mechanisms. There exists a perfect combination of water injection pressure and injection time for achieving the maximum profitability of a shale gas well. This work can give a better understanding of the two-phase flow process in shale reservoirs and shed light on the field application of hydraulic fracturing.

The source rock quality, organic pore structure, occurrence state and sealing mechanisms of shale gas in the Ordovician Wufeng – SilurianLongmaxi Formation (O3w-S1l), Fuling region, Sichuan Basin were studied using a series of techniques including ultra-microscopic organic maceral identification, FIB-SEM, high temperature/pressure isothermal adsorption and isotopic age dating of noble gas. The results show that: (1) O3w-S1l organic-rich shale was mainly formed in a sedimentary environment with high productivity in surface water and hypoxia in bottom water, which can be divided into two sections according to TOC. The lower section (TOC≥3%) is mainly composed of graptolite, phytoplankton, acritarch, bacteria and solid bitumen. Graptolite is the main contributor to TOC, but the shale gas is mainly derived from hydrogen-rich organic matter such as phytoplankton, acritarch and pyrolysis of liquid hydrocarbons produced by hydrogen-rich organic matter. (2) Organic pores, as principal reservoir space for shale gas, exist in hydrogen-rich organic matter and solid bitumen. The graptolites and plenty of other organic matter stacking distribution in lamina provide both reservoir space for supplement and effective pathways of connected pores for shale gas. (3) Shale gas in Fuling region is in supercritical state and dominated by free gas. The match of formation time of closed shale gas system and gas-generation peak, as well as slight alteration degree of sealing conditions in the later stage, are key factors controlling the retention and accumulation of shale gas in the regions with high thermal maturity and complex tectonic background. Adsorption, capillary sealing and slow diffusion of shale are the main microscopic mechanisms for the retention and accumulation of shale gas. It thus can be seen that the generation and accumulation of marine shale gas with high thermal maturity in complex structure areas is controlled jointly by anoxic depositional environment, excellent hydrocarbon rock quality, superior reservoir space and favorable sealing conditions. Key words: Sichuan Basin, Fuling gas field, shale gas, hydrocarbon-forming organisms, reservoir space, occurrence state, sealing mechanism

To enhance the compressive properties of syntactic foams, a new type of ternary composite named 3D spacer fabric/hollow microspheres reinforced composite (3DSMRC) was designed by adding warp-knitted space fabric (WKSF) into traditional syntactic foam. In order deeply understand the meso-mechanical properties of 3DSMRC composites, the compression tests of 3DSMRC were carried out and the quasi-static compression finite element models were established based on COMSOL Multiphysics. The results show that the compression properties of 3DSMRC were obviously controlled by structures of WKSF. To be specific, the 3DSMRC composites with more spacer yarns per unit area could withstand higher critical load, and with denser surface layers and larger spacer yarns inclination-angle could gain better compression capacities. Meanwhile, different types of microspheres also had important impact on the compression capacities of specimens, which could be improved by using smaller radius ratio (higher strength) microspheres. In addition, the finite element model can accurately reproduce the compression process and stress-strain curves of representative 3DSMRC samples, and then accurately simulate the values of compressive modulus and yield strength. The simulation and experimental studies of 3DSMRC can help to obtain a better and deeper understanding of the compression properties of this new type of composite, and finally provide a useful theoretical reference for the optimization design of 3DSMRC.

In this study, a new type ternary composite, called warp-knitted spacer fabric reinforced syntactic foam (WKSF-SF), with the advantages of high mechanical properties and a lower density, was proposed. Then, a meso-mechanics theoretical model based on the Eshelby−Mori−Tanaka equivalent inclusion method, average stress method and composite hybrid theory was established to predict the compression modulus of WKSF-SF. In order to verify the validity of this model, compression modulus values of theoretical simulations were compared with the quasi-static compression experiment results. The results showed that the addition of suitable WKSF produces at least 15% improvement in the compressive modulus of WKSF-SF compared with neat syntactic foam (NSF). Meanwhile, the theoretical model can effectively simulate the values and variation tendency of the compression modulus for different WKSF-SF samples, and is especially suitable for the samples with smaller wall thickness or a moderate volume fraction of microballoons (the deviations is less than 5%). The study of the meso-mechanical properties of WKSF-SF will help to increase understanding of the compression properties of this new type composite deeply. It is expected that WKSF-SF can be used in aerospace, marine, transportation, construction, and other fields.

The dissolution of gypsum rock is of significance to study because it affects the formation of hydrocarbon reservoirs, cap rocks and evaporite deposits. However, the characteristics and mechanism of the dissolution process remain unclear. Here, we present data from experiments performed to address this issue. The experiments simulate various geological conditions, including different diagenetic stages of burial under different fluid types. The diagenetic stages include: 30°C and 0.3 MPa for the epidiagenetic stage; 60°C and 13 MPa for the early diagenetic stage; 100°C and 27 MPa for the middle diagenetic stage; and 150°C and 43 MPa for the late diagenetic stage. The different fluid types include pure water representing continental water, seawater, 0.3 wt.% CO 2 solution representing meteoric water, and a 0.2 wt.% acetic acid solution representing organic fluid. We also carried out the experiments on limestones and dolomites, because these rocks also occur in saline water sedimentary systems with gypsum rocks. Experimental results show that lithology, fluid type and temperature–pressure conditions can all affect dissolution. In terms of lithology, gypsum rocks dissolve more easily than limestones and dolomites. Fluid type has little effect on the dissolution of gypsum rock, and gypsum is soluble in all four types of fluids. In contrast, limestones and dolomites are almost insoluble in pure water and seawater, but show clear dissolution in CO 2 and acetic acid solutions. The data indicate that gypsum rock has a dissolution peak close to the early diagenetic stage. In contrast, limestones and dolomites have dissolution peaks in the CO 2 solution at the early–middle diagenetic stage, and do not show a peak in the acetic acid solution under surficial temperature–pressure conditions. The dissolution rates of limestone and dolomite show different trends with increasing temperature and pressure: limestone dissolution rates decline whereas dolomite dissolution rates increase. Therefore, we infer that the physicochemical properties of a rock are important drivers of dissolution.

Abstract In this paper, ZnS one-dimensional (1D) nanostructures including tetrapods, nanorods, nanobelts, and nanoslices were selectively synthesized by using RF thermal plasma in a wall-free way. The feeding rate and the cooling flow rate were the critical experimental parameters for defining the morphology of the final products. The detailed structures of synthesized ZnS nanostructures were studied through transmission electron microscope, X-ray diffraction, and high-resolution transmission electron microscope. A collision-controlled growth mechanism was proposed to explain the growth process that occurred exclusively in the gas current by a flowing way, and the whole process was completed in several seconds. In conclusion, the present synthetic route provides a facile way to synthesize ZnS and other hexagonal-structured 1D nanostructures in a rapid and scalable way.

Many conductive fabrics have been widely used as fabric strain sensors in recent years due to their excellent flexibility. In this study, high-tenacity polyester warp yarn and silvercoated nylon weft yarn were used to produce six types of conductive fabrics with different structures. The surface morphology of silver-coated nylon yarn was observed under a microscope, and the yarn was placed in an airtight container to test the effect of different humidity on the resistance of the yarn. DM6500 digital multimeter was used to test the resistance sensitivity, fatigue resistance, repeatability, and antistatic properties of conductive fabric samples. The results showed that the change in yarn surface material, external humidity, and strain affected the change in yarn resistance. Different weave structures affected the sensing performance of the fabric. The tighter the structure, the better the sensitivity and antistatic properties, the looser the structure, the better the fatigue resistance and repeatability. Two types of fabric and nylon gloves with different structural tightness are used to make intelligent data gloves. The results showed that both fabrics had good application prospects in limb movement detection. [ABSTRACT FROM AUTHOR]

The present study was conducted with the aim of determining the role of mediators of teacher-student rapport in the relationship between the teachers' immediacy and academic engagement in EFL contexts. The participants of this correlational study were 285 students of Xinxiang which is an important central city in northern Henan province, China. They (195 females and 90 males) were selected as a convenient sampling. To collect the data, Teacher-Student Rapport Questionnaire (Wilson et al., 2010), Teachers' Immediacy Questionnaire (Gorham, 1988), and Learners' Academic Engagement (Kember & Leung, 2009) were employed. The collected data were analyzed using the Structural Equation Modeling (SEM) method. The results showed that the research model is confirmed in terms of significance and fit indicators, and the variable of teachers' immediacy indirectly affects academic engagement through teacher-student rapport (p