Bottom hole assembly components may be in contact with sour environments depending on the oil field. In this respect, the steels used to manufacture these components have to be resistant to various in-service conditions, including aggressive environments (containing H2S, CO2, O2, chlorides), static and dynamic mechanical stresses. In this respect, sulfide stress cracking and corrosion fatigue tests were conducted to study how a corrosive environment containing H2S and in-service loading affect the serviceability of different steel grades designed to be used for components such as drill collars and heavy weight drill pipes. The grades under study are 4145H Mod and 4145V Mod, and for the grade 4145V Mod, two different chemical compositions were investigated: The standard steel grade composition, and an optimized composition with regards to the level of residual elements. It is found that steel 4145V Mod exhibits improved behavior compared to the grade 4145H Mod. The above mentioned optimization of the chemical composition increases the corrosion fatigue life of the steel in corrosion environment such as NACE TM0177 solution A. Based on these results, a methodology is proposed to predict the behavior of the different steel grades in sour environment for a wide range of loads representative of in-service conditions.

Subject
Corrosion fatigue, Materials, Sour environments, Fracture surfaces, Chemical composition, Stress, Bending, Specimen preparation, Steel, Corrosion resistance, Elements, Sulfide stress cracking, Fracture
Keywords:
4145H Mod, 4145V Mod, sulfide stress cracking, SSC, corrosion fatigue, NACE TM0177 Solution A
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2005
Association for Materials Protection and Performance (AMPP)
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