Abstract
For decades, materials evaluation, selection and specification for sour service conditions has been based on the principal of partial pressure H2S. In certain cases, it is used in combination with in-situ pH and chloride concentration to define conditions for laboratory testing with the aim of being representative of actual field service conditions at conditions of much higher total pressures. However, more recently powerful thermodynamic models have been developed that allow accurate simulation of production conditions up to high pressure/high temperature conditions that in some cases are in excess of 20,000 psi and 500 F. The results of such simulations indicate that partial pressure is likely not a correct or scalable parameter especially when comparing low and high pressure environments at constant H2S partial pressure, and where salt concentrations vary from <1000 mg/L to in excess of 180,000 mg/L chlorides. This paper reviews the results of several studies in which conventional and sophisticated modeling techniques were used to understand test versus service conditions and specify loading conditions for sour service testing. It discusses the short comings of certain techniques and highlights requirements and new parameters for specification of laboratory test environments that correctly simulate conditions intended for sour service HPHT well environments.
