Hydrate Formation Temperature Research Articles

Rapid nucleation and growth of tetrafluoroethane hydrate enhanced by bubble and gas cycling

The application of hydrate technology is predominantly limited by the rapid nucleation and stable formation of hydrates, which could be promoted by the disturbance of bubbles. In this study, the effect of bubble generation and different bubble sizes on the nucleation and growth characteristics of R134a hydrates were investigated. The impact of three methods (depressurization-induced R134a vaporization, depressurization combined with stirring and gas cycling bubbling) of bubble effect and size on the nucleation, growth characteristics, and stability of R134a hydrate formation were explored. The research results indicate that utilizing only the depressurization method to induce R134a vaporization and bubble formation leads to a gas consumption rate of 19.6 mmol/min, which is 868 times higher than that in a pure water system. Furthermore, refining bubble size through stirring under depressurization conditions further augments the gas conversion rate by 8.6 %, and the optimal temperature for R134a hydrate formation is identified to be as low as 4 °C. Importantly, utilizing gas cycling as a means to generate bubbles enables uniform and rapid nucleation and growth of hydrates. Within a short 10 min, R134a hydrates was rapidly and stably formed, achieving a formation rate 35 times faster compared to the boiling-condensation method. In comparison to stirring-depressurization, the gas cycling method further increases the gas consumption rate by 10 %. The drawback of slow nucleation and growth rates in hydrates, as well as the need to enhance their stability, is addressed by the gas cycling method.

Exploring Machine Learning Techniques for Accurate Prediction of Methane Hydrate Formation Temperature in Brine: A Comparative Study

AbstractAccurate estimation of formation conditions plays a pivotal role in effectively managing various processes related to hydrates, including flow assurance, deep-water drilling, and hydrate-based technology development. The formation temperature of methane hydrates in the presence of brine greatly affects the efficacy and accuracy of these processes. This work presents a comprehensive and novel comparative analysis of nine distinct machine learning models for accurate prediction of formation temperatures of methane hydrate. This study investigated the application of major machine learning (ML) algorithms including multiple linear regression (MLR), long short-term memory (LSTM), radial basis function (RBF), support vector machine (SVM), artificial neural network (ANN), gradient boosting regression (GBR), gradient process regression (GPR), random forest (RF), and K-nearest neighbor (KNN). The model accuracy was validated against a large dataset comprising of over 1000 data points with diverse range of salt concentrations. In this regard, model accuracies were compared using several metrics including R2, ARD, and AARD. The experimental results exhibited KNN algorithm to be fast-converging, accurate, and consistent over the entire range of data points with an R2 score of 0.975 and AARD of 0.385%. The results enable efficient and accurate temperature estimation with ML algorithms for multiple hydrate-related processes.

Effective prevention of structure II gas hydrate formation using the newly synthesized kinetic inhibitors

Gas hydrate deposition is a complex issue with significant implications for the oil and gas industry. The formation of solid gas hydrates in the hydrocarbon transportation pipelines leads to production disruptions and potentially even complete blockages, resulting in huge financial losses and operational difficulties. For over two decades, kinetic gas hydrate inhibitors have played a crucial role in preventing the formation of gas hydrates within the flow lines of oil and gas production. They directly influence the kinetics of hydrate formation, hindering nucleation and slowing down crystal growth. In this study, five new waterborne polyurethanes (WPUs) with varying degrees of hydrophobicity as inhibitors for cubic structure II gas hydrates were synthesized and tested using rocking cells and differential scanning calorimetry. The synthesis of WPUs involved the reaction between dialkylamines (diethyl, dipropyl, dibutyl, dibenzyl, and dioctyl) and glycidol under mild conditions. All WPUs effectively prevented gas hydrate formation, and a correlation between their efficiency and the alkyl chain length was observed. The inhibitory efficacy of WPUs increased with the extension of the alkyl chain from ethyl to butyl. WPU-DBuA, featuring butyl groups, exhibited the highest inhibition activity. It provided a subcooling temperature of 12.9 and 15.6 °C at 0.25 and 0.5 wt%, respectively, surpassing commercial samples, such as Luvicap EG and Luvicap 55 W. Additionally, the solutions containing 1 and 2 wt% of WPU-DBu exhibited maximum subcooling temperatures of 16.2 °C and 16.7 °C, respectively, which correspond to a 79.7 % and 85.4 % reduction in gas uptake during hydrate growth compared to pure water. However, the inhibitory power of WPUs diminished with larger alkyl (dioctyl) or aromatic groups (dibenzyl), indicating that dibutyl represents the optimal alkyl length for achieving maximum performance. Moreover, WPUs demonstrated a reduction in hydrate conversion under static conditions, signifying their efficiency when the flow is stopped. WPUs lowered the onset temperature of hydrate formation from 3 °C in pure water to temperatures below −12 °C. Thus, WPUs demonstrated a remarkable ability to prevent the formation of structure II gas hydrates, even under high subcooling conditions. Additionally, WPU-DBuA exhibits a considerable degree of biodegradability, as evidenced by its biodegradation level of 44 %, suggesting that it has the potential to break down more easily in the environment compared to Luvicap 55 W. This research contributes to a deeper understanding of the structure–property relationships of KHIs. This can facilitate the development of more effective and eco-friendly inhibitors, which helps address environmental concerns associated with using KHIs in the oil and gas industry.

Direct measurement of hydrate equilibrium temperature in CO2 and CO2 rich fluids with low water content

A high-pressure experimental setup was used to obtain experimental data on the hydrate equilibrium (melting) temperature (HET) of hydrates formed from low water content CO2 and CO2 rich mixtures. A novel method was used to measure hydrate formation temperature in addition to melting temperature directly at realistic temperature/pressure conditions encountered in transport by pipelines or ship. The method can be used to evaluate the likelihood of hydrate formation in pipelines/ships transporting pure CO2 and CO2 coming from capture processes as well as from high CO2 content produced gas. The data generated from the measurement can also be used to investigate the kinetics of hydrate formation and dissociation in low water content fluids at pipeline/ship conditions. This paper details the experimental equipment, methods, test fluids and results. Experimental results are compared against predictions of the simplified cubic plus association equation of state (sCPA-EoS) coupled with the van der Waals and Platteeuw solid solution theory.

Analysis of Residual Pressure Power Generation in Natural Gas Pressure Regulating Station

Turboexpander, placed parallel to the regulator in natural gas pressure regulating station (PRS), was proposed to utilize the residual pressure by engineers and researchers. However, the relationship between the power generated by the turboexpander and the energy used to preheat the natural gas (NG) needs to be carefully analysed. This article estimated the electric power that could be generated using residual pressure based on an actual PRS in China. An analysis model was established to study the relationship between electric power generated by the turboexpander and energy used to preheat the NG. Pressures both inlet and outlet and inlet temperature of the established power generation model were carefully analysed as well as the natural gas hydrate formation temperature. The results indicate that the electric power generated by the turbine expander and the energy used to preheat natural gas decrease as the pressure difference decreases. Most of the energy needed to preheat NG in the procedure of PRS can be obtained through the established turboexpander. What’s more, residual electric power can be obtained when the difference pressure is less than the critical point in which the energy used to preheat NG is equal to the energy generated by the turboexpander.

Novel core–shell and recyclable gas hydrate promoter for efficient solidified natural gas storage

The storage and transportation of gases, including hydrogen, methane, and carbon dioxide in the form of gas hydrates, have recently garnered considerable attention. The practical implementation of gas hydrates crucially depends on the development of efficient and reusable promoters. In this study, novel core–shell magnetic nanoparticles (CSNs) developed as recyclable promoter to enhance gas uptake. Hydrate formation experiments indicated that the storage capacity can reach up to 132.7 ± 1.4 v/v and 160.6 ± 2.5 v/v in CSNs and CSNs + SDS solutions, respectively. Compared to pure water and SDS solution, the initial methane consumption rate (0.5972 mol/h) of CSNs increased by 12.2 times and 1.08 times at 3000 ppm, respectively. CSNs exhibited favorable characteristics in terms of cycling ability and preventing foam formation during repeated methane hydrate formation and dissociation experiments. Furthermore, the combination of CSNs and SDS resulted in a 72 % reduction in hydrate nucleation induction time and a 58.3 % decrease in foam formation ability compared to the sole use of SDS. In comparison to pure water, the addition of CSNs increased the onset temperature of hydrate formation by 4 °C and reduced the driving force required for methane hydrate formation. Additionally, molecular dynamics simulation studies revealed that CSNs effectively improved the amount of the ordered water structure, hydrate cage formation, and the growth state of methane hydrates. These properties make CSNs promising for potential use in the storage and transportation of gas, considering the economic and environmental advantages associated with the use of promoters.

Development of explicit models to predict methane hydrate equilibrium conditions in pure water and brine solutions: A machine learning approach

An important phase in the design of processes involving gas hydrates is predicting the hydrate formation conditions. In this study, three explicit correlations based on machine learning techniques, gene expression programming (GEP), and optimizing two correlations with predetermined structures were developed for the prediction of methane hydrate formation temperature (HFT) in pure water and brines. The proposed correlations are based on the pressure and ionic strength (IS) of solutions. Compared to the literature, this is the first time that the effect of salinity has been considered in the development of explicit models to predict methane HFT. To achieve practical correlations, the least number of coefficients was used. The error analysis revealed an acceptable agreement with the experimental data. Among the models, GEP-based correlation provided the best performance with an R2 and AARD of 0.8860 and 0.087%, respectively. The developed correlations are easy-to-use and accurate for both academics and non-academics.

Predicting the phase equilibria of refrigerant gas hydrate systems in the presence of electrolytes using molecular theory

Hydrate-based desalination (HyDesal) has been proposed as one of the promising technologies to remove salts from seawater and brackish water. At the appropriate temperature and pressure, water molecules in brine can form cages around a guest molecule, thereby forming a separate ice-like solid phase that is free of salt. The process can be energy intensive due to the high refrigeration load required to cool the brine and gas feed below the hydrate formation temperature. Fluorinated refrigerants have been proposed as potential guest molecules that can form hydrates near ambient conditions, thus minimizing the energy requirement of the process. Hence, understanding the inhibition effect of electrolytes on the phase behavior of refrigerant hydrates is vital for the design and optimization of HyDesal processes. We present a molecular model that is based on the electrolyte, polar, and perturbed chain form of the statistical associating fluid theory (e-Polar PC-SAFT) combined with the solid solution theory of van der Waals and Platteeuw to fully predict the three-phase equilibria of pure and mixed hydrochlorofluorocarbon and hydrofluorocarbon systems in the presence of NaCl, KCl, CaCl2, and MgCl2. The model captures the effect of the refrigerant structure on the hydrate dissociation conditions and the effect of cation size and charge number on the thermodynamic inhibition of gas hydrates well. Based on a detailed thermodynamic and environmental analysis, three refrigerants (R-32, R-152a, and R-410A) are shortlisted as viable options for HyDesal. All three refrigerants can form hydrates under reasonable conditions, and their phase equilibria show weak dependence on salt concentration.

RATIONALE FOR CHOOSING CORRELATIONS FOR GAS HYDRATE FORMATION TEMPERATURE COMPUTATION FOR GASES OF VARIOUS COMPOSITIONS

Gas hydrates are the object of continuous research in the oil and gas industry. Gas hydrates can form in gas production systems: in the bottomhole zone, in the wellbores, in plumes and infield reservoirs, in gas treatment systems, as well as in main gas transport systems, causing serious problems associated with the disruption of these processes. However, recently, the gas industry has found new uses for hydrates (for example, energy recovery, separation, storage, and transportation of gas) prompting scientists to conduct new and more detailed studies of the hydrate formation process.
 Understanding the conditions and mechanisms of hydrate formation makes an engineer able to control this process. Therefore, in practice, simplified models are often required to predict hydrate formation. This paper presents various correlations that are widely used in the oil and gas industry to determine the temperature of hydrate formation. The accuracy of the presented models is compared. The influence of the features of the gas composition on the conditions for the hydrates formation is studied.
 It is shown that for the considered gases, the most accurate results can be obtained using the G.V. Ponomarev correlation. When the relative density of gases is greater than 0.6, it is possible to use the Towler and Bahadori correlations. Correlations proposed by Hammerschmidt, Mottie and Berge show the worst results.
 Since the temperature of hydrate formation in the considered correlations does not depend on the gas composition, but only on the relative density, the influence of the content of non-hydrocarbon components on the temperature of hydrate formation was studied in this work. It was found that the content of hydrogen sulfide has the greatest influence. Moreover, at high contents of hydrogen sulfide in the gas composition, the temperature of hydrate formation shifts towards higher values. The content of nitrogen and carbon dioxide to a lesser extent affect the value of the temperature of hydrate formation.

Development of novel natural gas hydrate inhibitor and the synergistic inhibition mechanism with NaCl: Experiments and molecular dynamics simulation

Drilling fluid systems with exceptional performance serve as a foundation for commercial hydrate extraction. However, most hydrate reservoirs are located at relatively deep water depths and have shallow burial depths. As a result, there are high demands on the density of a hydrate drilling fluid system. Thus, the traditional hydrate drilling fluid system no longer meet the drilling needs in deep water shallow hydrate reservoirs. In this paper, a copolymer SYZ-2 was synthesized based on N-Vinyl-ε-caprolactam and N, N-dimethyl acrylamide. The effects of SYZ-2 and its NaCl system on methane hydrate were first tested by a constant rate cooling method, and the inhibition mechanisms of the system on hydrate nucleation and formation were investigated by molecular simulations. Meanwhile, the formulation and properties of a low-density hydrate drilling fluid system (1.06 g/cm3) based on SYZ-2 were also described in detail. The experimental results show that the hydrate formation temperature with the influence of SYZ-2 decreases from 10.6 °C to 2.7 °C, which can even be significantly reduced to −3.1 °C in the presence of 7 % NaCl. The molecular dynamic simulation results show that SYZ-2 inhibits the nucleation of hydrates by decreasing the solubility of methane molecules, primarily by promoting the agglomeration of methane molecules. Additionally, SYZ-2 can also adsorb to the surface of hydrates and prevent the hydrate cage structure from capturing methane molecules. In contrast, NaCl inhibits hydrates formation by restricting the movement of water molecules. These results provide valuable insights into a better understanding of the gas hydrate inhibition mechanisms, the rational development of high-performance hydrate inhibitors for drilling fluids, as well as the construction of drilling fluid systems.

Thermodynamic modeling for ternary clathrate hydrates of carbon dioxide, nitrogen and tetrahydrofuran

Hydrate-based CO2 separation technology is one of research hotspots in the field of Carbon Capture, Utilization, and Storage. However, thermodynamics, such as phase temperature and pressure, are very important for CO2 separation. In this study, a thermodynamic model was developed for calculating the temperature, pressure, separation efficiency and separation factor of the CO2-N2-THF/H2O system at the three-phase equilibrium of vapor–liquid-hydrates (V-L-H). The Chen-guo model was applied for the hydrate phase and the Patel-Teja equation of state (EOS) was used for the vapor phase. The Wilson activity coefficient model was employed for the liquid phase and the solubility of CO2 in solution was calculated using Henry's law. The average absolute deviation of the equilibrium pressure and temperature compared to the experimental data are 10.441% and 0.343%, respectively, which showed that the predicted three-phase equilibrium pressure and temperature were in good agreement with the experimental results. The three-phase equilibrium temperature and pressure of CO2 and N2 gas mixture in pure water and in THF aqueous solutions were compared. The results showed that THF had a promotion effect in reducing temperature and pressure of CO2 hydrate formation.

Evaluation of phase equilibrium conditions of clathrate hydrates in natural gas binary mixtures: Machine learning approach

Hydrate formation temperature (T) is an important parameter for any industrial process that deals with natural gas hydrates. In this study, the Group Method of Data Handling (GMDH) approach is used to predict hydrate formation T in natural gas binary mixtures. A comprehensive database containing 728 data samples is compiled from 46 published experimental works. To find the best combination of input variables, different sets of input variables were assessed. A total of seven models were developed using different sets of input variables. Compared to the correlations proposed in the literature, the developed models in this study performed better and the model developed based on input Set #7 was the most accurate: RMSE values of 1.6381 and 1.5499 for the training and testing datasets, respectively. All models also were evaluated using a blind dataset-that was not included in testing or training-to check model applicability to wider data. Similarly, all GMDH models performed excellently for the external dataset, where the developed model based on input Set #5 showed the best performance: RMSE values of 1.3482. The findings of this study contribute to our understanding of hydrate formation conditions in natural gas binary mixtures. As pure and binary mixtures of natural gas main constituents are studied, the results can be especially useful for purification and energy transport applications.

Novel Amino Acid Derivatives for Efficient Methane Solidification Storage via Clathrate Hydrates without Foam Formation

Although anionic surfactants are considered the most efficient kinetic gas hydrate promoters for gas storage applications, gas recovery and reuse of surfactants are difficult due to high foam formation during hydrate melting. Additionally, most anionic surfactants are toxic, which has an intense environmental effect. In this study, novel amino acid derivatives (ACDs) were developed as the first class of superior promoters compared to surfactants without foaming during the formation and recovery of gas hydrates. The results of high-pressure autoclave experiments indicated that all ACDs significantly enhanced the kinetics of methane hydrate formation at 500 ppm. ACD5 derived from leucine showed the best promotion effect in distilled water by providing a total mole consumption of 436.1 mmol. ACD5 increased the degree of water-to-hydrate conversion from 39.6% in pure water to 94.3%, which was higher than in sodium dodecyl sulfate (SDS) solution (87.8%). Moreover, differential scanning calorimetry experiments demonstrated that ACDs could form methane hydrates at relatively lower temperatures than pure water. They increased the onset temperature of methane hydrate formation from −15 °C in pure water to −12 °C at 500 ppm. A higher promotion activity than SDS was also observed for ACDs in salt water, suggesting that seawater can be used to produce methane hydrate instead of pure water to reduce gas storage costs. Besides, visual observations revealed that no foam was formed during melting hydrates and releasing methane in the presence of ACDs. These findings show that a slight modification of amino acids makes them efficient candidates for improving gas hydrate formation for seawater desalination and gas storage applications.

Microscopic insights into synergism effect of different hydrate inhibitors on methane hydrate formation: Experiments and molecular dynamics simulations

To reveal the synergism effect of hydrate inhibitors on the formation of methane hydrate was the key to developing new gas hydrate inhibitors and drilling and completion fluid systems. The characteristics of hydrate formation under thermodynamic inhibitors, kinetic inhibitors, and their compound systems were investigated by experiments and molecular simulations from macroscopic and microscopic points of view, respectively. The experimental results presented that a thermodynamic inhibitor was able to significantly reduce the hydrate formation temperature in combination with a kinetic inhibitor, where a compound system of 1% PVP and 5% CaCl2 was comparable to 9.76% CaCl2, or 10.84% NaCl, or 19.85% MEG for the formation of hydrate. The molecular simulation results showed that the thermodynamic inhibitors (NaCl) reduced the steric effects of the kinetic inhibitors (PVP) by limiting the motion of water molecules, which enhanced the effect of inhibitors on methane molecules and accelerated the aggregation of those to form nanobubbles. This study helps us to understand the mechanism of a synergism effect with different hydrate inhibitors on methane hydrate formation and is of applicable importance to develop new natural gas hydrate inhibitors and drilling and completion fluid systems.

Machine learning models for fast selection of amino acids as green thermodynamic inhibitors for natural gas hydrate

Natural amino acids are non-toxic thermodynamic hydrate inhibitors without negative environmental impact, but it is difficult to accurately select the appropriate amino acid as a quick response to the operational conditions changes in the natural gas pipeline. The objective of this study was to develop mathematical models to predict the hydrate formation temperature (HFT) in presence of amino acids, capture the relationship between amino acid structure properties and their hydrate inhibition strength, and determine the optimal type and concentration to use. The HFT prediction was evaluated using multiple linear regression (MLR) and three machine learning methods including random forest (RF), M5 Rule (M5R) and support vector machine (SVM). After parameter optimization using the trial-and-error method, the coefficient of determination (R2) of the four models were 0.9328, 0.9793, 0.9795 and 0.9980, respectively. The SVM prediction of HFT outperformed other models as the root mean square error (RMSE) was 83%, 76% and 69% lower than that of the MLR, RF and M5R, respectively. Results also demonstrated that the relative importance of the amino acid concentration to the hydrate phase equilibrium was 5-fold higher than that of the intrinsic properties of the amino acid molecular. The SVM model proposed in this study served an easy-to-use tool for reliable prediction of HFT by just providing a new set of input data. This made it possible to accurately determine the minimum concentration of amino acids to be used during the gas pipeline transportation.

Thermophysical property analysis of semi-clathrate hydrates of tetrabutyl-(ammonium/phosphonium) salts as phase change materials for cold storage

Hydrate has attracted extensive attention because of its adjustable phase change temperature and high cold storage density. In this paper, the thermophysical properties of semi-clathrate hydrates as the phase change materials (PCMs) formed by aqueous solutions of tetrabutyl-(ammonium/phosphonium) salts (TBAF, TBAC, TBAHSO4, and TBPB) with different concentrations (0.05∼0.44, mass fraction) were systematically studied, including formation/dissociation temperature, phase change enthalpy, cycle performance and hydrate number. The results showed that semi-clathrate hydrate had good cycle performance during cold storage and release. The randomness of hydrate formation temperature was much less than that of ice, which suggested the hydrate formation conditions were more controllable. With the increase of solution concentration, the apparent driving force for hydrate formation decreased, and the proportion of hydrate in total enthalpy increased from 5% to 100%. In addition, the adjustable range of phase change temperature of semi-clathrate hydrate formed by the solution above is 0.61∼27.9 °C, where ranged from high to low is TBAF, TBAC, TBPB, and TBAHSO4. The total phase change enthalpy was about 122∼302.6 kJ/kg. The range of the maximum, intermediate and minimum hydrate number of TBAHSO4 hydrate crystal were estimated to be 35∼38.7, 32∼35, and 24∼28.3, respectively, by dissociation temperature and enthalpy analysis using differential scanning calorimeter (DSC). This study could form the basis for energy saving in water-based cold storage process. According to the needs of different cold storage temperatures, different salt solutions can be selected as cold storage media, so as to achieve the purpose of energy saving.

Prevention and removal of hydrate formation at the Amangeldy gas field

Currently, antihydrate inhibitors such as methanol and diethylene glycol are used to reduce the temperature of hydrate formation during the transportation of gas and gas condensate in in-field gas pipelines, i.e. in plumes. If the desired results are not obtained during the production of gas and gas condensate without the use of anti-hydrate inhibitors (during operation, a certain volume of produced gases and condensate is blown onto a flare or a bleeder stack), this may, in turn, lead to a shutdown of the well, as a result of which the volume of production will also decrease.

Oxyvinylenelactam Polymers-A New Class of Lactam-Based Kinetic Hydrate Inhibitor Polymers.

The deployment of kinetic hydrate inhibitors (KHIs) is a chemical method for the prevention of gas hydrate plugging in gas, condensate, and oil production flow lines. Polymers made using the monomer N-vinylcaprolactam (VCap) are one of the most common KHI classes. Alternative classes of polymers containing caprolactam groups are rare. Here, we present a study on oxyvinylenelactam polymers and copolymers with pendant piperidone or caprolactam groups. Low-molecular-weight homo- and copolymers were obtained. The nonrotating vinylene groups impart rigidity to the polymer backbone. Poly(oxyvinylenecaprolactam) (POVCap) was insoluble in water, but poly(oxyvinylenepiperidone) (POVPip) and OVPip:OVCap copolymers with 60+ mol % OVPip were soluble with low cloud points. KHI screening tests were carried out using the slow constant cooling method in steel rocking cells. POVPip was water soluble with no cloud point up to 95 °C but showed a poor KHI performance. In contrast, OVPip:OVCap copolymers with about 60–70 mol % OVPip were also water soluble and showed a reasonable KHI performance, better than that of poly(N-vinylpyrrolidone) but not as good as that of poly(N-vinylcaprolactam). Surprisingly, several additives known to be good synergists for VCap-based polymers showed negligible synergy or were antagonistic with the 62:38 OVPip:OVCap copolymer with regard to lowering the onset temperature of hydrate formation. However, a blend with hexabutylguanidinium chloride showed a strong effect to delay the onset of rapid hydrate formation.

Effects of ethylene glycol on hydrate formation in subsea pipelines

This study evaluated the effect of Mono-Ethylene Glycol (MEG) on hydrate formation conditions in subsea pipelines for a typical gas deepwater field in Nigeria, using a flow assurance simulator 'PIPESIM'. At the turndown, normal and maximum conditions, the production rates were 1640, 2460, and 3280 sm3/day, respectively. The wellhead temperature varies between 50-55oC, and the inlet pressure at the wellhead is 25 bara. The outlet pressure at the topside facility must be 11 bara and above to achieve flow. From available flowline internal diameters of 0.24, 0.29, and 0.34m, a simulation was run to determine a suitable internal diameter which will not lead to erosion due to the velocity. In deciding the hydrate formation temperature, the wellhead pressure of 25 bara was utilized to run the estimation. Also, in determining the minimum MEG volume required to achieve flow above a hydrate appearance temperature of 30 °C, a simulation was run at MEG volumes of 0, 10, 20 and 30 wt%. From the simulations, hydrates were observed to form at a temperature of 11.4 °C, at the minimum MEG volume of 30wt%. The 30wt% MEG suppressed the hydrates to a temperature of 8.9 °C. A slug volume of 8.5m3 was observed to be adequate to ensure fluid transport to the topside. This work's outcomes and findings also suggest a flowline inner diameter of 0.29m, an overall heat transfer coefficient of 0.81W/m2oC, and an optimum flow rate of 3280 sm3/day to avoid temperature drop to be optimum for flow assurance.

Efficient Storage of Methane in Hydrate Form Using Soybean Powder

Natural gas is a promising future source for the increasing energy demand. It is partially clean energy with fewer environmental impacts, and it is necessary to develop technologies to cater to the supply chain. Due to their inherent structural properties, gas hydrates or clathrate hydrates are promising materials for capturing and storing methane gas. In the present study, the experimental investigations were performed to assess the utilization of soybean powder (SBP) as a promoting additive compared to sodium dodecyl sulfate (SDS) for methane hydrate formation. The methane hydrate formation temperature and pressure with SBP are 277.8 ± 3.2 K, 7050.9 ± 76.2 kPa, similar to SDS 277.2 ± 0.3 K, 7446.3 ± 5.7 kPa in the non-stirred system. The gas uptake capacity is about 94.2 ± 4.5 v/v and 92.4 ± 4.6 v/v with SBP and SDS, which is ~60% of the practical, achievable limit. The time for the 90% of hydrate conversion is ~4.6 times higher for SBP than SDS. The more prolonged kinetics is ascribed to the complex constituents in the SBP. In contrast to the SDS solution, no foam was produced in the sample of the SBP solution. The current studies demonstrate that SBP can be utilized to develop cleaner and more effective promoters for methane hydrate formation without foam creation.