Materials Science Forum Vol. 814

Abstract: The pitting behavior of 304 stainless steel in the simulated condensate with different salt content (4 mg/L, 8 mg/L, 16 mg/L, 32 mg/L, 64 mg/L) and sulfur content (1.2 g/L, 2.5 g/L, 5 g/L) was studied using potentiodynamic polarization curve and static immersion methods. The simulated condensate was simulating the condensed water in the unit of refining heavy oil with high salt and high sulfur. The results showed that with the increase in chloride ions concentration, the pitting potential of 304 stainless steel decreased and the pitting sensitivity increased. The pitting sensitivity of 304 stainless steel also increased with the increase in sulfide ions concentration. In several experimental mediums, when the concentration of chloride ions and sulfide ions were 64 mg/L, 5 g/L respectively, the number and the size of corrosion pits both were the largest, the pitting behavior was the most serious.

Abstract: The hole in the shale formation is in nanometer or micrometer scale, so the conventional plugging materials which are in the scale of millimeter cannot be used during the drilling of the shale formation. An effective way to solve this problem is to develop new plugging materials, which are in the nanometer or micrometer scale. In this article, the micron copolymer particles were prepared by the soap-free emulsion polymerization of the monomers methyl methacrylate (MMA) and acrylamide (AM). The structure of the copolymer particles was characterized by the Fourier transform infrared spectroscope (FT-IR). The particle size was determined by dynamic light scattering (DLS). In addition, the salt tolerance, temperature resistance and compatible property of the particles with the additives of drilling fluids were studied in detail.

Abstract: Due to the smalle hole of the shale formantion, particles with smaller size, such as nanoparticles was developed to be used as plugging materials during the drilling of shale formation. In this article, poly (styrene-acrylic acid) particles were synthesized by soap-free emulsion polymerization of styrene (St) and acrylic acid (AA). The as-prepared polymer particles were characterized by Fourier transform infrared spectroscope (FT-IR), dynamic light scattering (DLS). In addition, salt tolerance, temperature resistance and compatible properties with additives in drilling fluid of the polymer particles were also investigated.

Abstract: 0Cr18Ni9Ti stainless steels are used extremely broad, but the corrosion phenomena of 0Cr18Ni9Ti stainless steels will happen in its using because of various reasons. 0Cr18Ni9Ti stainless steels were taken with different process of heat treatment in order to change its corrosion resistance in this paper. The corrosion resistance performance of the samples was discussed by metallographic picture observation, weight-loss method and organizational analysis. The better heat treatment process was chosen, according to the contrast experiment method. The results indicate that the sample has the best corrosion resistance after 1040°C×1.5h solid solution and stabilization treatment of 890°C×2h. This study has certain positive meaning to improve the 0Cr18Ni9Ti stainless steel corrosion resistance.

Abstract: The traditional gold leaching method is cyanidation, which carries serious security and environmental problems. More and more attention is paid to the research on non-cyanide process. A high-arsenic-and-sulphur refractory gold concentrate in Sichuan was taken as the object of study. After the roasting-oxidation pretreatment of the sample, potassium ferricyanide was adopted to carry on the process experiment on gold-leaching. The leaching results as well as correlative process conditions were both investigated. The results showed that good leaching effects could be achieved by potassium ferricyanide. When the amount of potassium ferricyanide was 60g/L, the concentration of NaOH 0.2mol/L, the liquid-solid ratio 6:1 and the leaching process at room temperature lasted for 20h, the gold leaching rate reached 88.1%. If the leaching aid CaO₂ is added simultaneously, it can contribute to the gold leaching. When the amount of CaO₂ was 3g/L, the gold leaching rate increased to more than 94%, the amount of potassium ferricyanide decreased to 50g/L and the leaching time reduced to 14h.

Abstract: The deposition of BaSO₄ scale is always found in the oilfield. It is difficult to be removed. Therefore, it plays a negative role to the production. The effects of temperature and water chemistry on BaSO₄ scale have been investigated by using the conductivity method in this work. An environment-friendly copolymer was prepared to control the scaling of BaSO₄. The copolymer was proved by static scale inhibition method, and weight-loss test that it has excellent scale inhibition performance and corrosion inhibition efficiency. Furthermore, FTIR spectra was used to prove that the scale inhibitor was polyepoxysuccinic acid (PESA).

Abstract: Adopting the chemical activation method, the high specific surface area activated carbon (AC) was prepared by the solid mixing method using Daqing petroleum cokes as raw materials and KOH as activator. The influence of the ratio of KOH to carbon, activation temperature and activation time on the iodine and methylene blue adsorption properties of the AC were studied. The micro-graphitic structure of the AC was studied by X-ray diffraction (XRD). The BET specific surface area, BJH pore size distribution and pore volume of the AC were determined by N₂ adsorption (at 77K). The experimental results show that the high specific surface area AC can be prepared with the ratio of KOH to carbon of 4, activation temperature of 800°C and activation time of 1h. The specific surface area was as high as 2142 m²/g with the iodine adsorption value of 288mg/g and methylene blue adsorption value of 1266mg/g. The XRD and BJH results also show that amorphous carbon was the dominating form, and the pore size distribution represents micropore structure.

Abstract: Activated carbon (AC) is a kind of artificial carbon materials with highly developed pore structure and high specific surface area. As sound adsorption materials, the AC shows excellent adsorption property, good chemical stability, high mechanical strength and easy-to-regeneration characteristics, which makes it a widely application in the fields of chemical industry, environmental protection, food and pharmaceutical industry, electrode materials, and so on [1-3].

Abstract: High purity spherical silica powder was obtained using silica fume as the raw material in this study. The mixture acids of HF and HCl were used in the purification process to remove the impurities contained in the silica fume. The phase of the product was characterized by X-ray diffraction, indicating that the spherical silica powder was amorphous. The chemical composition of the product was investigated by X-ray fluorescence, showing the SiO₂ content was 99.9096 wt%. It had been proved that the purification process could improve the dispersion of the product powder via the morphology comparison and the laser particle analyses. The experimental results showed that the parameters of the product spherical silica powder met all the standards of the electronic-grade packaging materials.

Abstract: H₂S corrosion has become one of the key factors that has impact seriously on the exploration and development of high-sulfur oil and gas. In order to study the change of microstructure and properties of G105 steel drill pipe in H₂S environment, different concentrations of H₂S (300ppm, 400ppm, 500ppm, 600ppm) were used respectively at room temperature to make corrosion immersion test on the G105 drill pipe, and then tensile test, impact test, hardness test, metallographic analysis, scanning electron microscopy (SEM) observation and EDS spectrum analysis. The results showed that in the range of H₂S concentration provided in tests, pipe materials was corroded quite seriously, microstructure changed obviously, comprehensive mechanical properties decreased significantly, and the range decreased first and then increased and decreased again. The type of fracture is classified as the pore ductile fracture, some of them appear prospective cleavage characteristics, and, fracture place exist severe solute partial clustering phenomenon. In addition, high concentration of Sulfur was found in impact fracture surface. The results would provide a reference for our understanding of the corrosion behavior of the drill pipe materials in H₂S environment and the development of new anti-corrosion materials drill pipe.