Corrosion Inhibitors for Sour Oilfield Environment (H2S Corrosion)

Lower-grade steel materials are the most commonly used construction materials for oil and gas wells due to their low cost and high performance. However, they are susceptible to corrosion when they come in contact with corrosive environments that are highly acidic. In oil wells, particularly deep oil wells, hydrogen sulfide (H2S) is commonly found. The dissolution of H2S gas in produced water makes the fluid corrosive. The use of corrosion inhibitors is perhaps the most practical and costeffective means of controlling corrosion of low carbon steels in the sour environment. In this chapter, typical corrosion inhibitors used in oil and gas fields to control the internal corrosion of oilfield equipment caused by H2S are being examined. The inhibitors found to be effective are polar functional compounds, with many being based on nitrogen-containing compounds, such as amines, imidazolines, and quaternary ammonium salts. Drawbacks of these compounds in practical applications and potentials of future developments are discussed

Effect of Annealing on Hardness and the Modulus of Elasticity in Bulk Nanocrystalline Nickel

Experiments on hardness and the modulus of elasticity were conducted at room temperature on samples of electrodeposited (ED) nanocrystalline (nc) Ni that were annealed at temperatures ranging from 323 to 693 K (50 to 420 °C). The results showed the presence of three regions: I, II, and III. In region I (300 K (27 °C) < T < 350 K (77 °C)), the hardness and the elastic modulus remained essentially constant. In region II (350 K (77 °C) < T < 500 K (227 °C)), both the hardness and the elastic modulus increased. In region III (T > 500 K (227 °C)), the hardness dropped and then decreased with increasing grain size, whereas the modulus of elasticity approached a maximum plateau of ~240 GPa. It is suggested that while the increase in hardness in region II can be attributed in part to the formation of annealing twins, which serve as a source of strengthening, the decrease in hardness above 500 K (227 °C) is due to the occurrence of significant grain growth. The increase in the modulus of elasticity with increasing temperature in region II was attributed to the preferred orientation along (200) that was observed in the as-received samples and that continuously diminished with increasing temperature. In region III (T > 500 K (227 °C)), the preferred orientation disappeared and, a result, the modulus of elasticity approached a constant value of approximately 240 GPa