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TC11 alloy is a promising structural material, and has a wide range of applications in many corrosive and high temperature hydrothermal systems. The passive film has an important influence on its electrochemical behavior. In this study, in-situ electrochemical methods (that is, open circuit potential (OCP), linear polarization (LP) and electrochemical impedance spectroscopy (EIS)) were used to monitor the long period electrochemical behavior of TC11 alloy in 0.01 M Na2SO4 solution at 300 &deg, C/10 MPa. The growth kinetics of the passive film was mainly studied. The correlation between the evolution of the electrochemical behavior and the growth of the oxide film was discussed. The results showed that although the OCP gradually stabilized after twenty thousand seconds, henceforth the polarization resistance (Rp) was still increasing due to the thickening of the passive film. An equivalent circuit was proposed to fit the EIS experimental data, leading to determination of film capacitance and film resistance. Besides, the electrochemical data was interpreted in terms of the point defect model (PDM). The EIS results are consistent with the Rp results.

Hydraulic fracturing consumes massive volumes of freshwater that is usually scarce and costly. Such operation is not sustainable, and hence seawater could be used as an alternative. Nevertheless, seawater has high total dissolved solids (TDS), affecting the fracturing fluid rheology and providing a damage potential to the subterranean hydrocarbon reservoirs. Resolving these issues requires fracturing fluid systems with many additives, which results in an expensive and non-eco-friendly system. This study proposes eco-friendly and biodegradable chelating agents that could replace many additives such as scale inhibitors and crosslinkers. The study aims to optimize the rheology of seawater fracturing fluids using a chelating agent and polymer. By optimizing N,N-Dicarboxymethyl glutamic acid (GLDA) conditions, high viscosity was achieved using a standard industry rheometer. The GLDA was mixed with carboxymethyl hydroxypropyl guar (CMHPG) polymer and tested in both deionized water (DW) and seawater (SW). The polymer was examined first, where the rheology did not show a time-dependent behavior. The polymer in SW showed a slightly higher viscosity than in DW. The GLDA and CMHPG were tested at different temperatures, pH, and concentrations. These sets showed a time-dependent viscosity behavior, which can be utilized in various fracturing steps. Results showed that the solution pH and GLDA concentration significantly impacted the fluid viscosity magnitude and behavior. The developed formulation is shear thinning, where the viscosity declines as the shear rate increases. The temperature negatively impacted the viscosity and caused the formulation to break. The study provided an understanding of how to optimize the rheology of SW fracturing fluid based on GLDA chelating and CMHPG polymer.

Using the self-developed viscosity measuring device, the viscosity variations of coal–oil slurries with temperature increasing during coal–oil co-processing were studied. The results show that the viscosity of coal–oil slurries prepared by different kinds of oil varies differently during heating. The viscosity of the coal–oil slurry prepared by the catalytic cracking slurry (FCC) generally decreases during heating. However, the viscosity of the coal–oil slurry prepared by the high-temperature coal tar (CT) will peak at 338 °C during heating. The differences in viscosity variations of coal–oil slurries are analyzed. In addition to the temperature, the properties of the solvents and coal are the main influencing factors. Because the used coal contains a large number of polar functional groups, the swelling behavior of the coal in polar solvent (CT) is stronger than that in non-polar solvent (FCC). The swelling effect of the coal can result in the appearance of the viscosity peak. Therefore, before 100 °C, the solvent molecules entering into the coal pores is the main influencing factor of coal–oil slurries viscosity variations. After 100 °C, the increasing of particle size of coal particles is the main influencing factor of coal–oil slurries viscosity variations.

The state of gold in chloride solutions has been studied by the solubility method over a temperature range 350-500 °C and a pressure range 0.5-1.5 kbars as a function of acidity, ion CI' concentration and oxygen fugacity. The formation of the AuCl₂ complex have been calculated for the reaction : Au(s)+ HCl⁰ + Cl⁻ + 0.25 O₂(g)= AuCl₂₋+ 0.5 H₂O Our experimental data (lg K°) appear in agreement with a number of experimental data sets from literature using the model of S hock and Helgeson (1988). Using this approach we approximated the AuCl₂₋ thermodynamic properties over a wide range of temperatures (25-750 °C) and pressures (1-1500 bars)., L'état de l'or dans les solutions chlorurées a été étudié par la méthode de solubilisation pour des températures allant de 350 à 500 °C et des pressions de 0,5 à 1,5 kb, en fonction de l'acidité des solutions, de la concentration en ion Cl- et de la fugacité de l'oxygène. La formation de l'ion AuCl₂₋ a été démontrée. Les valeurs de la constante d'équilibre ont été calculées pour la réaction : Au(s)+ HCl⁰ + Cl⁻ + 0.25 O₂(g)= AuCl₂₋+ 0.5 H₂O Nos données expérimentales (log K°) apparaissent en bon accord avec une série d'autres données expérimentales de la littérature si on utilise le modèle de S hock et Helgeson (1988). Avec cette approche, les propriétés thermodynamiques de AuCl₂₋ ont été étudiées dans une large gamme de températures (25-750 °C) et de pressions (1-1500 bars)., Zotov Alexandr V., Baranova Nina N. Thermodynamic properties of the aurochloride solute complex AuCI2- at temperatures of 350-500 °C and pressures of 500-1500 bars. Propriétés thermodynamiques du complexe aqueux auro-chloré AuCl2-de 350 à 500°C et de 500 à 1500 bars. In: Sciences Géologiques. Bulletin, tome 42, n°4, 1989. Thermodynamique des processus naturels. Thermodynamics of natural processes pp. 335-342.