During the development and application of natural gas,hydrate plugging the pipelines is a very important issue to solve.Currently,adding thermodynamic hydrate inhibitors(THIs)and kinetic hydrate inhibitors(KHIs)in gas...During the development and application of natural gas,hydrate plugging the pipelines is a very important issue to solve.Currently,adding thermodynamic hydrate inhibitors(THIs)and kinetic hydrate inhibitors(KHIs)in gas-dominated pipelines is a main way to prevent hydrate plugging of flow lines.This paper mainly reviews the efforts to develop THIs and KHIs in the past 20 years,compare the role of various THIs,such as methanol,ethylene glycol and electrolyte,and give the tips in using.The direction of KHIs is toward high efficiency,low toxicity,low pollution and low cost.More than a hundred inhibitors,including polymers,natural products and ionic liquids,have been synthesized in the past decade.Some of them have better performance than the current commercial KHIs.However,there are still few problems,such as the complex synthesis process,high cost and low solubility,impeding the commercialization of these inhibitors.The review also summarized some application of KHIs in China.Research of KHIs in China began late.There are no KHIs used in gas pipelines.Only a few field tests have been carried out.In the end of this paper,the field test of self-developed KHIs by China is summarized,and the guidance is given according to the application results.展开更多
Gas hydrate-caused pipeline plugging is an industrial nuisance for petroleum flow assurance that calls for technological innovations.Traditional thermodynamic inhibitors such as glycols and inorganic salts suffer from...Gas hydrate-caused pipeline plugging is an industrial nuisance for petroleum flow assurance that calls for technological innovations.Traditional thermodynamic inhibitors such as glycols and inorganic salts suffer from high dosing,environmental unfriendliness,corrosiveness,and economical burden.The development and use of kinetic hydrate inhibitors(KHIs),mostly polymeric compounds,with their inhibiting effects on hydrate nucleation and growth are considered an effective and economically viable chemical treatment for hydrate prevention.However,the actual performance of a KHI candidate is dependent on various factors including its chemical structure,molecular weight,spatial configuration,effective concentration,pressure and temperature,evaluation methods,use of other additives,etc.This review provides a short but systematic overview of the fundamentals of natural gas hydrates,the prevailing categories of polymeric kinetic hydrate inhibitors with proposed inhibition mechanisms,and the various synergists studied for boosting the KHI performance.Further research endeavors are in need to unveil the KHI working modes under different conditions.The conjunctive use of KHIs and synergists may facilitate the commercial application of effective KHIs to tackle the hydrate plugging problem in the oil and gas flow assurance practices.展开更多
Natural gas hydrate inhibitor has been serving the oil and gas industry for many years. The development and search for new inhibitors remain the focus of research. In this study, the solution polymerization method was...Natural gas hydrate inhibitor has been serving the oil and gas industry for many years. The development and search for new inhibitors remain the focus of research. In this study, the solution polymerization method was employed to prepare poly(N-vinyl caprolactam-co-butyl methacrylate)(P(VCap-BMA)), as a new kinetic hydrate inhibitor(KHI). The inhibition properties of P(VCap-BMA) were investigated by tetrahydrofuran(THF) hydrate testing and natural gas hydrate forming and compared with the commercial KHIs. The experiment showed that PVCap performed better than copolymer P(VCap-BMA). However,low doses of methanol or ethylene glycol are compounded with KHIs. The compounding inhibitors show a synergistic inhibitory effect. More interesting is the P(VCap-BMA)-methanol system has a better inhibitory effect than the PVCap-methanol system. 1% P(VCap-BMA) + 5% methanol presented the best inhibiting performance at subcooling 10.3 °C, the induction time of natural gas hydrate was 445 min.Finally, the interaction between water and several dimeric inhibitors compared by natural bond orbital(NBO) analyses and density functional theory(DFT) indicated that inhibitor molecules were able to form the hydrogen bond with the water molecules, which result in gas hydrate inhibition. These exciting properties make the P(VCap-BMA) compound hydrate inhibitor promising candidates for numerous applications in the petrochemical industry.展开更多
It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are norma...It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.展开更多
Natural gas hydrates easily form in pipelines,causing potential safety issues during oil and gas production and transportation.Injecting gas hydrate inhibitors is one of the most effective methods for preventing gas h...Natural gas hydrates easily form in pipelines,causing potential safety issues during oil and gas production and transportation.Injecting gas hydrate inhibitors is one of the most effective methods for preventing gas hydrate formation or aggregation.However,some thermodynamic hydrate inhibitors are toxic and harmful to the environment,whereas degradation of kinetic inhibitors is difficult.Therefore,environmentally friendly and easily biodegradable novel green inhibitors have been proposed and investigated.This paper provides a short but systematic review of the inhibitory performance of amino acids,antifreeze proteins,and ionic liquids.For different hydrate formation systems,the influences of the inhibitor type,structure,and concentration on the inhibitory effects are summarized.The mechanism of green inhibitors as kinetic inhibitors is also discussed.The progress described here will facilitate further developments of such green inhibitors for gas hydrate formation.展开更多
Gas Hydrate is usually formed during the transportation and treatment of oil and gas, resulting in the plugging of gas pipeline and equipment. Three thermodynamic calculation formulas are analyzed to deal with this pr...Gas Hydrate is usually formed during the transportation and treatment of oil and gas, resulting in the plugging of gas pipeline and equipment. Three thermodynamic calculation formulas are analyzed to deal with this problem. The lowering of the freezing point of the inhibitors △T is used to calculate the formation temperature of natural gas hydrates. This is considered to be a good approach because it is not limited by what kind and what concentration of inhibitors one uses. Besides, the rate of lowering of the freezing point could be easily measured. The result of testing methanol and mono-ethylene glycol in a reactor shows that adding 10% inhibitors to the reactor can prevent the hydrates formation. Kinetic inhibitors are favored in the present research. They are divided into two types, polymer and surface-active agents. Their characteristics, mechanisms, and application prospect are separately discussed. Polymer inhibitors exhibit better efficiency. The result of field application of VC-713 inhibiter is also given in this article. In practice, the combination of thermodynamic inhibitors and kinetic inhibitors gives better result.展开更多
In oil and gas field, the application of kinetic hydrate inhibitors （KHIs） independently has remained problematic in high subcooling and high water-cut situation. One feasible method to resolve this problem is the c...In oil and gas field, the application of kinetic hydrate inhibitors （KHIs） independently has remained problematic in high subcooling and high water-cut situation. One feasible method to resolve this problem is the combined use of KHIs and some synergists, which would enhance KHIs’ inhibitory effect on both hydrate nucleation and hydrate crystal growth. In this study, a novel kind of KHI copolymer poly（N-vinyl-2-pyrrolidone-co-2-vinyl pyridine）s （HGs） is used in conjunction with TBAB to show its high performance on hydrate inhibition. The performance of HGs with different monomer ratios in structure II tetrahydrofuran （THF） hydrate is investigated using kinetic hydrate inhibitor evaluation apparatus by step-cooling method and isothermal cooling method. With the combined gas hydrate inhibitor at the concentration of 1.0 wt%, the induction time of 19 wt% THF solution could be prolonged to 8.5 h at a high subcooling of 6℃. Finally, the mechanism of HGs inhibiting the formation of gas hydrate is proposed.展开更多
In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is ...In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is studied. A novel method namely ＂sudden cooling＂ is used for performing the relevant measurements, in which the induction time of H2S hydrate in the presence/absence of PVP and L-tyrosine with different concentrations （100, 500, and 1000 ppm） is determined. As a result, PVP with the concentration of 1000 ppm in aqueous solution is detected as a more suitable material for increasing the induction time of H2S hydrate formation among the investigated kinetic hydrate inhibitors.展开更多
Kinetic data of methane hydrate formation in the presence of purewater, brines with single salt and mixed salts, and aqueous solutionsof ethylene glycol (EG) and salt + EG were measured. A new kineticmodel of hydrate ...Kinetic data of methane hydrate formation in the presence of purewater, brines with single salt and mixed salts, and aqueous solutionsof ethylene glycol (EG) and salt + EG were measured. A new kineticmodel of hydrate formation for the methane + water systems wasdeveloped based on a four-step formation mechanism and reactionkinetics approach. The proposed kinetic model predicts the kineticbehavior of methane hydrate formation in pure water with goodaccuracy. The feasibility of extending the kinetic model to salt (s)and EG containing systems was explored.展开更多
Gas hydrate reserves are potential source of clean energy having low molecular weight hydrocarbons trapped in water cages.In this work,we report how organic compounds of different chain lengths and hydrophilicities wh...Gas hydrate reserves are potential source of clean energy having low molecular weight hydrocarbons trapped in water cages.In this work,we report how organic compounds of different chain lengths and hydrophilicities when used in small concentration may modify hydrate growth and either act as hydrate inhibitors or promoters.Hydrate promoters foster the hydrate growth kinetics and are used in novel applications such as methane storage as solidified natural gas,desalination of sea water and gas separation.On the other hand,gas hydrate inhibitors are used in oil and gas pipelines to alter the rate at which gas hydrate nucleates and grows.Inhibitors such as methanol and ethanol which form strong hydrogen bond with water have been traditionally used as hydrate inhibitors.However,due to relatively high volatility a significant portion of these inhibitors ends up in gas stream and brings further complexity to the safe transportation of natural gas.In this study,organic additives such as oxalic acid,succinic acid and L-aspartic acid(all three)having––COOH group(s)with aspartic acid having an additional––NH2 group,are investigated for gas hydrate promotion/inhibition behavior.These compounds are polar in nature and thus have significant solubility in liquid water;the presence of weak acidic and water loving(carboxylic/amine groups)moieties makes these organic acids an excellent candidate for further study.This study would pave ways to identify a novel(read better)promoter/inhibitor for gas hydrate formation.Suitable thermodynamic conditions were generated in a stirred tank reactor coupled with cooling system;comparison of gas hydrate formation kinetics with and without additives were carried out to identify the effect of these acids on the formation and growth of hydrates.The possible mechanisms by which these additives inhibit or promote the hydrate growth are also discussed.展开更多
Low dosage kinetic hydrate inhibitors(KHIs)are a kind of alternative chemical additives to high dosage thermodynamic inhibitors for preventing gas hydrate formation in oil&gas production wells and transportation p...Low dosage kinetic hydrate inhibitors(KHIs)are a kind of alternative chemical additives to high dosage thermodynamic inhibitors for preventing gas hydrate formation in oil&gas production wells and transportation pipelines.In this paper,a new KHI,poly(N-vinyl caprolactam)-co-tert-butyl acrylate(PVCapco-TBA),was successfully synthesized with N-vinyl caprolactam(NVCap)and tert-butyl acrylate.The kinetic inhibition performances of PVCap-co-TBA on the formations of both structureⅠmethane hydrate and structureⅡnatural gas hydrate were investigated by measuring the onset times of hydrate formation under different conditions and compared with commercial KHIs such as PVP,PVCap and inhibex 501.The results indicated that PVCap-co-TBA outperformed these widely applied inhibitors for both structureⅠand structureⅡhydrates.At the same dosage of KHI,the maximum tolerable degree of subcooling under which the onset time of hydrate formation exceeded 24 hours for structureⅠhydrate was much lower than that for structureⅡhydrate.The inhibition strength increased with the increasing dosage of PVCap-co-TBA;The maximum tolerable degree of subcooling for the natural gas hydrate is more than10 K when the dosage was higher than 0.5%(mass)while it achieved 12 K when that dosage rose to0.75%(mass).Additionally,we found polypropylene glycol could be used as synergist at the dosage of 1.0%(mass)or so,under which the kinetic inhibition performance of PVCap-co-TBA could be improved significantly.All evaluation results demonstrated that PVCap-co-TBA was a very promising KHI and a competitive alternative to the existing commercial KHIs.展开更多
One surfactant as sodium dodecyl sulfate (SDS) and one synthesized sample as gas hydrate inhibitor are introduced in this paper. Through experiments we prove sodium dodecyl sulfate can accelerate the formation rate of...One surfactant as sodium dodecyl sulfate (SDS) and one synthesized sample as gas hydrate inhibitor are introduced in this paper. Through experiments we prove sodium dodecyl sulfate can accelerate the formation rate of gas hydrate and the synthesized sample can inhibit the formation and growth.展开更多
基金Supported by the National Key R&D Program of China(2016YFC0304006 and 2017YFC0307302/03)National Natural Science Foundation of China(51576069,51876069)+1 种基金the Natural Science Foundation of Guangdong Province(2016A030313488)Fundamental Research Funds for the Central Universities
文摘During the development and application of natural gas,hydrate plugging the pipelines is a very important issue to solve.Currently,adding thermodynamic hydrate inhibitors(THIs)and kinetic hydrate inhibitors(KHIs)in gas-dominated pipelines is a main way to prevent hydrate plugging of flow lines.This paper mainly reviews the efforts to develop THIs and KHIs in the past 20 years,compare the role of various THIs,such as methanol,ethylene glycol and electrolyte,and give the tips in using.The direction of KHIs is toward high efficiency,low toxicity,low pollution and low cost.More than a hundred inhibitors,including polymers,natural products and ionic liquids,have been synthesized in the past decade.Some of them have better performance than the current commercial KHIs.However,there are still few problems,such as the complex synthesis process,high cost and low solubility,impeding the commercialization of these inhibitors.The review also summarized some application of KHIs in China.Research of KHIs in China began late.There are no KHIs used in gas pipelines.Only a few field tests have been carried out.In the end of this paper,the field test of self-developed KHIs by China is summarized,and the guidance is given according to the application results.
基金Supported by China Postdoctoral Science Foundation Funded Project(2017M620050)
文摘Gas hydrate-caused pipeline plugging is an industrial nuisance for petroleum flow assurance that calls for technological innovations.Traditional thermodynamic inhibitors such as glycols and inorganic salts suffer from high dosing,environmental unfriendliness,corrosiveness,and economical burden.The development and use of kinetic hydrate inhibitors(KHIs),mostly polymeric compounds,with their inhibiting effects on hydrate nucleation and growth are considered an effective and economically viable chemical treatment for hydrate prevention.However,the actual performance of a KHI candidate is dependent on various factors including its chemical structure,molecular weight,spatial configuration,effective concentration,pressure and temperature,evaluation methods,use of other additives,etc.This review provides a short but systematic overview of the fundamentals of natural gas hydrates,the prevailing categories of polymeric kinetic hydrate inhibitors with proposed inhibition mechanisms,and the various synergists studied for boosting the KHI performance.Further research endeavors are in need to unveil the KHI working modes under different conditions.The conjunctive use of KHIs and synergists may facilitate the commercial application of effective KHIs to tackle the hydrate plugging problem in the oil and gas flow assurance practices.
基金supported by the Key Science and Technology Program of Shaanxi Province (2014K10-03)。
文摘Natural gas hydrate inhibitor has been serving the oil and gas industry for many years. The development and search for new inhibitors remain the focus of research. In this study, the solution polymerization method was employed to prepare poly(N-vinyl caprolactam-co-butyl methacrylate)(P(VCap-BMA)), as a new kinetic hydrate inhibitor(KHI). The inhibition properties of P(VCap-BMA) were investigated by tetrahydrofuran(THF) hydrate testing and natural gas hydrate forming and compared with the commercial KHIs. The experiment showed that PVCap performed better than copolymer P(VCap-BMA). However,low doses of methanol or ethylene glycol are compounded with KHIs. The compounding inhibitors show a synergistic inhibitory effect. More interesting is the P(VCap-BMA)-methanol system has a better inhibitory effect than the PVCap-methanol system. 1% P(VCap-BMA) + 5% methanol presented the best inhibiting performance at subcooling 10.3 °C, the induction time of natural gas hydrate was 445 min.Finally, the interaction between water and several dimeric inhibitors compared by natural bond orbital(NBO) analyses and density functional theory(DFT) indicated that inhibitor molecules were able to form the hydrogen bond with the water molecules, which result in gas hydrate inhibition. These exciting properties make the P(VCap-BMA) compound hydrate inhibitor promising candidates for numerous applications in the petrochemical industry.
文摘It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.
基金Supported by National Key Research and Development Plan of China(2017YFC0307306)the National Natural Science Foundation of China(51876211)
文摘Natural gas hydrates easily form in pipelines,causing potential safety issues during oil and gas production and transportation.Injecting gas hydrate inhibitors is one of the most effective methods for preventing gas hydrate formation or aggregation.However,some thermodynamic hydrate inhibitors are toxic and harmful to the environment,whereas degradation of kinetic inhibitors is difficult.Therefore,environmentally friendly and easily biodegradable novel green inhibitors have been proposed and investigated.This paper provides a short but systematic review of the inhibitory performance of amino acids,antifreeze proteins,and ionic liquids.For different hydrate formation systems,the influences of the inhibitor type,structure,and concentration on the inhibitory effects are summarized.The mechanism of green inhibitors as kinetic inhibitors is also discussed.The progress described here will facilitate further developments of such green inhibitors for gas hydrate formation.
文摘Gas Hydrate is usually formed during the transportation and treatment of oil and gas, resulting in the plugging of gas pipeline and equipment. Three thermodynamic calculation formulas are analyzed to deal with this problem. The lowering of the freezing point of the inhibitors △T is used to calculate the formation temperature of natural gas hydrates. This is considered to be a good approach because it is not limited by what kind and what concentration of inhibitors one uses. Besides, the rate of lowering of the freezing point could be easily measured. The result of testing methanol and mono-ethylene glycol in a reactor shows that adding 10% inhibitors to the reactor can prevent the hydrates formation. Kinetic inhibitors are favored in the present research. They are divided into two types, polymer and surface-active agents. Their characteristics, mechanisms, and application prospect are separately discussed. Polymer inhibitors exhibit better efficiency. The result of field application of VC-713 inhibiter is also given in this article. In practice, the combination of thermodynamic inhibitors and kinetic inhibitors gives better result.
基金supported by the National Basic Research Program of China ("973" Program) (Grant No. 2009CB219504-03)the National Natural Science Foundation of China (Grant No 51106054)the Colleges and Universities High-level Talents Program of Guangdong
文摘In oil and gas field, the application of kinetic hydrate inhibitors （KHIs） independently has remained problematic in high subcooling and high water-cut situation. One feasible method to resolve this problem is the combined use of KHIs and some synergists, which would enhance KHIs’ inhibitory effect on both hydrate nucleation and hydrate crystal growth. In this study, a novel kind of KHI copolymer poly（N-vinyl-2-pyrrolidone-co-2-vinyl pyridine）s （HGs） is used in conjunction with TBAB to show its high performance on hydrate inhibition. The performance of HGs with different monomer ratios in structure II tetrahydrofuran （THF） hydrate is investigated using kinetic hydrate inhibitor evaluation apparatus by step-cooling method and isothermal cooling method. With the combined gas hydrate inhibitor at the concentration of 1.0 wt%, the induction time of 19 wt% THF solution could be prolonged to 8.5 h at a high subcooling of 6℃. Finally, the mechanism of HGs inhibiting the formation of gas hydrate is proposed.
文摘In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is studied. A novel method namely ＂sudden cooling＂ is used for performing the relevant measurements, in which the induction time of H2S hydrate in the presence/absence of PVP and L-tyrosine with different concentrations （100, 500, and 1000 ppm） is determined. As a result, PVP with the concentration of 1000 ppm in aqueous solution is detected as a more suitable material for increasing the induction time of H2S hydrate formation among the investigated kinetic hydrate inhibitors.
基金Supported by the National Natural Science Foundation(No. 20003010) and Postdoctoral Research Foundation.
文摘Kinetic data of methane hydrate formation in the presence of purewater, brines with single salt and mixed salts, and aqueous solutionsof ethylene glycol (EG) and salt + EG were measured. A new kineticmodel of hydrate formation for the methane + water systems wasdeveloped based on a four-step formation mechanism and reactionkinetics approach. The proposed kinetic model predicts the kineticbehavior of methane hydrate formation in pure water with goodaccuracy. The feasibility of extending the kinetic model to salt (s)and EG containing systems was explored.
基金the Department of Science and Technology, Science and Engineering Research Board, India for the project grant EMR/2017/000810the Department of Science and Technology-Science and Engineering Research Board, India for the award of National Postdoctoral Fellowship (Principal Investigator) and project grant DST-SERB-PDF-2017/003075
文摘Gas hydrate reserves are potential source of clean energy having low molecular weight hydrocarbons trapped in water cages.In this work,we report how organic compounds of different chain lengths and hydrophilicities when used in small concentration may modify hydrate growth and either act as hydrate inhibitors or promoters.Hydrate promoters foster the hydrate growth kinetics and are used in novel applications such as methane storage as solidified natural gas,desalination of sea water and gas separation.On the other hand,gas hydrate inhibitors are used in oil and gas pipelines to alter the rate at which gas hydrate nucleates and grows.Inhibitors such as methanol and ethanol which form strong hydrogen bond with water have been traditionally used as hydrate inhibitors.However,due to relatively high volatility a significant portion of these inhibitors ends up in gas stream and brings further complexity to the safe transportation of natural gas.In this study,organic additives such as oxalic acid,succinic acid and L-aspartic acid(all three)having––COOH group(s)with aspartic acid having an additional––NH2 group,are investigated for gas hydrate promotion/inhibition behavior.These compounds are polar in nature and thus have significant solubility in liquid water;the presence of weak acidic and water loving(carboxylic/amine groups)moieties makes these organic acids an excellent candidate for further study.This study would pave ways to identify a novel(read better)promoter/inhibitor for gas hydrate formation.Suitable thermodynamic conditions were generated in a stirred tank reactor coupled with cooling system;comparison of gas hydrate formation kinetics with and without additives were carried out to identify the effect of these acids on the formation and growth of hydrates.The possible mechanisms by which these additives inhibit or promote the hydrate growth are also discussed.
基金supported by the National Natural Science Foundation of China(U20B6005)Hainan Province Science and Technology Special Fund(ZDKJ2021026)。
文摘Low dosage kinetic hydrate inhibitors(KHIs)are a kind of alternative chemical additives to high dosage thermodynamic inhibitors for preventing gas hydrate formation in oil&gas production wells and transportation pipelines.In this paper,a new KHI,poly(N-vinyl caprolactam)-co-tert-butyl acrylate(PVCapco-TBA),was successfully synthesized with N-vinyl caprolactam(NVCap)and tert-butyl acrylate.The kinetic inhibition performances of PVCap-co-TBA on the formations of both structureⅠmethane hydrate and structureⅡnatural gas hydrate were investigated by measuring the onset times of hydrate formation under different conditions and compared with commercial KHIs such as PVP,PVCap and inhibex 501.The results indicated that PVCap-co-TBA outperformed these widely applied inhibitors for both structureⅠand structureⅡhydrates.At the same dosage of KHI,the maximum tolerable degree of subcooling under which the onset time of hydrate formation exceeded 24 hours for structureⅠhydrate was much lower than that for structureⅡhydrate.The inhibition strength increased with the increasing dosage of PVCap-co-TBA;The maximum tolerable degree of subcooling for the natural gas hydrate is more than10 K when the dosage was higher than 0.5%(mass)while it achieved 12 K when that dosage rose to0.75%(mass).Additionally,we found polypropylene glycol could be used as synergist at the dosage of 1.0%(mass)or so,under which the kinetic inhibition performance of PVCap-co-TBA could be improved significantly.All evaluation results demonstrated that PVCap-co-TBA was a very promising KHI and a competitive alternative to the existing commercial KHIs.
基金supported by the National Natural Science Foundation of China (No.50176051)the State Key Development Program for Basic Research of China (No.2000026306).
文摘One surfactant as sodium dodecyl sulfate (SDS) and one synthesized sample as gas hydrate inhibitor are introduced in this paper. Through experiments we prove sodium dodecyl sulfate can accelerate the formation rate of gas hydrate and the synthesized sample can inhibit the formation and growth.
