Transition of tubing and casing materials in Minami-Nagaoka gas field

Abstract

Transition of tubing and casing materials in Minami-Nagaoka gas field is summarized based on more than 30 years' experience. The field commenced the production in 1984. The tubing material was replaced from carbon steel to some corrosion resistant alloys including 22Cr duplex stainless steel after faced with several corrosion problems such as CO₂ corrosion of carbon steel tubing, localized corrosion of 13Cr stainless steel and sulfide stress corrosion cracking of P-110 grade casing material. Newly developed 17Cr is tested in high pressure and high temperature CO₂ corrosion conditions and shows excellent general corrosion performance, equivalent to 22Cr duplex stainless steel, in the field condition. That is why 17Cr martensitic stainless steel is considered as the next candidate for the tubing material. This report describes the cause of corrosion and those measures.