Abstract
Oil and gas is increasingly being produced at higher temperatures and/or from deep oil reservoirs that contain high concentrations of chloride, H2S and CO2. Commonly, materials for service in these wells are qualified for a particular environment using stressed-immersion testing to show the susceptibility to stress corrosion cracking (SCC) and/or sulfide stress cracking (SSC). These qualification tests are frequently performed in simulated field conditions using high pressure, sour testing in an autoclave. However, there are numerous techniques for charging H2S and CO2 into these exposures. The concentration of these gases is affected by the charging technique, and thus the results of a particular qualification test can be influenced by the gas charging method.
The objective of the present work was to discuss three gas charging methods described by Hausler1 and compare the results obtained using each technique. This analysis was made via thermodynamic modeling and includes discussion related to the evaluation of the results versus the experimental recommendations in NACE MR0175 / ISO 15156:20092 and NACE TM0177-20053. Future work will include laboratory experiments and validation of gas concentrations predicted.
