Srinivansan7 describes an autoclave system developed to simulate fluid flow induced corrosion in CO2/H2S systems. Sour gas corrosion research has been limited to small-scale studies, which do not provide an adequate environment for the simulation of corrosion in multiphase slug flow.Ĭurrent laboratory research associated with sour gas is conducted in autoclaves because of the ability to reproduce the wellhead temperature and pressure conditions some even have circulatory pumps to achieve better mass transfer in the corrosion process.
However, this information fails to show the mechanical action of the flow regime on the scale or corrosion product film. The addition of hydrogen sulfide to a corrosive system contained in a bubble cell or other small volume test apparatus provides information necessary for characterizing the reactions and by-products of the corrosion process. A similar film was seen at low concentrations of H2S in a brine containing CO2 and acted as a corrosion film that greatly decreased the corrosion rates in 2-liter glass cells6. Corrosion in the presence of H2S has resulted in the formation of an iron sulfide film that decelerated the corrosion rate at temperatures between 20✬ and 60✬5. In the presence of H2S, acidity of the corrosive media is a parameter known to play a determining role in the cracking phenomena (SWC, SSC, SCC) of low alloy steels as well as stainless steel and must be accurately evaluated4. Longer transmission lines of multiphase fluids over various terrains provide opportune environments for slug flow regimes. H2S-related corrosion is a topic of great concern due to the increased oil and gas production technology that allows deeper wells producing more corrosive fluids and longer transmission lines. These pulses of bubbles impact the pipe wall and collapse causing a cavitation-type effect, leading to increased corrosion rates in slug flow3.
High velocity slugs are very turbulent with the existence of pulses of entrained bubbles in the mixing zone behind the front of the slug. Under various multiphase conditions, the slug flow regime has been shown to increase the corrosion damage to pipelines1,2.
INTRODUCTION CO2 and H2S content in produced fluids constitute a very corrosive environment that has been studied extensively in glass cells and autoclaves since the early 1970?s, but little research work has been completed to model corrosion in slug flow of a sour system. Initial baseline testing of the entire system consisted of slug flow and full-pipe flow regimes in seawater and the resulting effect on corrosion rates under partial pressures of CO2. This report describes the fluid pumping system, the flow monitoring system, the corrosion monitoring methods, and safety systems associated with the new experimental loop. This unique system is housed in an environmentally isolated, explosion-proof area providing a safe location where an operator can study the effects of a single parametric change on corrosion. ABSTRACT A state-of-the-art laboratory flow loop has been researched, designed, and developed to study the corrosive effects of sour gas in multiphase flow.
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