Environmental Cracking Performance of Super Martensitic Stainless Steels “13-5-2” (grades 110ksi and 125ksi) for Tubing Applications in High Chloride Reservoir Fluids Containing H2S/CO2

Environmental Cracking Performance of Super Martensitic Stainless Steels

“13-5-2” (grades 110ksi and 125ksi) for Tubing Applications

in High Chloride Reservoir Fluids Containing H₂S/CO₂

Roberto Morana ¹⁾ , Eugenio Lo Piccolo ¹⁾ , Lucrezia Scoppio ²⁾ , Perry Ian Nice ³⁾

1) Centro Sviluppo Materiali SpA, Via di Castel Romano 100, 00128 Rome, Italy

2) Pipe Team srl, Via Resistenza 2, 20070 Vizzolo P. (Mi), Italy

3) StatoilHydro, Forusbeen 50, N4035 Stavanger, Norway

<>ABSTRACT

Within the Oil & Gas industry there is an increasing interest in the use of high strength tubing alloys in deep water, high temperature/high pressure (HPHT) and ultra high pressure wells.

“13-5-2” super martensitic stainless steels (ISO13680) grade 110ksi have been developed and typically used in HPHT fields containing CO2 and small amount of H2S. The alloy application limits have not been fully defined with respect to parameters such as chloride concentration, pH, temperature and H2S partial pressure. These parameters influence both localized corrosion resistance and Stress Corrosion Cracking (SCC) susceptibility.

The present work has been aimed at evaluating the SCC resistance of alloy “13-5-2” grades 110ksi and 125ksi. This has been performed by means of the Four Point Bent (FPB) testing method according to EFC publication n°17.

SCC-resistance application limits are proposed for both grades as a function of chloride concentration, pH, temperature and H2S partial pressure.

Key words: Super 13Cr steel, super martensitic stainless steel, SCC, chlorides, pH, H₂S, CO₂.