Exacerbation of Hydrate Agglomeration in the Presence of Kinetic Hydrate Inhibitor under High pH Conditions

Abstract

The performance of Luvicap EG was investigated to verify the efficacy of mixing kinetic hydrate inhibitors (KHIs) and monoethylene glycol (MEG) while varying the pH conditions in an aqueous phase. The relative torque changes were relatively stable in an early stage of hydrate formation; however, they started to increase and showed fluctuation when the hydrate fraction was larger than the transition value. Interestingly, the transition value was smaller for the base solution, suggesting that the efficacy of Luvicap deteriorated at high pH conditions. MEG was added to the Luvicap solution to confirm its synergistic effect at low and high pH conditions. The addition of MEG effectively slowed down the growth rate and the relative torques for the acid and the neutral solutions. However, for the base solution, dramatic changes in the growth rate were observed, followed by a severe fluctuation of the relative torque. Visual observation suggested that the catastrophic hydrate growth had occurred, and the formed hydrate particles were prone to deposit on the autoclave wall and to the impeller. Additional experiments varying the impeller speed indicated the occurrence of a thick hydrate film on the interface between the gas and the aqueous phases at a slow impeller speed, which increased the resistance-to-flow. Under all pH conditions, at 200 rpm, fluctuation of the relative torque was observed, and a high relative torque or severe fluctuation was observed at high pH conditions than in other pH conditions. It can be concluded that Luvicap EG would perform well under a high pH and a high impeller speed with an enhanced effect by the addition of MEG. However, a low pH and a low impeller speed would be the worst combination of exacerbating the agglomeration of hydrate particles, which would result in hydrate blockage.

Powerful Synergy of Acetylenic Diol Surfactants with Kinetic Hydrate Inhibitor Polymers—Choosing the Correct Synergist Aqueous Solubility

“…Therefore, at such a small amount of water-tohydrate conversion, it is possible that the hydrates are still dispersed in the aqueous phase and not agglomerated or deposited. 34,35 When 1 mL of decane was added to the same system of 7500 ppm PVCap and 2500 ppm TMDD, the hold times decreased relative to the system without decane. This agrees with the SCC tests.…”

“…Vinyl caprolactam-based polymers such as PVCap are known to be good hydrate crystal growth inhibitors. Therefore, at such a small amount of water-to-hydrate conversion, it is possible that the hydrates are still dispersed in the aqueous phase and not agglomerated or deposited. , …”

Flow Assurance of Hydrate Risk in Natural Gas/Oil Transportation: State-of-the-Art and Future Challenges

“…When the hydrate is formed, irreversible aggregation between hydrate particles is the key factor that triggers hydrate adhesion, deposition, and ultimately blockage in wellbores and pipelines. ,,, Furthermore, the multiphase flow characteristics and flow pattern transformation in wellbores and pipelines also have a crucial impact on hydrate blockage. For subsea horizontal pipelines, there are three types of systems, oil-dominated, water-dominated, and gas-dominated, depending on the medium.…”

Navigating pH Influence: A Detailed Study on the Performance of Vitamin E-TS, Span-60, DTAB, and Monoethylene Glycol in Controlling Gas Hydrate Formation

“…An overview of the experimental apparatus is provided below, while an in-depth description has been reported in previous work. , Employed in this study was a high-pressure autoclave equipped with a magnetic stirrer coupling and a two-blade impeller (Figure ). A liquid volume of 200 mL was introduced into the autoclave cell, which possesses an internal volume of 510 mL.…”

“…Evaluating the performance of AAs and MEG, not only individually but also in combination, is crucial to understanding their efficacy in hydrate formation. , The significance of measuring properties during hydrate formation, particularly through torque measurements, provides insights into the resistance to flow and the agglomeration or bedding of hydrate particles. − This dual use of AAs and MEG necessitates a thorough investigation to elucidate the synergistic effects and benefits it brings to hydrate inhibition. , Moreover, understanding the correlation between the stability of the sample mixture, relative torque, and hydrate properties is essential. , Delving into the mechanisms underlying these relationships will offer valuable insights and contribute to the refinement of hydrate inhibition strategies. Numerous studies have delved into the intricacies of hydrate inhibition and antiagglomeration, examining the impact of varying conditions, the efficacy of different compounds, and the synergistic effects of compound combinations. ,,− These research efforts underscore the complexity of hydrate-related challenges and highlight the need for continued exploration and innovation.…”