Natural Gas Hydrate Formation and Decomposition in the Presence of Kinetic Inhibitors. 2. Stirred Reactor Experiments

Abstract

A newly fabricated, stirred reactor was used to investigate hydrate inhibition and decomposition in the presence of two commercial, chemical kinetic inhibitors, polyvinylpyrrolidone (PVP) and H1W85281, as well as two antifreeze proteins (AFPs), type I and type III. The longest induction times and the slowest growth rates were observed with HIW8581, with the fastest growth recorded for PVP. Type I AFP (AFP-I) was a more effective inhibitor, with respect to induction time and growth, than either PVP or type III AFP (AFP-III). Complete hydrate decomposition occurred earlier in the presence of any of the inhibitors compared to water controls. However, depending on the type of inhibitor present during crystallization, hydrate decomposition profiles were distinct, with a longer, two-stage decomposition profile in the presence of the chemical kinetic inhibitors (PVP and H1W85281). The fastest, single-stage decompositions were characteristic of hydrates in experiments with either of the AFPs. These results argue that thought must be given to inhibitor-mediated decomposition kinetics in screens and designs of potential kinetic inhibitors. This is a necessary, practical consideration for industry in cases when, because of long shut in periods, hydrate formation may be unavoidable, even when inhibitors are utilized.

Oil and gas pipelines with hydrophobic surfaces better equipped to deal with gas hydrate flow assurance issues

“…This indicates that neither LuvicapBio nor AFP I have an influence on the hydrate nucleation in the stainless steel crystallizer. This is in contrast to previously reported performance of 0.5 wt% AFP I in deionized water with multi-component gas which delayed the induction time in small crystallizers (Daraboina et al, 2011a). A similar observation was made with 0.1 mM AFP I with multi-component gas applying the high pressure crystallizer setup used in our study (Sharifi et al, 2014c).…”

“…Recently, AFPs have been studied as a green and environmentally friendly kinetic hydrate inhibitor (Walker et al, 2015). Promising results has been obtained in THF Zeng et al, 2003Zeng et al, , 2006, methane (Al-Adel et al, 2008;Jensen et al, 2010Jensen et al, , 2011Perfeldt et al, 2014) and multi-component gas systems (Daraboina et al, 2011a(Daraboina et al, , 2011b(Daraboina et al, , 2011cOhno et al, 2010;Sharifi et al, 2014aSharifi et al, , 2014c showing that AFPs may have potential as gas hydrate inhibitors. Although, AFPs offer potential as KHIs the large-scale manufacturing costs have been a challenge for the transition from research to industrial application (Kelland, 2006).…”

Natural gas hydrate formation and inhibition in gas/crude oil/aqueous systems

“…6). The possible inhibition mechanisms for these kinetic inhibitors were explained in previous studies [4,27,[35][36][37]. As seen from Fig.…”

Influence of cationic and non-ionic surfactants on the kinetics of mixed hydrogen/tetrahydrofuran hydrates

“…The difference between the increase in amount of gas between dissociation experiments Δn dissociation;↑ À Á and the base case experiment Δn base case;↑ À Á provides the actual amount of gas released due to hydrate dissociation (Babu et al, 2013b;Daraboina et al, 2011). Amount of gas recovered due to hydrate dissociation can then be calculated from Eq.…”