A Review of the Main Techniques to Avoid the Formation of Hydrates

Fonte, Sandra Soares Della; Simonelli, G.; Santos, Luiz Carlos Lobato dos

doi:10.5419/bjpg2018-0006

Cited by 4 publications

(1 citation statement)

References 13 publications

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“…Experimental procedures can be used to establish the thermodynamic curves (or gas hydrate envelope). The experimental data includes the pressure, temperature, gas composition, brine composition, and other elements that may be present in the fluid system flow in the pipeline. , An example of a gas hydrate envelope can be seen in Figure . The regions on the right of the curve represent the conditions at which there is no gas hydrate formation, while the regions on the left represent the conditions under which a gas hydrate may form.…”

Section: Introductionmentioning

confidence: 99%

Safer Dual-Functional Gas Hydrate Dissolver and Inhibitor to Replace Methanol

et al. 2021

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In the presence of free water and under certain conditions of temperature and pressure, low-molecular-weight gases such as methane and ethane present in the fluid stream flowing in pipelines cause the formation of gas hydrate crystals. These gas hydrate crystals may accumulate and cause a partial or complete plugging of pipelines in the vertical or horizontal section. Methanol has been used in the industry as an effective gas hydrate dissolver and inhibitor, but its low flashpoint temperature makes it unsafe to be stored and pumped in large volumes. The objective of the current work is to develop a safer dissolver and inhibitor for gas hydrate plugs that form in pipelines. Methanol has a very low freezing point (−90 °C) and it is completely miscible with water, which can shift the hydrate phase equilibrium to lower temperatures. Solvent- and aqueous-based formulations were selected as alternatives to methanol, keeping in mind parameters such as higher flashpoint, miscibility with water, freezing point, viscosity, and local availability. The performance of these formulations was evaluated in a see-through gas hydrate reactor. Representative gas and water compositions were used in the experiments to form the gas hydrate inside the reactor. Hydrate formation was detected by the change in torque or by visual inspection through the see-through window of the reactor. Methanol was able to mobilize the hydrate plug when used at 10 vol %, while complete dissolution was achieved at 30 vol %. In comparison, the potassium formate saturated solution achieved complete dissolution of the hydrate plugs at 10 vol % in a lesser time compared to methanol. The tested formulations worked not only as a dissolver but also as an inhibitor to prevent the formation of hydrates once they are melted or dissolved. These formulations enable safer operations in the field and improve the performance when it comes to melting gas hydrate plugs.

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Section: Introductionmentioning

confidence: 99%

Safer Dual-Functional Gas Hydrate Dissolver and Inhibitor to Replace Methanol

et al. 2021

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Coalescence process to treat produced water: an updated overview and environmental outlook

Almeida

Esquerre

Soletti

et al. 2019

Environ Sci Pollut Res

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From Laboratory to Field Applications: A Safer Gas Hydrate Dissolver to Replace Methanol

Sayed

Saini

Alali

et al. 2022

Day 4 Thu, May 05, 2022

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Low-molecular-weight hydrocarbon gases, such as methane and ethane, along with other low-molecular-weight species, such as CO2 and H2S, exist within the gas stream flowing through the pipelines used to transport natural gas and crude oils. Under certain conditions of low temperature and high pressure, and in the presence of free water molecules, gas-hydrate crystals will start to form. These gas hydrate crystals may accumulate and cause partial or complete plugging of the pipeline in the vertical or horizontal sections of the pipe. Methanol was previously found to be the only effective chemical able to clear gas hydrate plugs in many cases. The low flashpoint of methanol makes it unsafe to be pumped or stored in large volumes in hot regions such as in the Middle East. The main objective of the current work is to develop a safer chemical treatment with a higher flashpoint for the dissolution/mitigation of in-place gas hydrate plugs in pipelines. The parameters that make methanol an effective hydrate dissolver were investigated before development of the new hydrate dissolver. Methanol has a very low freezing point (-90°C) and is completely miscible with water. Solvent-based and aqueous-based formulations were chosen while considering parameters such as miscibility with water, freezing point, viscosity, and availability. The performance of these formulations was evaluated using a see-through gas hydrate cell. Pressure and temperature were modified to allow the formation of hydrates at simulated field conditions. Representative gas and water compositions were used in the experiments to form gas hydrate inside the gas hydrate cell. Hydrate formation can be detected either by detecting the change in torque on the stirring shaft or by visual inspection of the cell. The performance of these formulations was evaluated and compared to methanol. Two solvent-based formulations and two aqueous-based treatments met the flashpoint requirement and were effective in dissolving hydrate plugs at similar dosage when compared to methanol. These formulations proved to dissolve gas hydrate plugs in similar or less time than methanol. Two field trials were conducted to test one of the aqueous-based treatments and the outcome showed that the hydrate plug was dissolved in less than 17 minutes from the moment the aqueous solution was injected. The tested formulations have been shown to not only work as a dissolver, but also as an inhibitor to prevent the fresh formation of hydrate downstream. In addition to improving the performance of dissolving gas hydrate plugs in the pipelines, the use of these treatments has enabled safer operations in the field.

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A Review of the Main Techniques to Avoid the Formation of Hydrates

Cited by 4 publications

References 13 publications

Safer Dual-Functional Gas Hydrate Dissolver and Inhibitor to Replace Methanol

Safer Dual-Functional Gas Hydrate Dissolver and Inhibitor to Replace Methanol

Coalescence process to treat produced water: an updated overview and environmental outlook

From Laboratory to Field Applications: A Safer Gas Hydrate Dissolver to Replace Methanol

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