The Experts below are selected from a list of 17598 Experts worldwide ranked by ideXlab platform
Mahmut Parlaktuna - One of the best experts on this subject based on the ideXlab platform.
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Hydrate Formation Conditions of Methane Hydrogen Sulfide Mixtures
Energy Sources Part A: Recovery Utilization and Environmental Effects, 2014Co-Authors: S. Bulbul, Mahmut Parlaktuna, Tanju Mehmetoğlu, U. KarabakalAbstract:The objective of the study is to determine Hydrate Formation conditions of methane-hydrogen sulfide mixtures. An experimental work is carried out with different H2S concentrations and both brine and distilled water. The Black Sea conditions, which are suitable for methane-hydrogen sulfide Hydrate Formation, are examined. Effects of H2S concentration and salinity on the Hydrate Formation conditions are also obtained during the study. It is concluded that an increase in the salinity shifts the methane-hydrogen sulfide Hydrate equilibrium condition to lower equilibrium temperatures at a given pressure. With an increase in H2S concentration, the methane hydrogen sulfide Hydrate Formation conditions reach higher equilibrium temperature values at a given pressure.
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Black Sea Hydrate Formation Conditions of Methane Hydrogen Sulfide Mixtures
Energy Sources Part A: Recovery Utilization and Environmental Effects, 2014Co-Authors: S. Bulbul, Mahmut Parlaktuna, Tanju Mehmetoğlu, U. KarabakalAbstract:The objective of the study is to examine Hydrate Formation conditions of methane-hydrogen sulfide mixtures providing the Black Sea conditions. An experimental work is carried out by using a system that contains a high-pressure Hydrate Formation cell with different H2S concentrations and both brine and distilled water. Hydrate equilibrium conditions, the number of moles of free gas in the Hydrate Formation cell, and rate of Hydrate Formation are determined. Effects of H2S concentration on the Hydrate Formation conditions are also obtained during the study. It is observed that with an increase in H2S concentration, the methane hydrogen sulfide Hydrate Formation conditions reach higher equilibrium temperature values at a given pressure. According to the experimental results, it is concluded that the Black Sea has suitable conditions for Hydrate Formation of methane hydrogen sulfide mixtures.
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Promotion Effect of Polymers and Surfactants on Hydrate Formation Rate
Energy & Fuels, 2002Co-Authors: Ugur Karaaslan, Mahmut ParlaktunaAbstract:The promotion effect of two polymers and three surfactants on methane Hydrate Formation was investigated in a high-pressure system. For all of the tested chemicals, 1 wt % aqueous solutions were prepared and methane Hydrate was formed in those media to detect their effect on Hydrate Formation rate. It was determined that Igepal-520 is the most effective promoter on methane Hydrate Formation rate with respect to a reference test carried out by using only pure water.
Bao-jiang Sun - One of the best experts on this subject based on the ideXlab platform.
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Experimental Investigation of Methane Hydrate Formation in the Carboxmethylcellulose (CMC) Aqueous Solution
SPE Journal, 2020Co-Authors: Zhi-yuan Wang, Litao Chen, Bao-jiang SunAbstract:Summary In the development of deepwater crude oil, gas, and gas Hydrates, Hydrate Formation during drilling operations becomes a crucial problem for flow assurance and wellbore pressure management. To study the characteristics of methane Hydrate Formation in the drilling fluid, the experiments of the methane Hydrate Formation in water with carboxmethylcellulose (CMC) additive are performed in a horizontal flow loop under flow velocity from 1.32 to 1.60 m/s and CMC concentration from 0.2 to 0.5 wt%. The flow pattern is observed as bubbly flow in experiments. The experiments indicate that the increase of CMC concentration impedes the Hydrate Formation while the increase of liquid velocity enhances Formation rates. In the stirred reactor, the Hydrate Formation rate generally decreases as the subcooling condition decreases. However, in this work, with the subcooling condition continuously decreasing, Hydrate Formation rate follows a “U” shaped trend—initially decreasing, then leveling out and finally increasing. It is because the Hydrate Formation rate in this work is influenced by multiple factors, such as Hydrate shell Formation, fracturing, sloughing, and bubble breaking up, which has more complicated mass transfer procedure than that in the stirred reactor. A semiempirical model that is based on the mass transfer mechanism is developed for current experimental conditions, and can be used to predict the Formation rates of gas Hydrates in the non-Newtonian fluid by replacing corresponding correlations. The rheological experiments are performed to obtain the rheological model of the CMC aqueous solution for the proposed model. The overall Hydrate Formation coefficient in the proposed model is correlated with experimental data. The Hydrate Formation model is verified and the predicted quantity of gas Hydrates has a discrepancy less than 10%.
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characterizing methane Hydrate Formation in the non newtonian fluid flowing system
Fuel, 2019Co-Authors: Zhi-yuan Wang, Jianbo Zhang, Wenguang Duan, Zhennan Zhang, Bao-jiang SunAbstract:Abstract Developing natural gas Hydrates in deep water faces serious well control problem and flow assurance problem, induced by the reFormation of gas Hydrate in the drilling fluid. In order to solve this problem, developing a Hydrate Formation predicting model becomes necessary. In this work, the methane Hydrate Formation experiments are performed in the xanthan gum (XG) aqueous solution under flow velocities from 1.8 to 1.5 m/s, XG concentrations from 0.1 to 0.3% and void fraction of 4.5%. The Hydrate Formation rates decrease with the XG concentration increasing and increases with the flow velocity increasing. The Hydrate Formation rate at the moment of the experiment onset will decrease sharply due to the Formation of Hydrate shell on gas bubbles and gas Hydrates will form at the almost constant rate, because the second growth of Hydrate shells on the fractures of gas bubbles and collisions between gas bubbles enhances the Hydrate Formation rates. The Hydrate Formation rate increases rapidly when the Hydrate Formation process is near the end of Hydrate Formation since the breakage rates of gas bubbles increase the Hydrate Formation rates. A mass transfer model is developed to describe the methane Hydrate Formation under the non-Newtonian fluid flowing condition. Since the volumetric mass transfer coefficient closely depends on the rheological properties of carrying fluid, the rheological experiments for the XG aqueous solution are conducted and an empirical rheology model is developed correspondingly. An integrated constant is proposed to improve the accuracy of the model which reflects influences of the Hydrate shell Formation, the second growth of Hydrate shell and the bubble breakage on methane Hydrate Formation. The correlations of the integrated constant are functions of the XG concentration, the flow velocity and the subcooling temperature. Through validation, the proposed mass transfer model shows good agreements with experimental data and the maximum discrepancy is 11.64%.
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Experimental Study of Methane Hydrate Formation in Water-Continuous Flow Loop
2019Co-Authors: Zhi-yuan Wang, Xinjian Yue, Jianbo Zhang, Bao-jiang SunAbstract:As the offshore oil and gas fields are maturing, the water production rate from the reservoir is increasing progressively year by year. The methane Hydrate Formation in water-continuous systems has become a significant flow assurance issue for offshore oil and gas production. In this study, a group of methane Hydrate Formation experiments are designed to study characteristics of Hydrate Formation in the water-continuous flow loop, which were performed under void fractions from 2.6 to 5.0%, flow velocities from 1.24 to 1.57 m/s, subcooling temperatures from 4.5 to 7.2 °C, and Hydrate particle concentration from 0 to 0.14 kg/kg. The methane Hydrate Formation process is considered as a mass transfer process, and the multiple influencing factors on the Hydrate Formation are analyzed experimentally, such as flow velocity, subcooling temperature, and Hydrate particle concentration. Results show that higher flow velocity induces higher Hydrate Formation rate. Higher Hydrate particle concentration results in lower Hydrate Formation rate. Thus, an integrated mass transfer coefficient is proposed, including the effect of the Hydrate particle concentration and the flow velocity. In this work, the effect of subcoolings on the integrated mass transfer coefficient is found to be negligible. A corresponding mass transfer-limited Hydrate Formation model is proposed to predict methane Hydrate Formation in the water-continuous system, which is a function of the proposed integrated mass transfer coefficient, flow velocity, Hydrate particle concentration, subcooling, and gas–liquid interfacial area. After comparing with experimental data, the proposed Hydrate Formation model shows its good agreement with experimental data
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Hydrate Formation/Dissociation in (Natural Gas + Water + Diesel Oil) Emulsion Systems
Energies, 2013Co-Authors: Chang-sheng Xiang, Guang-jin Chen, Chang-yu Sun, Bao-zi Peng, Huang Liu, Bao-jiang SunAbstract:Hydrate Formation/dissociation of natural gas in (diesel oil + water) emulsion systems containing 3 wt% anti-agglomerant were performed for five water cuts: 5, 10, 15, 20, and 25 vol%. The natural gas solubilities in the emulsion systems were also examined. The experimental results showed that the solubility of natural gas in emulsion systems increases almost linearly with the increase of pressure, and decreases with the increase of water cut. There exists an initial slow Hydrate Formation stage for systems with lower water cut, while rapid Hydrate Formation takes place and the process of the gas-liquid dissolution equilibrium at higher water cut does not appear in the pressure curve. The gas consumption amount due to Hydrate Formation at high water cut is significantly higher than that at low water cut. Fractional distillation for natural gas components also exists during the Hydrate Formation process. The experiments on Hydrate dissociation showed that the dissociation rate and the amount of dissociated gas increase with the increase of water cut. The variations of temperature in the process of natural gas Hydrate Formation and dissociation in emulsion systems were also examined
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Prediction of gas Hydrate Formation region in the wellbore of deepwater drilling
KeAi Communications Co. Ltd., 2008Co-Authors: Zhi-yuan Wang, Haiqing Cheng, Bao-jiang Sun, Yong-hai GaoAbstract:It is essential to consider the thermodynamics, temperature, and pressure conditions of gas Hydrate Formation in order to predict the gas Hydrate Formation region in the wellbore of deepwater drilling. Multiphase flow governing equations (including continuity equation and momentum conservation equation), temperature field equations in annulus and drill pipe, and Hydrate Formation thermodynamics equation are established based on the characteristics of deepwater drilling. The definite conditions, discrete methods, and iterative steps are given to solve the equations under different working conditions. Through examples of calculation, the impacts of relevant parameters on gas Hydrate Formation region during drilling, off drilling, and well killing process are discussed. The result shows that the Hydrate Formation region is getting small when circulation volume becomes great, inhibitor concentration becomes high, downtime becomes short, or choke line size becomes large. And the result also indicates that it is more efficient to consider multifactors to suppress Hydrate Formation. The parameters can be optimized based on the method. Key words: deepwater drilling, natural gas Hydrate, multiphase flow governing equation, temperature field, thermodynamics equatio
Carolyn A. Koh - One of the best experts on this subject based on the ideXlab platform.
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Hydrate Formation from high water content crude oil emulsions
Chemical Engineering Science, 2008Co-Authors: David Greaves, John A Boxall, James Mulligan, Dendy E Sloan, Carolyn A. KohAbstract:Methane Hydrate Formation and dissociation studies from high water content (>60vol% water) – crude oil emulsions were performed. The Hydrate and emulsion system was characterized using two particle size analyzers and conductivity measurements. It was observed that Hydrate Formation and dissociation from water-in-oil (W/O) emulsions destabilized the emulsion, with the final emulsion formulation favoring a water continuous state following re-emulsification. Hence, following dissociation, the W/O emulsion formed a multiple o/W/O emulsion (60 vol% water) or inverted at even higher water cuts, forming an oil-in-water (O/W) emulsion (68 vol% water). In contrast, Hydrate Formation and dissociation from O/W emulsions (⩾71vol% water) stabilized the O/W emulsion.
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Mechanisms of gas Hydrate Formation and inhibition
Fluid Phase Equilibria, 2001Co-Authors: Carolyn A. Koh, Robin E. Westacott, W. Zhang, K. Hirachand, Jefferson L. Creek, Alan K. SoperAbstract:Abstract The Formation of gas Hydrates in gas and oil subsea pipelines often results in blockage and shutdown of these pipelines. Modern control methods depend on understanding the mechanisms through which gas Hydrates form. This paper reviews our recent studies of clathrate Hydrate Formation and inhibition mechanisms using neutron diffraction, differential scanning calorimetry (DSC) and a multiple cell photo-sensing instrument. The structural transFormations of water around methane during methane Hydrate Formation have been studied using neutron diffraction with isotope substitution over the temperature range 4–18 °C and at pressures of 3.4–14.5 MPa. The hydration sphere around methane in the liquid only changes significantly when methane Hydrate is formed, with the water shell in the crystalline Hydrate being about 1 A larger than the shell in the liquid. The hydration shell is disordered during methane Hydrate Formation, with ordering of solvent separated methane molecules occurring only when Hydrate has formed. The effects of the addition of three low dosage Hydrate inhibitors, PVP, VC-713 and QAB on THF Hydrate Formation at the surface and in bulk solution have been examined. The QAB inhibitor exhibits the greatest Hydrate crystal growth control, while VC-713 is most effective at inhibiting Hydrate nucleation. Insight into the perturbations on host and guest molecules due to the presence of these inhibitor molecules has been obtained.
Peter G. Kusalik - One of the best experts on this subject based on the ideXlab platform.
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Induction Time of Hydrate Formation in Water-in-Oil Emulsions
Industrial & Engineering Chemistry Research, 2017Co-Authors: Haimin Zheng, Qiyu Huang, Wei Wang, Zhen Long, Peter G. KusalikAbstract:Blockage of pipelines due to Hydrate Formation is a major problem for subsea flow assurance. Induction time for Hydrate Formation from the multiphase system within a pipeline is a critical parameter to determine whether Hydrates may form at a given time. In this work, the induction time for Hydrate Formation in water-in-oil emulsions was investigated under different conditions. For this purpose, an autoclave with an online viscometer was designed and built. Based on the viscosity variation observed in the experiments during Hydrate Formation, a new avenue for defining induction time is proposed, which should be more convenient for determining the Hydrate Formation time in some pipelines. As Hydrate Formation in emulsions is more complicated than in pure water, the effects of several factors were considered in this study, including water cut of the emulsions, shear rate, driving force, and memory effect. Additionally, wax precipitation is also a common problem in subsea pipelines and can impact flow assura...
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Induction Time of Hydrate Formation in Water-in-Oil Emulsions
2017Co-Authors: Haimin Zheng, Qiyu Huang, Wei Wang, Zhen Long, Peter G. KusalikAbstract:Blockage of pipelines due to Hydrate Formation is a major problem for subsea flow assurance. Induction time for Hydrate Formation from the multiphase system within a pipeline is a critical parameter to determine whether Hydrates may form at a given time. In this work, the induction time for Hydrate Formation in water-in-oil emulsions was investigated under different conditions. For this purpose, an autoclave with an online viscometer was designed and built. Based on the viscosity variation observed in the experiments during Hydrate Formation, a new avenue for defining induction time is proposed, which should be more convenient for determining the Hydrate Formation time in some pipelines. As Hydrate Formation in emulsions is more complicated than in pure water, the effects of several factors were considered in this study, including water cut of the emulsions, shear rate, driving force, and memory effect. Additionally, wax precipitation is also a common problem in subsea pipelines and can impact flow assurance when Hydrate Formation and wax precipitation both occur. Consequently, the effect of wax solid particles on Hydrate Formation was also considered in this work. The presence of wax particles is observed to impede Hydrate Formation. In this work, it is determined from induction time that the Hydrate Formation is initiated at the water–oil surface for water-in-oil emulsion. Moreover, the memory effect can shorten induction times of Hydrate Formation due to the remaining small CO2 bubbles at the surface of water droplets
Jerome Rajnauth - One of the best experts on this subject based on the ideXlab platform.
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The Natural Gas Composition is Key in Hydrate Formation
Advances in Petroleum Exploration and Development, 2019Co-Authors: Jerome RajnauthAbstract:This analysis will evaluate the effects of the natural gas composition on the Formation of Hydrate for the purpose of storage and transporting natural gas. Results show that the composition of the natural gas can affect the temperature and pressure required for Formation of the Hydrate. Carbon dioxide, hydrogen sulfide and nitrogen impurities in natural gas affect the Hydrate Formation and may result in additional processing of the gas is required Hydrate Formation. The composition of the sample also affects the water to gas mole ratio and hence the amount of water required for Hydrate Formation.
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Hydrate Formation: Considering the Effects of Pressure, Temperature, Composition and Water
Energy Science and Technology, 2012Co-Authors: Jerome Rajnauth, Maria A. Barrufet, Gioia FalconeAbstract:The main components in producing natural gas Hydrate (whether for gas storage or for transportation), are water and natural gas, at low temperatures and high pressures. Each variable has a significant effect on the Formation of gas Hydrate. It is therefore critical to analyze the effect of each variable on Hydrate Formation to ascertain the best conditions required for a successful gas Hydrate Formation process. This research evaluates the effect of these critical elements: temperature, pressure, gas composition, and water upon gas Hydrate Formation. This paper summarizes the findings of a sensitivity analysis using varying natural gas compositions. Results show that the composition of the natural gas can affect the temperature and pressure required for Formation of the Hydrate. Even more significant is the effect of impurities in the natural gas on the pressure temperature (PT) curves of the Hydrate. Carbon dioxide, hydrogen sulfide and nitrogen are the main impurities in natural gas affecting the Hydrate Formation. At a particular temperature, nitrogen increases the required Hydrate Formation pressure while both carbon dioxide and hydrogen sulfide lower the required Hydrate Formation pressure. The quantity of water required for Hydrate Formation is an important variable in the process. The water to gas ratio vary depending on the composition of the natural gas and the pressure. Generally the mole ratio of water to natural gas is about 6:1; however, to achieve maximum Hydrate Formation an incremental increase in water or pressure may be required. This is an interesting trade-off between additional water and additional pressure in obtaining maximum volume of Hydrate and is shown in this analysis. Key words: Hydrate Formation; Temperature; Pressure; Gas composition; Water
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Hydrate Formation: Considering the effects of Pressure, Temperature, Composition and Water
All Days, 2010Co-Authors: Jerome Rajnauth, Maria A. Barrufet, Gioia FalconeAbstract:Abstract The main components in producing natural gas Hydrate (whether for gas storage or for transportation), are water and natural gas, at low temperatures and high pressures. Each variable has a significant effect on the Formation of gas Hydrate. It is therefore critical to analyze the effect of each variable on Hydrate Formation to ascertain the best conditions required for a successful gas Hydrate Formation process. This research evaluates the effect of these critical elements: temperature, pressure, gas composition, and water upon gas Hydrate Formation. This paper summarizes the findings of a sensitivity analysis using varying natural gas compositions. Results show that the composition of the natural gas can affect the temperature and pressure required for Formation of the Hydrate. Even more significant is the effect of impurities in the natural gas on the pressure temperature (PT) curves of the Hydrate. Carbon dioxide, hydrogen sulfide and nitrogen are the main impurities in natural gas affecting the Hydrate Formation. At a particular temperature, nitrogen increases the required Hydrate Formation pressure while both carbon dioxide and hydrogen sulfide lower the required Hydrate Formation pressure. The quantity of water required for Hydrate Formation is an important variable in the process. The water to gas ratio vary depending on the composition of the natural gas and the pressure. Generally the mole ratio of water to natural gas is about 6:1; however, to achieve maximum Hydrate Formation an incremental increase in water or pressure may be required. This is an interesting trade off between additional water and additional pressure in obtaining maximum volume of Hydrate and is shown in this analysis.
