By combining the micro-CT, SEM, FIB-SEM and FIB-HIM, a multiscale characterization method was explored to study the pores in Wufeng-Longmaxi shale, Sichuan Basin, China. This method extends the ...previous test scale so that the sub-10 nm pores can be visualized in both 2D and 3D. In order to consider the homogeneity or heterogeneity and verify the representativeness of samples, REV and REA (representative elementary volume and area) was determined. Pores in shale were classified as organic pore, inorganic pore and micro-fracture based on SEM, and their surface porosity and pore size distribution were calculated. By 3D reconstruction of FIB-SEM and FIB-HIM, the pore networks were visualized down to sub-10 nm, and the connect patterns of pores through throats were carefully investigated. Results show that, REV and REA are different at different scale. The cube and square growing pattern, grain size, feature distribution and imaging accuracy can affect REV and REA in different degree. SEM quantification results indicate that, the surface porosities of OM particles (ϕS OM) of two 1st member of Longmaxi samples are larger than those of Wufeng samples, indicating the organic pores of 1st member of Longmaxi samples are more developed than Wufeng samples. The size of inorganic pores of Wufeng samples are larger than those of Longmaxi samples. The permeability shows a positive correlation with surface density of micro-fractures. The 3D pore network analysis of FIB-SEM further shows the interconnectivity of 1st member of Longmaxi samples are better than Wufeng samples. The interconnected pores are mainly between 10 and 30 nm, and the throats are concentrated between 0 and 30 nm for both 1st member of Longmaxi samples and Wufeng samples. This is further refined by FIB-HIM, in which, the interconnected pores and throats are concentrated below 10 nm. FIB-HIM also provides clear 3D images of how organic pores can be connected by throats, which is a great progress in shale pore characterization.
•A novel multiscale method was employed to extend the pore imaging scale down to sub-10 nm both in 2D and 3D.•REV/REA was carefully determined under the imaging scale of micro-CT and SEM.•Pores and micro-fractures were quantitatively identified.•The network and connectivity of pores were visualized and quantified by the correlative FIB-SEM and FIB-HIM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Based on the understandings on enrichment rules of marine shale gas in southern China and data obtained from exploration and development in Fuling shale gas field, this article discusses the key ...controlling factors on shale gas enrichment and their relationships, it also discusses further the theory of Two-Factor Enrichment of marine shale gas in southern China. The bases for shale gas enrichment are shale gas generation and accumulation, the shale gas reservoirs of deep-water shelf are characterized by high TOC, high porosity, high gas contents and high siliceous contents, with high hydrocarbon-generation intensity. The organic pores are rich in shales in favorable for stimulation, so they are the bases for large scale hydrocarbon accumulation. Preservation conditions are vital to the formation and enrichment of shale gas reservoirs, good top and base layers can effectively prevent hydrocarbon from escaping vertically at the beginning of hydrocarbon generation. Shale gas preservation conditions depend on the intensity and duration of tectonic movements, good preservation conditions are key geological factors for shale gas accumulation, shale reservoirs have high gas contents, high porosity and high pressure and are likely to form high yield area of shale gas.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sandwich‐like stacked titanate nanosheets with the thickness of ≈0.4 nm are successfully synthesized on a large scale using a clean and facile method. The unique material exhibits superior capacity ...and excellent high rate performance for ultrafast lithium storage.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In recent years, major breakthroughs have been made in natural gas exploration in deep and ultra-deep strata in the Sichuan Basin, but the overall successful rate is low. To further clarify the ...prospects there, it is necessary to make an in-depth analysis of the previously discovered large-scale reef-shoal gas fields such as Puguang, Yuanba, Anyue and Longgang and deep shale gas discovery in Dingshan and Dongxi, southern Sichuan Basin. On one hand, large high-energy facies are the basis for controlling the development of large-scale reef-shoal reservoirs in conventional reef-shoal areas. The reservoir original porosity is high. The atmospheric freshwater dissolution in the early diagenetic stage, dolomitization, unconformity karst, and “pore–fracture coupling” mainly control the development of secondary pores. The contribution of hydrothermal fluids to reservoir is double-sided, and such early pores can be preserved till present due to those retention processes such as early hydrocarbon charging. Apart from continuous preservation as the key factor, most gas reservoirs are featured by “near-source enrichment, phase transformation, and dynamic adjustment”. On the other hand, deep shale gas generally has the characteristics of “high pressure, high porosity, and high gas content”, that is, “overpressure and rich gas”. The key to the development of high-quality deep shales with high pores are “quartz compression retaining pore" and “reservoir fluid overpressure”. The weak tectonic effect in the late stage is the main reason for deep shale gas to maintain the “high pressure and high gas content”. In conclusion, technological advances like geological target identification and “sweet spot” prediction, as well as deep, high-temperature and high-pressure engineering processes, are the guarantee for efficient exploration of conventional and unconventional deep and ultra-deep natural gas, which has great potential in the Sichuan Basin.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Due to their many varieties of excellent optoelectric properties, perovskites have attracted large numbers of researchers in the past few years. For the hybrid perovskites, a long diffusion length, ...long carrier lifetime, and high μτ product are particularly noticeable. However, some disadvantages, including high toxicity and instability, restrict their further large-scale application. By contrast, all-inorganic perovskites not only have remarkable optoelectric properties but also feature high structure stability due to the lack of organic compositions. Benefiting from these, all-inorganic perovskites have been extensively explored and studied. Compared with the thin film type, all-inorganic perovskite single crystals (PSCs) with fewer grain boundaries and crystalline defects have better optoelectric properties. Nevertheless, it is important to note that only a few reports to date have presented a summary of all-inorganic PSCs. In this review, we firstly make a summary and propose a classification method according to the crystal structure. Then, based on the structure classification, we introduce several representative materials and focus on their corresponding growth methods. Finally, applications for detectors of all-inorganic PSCs are listed and summarized. At the end of the review, based on the current research situation and trends, some perspectives and advice are proposed.
Early Carboniferous Luzhai Formation developed continuous and thick shales, which is a critical succession for hydrocarbon exploration and production in southern China. However, no high-resolution ...stratigraphic sequence framework or cyclostratigraphic studies on early Carboniferous (Tournaisian Stage) are available for this organic-rich shale formation. In this research, Milankovitch cycle evidence has been reported in two boreholes of Luzhai Formation in Guizhong Depression. Natural gamma-ray logging data allowed the establishment of a ∼5.9-Myr floating astronomical timescale (FATS) based on stable long eccentricity (405-kyr) cycles in Luzhai Formation. We anchored FATS to Devonian and Carboniferous boundary age (359.3 ± 0.4 Ma), and an absolute timescale for intervals of 359.3 to 353.4 Ma was developed. Correlation coefficient (COCO), evolutionary COCO, and evolutionary TimeOpt method (eTimeOpt) were employed for quantitatively fit observed stratigraphic cycles to astronomical cycles for providing possible range of sedimentation rates. Sedimentary noise model was adopted for detecting orbital forcing-controlled high-resolution sea-level changes which were correlated to ∼1.2-Myr obliquity amplitude modulation (AM) cycles. Sedimentary noise models (autocorrelation coefficient analysis, ρ1, and dynamic noise after orbital tuning analysis, DYNOT) revealed a correlation between obliquity AM cycle (∼1.2-Myr) and sea level changes in early Carboniferous Luzhai Formation. The ∼1.2-Myr obliquity AM was the main driver of third-order sequence development, the 3rd-order sequence boundaries were related to maximum values of DYNOT median curve and minima values of ∼1.2-Myr amplitude modulation (AM) curve.
•A new Floating ATS for the first time to calibrate the Tournaisian depositional sequences.•The deposition of Luzhai Formation shale in Early Carboniferous lasted ∼5.9-Myr.•Third-order sequences and sea-level change can be generated by cyclostratigraphic research.•∼1.2-Myr obliquity amplitude modulation dominated sea-level changes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Ultrafine E-g-C3N4 is synthesized by H2SO4 intercalation and NH3 stripping.•E-g-C3N4 could self-recognize CH3NH3PbI3 grain boundaries and locate on them.•The power conversion ...efficiency of 15.8% is achieved for E-g-C3N4 modified PSCs.
In CH3NH3PbI3 based perovskite solar cells (PSCs), the subtle pinholes and grain boundaries are hardly avoided in the formation of perovskite film. The defected film often leads to a reduced efficiency due to a larger amount of electron trap sites which induce carrier recombination leading to electron loss. In this work, ultrafine exfoliated graphitic carbon nitride (E-g-C3N4) nanoparticles are successfully synthesized by H2SO4 intercalation and NH3 stripping. The E-g-C3N4 has a lot of NH or OH groups, which could coil into nanoparticles spontaneous from nanosheets by hydrogen bonds. As an application in PSCs, the E-g-C3N4, as doping materials between MAPbI3 and the hole transport materials (HTMs), could magically self-recognize CH3NH3PbI3 grain boundaries and locate on them. Electron-hole recombination is greatly reduced even after incorporating trace of E-g-C3N4 by decreasing the deep electron trap centers at grain boundaries. As a result, the power conversion efficiency (PCE) of 15.8% is achieved for the MAPbI3 based PSCs, which is 35% higher than the reference cell. Thus, it is a universal and efficient method to weaken the influence of unavoidable defects existing in pinholes and grain boundaries, and develop the low-cost preparation for large-area PSCs in general conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In addition to marine and marine-continental transitional strata, the continental ones are also widely distributed in various oil and gas-bearing basins in China. The continental shale generally ...provides favorable material bases for hydrocarbon generation, such as wide distribution, large thickness, multiple series of strata, high TOC content, nice organic matter type, and moderate thermal evolution. Part of such shale contains shale oil, but the pore space characteristics for the occurrence of this oil are not thoroughly studied. In order to accurately and quantitatively characterize the pore space where the continental shale oil in different types of lithofacies occurs, we sampled the rock cores from the Middle Jurassic Lianggaoshan Formation in the southeastern Sichuan Basin of the Upper Yangtze Area. The TOC content and mineral composition were analyzed, and we also carried out experiments on CO2 and N2 adsorptions, high-pressure mercury injection, and wash oil. Results show significant differences in pore space characteristics for the occurrence of shale oil in different types of lithofacies. In organic-rich mixed and clayey mudstones with the highest TOC content, the free shale oil, occupying the largest reservoir space, mainly occurs in macropores and mesopores, and the adsorbed shale oil, occupying the largest reservoir space, mainly occurs in mesopores. In the organic-bearing clayey mudstone, which has a higher TOC content, the free shale oil takes a larger reservoir space and mainly occurs in macropores, followed by mesopores, and the absorbed one, occupying a larger reservoir space, mostly occurs in micropores and then the mesopores. The organic-bearing mixed mudstone has a moderate TOC content, in which the free shale oil occupies a smaller reservoir space and primarily occurs in mesopores, followed by macropores, and the absorbed one, which takes a larger reservoir space, all occurs in mesopores. In the fine sandstone, the free shale oil occupies a smaller reservoir space and primarily occurs in mesopores, while the absorbed one occupies a smaller reservoir space and all occurs in mesopores.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Lithium-sulfur batteries have been widely nominated as one of the most promising next-generation electrochemical storage systems due to its low cost, high capacity and energy density. However, its ...practical application is still hindered by poor cycling lifetime, low Coulombic efficiency, instability and small scales. In the last decade, the electrochemical performances of the lithium-sulfur batteries have been improved by developing various novel nanoarchitectures as qualified hosts, and enhancing the sulfur loading with effective encapsulating strategies. The review summarizes the major sulfur cooperating strategies of cathodes based on background and latest progress of the lithium-sulfur batteries. The novel cooperating strategies of physical techniques and chemical synthesis techniques are discussed in detail. Based on the rich chemistry of sulfur, we paid more attention to the highlights of sulfur encapsulating strategies. Furthermore, the critical research directions in the coming future are proposed in the conclusion and outlook section.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow (7.5 × 104 m3/d gas and 9.8 m3/d oil) from the Middle Jurassic Lianggaoshan Formation, ...presenting a good test production effects, which means the realization of a major breakthrough in the exploration of Jurassic lacustrine shale oil and gas in the Sichuan Basin. In order to further determine the exploration potential of lacustrine shale oil and gas in this area and realize the large-scale efficient development and utilization of lacustrine shale oil and gas, this paper analyzes the geological conditions for the accumulation of lacustrine shale oil and gas in this area by using the drilling data of 10 key wells, such as wells Taiye 1 and Fuye 10. Then, the main factors controlling the enrichment of lacustrine shale oil and gas are discussed, and the exploration potential and favorable target zones of Jurassic lacustrine shale oil and gas in the Fuling area are defined. And the following research results are obtained. First, the quality Jurassic semi-deep lake shale in the Fuling area is characterized by high organic matter abundance, high porosity and high gas content, and it is the geological base of shale oil and gas enrichment. Second, the developed large wide and gentle syncline, good preservation condition and higher pressure coefficient (generally >1.2) are the key to the enrichment and high yield of shale oil and gas. Third, the developed microfractures in lacustrine shale are conducive to the enrichment and later fracturing of shale oil and gas. In conclusion, the Lianggaoshan Formation lacustrine shale in the Fuling area is widely distributed with moderate burial depth, developed microfractures and moderate thermal evolution, and its shale gas resource extent and shale oil resource extent are 1 922 × 108 m3 and 2800 × 104 t, respectively, indicating greater potential of shale oil and gas exploration, so shale oil and gas is the important field of oil and gas reserves and production increase in this area in the following stage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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