The research on phenolic resin modified by nanoparticles and used for magnesite-carbon brick binder
The research method use nanoparticles to modify the phenolic resin binder for magnesite-carbon brick. The normal detection indexes of phenolic resins is suited to used as the binder. FESEM images show that the nanoparticles are distributed uniformly without agglomeration almost. The physical-chemical property analyses show that the magnesite-carbon brick using this modified phenolic resin as binder possesses a low apparent porosity and a high bulk density and compression strength. Especially, the compression strength of the magnesite-carbon bricks after heat treatment for 200°C×12h increase to 43.94MPa and 41.35MPa, respectively. The results also show that with the increase of heat treatment temperature, the compression strength and the bulk density of magnesite-carbon bricks decrease and the apparent porosity magnesite-carbon bricks increases. The physical-chemical property shows a significant change from 200°C to 1100°C. However the change is not obviously from 1100°C to 1550°C and shows worse trend with the increase of heat treatment temperature.
Thermal characteristics of addition-cure phenolic resins
Abstract The thermal and pyrolysis characteristics of four different types of addition-cure phenolic resins were compared as a function of their structure. Whereas the propargyl ether resins and phenyl azo functional phenolics underwent easy curing, the phenyl ethynyl- and maleimide-functional ones required higher thermal activation to achieve cure. All addition-cure phenolics exhibited improved thermal stability and char-yielding property in comparison to conventional phenolic resole resin. The maleimide-functional resins exhibited lowest thermal stability and those crosslinked via ethynyl phenyl azo groups were the most thermally stable systems. Propargylated novolac and phenyl ethynyl functional phenolics showed intermediate thermal stability. The maximum char yield was also given by ethynyl phenyl azo system. Non-isothermal kinetic analysis of the degradation reaction implied that all the polymers undergo degradation in at least two steps, except in the case of ethynyl phenyl azo resin, which showed an apparent single step degradation. The very low pre-exponential factor common to all polymers implied the significance of volatilisation process in the kinetics of degradation. Isothermal pyrolysis studies led to the conclusion that in the case of nitrogen-containing polymer, the pyrolysis occurs via loss of nitrogenous products, which is conducive for enhancing the carbon-content of the resultant char. FTIR spectra of the pyrolysed samples confirmed the presence of C–O groups in the char. XRD analysis of the partially carbonised polymers did not give any indication of crystallites except in the case of ethynyl phenyl azo system.
Prevention of Barite Sag in Oil-Based Drilling Fluids Using a Mixture of Barite and Ilmenite as Weighting Material
Drilling high-pressure high-temperature (HPHT) wells requires a special fluid formulation that is capable of controlling the high pressure and is stable under the high downhole temperature. Barite-weighted fluids are common for such purpose because of the good properties of barite, its low cost, and its availability. However, solids settlement is a major problem encountered with this type of fluids, especially at elevated downhole temperatures. This phenomenon is known as barite sag, and it is encountered in vertical and directional wells under static or dynamic conditions leading to serious well control issues. This study aims to evaluate the use of barite-ilmenite mixture as a weighting agent to prevent solids sag in oil-based muds at elevated temperatures. Sag test was conducted under static conditions (vertical and inclined) at 350 °F and under dynamic conditions at 120 °F to determine the optimum ilmenite concentration. Afterward, a complete evaluation of the drilling fluid was performed by monitoring density, electrical stability, rheological and viscoelastic properties, and filtration performance to study the impact of adding ilmenite on drilling fluid performance. The results of this study showed that adding ilmenite reduces sag tendency, and only 40 wt.% ilmenite (from the total weighting material) was adequate to eliminate barite sag under both static and dynamic conditions with a sag factor of around 0.51. Adding ilmenite enhanced the rheological and viscoelastic properties and the suspension of solid particles in the drilling fluid, which confirmed sag test results. Adding ilmenite slightly increased the density of the drilling fluid, with a slight decrease in the electrical stability within the acceptable range of field applications. Moreover, a minor improvement in the filtration performance of the drilling fluid and filter cake sealing properties was observed with the combined weighting agent. The findings of this study provide a practical solution to the barite sag issue in oil-based fluids using a combination of barite and ilmenite powder as a weighting agent to drill HPHT oil and gas wells safely and efficiently with such type of fluids.