High Pressure High Temperature Testing of PH Nickel Alloy and Super Martensitic Stainless Steel in Cesium Formate Completion Fluid

AUTHOR/S: E. Lo Piccolo - P. I. Nice - O. Fattnes R. Morana - A. Bufalini - A. Lucci - L.Scoppio NACE CORROSION CONFERENCE 2012, March 11-15, 2012 Salt Lake City, Utah, USA


The use of high density brine is required for High Pressure High Temperature (HPHT) gas condensate wells to ensure safe well operations during drilling and completion phases. Cesium formate brine is one of the latest high-density brine used for this application, being both environmentally friendly and non-corrosive.


The present work investigated the use of high density cesium/potassium formate brine solution at bottom hole environmental conditions for long term exposure periods. In particular the influence of total pressure and temperature on the thermal degradation of the formate-based brine was studied and evaluated.


The results of the testing program demonstrated that thermal decomposition of the fluid occurred, producing a build up of the internal pressure, in the low pressure tests only, with a development of hydrogen into the gas phase. Furthermore, SCC phenomenon was observed in super martensitic stainless steel samples at certain stress levels together with evidence of hydrogen embrittlement of PH Ni alloy 718. A mechanism for the reactions involved is proposed and discussed.

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