Sulfide Stress Cracking Resistance of High Strength Low Alloy Steels for High H_2S Pressure Wells: Improvements of the H_2S Gas Loading Procedure of the Autoclave and Results for T95 and C110 Steel Grades

摘要

The susceptibility of High Strength Low Alloy steels to Sulfide Stress Cracking (SSC) in H_2S containing environments is evaluated by NACE TM0177-2005 test methods. Those SSC tests are commonly conducted at room temperature and atmospheric pressure. However, because of the severity of some O&G wells, there is a need for assessing the SSC susceptibility at higher partial pressures of H_2S. The evolution of the SSC resistance of Sour Service grades (T95 and C110) with the H_2S partial pressure has been investigated according to the uniaxial tensile (Method A) and double cantilever beam (Method D) corrosion tests in autoclaves. Up to 0.6 or 1 MPa, no detrimental effect of the increase of the H_2S gas pressure has been observed on the failure susceptibility with the NACE uniaxial tensile test. However, a significant decrease of K|_(ISSC) values occurred. DCB tests conducted in the temperature range 21 °C to 27°C indicate that the bath temperatu re, in addition to the H_2S pressure, is another controlling parameter for K|SSc-