During the recent economical growth period the lead time of stainless steel tubular reached in excess of
a year. This was considered inadequate particularly for the completion of wells in some marginal reservoirs with
short expected production capacities and life times. A systematic and comprehensive study was therefore,
undertaken to select and optimize suitable materials for the completion of lower part of a number of gas
producing wells. Key challenges included economy and appropriateness to allow a fitness for service choice of
tubing material. The study covered two parallel elements including (i) corrosivity assessment and (ii) placement
of downhole coupons and tubing string in the cemented part of the wells. This aided materials optimization by
developing application domain diagrams (ADDs) for candidate materials including carbon steel (C-steel) and low
carbon 3%Cr steels. Operational experience was captured through analysis of downhole corrosion coupons after
six months of exposure to evaluate the in-situ system corrosivity. In addition, a limited number of wells were
completed with 3 % Cr and carbon steel. After one year of production they were inspected by caliper runs
showing encouraging results which led to additional wells being completed with C-steel. This paper summarizes
the outcome of different studies and inspection and demonstrates the significance of correct materials selection
approach and implementation of corrosion management strategy in meeting economy and appropriateness to
enable fitness for service.
Key words: Corrosion prediction, CO2 corrosion, modeling, material selection, tubing corrosion