Wettability is a crucial factor controlling shale oil recovery, yet it is extremely difficult to measure in the lab under in-situ reservoir pressure and temperature conditions. Existing molecular simulations on shale wettability relying largely on idealized hydrocarbon models fail to capture its complexity. Here we present a more realistic molecular simulation study on shale wettability by creating a sophisticated 13-component molecular model based on the Gulong shale oil from the Songliao Basin, NE China. We simulate the interaction of oil and kerogen, a key component affecting shale oil mobility, at a range of reservoir pressures, temperatures and formation water salinities to understand wettability changes in subsurface. The results show that kerogen turns to be oil wet at 28.5 MPa and 388 K, with a water-kerogen contact angle of approximately 120 degrees. The kerogen wettability is dually controlled by the density difference between oil and formation water, and by the oil-water interfacial tension. Within the pressure range of 23.5-43.5 MPa (within shale development depth range), increasing pressure enhances lipophilicity and strengthens kerogen's affinity for oil. Over the temperature range of 370-433 K (corresponding to depths of 1900-3300 m), a critical temperature threshold for wettability switching occurs at 388 K (similar to 2300 m), below which lipophilicityreases as temperature risesabove which, lipophilicity increases with elevating temperature. Salinity also pushes the kerogen toward more lipophilic, even forcing water into the oil at high salinity concentrations. This work addresses the scarcity of high-pressure, high-temperature wettability studies on shale kerogen, elucidating the microscopic mechanisms governing wettability of kerogen, and provides new insight on how wettability influences the occurrence, migration, enrichment, and preservation of shale oil.
The dynamic imbibition process in shale oil reservoirs plays a crucial role in enhancing oil recovery (EOR). In this study, an innovative online nuclear magnetic resonance (NMR) dynamic imbibition physical simulation method was developed for shale oil. By combining two-dimensions (2D) NMR T1-T2 spectra, a quantitative identification model was established to characterize the distribution of various crude oil components. Real-time dynamic monitoring of multiphase flow and crude oil migration behaviors during the imbibition process was conducted, and high-pressure dynamic imbibition experiments were systematically performed on different rock facies of shale under various imbibition systems. The microscopic production characteristics and the contribution of oil in different occurrence states to recovery were visualized and quantitatively analyzed. The results reveal significant differences in the imbibition development characteristics across shale reservoirs with different rock facies. In felsic shale, the yield of free oil in large pores showed a positive correlation with imbibition volume. The total recovery for low-viscosity slickwater, high-viscosity slickwater, and CO2 systems was 12.60%, 12.67%, and 15.12%, respectively. The main contribution to recovery came from the mesopores and macropores, and increasing the imbibition pressure is beneficial for enhancing capillary imbibition and achieving greater EOR. In mixed shale, the total recovery for low-viscosity and high-viscosity slickwater was 8.21% and 8.73%, respectively. Besides significant contributions from mesopores and macropores, clay interlayer pores and micropores demonstrated considerable recovery potential. High-viscosity slickwater enhanced oil recovery by modulating oil-water interface properties and altering rock wettability, which promoted fluid exchange between the matrix and fractures, thereby improving oil recovery across various pore types. For gray dolomitic shale, the total recovery under low-viscosity and high-viscosity slickwater was 7.84% and 8.06%, respectively. Recovery in this case was primarily driven by clay interlayer pores and micropores, while mesopores and macropores showed limited contributions. Notably, the "imbibition-stripping-displacement" behavior activated the capillary imbibition force, leading to the aggregation and release of trapped dispersed crude oil from the matrix. The dynamic imbibition system should be considered as an organism, which means that maximizing oil recovery from small pores while enhancing recovery from larger pores is essential for achieving optimal overall recovery. These findings provide theoretical insights into the interaction between matrix-fracture imbibition and displacement and offer guidance for the efficient development of shale oil reservoirs.
Transparent ceramics have optical, mechanical, and thermal properties comparable to those of single-crystal materials, and are widely used in a variety of applications such as transparent armor, infrared windows, high-power lasers, white-light illumination, and medical diagnostics. Optical transparency is one of the most important properties of transparent ceramics, yet preparing high-quality transparent ceramic materials with excellent mechanical properties remains challenging. Hot isostatic pressing technology, widely applied in many fields such as powder metallurgy near-net molding and alloy diffusion joining, is considered to be an effective method to develop and produce transparent ceramics with high optical quality. This paper reviews the materials commonly used in the preparation of transparent ceramics and the recent achievements in HIP-based transparent ceramic research, analyzes the mechanism by which HIP enhances transparent ceramic performance, and discusses and prospects the development of HIP-applied transparent ceramics. It is summarized that common ceramic sintering techniques often result in internal pores (which act as optical scattering sources and reduce transmittance), while HIP is an effective method to obtain high-quality transparent ceramics by improving densification and optimizing microstructures.
Catalytic transfer hydrogenation (CTH) of furfural to furfuryl alcohol is a pivotal strategy for valorizing biomass-derived platform molecules. Herein, we report the design of a yolk-shell MOF-808@hollow mesoporous silica spheres (MOF-808@HMSS) catalyst, where MOF-808 nanocrystals are uniformly confined within the internal cavities of HMSS. Compared to pure MOF-808, the spatial confinement effect imposed by HMSS induces the formation of smaller MOF-808 nanocrystals, increasing the density of accessible active sites. The mechanically robust HMSS shell significantly enhances the structural integrity of the catalyst by mitigating mechanical attrition and suppressing leaching of active components during reaction. Notably, the unique yolk-shell architecture creates a confined nanoscale microenvironment that promotes efficient adsorption and activation of reactants at catalytic centers. Consequently, MOF-808@HMSS exhibits markedly superior performance in CTH of furfural as well as higher reusability and cycling stability compared to pure MOF-808. Detailed characterization reveals abundant Lewis acid sites with a minor proportion of basic sites in MOF-808@HMSS. Selective poisoning experiments confirm that Lewis acid sites play a predominant role in the Meerwein-Ponndorf-Verley reaction, while synergistic interplay between acidic and basic sites enhances reactant adsorption and facilitates i-propanol deprotonation, collectively accelerating the overall CTH process.
With growing environmental and economic concerns over fossil fuels, solar power has become an increasingly important renewable option. This study evaluates lead-free MASnIBr2 perovskite solar cells using COMSOL Multiphysics simulations, focusing on absorber thickness, bulk defect concentration, and interfacial passivation effects. Incorporation of a porous insulating contact (PIC) structure suppresses non-radiative recombination, increasing the power conversion efficiency (PCE) to 22.65
