Modeling the formation of iron sulfide scales using thermodynamic simulation software

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:351760

Anderko, A ^[1]; Shuler, P J ^[2]

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1. OLI Systems Inc., Morris Plains, NJ (United States)
2. Chevron Petroleum Technology Co., La Habra, CA (United States)

A program has been developed for generating stability diagrams that concisely represent the thermodynamic state of multicomponent, multiphase aqueous systems in wide ranges of temperature and component concentrations. The diagrams are based on a thermodynamic model that combines the Helgeson-Kirkham-Flowers equation of state for standard-state properties with a solutions nonideality model based on the activity coefficient expressions developed by Bromley and Pitzer. The diagrams offer a flexible choice of independent variables, which include component concentrations in addition to the potential and pH. The stability diagrams are used to predict the conditions that favor the formation of stable and metastable iron sulfide species, which are commonly deposited under oil field-related conditions. First, the diagrams have been applied to establish a sequence of transformations that iron sulfides undergo as they age. The predicted transformation sequences take into account environmental variables (e.g., hydrogen sulfide concentration, oxygen availability, etc.). The predictions are in agreement with experimental data on iron sulfide formation at the iron/solution interface and in bulk solution. The understanding of iron sulfide transformation sequences makes it possible to simulate experimental studies of H{sub 2}S/CO{sub 2} corrosion in the presence or absence of oxygen. A comparison with laboratory corrosion rate data under gas pipeline conditions indicates that the magnitude of corrosion rates can be correlated with the predicted stability of metastable iron sulfide phases.

• OSTI ID: 351760
• Report Number(s): CONF-980316--
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
36 MATERIALS SCIENCE
CARBON DIOXIDE
CARBON STEELS
CORROSION
HYDROGEN SULFIDES
IRON SULFIDES
LOW ALLOY STEELS
MATHEMATICAL MODELS
NATURAL GAS
PIPELINES
SCALING
THERMODYNAMICS