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The influence of P content on Curie temperature, magnetic properties and microstructures of Fe81.5Si3B10+xP3.5−xC0.2Cu0.8Nb1 (x = 0, 1, 2, and 3 at.%) alloys subjected to magnetic field annealing has been studied. Here, the decrease in P content can improve Curie temperature of alloys from about 575 to 584 K, which increases the operating temperature of magnetic device. Via optimal field annealing technique, the amorphous alloy with x = 3 exhibits good soft magnetic properties, including saturation magnetic flux density of 1.53 T, high effective permeability above 12,000, low coercivity below 3 A/m, and low core loss around 0.18 W/kg. The hysteresis loops show that tuning down the content of P relative to B can increase the saturation magnetic flux density of alloy system. Besides, the investigation about the microstructures of alloys annealed at optimal conditions indicates that longitudinal magnetic field annealing can improve the stability of amorphous phase, thereby ensuring the amorphous structure annealed at a higher annealing temperature compared with the general annealing for alloys.

Phosphorus (P) is a cheap and effective element that inhibits grain growth and improves soft magnetic properties in Fe-based nanocrystalline alloys. However, most alloys usually require high P content, leading to problems such as volatilization and oxidation during production process. In this paper, we study and report new findings regarding the effect of P microalloying on the magnetic properties, microstructure and magnetic domain structure of Fe77.8Si10B9−xCu0.6Nb2.6Px (x = 0 and 1) nanocrystalline alloys. The substitution of B by 1 at% P has little influence on the crystallization behavior, saturation magnetic flux density (Bs) and permeability (μ) of the alloy, while effectively reduces the coercivity (Hc) in a wide annealing temperature range. The reduced Hc can be attributed to the low magnetocrystalline anisotropy and wide magnetic domains caused by uniform and fine α-Fe(Si) grains. The mechanism of structural evolution induced by 1 at% P is also been discussed. The P microalloyed nanocrystalline alloy with high Bs of 1.43 T, high μ up to 27,000 at 1 kHz, and low Hc of 1.4 A/m is suitable for magnetic shielding piece of wireless charging.

Steam channeling is one of the main barriers for EOR after steam flooding. In order to enhance the oil recovery in steam flooded reservoirs, steam channel volumes should be precisely known. In this paper, a set of methods has been established in order to study steam channeling quantitatively by using dynamic data. Firstly, steam channeling wells are identified through curves of watercut and temperature. Then, considering the hysteresis phenomenon, channeling relations are identified with the correlation coefficients between injection wells and production wells under different conditions. Lastly, an analytic model, in which steam condensation, pressure and temperature are considered, is established to calculate the steam channel volumes. A production well named L31615 in some block in Henan Oilfield in China is systematically analyzed by using the method established. The whole block is further analyzed, and the distribution map of steam channels and the steam channel volumes are obtained. The results show that steam channeling does not only occur inside a well group, but also sometimes occurs between wells in different well groups. The calculation of the steam channel volumes provides a theoretical basis for bringing a remedial action like plugging into operation.

As a temperature-sensitive non-Newtonian fluid, the seepage of heavy crude oil in porous media shows the non-linear characteristics. The flowing behavior of three heavy oils through porous media is experimentally investigated, and the influence of temperature and pressure-drop on this flowing process is also described. Thereafter, based on the flowing behavior of heavy crude oil, the new models of productivity of the thermal producers (including vertical well and horizontal well) are proposed. In these models, both the threshold pressure gradient (TPG) and thermal effect are taken into account. The flowing experiments of heavy oil in porous media indicate that the pressure gradient and temperature have the significant influence on the flowing process because of the existence of threshold temperature and TPG. Heavy crude oil begins to flow only when the pressure gradient is in excess of TPG, and there dose not actually exist TPG above the threshold temperature. The viscosity-temperature curves demonstrate that the viscosity of heavy crude oil has an obvious feature of two straight-lines on semilog coordinate. On account of the damage of overlapping phenomena of asphaltenes in crude oil, when temperature is higher than the critical temperature, the reducing trend of TPG (with the increase of temperature) will be lessened. Furthermore, on the basis of flowing process of heavy crude oil, the concepts of threshold temperature and certain production temperature of thermal wells are introduced. That heavy oil with a higher viscosity would have a higher threshold temperature, as well as the certain production temperature. The application of horizontal wells tremendously increases the oil recovery rate in comparison with the vertical wells. This investigation could be used as a tool to study the flowing process of heavy oil and productivity calculation of thermal wells in heavy oil reservoirs.