Oil-grade alloy 718 in oil field drilling application

Due to continuous advancements in drilling technology, the materials in use have to fulfill higher demands in regards to mechanical properties and corrosion resistance. The complex working loads and high vibration, the hostile downhole environments, together with the high working temperature and pressure encountered when operating in an ultra deep drilling environment, provide major challenges for the drilling tool materials. This paper focuses on the performance of oil-grade alloy 718 for applications in bottom hole assemblies (BHAs) under drilling conditions. Potentiodynamic polarization was applied to investigate the general characteristics of corrosion and pitting attack. Key influence factors including working temperature, cation species in corrosive medium, and post-mortem heat treatment were discussed. These results will help to direct the optimization strategy of Ni-base superalloys in oil field drilling. (AU) © 2010 by The Materials, Metals, & Materials Society. All rights reserved.