Novel Correlations for Determining Appropriate Mono-Ethylene Glycol Injection Rate to Avoid Gas Hydrate Formation

2009 ◽  
Author(s):  
A. Bahadori ◽  
H.B. Vuthaluru ◽  
M.O. Tade ◽  
S. Mokhatab
Keyword(s):  
Ethylene Glycol ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Injection Rate ◽  
Gas Hydrate Formation

Scale Formation and Prevention in the Presence of Hydrate Inhibitors

SPE Journal ◽  
2006 ◽  
Vol 11 (02) ◽  
pp. 248-258 ◽  
Author(s):  
Mason B. Tomson ◽  
Amy T. Kan ◽  
Gongmin Fu ◽  
Musaed Al-Thubaiti ◽  
Dong Shen ◽  
...  
Keyword(s):  
Adverse Effect ◽  
Ethylene Glycol ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Triethylene Glycol ◽  
Scale Formation ◽  
Mineral Salts ◽  
Scale Inhibition ◽  
Gas Hydrate Formation ◽  
Mineral Scale

Summary There is no accepted methodology to correlate the effects of hydrate inhibitors on scale formation as there is for electrolytes. Similarly, the effect of hydrate inhibitor on scale inhibition with common inhibitors is not well known. In this paper, a semi-empirical approach is proposed to correlate the effect of hydrate inhibitors on scale formation from experimental solubility measurements of halite, barite, gypsum, calcite, and carbonate equilibrium chemistry. The ion-cosolvent activity coefficients can be used directly in any solution speciation code to evaluate the effect of cosolvent on mineral scale formation. The validity of the equation has been tested between 4 and 50°C as well as between 1 and 6 M ionic strength. Working equations that can be used in gas and oil production to calculate the effect of cosolvents on scale formation are presented. Details about how to predict hydrate-inhibitor-induced scale formation and case studies that demonstrate the severity of methanol on scaling tendency are also discussed. Finally, barite nucleation and kinetics are studied in the presence and absence of methanol. A semi-empirical equation to predict the nucleation time is proposed. Preliminary studies of scale-inhibitor efficiency in the presence of methanol are also discussed. At high methanol concentration, scale inhibition may not be possible because of precipitation of metal-inhibitor salt. Glycols have a less adverse effect than methanol on both mineral scale formation and inhibition. Introduction Methanol, ethylene glycol, and triethylene glycol are industrial solvents and raw materials for a variety of processes. In the oil and gas industries, methanol, ethylene glycol, and triethylene glycol are often used to inhibit gas-hydrate formation during production. Gas hydrate is a crystalline solid consisting of a gas molecule surrounded by a cage of water molecules, which forms at certain high-pressure and low-temperature regimes. Gas-hydrate formation is particularly troublesome for offshore gas wells, where the producing temperature is low because of both adiabatic expansion of gas and seawater cooling. Once gas hydrate forms, it can plug up the well and prevent gas production. One economic solution to prevent hydrate formation is to inject a large quantity of methanol, ethylene glycol, or triethylene glycol. These organic solvents are thermodynamic inhibitors (i.e., they increase the thermodynamic solubility of gas hydrate). This type of inhibitor is only effective at high cosolvent concentrations. Unfortunately, the use of high cosolvent concentration has an adverse effect on scale formation. because the mineral salts are generally less soluble in the cosolvent. Production from reservoir oilfield brines are often close to saturation as they enter a well; therefore, even a small amount of added methanol or ethanol is often sufficient to induce various minerals to precipitate. The scaling tendency of sparingly soluble mineral salts (e.g., calcite and barite) in methanol/brine and ethanol/brine solutions is observed to be orders of magnitude larger than in the brine alone. Halite scaling is also severely affected in the presence of methanol or ethanol. Ethylene glycol and triethylene glycol have less adverse effect on mineral-salt-scaling tendency.

Thermodynamic Modelling of Gas Hydrate Formation in the Presence of Inhibitors and the Consideration of their Effect

2014 ◽  
Vol 14 (1) ◽  
pp. 45
Author(s):  
Peyman Sabzi ◽  
Saheb Noroozi
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Low Temperatures ◽  
Hydrate Formation ◽  
Transportation Systems ◽  
Flow Lines ◽  
Main Approach ◽  
Efficient Inhibitor ◽  
System A ◽  
Gas Hydrate Formation

Gas hydrates formation is considered as one the greatest obstacles in gas transportation systems. Problems related to gas hydrate formation is more severe when dealing with transportation at low temperatures of deep water. In order to avoid formation of Gas hydrates, different inhibitors are used. Methanol is one of the most common and economically efficient inhibitor. Adding methanol to the flow lines, changes the thermodynamic equilibrium situation of the system. In order to predict these changes in thermodynamic behavior of the system, a series of modelings are performed using Matlab software in this paper. The main approach in this modeling is on the basis of Van der Waals and Plateau's thermodynamic approach. The obtained results of a system containing water, Methane and Methanol showed that hydrate formation pressure increases due to the increase of inhibitor amount in constant temperature and this increase is more in higher temperatures. Furthermore, these results were in harmony with the available empirical data.Keywords: Gas hydrates, thermodynamic inhibitor, modelling, pipeline blockage

scholarly journals Rapid Gas Hydrate Formation—Evaluation of Three Reactor Concepts and Feasibility Study

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3615
Author(s):  
Florian Filarsky ◽  
Julian Wieser ◽  
Heyko Juergen Schultz
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Synthetic Natural Gas ◽  
Operation Conditions ◽  
Gas Hydrate Formation ◽  
Gas Conditioning ◽  
And Storage ◽  
Economic Considerations ◽  
High Storage

Gas hydrates show great potential with regard to various technical applications, such as gas conditioning, separation and storage. Hence, there has been an increased interest in applied gas hydrate research worldwide in recent years. This paper describes the development of an energetically promising, highly attractive rapid gas hydrate production process that enables the instantaneous conditioning and storage of gases in the form of solid hydrates, as an alternative to costly established processes, such as, for example, cryogenic demethanization. In the first step of the investigations, three different reactor concepts for rapid hydrate formation were evaluated. It could be shown that coupled spraying with stirring provided the fastest hydrate formation and highest gas uptakes in the hydrate phase. In the second step, extensive experimental series were executed, using various different gas compositions on the example of synthetic natural gas mixtures containing methane, ethane and propane. Methane is eliminated from the gas phase and stored in gas hydrates. The experiments were conducted under moderate conditions (8 bar(g), 9–14 °C), using tetrahydrofuran as a thermodynamic promoter in a stoichiometric concentration of 5.56 mole%. High storage capacities, formation rates and separation efficiencies were achieved at moderate operation conditions supported by rough economic considerations, successfully showing the feasibility of this innovative concept. An adapted McCabe-Thiele diagram was created to approximately determine the necessary theoretical separation stage numbers for high purity gas separation requirements.

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