Options In Material, Coating And Chemical Selection to Mitigate Failure In Hydrocarbon Production

In recent years, as project design lives have increased, many operators are utilizing higher performance materials such as high nickel corrosion resistant alloys (CRA) or non-metallic materials. Normally, by definition the selection of CRA materials incurs a higher CAPEX cost as opposed to the option of carbon steel and chemical treatment with lower CAPEX cost but inherently possible higher OPEX costs. In many cases the comparative economic analysis can break even over a thirty year design life depending on the accuracy of the life cycle cost analysis and the project assumptions such as net present value etc. As an additional consideration, enhanced oil recovery (EOR) methods, including water and gas injection have resulted in a much greater risk of hydrogen sulfide souring in hydrocarbon reservoirs that have presented newer technical challenges, particularly in HP/HT wells, to avoid corrosion failures and other forms of degradation in either down hole, subsea or topside process components, that must now also consider more enhanced integrity monitoring. Further, the development of new methods to prevent souring and associated chemical treatments has also prompted the need to test materials for service compatibility, especially for non-metallic and elastomeric materials in the more highly sour environments. Explosion decompression (ED) testing at high pressure and resistance to Xylene, Toluene, drilling/completion fluids and methanol are also particularly important in this respect. Recent failure incidents in oil and gas production including those of higher performance materials have highlighted the need to re-evaluate the use of fabrication methods, material selection and certain chemical treatments or coatings that were once considered standard industry practice. This paper presents a "state of the art" review on this complex technical issue with some case histories.