Impact of Chemical Additives on Gas Evolution Behavior in Supersaturated Solutions at Elevated Pressures

Abstract

There is a need to better understand the mechanisms that govern gas evolution (i.e., desorption) from supersaturated solutions at elevated pressures for improved design and troubleshooting of gas−liquid separators used in the oil and gas industry. The rate of gas evolution is generally represented in terms of the mass transfer coefficient, which can be affected by the presence of chemical additives. In the oil and gas industry, a wide variety of chemical additives are used, such as demulsifiers, antifoamers, and corrosion inhibitors. Two different classes of chemical additives were evaluated in this work, Xiameter PMX-200 (silicone-based) and Synperonic PE/L61 (alcohol-based). The rate of gas evolution (volumetric mass transfer coefficient) was determined at two different mixing speeds (25 and 500 rpm). The impact of the chemical additive concentration (Xiameter PMX-200) on the volumetric mass transfer coefficient was investigated using Exxsol D-110 (model oil) at different concentrations, while Synperonic PE/L61 (alcohol-based) was investigated only at a concentration of 80 ppm in Exxsol D-110. The effect of chemical additives in crude oils was also investigated using two crude oils (Crude A and B). For the measurements with crude oil, the concentration of Xiameter PMX-200 (silicone-based) was 10 ppm and that of Synperonic PE/L61 (alcohol-based) was 80 ppm. Results showed that the addition of chemical additives did not affect the number of moles of methane solubilized into the crude and model oils. However, the addition of chemical additives reduced the volumetric mass transfer coefficient during absorption and desorption into/ from the crude and model oils. Based on these data, we hypothesize that chemical additives can form a resistive layer (near the bulk liquid−gas interface), thereby causing a reduction in the volumetric mass transfer coefficient.

A Predictive Methodology to Determine the Rate of Gas Evolution in Hydrocarbon Systems at Elevated Pressures

“…However, the impact of mixing speed/shear rate/rate of energy dissipation has not been fully investigated. The supersaturation ratio and the presence of chemical additives also influence the rate of gas evolution as shown in our earlier studies. , …”

“…The supersaturation ratio and the presence of chemical additives also influence the rate of gas evolution as shown in our earlier studies. 29,30 To the best of our knowledge, there is no existing correlation to determine the mass transfer coefficient at elevated pressures using dead oil properties (without dissolved gas). This work focuses on developing a correlation capable of determining the mass transfer coefficient using dead oil properties for a particular liquid.…”

Elucidating the Influence of Bubble Surface Area on Mass Transfer Kinetics in Gas/Liquid Systems

“…The experimental protocol unfolds in three main phases: absorption, depressurization, and gas evolution, a methodology consistently applied in previous articles from our research group (15,16). To ascertain the experimental uncertainty and volumetric mass transfer coefficients, established methods from prior studies within our group were utilized (15,16).…”

“…Miranda et al delved into gas evolution at elevated pressures to comprehend the various underlying forces involved (13). Parameters explored in the work of Miranda et al encompassed the presence of emulsions, emulsion droplet sizes, temperature, pressure, and chemical additives (14,15). Additionally, studies have been conducted to discern the impact of varying shear environments on the gas evolution process (16).…”

“…The presence of varying shear rates gives rise to the phenomenon of bubbling. In conventional gas-liquid separators, inlet conditioning devices such as vane-type or cyclone-type devices are commonly employed (16). Gas-liquid cylindrical cyclones (GLCCs) are also utilized for separation in the petroleum industry (18).…”