Asphaltenes precipitation and deposition is one of the main problems in the petroleum industries which has attracted the attention of many scholars. Precipitation and deposition of asphaltenes can lead to many problems in oil reservoirs such as plugging the pores of the reservoir rocks and changing the wettability of the rocks from water-wet to oil-wet. This ultimately causes a reduction or puts an end to production from reservoirs. Therefore, understanding the factors affecting the formation of asphaltenes precipitation can help us to avoid these drawbacks. Several factors including pressure, temperature, and composition changes have been studied in the literature. The effects of these parameters on the stability of asphaltenes are almost clear. However, the effects of water emulsions, which are formed during the water-based enhanced oil recovery (EOR) methods such as smart water and low salinity water flooding, on the instability of asphaltenes are still unknown and blurred. In this study, the effects of several synthetic brines which were prepared by different salts in a wide range of concentrations were investigated to understand the mechanism of ions on the instability of asphaltenes. It was found that the divalent cations have more effects on the instability of asphaltenes compared to monovalent cations due to the chelate formation. Furthermore, the presence of divalent anions in the system can hinder the effect of cations on the instability of asphaltenes.

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Three models were developed for a conventional fluidized‐bed reactor and a cocurrent and a countercurrent membrane fluidized‐bed reactor for methane trireforming. Firstly, the effects of the operating parameters on the reactor performance were assessed. Then, a single‐objective optimization was established. Finally, a membrane was added to the reactor to improve the reactor performance. The simulated results illustrate that the reaction rates are highest near the reactor entrance due to the high volume fraction of the dispersed phase and the existence of a hot zone. Moreover, the optimization process indicates that the maximum H2 yield in the conventional fluidized‐bed reactor is obtained when the inlet temperature, inlet flow rate, and H2O/CH4 ratio, are 804 °C, 3.6 × 105 L h−1, and 2.5, respectively.

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