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Alkylphenols are a kind of compounds produced by alkylation of phenolic compounds. Compared with other non-hydrocarbon compounds, alkylphenols are more soluble in water. In this paper, through three groups of oil-water distribution experiments at different temperatures (25 ℃, 45 ℃ and 65 ℃), different brine concentrations (4000 mg/L, 6000 mg/L and 8000 mg/L) and different crude oil types (X37, X45 and X61), the distribution characteristics of alkylphenols between oil and water were studied, and the variation law of alkylphenol distribution coefficient was determined. The results show that the oil-water partition coefficient increases with the increase of alkyl molecular weight of homologues; The oil-water partition coefficient of alkylphenols decreases with the increase of temperature, and alkyl homologues with higher molecular weights are more sensitive to temperature; The partition coefficient of alkylphenol in oil-water system increases with the increase of water salinity. According to the experimental results, temperature and salinity of water phase will cause the difference of oil-water partition coefficient of alkylphenol, and the influence of temperature is greater than that of salinity. The distribution behavior of alkylphenols between oil and water can provide more reference for the secondary migration of crude oil and the direction of water drive front in reservoir development.

Accurately predicting permeability is important to elucidate the fluid mobility and development potential of tight reservoirs. However, for tight sandstones with the same porosity, permeability can change by nearly three orders of magnitude, which greatly increases the difficulty of permeability prediction. In this paper, we performed casting thin section, scanning electron microscopy and high-pressure mercury injection experiments to analyze the influence of pore structure parameters and fractal dimensions on the permeability of Chang 7 tight sandstones. Furthermore, the key parameters affecting the permeability were optimized, and a new permeability prediction model was established. The results show that the pore throat structure of Chang 7 tight sandstone exhibits three-stage fractal characteristics. Thus, the pore throat structure was divided into large pore throat, medium pore throat and small pore throat. The large pore throat reflects the microfracture system, whose fractal dimension was distributed above 2.99, indicating that the heterogeneity of the large pore throat was the strongest. The medium pore throat is dominated by the conventional pore throat system, and its fractal dimension ranged from 2.378 to 2.997. Small pore throats are mainly composed of the tree-shaped pore throat system, and its fractal dimension varied from 2.652 to 2.870. The medium pore throat volume and its fractal dimension were key factors affecting the permeability of Chang 7 tight sandstones. A new permeability prediction model was established based on the medium pore throat volume and its fractal dimension. Compared to other models, the prediction results of the new model are the best according to the analysis of root mean square value, average absolute percentage error and correlation coefficient. These results indicate that the permeability of tight sandstones can be accurately predicted using mesopore throat volume and fractal dimension. [ABSTRACT FROM AUTHOR]

Establishing a suitable classification and evaluation scheme is crucial for sweet spot prediction and efficient development of shale oil in the Chang 71-2 sub-member of the Longdong area. In this paper, a series of experiments, such as casting thin sections (CTS), scanning electron microscopy (SEM), low-temperature nitrogen adsorption (LTNA), high-pressure mercury intrusion porosimetry (HMIP), and nuclear magnetic resonance (NMR), were integrated to classify the pore throats and shale oil reservoirs in the study area. Moreover, the pore structure characteristics of different types of reservoirs and their contributions to productivity were revealed. The results show that the pore-throat system can be divided into four parts: large pore throats (>0.2 μm), medium pore throats (0.08~0.2 μm), small pore throats (0.03~0.08 μm), and micropore throats (<0.03 μm). Based on the development degree of various pore throats, the reservoir is divided into four types: type I (Φ ≥ 10%, K > 0.1 mD), type II (Φ ≥ 8%, 0.05 mD < K < 0.1 mD), type III (Φ ≥ 5%, 0.02 mD < K < 0.05 mD) and type IV (Φ < 5% or K < 0.02 mD). From type I to IV reservoirs, the proportion of dissolved pores and intergranular pores gradually decreases, and the proportion of intercrystalline pores increases. The proportion of large pore throats gradually decreases, and the proportions of medium pore throats and small pore throats increase initially and then decrease, while the proportion of micropore throats increases successively. The NMR pore size distribution changes from the right peak to the left peak. The developed section of the type I reservoir corresponds to the oil layer, and the developed section of the type I and II reservoirs corresponds to the poor oil layer. In contrast, the developed section of the type III and IV reservoirs corresponds to the dry layer. The daily production from single wells is primarily attributable to type I and II reservoirs. [ABSTRACT FROM AUTHOR]

In this paper, the LiMn0.6Fe0.4PO4/C with 3D conductive network was synthesized using β-cyclodextrin (β-CD) and carbon nanotubes (CNTs) as complex carbon source by a simple preparation route which include combination of wet ball milling, spray drying, and carbothermal reduction. The unique conductive network result in the composite has sufficient contact with electrolyte and three-dimensional electron conduction path. SEM and TEM images indicate that the active materials were uniformly coated by amorphous carbon and CNTs. The addition of β-CD and CNTs not only restricted growth of active particle but also reduced electron conduction distance. The composite possesses superior electron conductivity (8.8 × 10−2 S cm−1) and Li+ diffusion efficiency (6.1 × 10−13 cm2 s−1) due to unique 3D conductive network. As a result, the prepared sample exhibits distinguished discharge capacity of 160.2 mAh g−1 at 0.2 C and 131.7 mAh g−1 capacity even in 10 C. [ABSTRACT FROM AUTHOR]

High tap density and superior electronic conductivity of LiFePO4/KB was synthesized by a combination of wet ball‐milling, spray drying, and carbothermal reduction with Ketjen black (KB) as a carbon additive. KB is a conductive carbon black with the special chain‐like structure. When KB is used to coat on the surface of primary particles of LiFePO4, the chain‐like structure can form a developed 3D network structure between the primary particles of LiFePO4. This special structure can not only provide conductive channels for electrons but also cause the primary particles of LiFePO4 to aggregate tightly. Comparing to the conventional carbon coating materials (only glucose as the carbon source) with a low volumetric energy density of 452.5 Wh L−1 at 1 C rate, we simultaneously increased the electrical conductivity (7.8×10−2 S cm−1) and tap density (1.6 g cm−3) by adding KB, resulting in a higher volumetric energy density of 829.9 Wh L−1 at 1 C rate. When KB is added at 5 % of glucose mass, the LiFePO4/KB composite shows an excellent discharge capacity of 161.6 mAh g−1 at 0.2 C and the 97.7 % retention rate after 500 cycles at 5 C. [ABSTRACT FROM AUTHOR]