Allelochemicals of Chinese-fir root was extracted by technology ofsupercritical CO_2 extraction under orthogonal experiment design, and it was used to analyzeallelopathic activity of Chinese-fir through bioassay of se...Allelochemicals of Chinese-fir root was extracted by technology ofsupercritical CO_2 extraction under orthogonal experiment design, and it was used to analyzeallelopathic activity of Chinese-fir through bioassay of seed germination. The results showed thatas to the available rate of allelochemicals, the pressure and temperature of extraction were themost important factors. The allelochemicals of Chinese-fir root extracted by pure CO_2 and ethanolmixed with CO_2 have different allelopathic activities to seed germination, and the allelochemicalsextracted by ethanol mixed with CO_2 had stronger inhibitory effects on seed germination than thatextracted by pure CO_2.展开更多
[Objective] This study aimed to investigate the differences in chemical composition of supercritical CO2 extraction products in peels of Trichosanthes kirilowii Maxim. from Changqing district. [Method] Supercritical f...[Objective] This study aimed to investigate the differences in chemical composition of supercritical CO2 extraction products in peels of Trichosanthes kirilowii Maxim. from Changqing district. [Method] Supercritical fluidextraction （SFE） and GCMS method were applied to determine and analyze the chemical components of the extracts in peels of three strains of Trichosanthes kirilowii Maxim. [Result] The chemical components of supercritical CO2 extraction products in peels of three strains of Trichosanthes kirilowii Maxim. varied., and the number of chemical components with normalized percentage content higher than 1% was 5, 7 and 8, respectively. There are 14 kinds of common components, and the relative content of hexadecanoic acid was the highest. [Conclusion] Supercritical CO2 extracts in peels of different strains of Trichosanthes kirilowii Maxim. contain different chemical components, providing scientific basis for breeding excellent varieties and the development and utilization of Trichosanthes kirilowii Maxim.展开更多
Supercritical CO_(2)(SC-CO_(2))fracturing stands out a promising waterless stimulation technique in the development of unconventional resources.While numerous studies have delved into the inducedfracture mechanism of ...Supercritical CO_(2)(SC-CO_(2))fracturing stands out a promising waterless stimulation technique in the development of unconventional resources.While numerous studies have delved into the inducedfracture mechanism of SC-CO_(2),the small scale of rock samples and synthetic materials used in many studies have limited a comprehensive understanding of fracture propagation in unconventional formations.In this study,cubic tight sandstone samples with dimensions of 300 mm were employed to conduct SC-CO_(2)fractu ring experiments under true-triaxial stre ss conditions.The spatial morphology and quantitative attributes of fracture induced by water and SC-CO_(2)fracturing were compared,while the impact of in-situ stress on fracture propagation was also investigated.The results indicate that the SCCO_(2)fracturing takes approximately ten times longer than water fracturing.Furthermore,under identical stress condition,the breakdown pressure(BP)for SC-CO_(2)fracturing is nearly 25%lower than that for water fracturing.A quantitative analysis of fracture morphology reveals that water fracturing typically produces relatively simple fracture pattern,with the primary fracture distribution predominantly controlled by bedding planes.In contrast,SC-CO_(2)fracturing results in a more complex fracture morphology.As the differential of horizontal principal stress increases,the BP for SC-CO_(2)fractured rock exhibits a downward trend,and the induced fracture morphology becomes more simplified.Moreover,the presence of abnormal in-situ stress leads to a further increase in the BP for SC-CO_(2)fracturing,simultaneously enhancing the development of a more conductive fracture network.These findings provide critical insights into the efficiency and behavior of SC-CO_(2)fracturing in comparison to traditional water-based fracturing,offering valuable implication for its potential applications in unconventional reservoirs.展开更多
With the increasing demand for energy,traditional oil resources are facing depletion and insufficient supply.Many countries are rapidly turning to the development of unconventional oil and gas resources.Among them,sha...With the increasing demand for energy,traditional oil resources are facing depletion and insufficient supply.Many countries are rapidly turning to the development of unconventional oil and gas resources.Among them,shale oil and gas reservoirs have become the focus of unconventional oil and gas resources exploration and development.Based on the characteristics of shale oil and gas reservoirs,supercritical CO_(2) fracturing is more conducive to improving oil recovery than other fracturing technologies.In this paper,the mechanism of fracture initiation and propagation of supercritical CO_(2) in shale is analyzed,including viscosity effect,surface tension effect,permeation diffusion effect of supercritical CO_(2),and dissolution-adsorption effect between CO_(2) and shale.The effects of natural factors,such as shale properties,bedding plane and natural fractures,and controllable factors,proppant,temperature,pressure,CO_(2) concentration and injection rate on fracture initiation and propagation are clarified.The methods of supercritical CO_(2) fracturing process,thickener and proppant optimization to improve the efficiency of supercritical CO_(2) fracturing are discussed.In addition,some new technologies of supercritical CO_(2) fracturing are introduced.The challenges and prospects in the current research are also summarized.For example,supercritical CO_(2) is prone to filtration when passing through porous media,and it is difficult to form a stable flow state.Therefore,in order to achieve stable fracturing fluid suspension and effectively support fractu res,it is urge nt to explo re new fracturing fluid additives or improve fracturing fluid formulations combined with the research of new proppants.This paper is of great significance for understanding the behavior mechanism of supercritical CO_(2) in shale and optimizing fracturing technology.展开更多
High-water-cut mature reservoirs typically serve as the“ballast”for ensuring China’s annual crude oil production of 200 million tons.Despite the use of water flooding and chemical methods,over 40%of crude oil remai...High-water-cut mature reservoirs typically serve as the“ballast”for ensuring China’s annual crude oil production of 200 million tons.Despite the use of water flooding and chemical methods,over 40%of crude oil remains unexploited.It is critical to develop efficient revolutionary technologies to further enhance oil recovery(EOR)by a large percentage in high-water-cut mature reservoirs.To address this issue,the potential of vertical remaining oil in Daqing Oilfield is first analyzed from massive monitoring data.Using molecular dynamics simulation to design optimal synthetic routine,a copolymer without flu-orine or silicon is synthesized by modifying vinyl acetate(VAc)with maleic anhydride(MA)and styrene(St),and treated as a supercritical CO_(2)(scCO_(2))thickener.The underlying EOR mechanism of the scCO_(2) thickener is thereafter clarified by high-temperature,high-pressure oil displacement experiments.The EOR effect by thickened scCO_(2) flooding in a typical high-water-cut mature reservoir is predicted,and future technological advancements of the technique are ultimately discussed.Results show that the ver-tical remaining oil enriched in weakly swept zones is a primary target for further EOR in high-water-cut mature reservoirs.The copolymer typically exhibits good solubility,strong dispersion stability,and high thickening effect in scCO_(2).Under an ambient pressure of 10 MPa and a temperature of 50℃,the disso-lution of copolymer at a mass concentration of 0.2%can effectively increase the viscosity of scCO_(2) by 39.4 times.Due to the synergistic effect between expanding vertical swept volume and inhibiting gas channel-ing,crude oil recovery can be further enhanced by 23.1%for a typical high-water-cut mature reservoir when the scCO_(2) viscosity is increased by 50 times.Our understandings demonstrate that the thickened scCO_(2) flooding technology has significant technical advantages in high-water-cut mature reservoirs,with challenges and future development directions in field-scale applications also highlighted.展开更多
Understanding the solubility of supercritical CO_(2)and its mixtures with other fluids at various temperatures and pressures conditions is critical for their applications,such as extraction processes,material design,a...Understanding the solubility of supercritical CO_(2)and its mixtures with other fluids at various temperatures and pressures conditions is critical for their applications,such as extraction processes,material design,and carbon capture.In the present study,the solubility parameters of supercritical CO_(2),H_(2)O,and their mixtures were calculated by molecular dynamics simulations.The results show that the solubility parameters decrease with increasing temperature and increase with increasing pressure and are linearly proportional to the density.Furthermore,the intermolecular interactions,including the hydrogen bonds,significantly affect the solubility parameter of the CO_(2)-H_(2)O system.展开更多
The study of the effects of supercritical CO_(2)(ScCO_(2))under high temperature and high pressure on the mechanical properties and fracturing potential of shale holds significant implications for advancing our unders...The study of the effects of supercritical CO_(2)(ScCO_(2))under high temperature and high pressure on the mechanical properties and fracturing potential of shale holds significant implications for advancing our understanding of enhanced shale gas extraction and reservoir exploration and development.This study examines the influence of three fluids,i.e.ScCO_(2),deionized water(DW),and ScCO_(2)tDW,on the mechanical properties and fracturability of shale at immersion pressures of 15 MPa and 45 MPa,with a constant temperature of 100C.The key findings are as follows:(1)Uniaxial compressive strength(UCS)of shale decreased by 10.72%,11.95%,and 23.67%at 15 MPa,and by 42.40%,46.84%,and 51.65%at 45 MPa after immersion in ScCO_(2),DW,and ScCO_(2)tDW,respectively,with the most pronounced effect observed in ScCO_(2)tDW;(2)Microstructural analysis revealed that while ScCO_(2)and DW do not significantly alter the microstructure,immersion in ScCO_(2)tDW results in a more complex surface morphology;(3)Acoustic emission(AE)analysis indicates a reduction in stress for crack damage,with a decreased fractal dimension of AE signals in different fluids.AE energy is primarily generated during the unstable crack propagation stage;(4)A quantitative method employing a multi-factor approach combined with the brittleness index(BI)effectively characterizes shale fracturability.Evaluation results show that ScCO_(2)tDW has a more significant effect on shale fracturability,with fracturability indices of 0.833%and 1.180%following soaking at 15 MPa and 45 MPa,respectively.Higher immersion pressure correlates positively with increased shale fracturability.展开更多
Deep shale reservoirs are often associated with extreme geological conditions,including high tem-peratures,substantial horizontal stress differences,elevated closure stresses,and high breakdown pressures.These factors...Deep shale reservoirs are often associated with extreme geological conditions,including high tem-peratures,substantial horizontal stress differences,elevated closure stresses,and high breakdown pressures.These factors pose significant challenges to conventional hydraulic fracturing with water-based fluids,which may induce formation damage and fail to generate complex fracture networks.Supercritical carbon dioxide(SC-CO_(2)),with its low viscosity,high diffusivity,low surface tension,and minimal water sensitivity,has attracted growing attention as an alternative fracturing fluid for deep shale stimulation.This study presents a series of true triaxial large-scale physical experiments using shale samples from the Longmaxi Formation in the southern Sichuan Basin to investigate fracture initiation and propagation behavior under different fracturing fluids.The results show that,under identical experimental conditions,SC-CO_(2)fracturing results in a significantly lower breakdown pressure compared to slick water and promotes the formation of more complex fracture geometries.These advantages are attributed to both the favorable flow characteristics of SC-CO_(2)and its potential chemical interactions with shale minerals.The findings not only confirm the effectiveness of SC-CO_(2)as a fracturing fluid in deep shale environments but also provide new insights into its fracture propagation mechanisms.展开更多
Alkaline water electrolysis poses significant potential for large-sc ale indus trial hydrogen generation,but is impeded by the absence of an efficient electrocatalyst capable of operating at high current densities whi...Alkaline water electrolysis poses significant potential for large-sc ale indus trial hydrogen generation,but is impeded by the absence of an efficient electrocatalyst capable of operating at high current densities while maintaining with minimal overpotential.Herein,we construct a mechanically stable and highly active RuSe_(2)/MXene heterojunction electrocatalyst.A typical SC-Ti_(3)C_(2)T_(x)MXene substrate was successfully prepared by supercritical CO_(2)(SC-CO_(2))etching,combined by subsequent DMSO intercalation treatment.Further,the RuSe_(2)nanoparticles were uniformly deposited on the surface of SC-Ti_(3)C_(2)T_(x).Theoretical calculations and experimental results demonstrate that fluorine-rich MXene exhibits stable binding with the active 1T phase RuSe_(2).The as-prepared representative RuSe_(2)@SC-Ti_(3)C_(2)T_(x)-3 heterostructure showed exceptional alkaline hydrogen evolution performance,demonstrating an overpotential of 15 mV at 10 mA cm^(-2)and a Tafel slope of 21.84 mV dec^(-1),which presents excellent HER performance and stability at high-current-density conditions.Moreover,the overpotential under the current density of 500 mA cm^(-2)is merely 182 mV,and the HER efficiency remains unaffected even after 5000 cycles and 120 h of continuous testing.展开更多
Extraction of the Ligusticum Chuanxiong oil with supercritical CO2 （SC-CO2） was investigated at the temperatures ranging from 55℃ to 70℃ and pressure from 25 MPa to 35 MPa. The mass of Ligusticum Chuanxiong oil ex...Extraction of the Ligusticum Chuanxiong oil with supercritical CO2 （SC-CO2） was investigated at the temperatures ranging from 55℃ to 70℃ and pressure from 25 MPa to 35 MPa. The mass of Ligusticum Chuanxiong oil extracted increased with pressure at constant temperature. The initial slope of the extraction was considered as the solubility of oil in SC-CO2. Chrastil equation was used to correlate the solubility data of Ligusticum Chuanxiong oil. An improved Chrastil equation was also presented and was employed to correlate the solubility data, The correlation results show that the values of the average absolute relative deviation are 5.94% and 3.33% respectively, indicating the improved version has better correlation accuracy than that of Chrastil equation.展开更多
Direct extraction of metals from solids with complexing agents in supercritical CO2(SC-CO2) has recently attracted interests in separation,purification,recovery,and analysis of metals.In the present study,the static/d...Direct extraction of metals from solids with complexing agents in supercritical CO2(SC-CO2) has recently attracted interests in separation,purification,recovery,and analysis of metals.In the present study,the static/dynamic extraction of rare earth elements(Nd,Ce) from their oxides(Nd2O3,CeO2) with organophosphorus complexes with HNO3 and H2O in SC-CO2 was investigated.The static extraction efficiency of Nd from Nd2O3 with the tri-n-butylphosphate(TBP)-HNO3 complex could reach 95% under optimized experiment...展开更多
The feasibility of removal of the organochlorine pesticides residues of hexachlorocyclohexane(BHC) from radix ginseng with supercritical CO2 was explored. Some factors, such as extraction pressure, extraction temperat...The feasibility of removal of the organochlorine pesticides residues of hexachlorocyclohexane(BHC) from radix ginseng with supercritical CO2 was explored. Some factors, such as extraction pressure, extraction temperature, and kinds of co-solvents were investigated. The experimental results indicate that it is possible to reduce BHC residues in radix ginseng to the level of 0.1 × 10^-6 with supercritical CO2 in the presence of suitable amount of co-solvent, such as water.展开更多
An experimental setup for separating ginger essential oil by supercritical fluid extraction is established. The effects of the extraction pressure, temperature, CO2 flow rate and particle size of raw material on the e...An experimental setup for separating ginger essential oil by supercritical fluid extraction is established. The effects of the extraction pressure, temperature, CO2 flow rate and particle size of raw material on the extraction rate are investigated, and the optimum process conditions of supercritical CO2 extraction are determined. A mathematical simulation model is established based on the mass conservation in differential units of extraction bed. The total mass transfer driving force and the equilibrium absorption constant are evaluated by the linear driving force theory. The results from numerical simulation agree well with the experimental data.展开更多
Microporous poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)membranes following supercritical CO_2 induced phase separation process were prepared using four solvents.The solid electrolytes of PVDF-HFP were f...Microporous poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)membranes following supercritical CO_2 induced phase separation process were prepared using four solvents.The solid electrolytes of PVDF-HFP were formed by microporous PVDF-HFP membranes filled and swollen by a liquid electrolyte.The effect of the solvents on the morphology and structure,electrolyte absorptions and lithium ionic conductivity of the activated membranes were investigated.It was approved that all the membrane had the similar...展开更多
The thermal decomposition of 2, 2'-azobis (isobutyronitrile) (AIBN) in supercritical CO2 with cosolvent methanol or cyclohexane has been studied by using UV/Vis spectroscopic method at 335.15 K and at 12.0 MPa and...The thermal decomposition of 2, 2'-azobis (isobutyronitrile) (AIBN) in supercritical CO2 with cosolvent methanol or cyclohexane has been studied by using UV/Vis spectroscopic method at 335.15 K and at 12.0 MPa and 14.0 MPa. Both of the cosolvents can accelerate the decomposition rate, and the effect of methanol is more significant than that of the cyclohexane.展开更多
High-pressure phase behavior of supercritical (SC) CO2+ethanol system was investigated at 333.2 K,348.2K, 353.2K, 368.2K, 413.2K and 453.2K and pressure from 2.0MPa to 14.3MPa. The measurement was carried out in a cy...High-pressure phase behavior of supercritical (SC) CO2+ethanol system was investigated at 333.2 K,348.2K, 353.2K, 368.2K, 413.2K and 453.2K and pressure from 2.0MPa to 14.3MPa. The measurement was carried out in a cylindrical autoclave with a moveable piston and a window for adjustment and observation of phase equilibria at given T and p. The samples were taken from two coexisting phases and were analyzed to obtain their compositions. It is shown that the solubility of SC CO2 in ethanol increases drastically with pressures at the given temperature, but the content of ethanol in CO2-rich phase increase faintly.展开更多
A series of gluscose derivatives were designed, synthesized, and their structures were confirmed by IR, NMR and elementary analysis. All new compounds are highly soluble in liquid or supercritical carbon dioxide. The ...A series of gluscose derivatives were designed, synthesized, and their structures were confirmed by IR, NMR and elementary analysis. All new compounds are highly soluble in liquid or supercritical carbon dioxide. The compound with electron-withdrawing substituent on benzene ring had even better solubility than the compounds with electron-donating substituent.展开更多
The effect of cosolvent on the palladium catalyst which catalyze alkoxycarbonylation of allyl bromide in supercritical CO2 has been investigated. It was found that a small amount of cosolvent such as ethanol, CH2Cl2 a...The effect of cosolvent on the palladium catalyst which catalyze alkoxycarbonylation of allyl bromide in supercritical CO2 has been investigated. It was found that a small amount of cosolvent such as ethanol, CH2Cl2 and cyclohexane can affect both reaction yields and selectivities largely. Ethanol was the most favorable cosolvent for increasing the total yield of unsaturated esters and the selectivity of 3-butenoic acid ester. Using cosolvent ethanol and cocatalyst FeCl2 Simultaneously can lead to better reaction results.展开更多
1 Introduction Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and indu...1 Introduction Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry.展开更多
Polystyrene/Poly(ethylene terephthlate) (PET) blends have been prepared by theheterogeneous free-radical polymerization of styrene within supercritical carbon dioxide-swollenPET substrates. Composition of the blends ...Polystyrene/Poly(ethylene terephthlate) (PET) blends have been prepared by theheterogeneous free-radical polymerization of styrene within supercritical carbon dioxide-swollenPET substrates. Composition of the blends and the average molecular weight of polystyrene inthe blends can be controlled by equilibration time and reaction condition.展开更多
基金This paper was supported by Natural Science Foundation of Fujian Province (B0010020)
文摘Allelochemicals of Chinese-fir root was extracted by technology ofsupercritical CO_2 extraction under orthogonal experiment design, and it was used to analyzeallelopathic activity of Chinese-fir through bioassay of seed germination. The results showed thatas to the available rate of allelochemicals, the pressure and temperature of extraction were themost important factors. The allelochemicals of Chinese-fir root extracted by pure CO_2 and ethanolmixed with CO_2 have different allelopathic activities to seed germination, and the allelochemicalsextracted by ethanol mixed with CO_2 had stronger inhibitory effects on seed germination than thatextracted by pure CO_2.
基金Supported by Science and Technology Development Project of Shangdong Province "Study on Standardized Planting of Chinese Herbal Medicines in Central China and Comprehensive Development and Utilization Technology of Bulk Chinese Herbs"(2011BAI06B00)Construction Project of Scientific and Technological Plat form for Quality Control of Genuine Medicinal Materials in Shangdong Province(2008GG-2NS02022)+1 种基金Agricultural Thoroughbred Breeding Project of Shangdong Province(2009LZ01-03)Independent Innovation Project of Universities and Institutes from Science and Technology Bureau of Ji'nan City(200906028)~~
文摘[Objective] This study aimed to investigate the differences in chemical composition of supercritical CO2 extraction products in peels of Trichosanthes kirilowii Maxim. from Changqing district. [Method] Supercritical fluidextraction （SFE） and GCMS method were applied to determine and analyze the chemical components of the extracts in peels of three strains of Trichosanthes kirilowii Maxim. [Result] The chemical components of supercritical CO2 extraction products in peels of three strains of Trichosanthes kirilowii Maxim. varied., and the number of chemical components with normalized percentage content higher than 1% was 5, 7 and 8, respectively. There are 14 kinds of common components, and the relative content of hexadecanoic acid was the highest. [Conclusion] Supercritical CO2 extracts in peels of different strains of Trichosanthes kirilowii Maxim. contain different chemical components, providing scientific basis for breeding excellent varieties and the development and utilization of Trichosanthes kirilowii Maxim.
基金funded by the National Natural Scientific Foundation of China(Nos.52304008,52404038,52474043)the China Postdoctoral Science Foundation(No.2023MD734223)+1 种基金the Key Laboratory of Well Stability and Fluid&Rock Mechanics in Oil and Gas Reservoir of Shaanxi Province(No.23JS047)the Youth Talent Lifting Program of Xi'an Science and Technology Association(No.959202413078)。
文摘Supercritical CO_(2)(SC-CO_(2))fracturing stands out a promising waterless stimulation technique in the development of unconventional resources.While numerous studies have delved into the inducedfracture mechanism of SC-CO_(2),the small scale of rock samples and synthetic materials used in many studies have limited a comprehensive understanding of fracture propagation in unconventional formations.In this study,cubic tight sandstone samples with dimensions of 300 mm were employed to conduct SC-CO_(2)fractu ring experiments under true-triaxial stre ss conditions.The spatial morphology and quantitative attributes of fracture induced by water and SC-CO_(2)fracturing were compared,while the impact of in-situ stress on fracture propagation was also investigated.The results indicate that the SCCO_(2)fracturing takes approximately ten times longer than water fracturing.Furthermore,under identical stress condition,the breakdown pressure(BP)for SC-CO_(2)fracturing is nearly 25%lower than that for water fracturing.A quantitative analysis of fracture morphology reveals that water fracturing typically produces relatively simple fracture pattern,with the primary fracture distribution predominantly controlled by bedding planes.In contrast,SC-CO_(2)fracturing results in a more complex fracture morphology.As the differential of horizontal principal stress increases,the BP for SC-CO_(2)fractured rock exhibits a downward trend,and the induced fracture morphology becomes more simplified.Moreover,the presence of abnormal in-situ stress leads to a further increase in the BP for SC-CO_(2)fracturing,simultaneously enhancing the development of a more conductive fracture network.These findings provide critical insights into the efficiency and behavior of SC-CO_(2)fracturing in comparison to traditional water-based fracturing,offering valuable implication for its potential applications in unconventional reservoirs.
文摘With the increasing demand for energy,traditional oil resources are facing depletion and insufficient supply.Many countries are rapidly turning to the development of unconventional oil and gas resources.Among them,shale oil and gas reservoirs have become the focus of unconventional oil and gas resources exploration and development.Based on the characteristics of shale oil and gas reservoirs,supercritical CO_(2) fracturing is more conducive to improving oil recovery than other fracturing technologies.In this paper,the mechanism of fracture initiation and propagation of supercritical CO_(2) in shale is analyzed,including viscosity effect,surface tension effect,permeation diffusion effect of supercritical CO_(2),and dissolution-adsorption effect between CO_(2) and shale.The effects of natural factors,such as shale properties,bedding plane and natural fractures,and controllable factors,proppant,temperature,pressure,CO_(2) concentration and injection rate on fracture initiation and propagation are clarified.The methods of supercritical CO_(2) fracturing process,thickener and proppant optimization to improve the efficiency of supercritical CO_(2) fracturing are discussed.In addition,some new technologies of supercritical CO_(2) fracturing are introduced.The challenges and prospects in the current research are also summarized.For example,supercritical CO_(2) is prone to filtration when passing through porous media,and it is difficult to form a stable flow state.Therefore,in order to achieve stable fracturing fluid suspension and effectively support fractu res,it is urge nt to explo re new fracturing fluid additives or improve fracturing fluid formulations combined with the research of new proppants.This paper is of great significance for understanding the behavior mechanism of supercritical CO_(2) in shale and optimizing fracturing technology.
基金the National Natural Science Foundation of China(U22B6005,52174043,52474035)the Beijing Natural Science Foundation(3242019)the China National Petroleum Corporation(CNPC)Innovation Foundation(2022DQ02-0208 and 2024DQ02-0114).
文摘High-water-cut mature reservoirs typically serve as the“ballast”for ensuring China’s annual crude oil production of 200 million tons.Despite the use of water flooding and chemical methods,over 40%of crude oil remains unexploited.It is critical to develop efficient revolutionary technologies to further enhance oil recovery(EOR)by a large percentage in high-water-cut mature reservoirs.To address this issue,the potential of vertical remaining oil in Daqing Oilfield is first analyzed from massive monitoring data.Using molecular dynamics simulation to design optimal synthetic routine,a copolymer without flu-orine or silicon is synthesized by modifying vinyl acetate(VAc)with maleic anhydride(MA)and styrene(St),and treated as a supercritical CO_(2)(scCO_(2))thickener.The underlying EOR mechanism of the scCO_(2) thickener is thereafter clarified by high-temperature,high-pressure oil displacement experiments.The EOR effect by thickened scCO_(2) flooding in a typical high-water-cut mature reservoir is predicted,and future technological advancements of the technique are ultimately discussed.Results show that the ver-tical remaining oil enriched in weakly swept zones is a primary target for further EOR in high-water-cut mature reservoirs.The copolymer typically exhibits good solubility,strong dispersion stability,and high thickening effect in scCO_(2).Under an ambient pressure of 10 MPa and a temperature of 50℃,the disso-lution of copolymer at a mass concentration of 0.2%can effectively increase the viscosity of scCO_(2) by 39.4 times.Due to the synergistic effect between expanding vertical swept volume and inhibiting gas channel-ing,crude oil recovery can be further enhanced by 23.1%for a typical high-water-cut mature reservoir when the scCO_(2) viscosity is increased by 50 times.Our understandings demonstrate that the thickened scCO_(2) flooding technology has significant technical advantages in high-water-cut mature reservoirs,with challenges and future development directions in field-scale applications also highlighted.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFE0117200)the National Natural Science Foundation of China(Grant No.41977304).
文摘Understanding the solubility of supercritical CO_(2)and its mixtures with other fluids at various temperatures and pressures conditions is critical for their applications,such as extraction processes,material design,and carbon capture.In the present study,the solubility parameters of supercritical CO_(2),H_(2)O,and their mixtures were calculated by molecular dynamics simulations.The results show that the solubility parameters decrease with increasing temperature and increase with increasing pressure and are linearly proportional to the density.Furthermore,the intermolecular interactions,including the hydrogen bonds,significantly affect the solubility parameter of the CO_(2)-H_(2)O system.
基金financial support from the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC1021)the National Natural Science Foundation of China(Grant No.52231012)+1 种基金the Natural Science Foundation of Hainan Province(Grant No.424QN213)the Scientific Research Foundation of Hainan University.
文摘The study of the effects of supercritical CO_(2)(ScCO_(2))under high temperature and high pressure on the mechanical properties and fracturing potential of shale holds significant implications for advancing our understanding of enhanced shale gas extraction and reservoir exploration and development.This study examines the influence of three fluids,i.e.ScCO_(2),deionized water(DW),and ScCO_(2)tDW,on the mechanical properties and fracturability of shale at immersion pressures of 15 MPa and 45 MPa,with a constant temperature of 100C.The key findings are as follows:(1)Uniaxial compressive strength(UCS)of shale decreased by 10.72%,11.95%,and 23.67%at 15 MPa,and by 42.40%,46.84%,and 51.65%at 45 MPa after immersion in ScCO_(2),DW,and ScCO_(2)tDW,respectively,with the most pronounced effect observed in ScCO_(2)tDW;(2)Microstructural analysis revealed that while ScCO_(2)and DW do not significantly alter the microstructure,immersion in ScCO_(2)tDW results in a more complex surface morphology;(3)Acoustic emission(AE)analysis indicates a reduction in stress for crack damage,with a decreased fractal dimension of AE signals in different fluids.AE energy is primarily generated during the unstable crack propagation stage;(4)A quantitative method employing a multi-factor approach combined with the brittleness index(BI)effectively characterizes shale fracturability.Evaluation results show that ScCO_(2)tDW has a more significant effect on shale fracturability,with fracturability indices of 0.833%and 1.180%following soaking at 15 MPa and 45 MPa,respectively.Higher immersion pressure correlates positively with increased shale fracturability.
文摘Deep shale reservoirs are often associated with extreme geological conditions,including high tem-peratures,substantial horizontal stress differences,elevated closure stresses,and high breakdown pressures.These factors pose significant challenges to conventional hydraulic fracturing with water-based fluids,which may induce formation damage and fail to generate complex fracture networks.Supercritical carbon dioxide(SC-CO_(2)),with its low viscosity,high diffusivity,low surface tension,and minimal water sensitivity,has attracted growing attention as an alternative fracturing fluid for deep shale stimulation.This study presents a series of true triaxial large-scale physical experiments using shale samples from the Longmaxi Formation in the southern Sichuan Basin to investigate fracture initiation and propagation behavior under different fracturing fluids.The results show that,under identical experimental conditions,SC-CO_(2)fracturing results in a significantly lower breakdown pressure compared to slick water and promotes the formation of more complex fracture geometries.These advantages are attributed to both the favorable flow characteristics of SC-CO_(2)and its potential chemical interactions with shale minerals.The findings not only confirm the effectiveness of SC-CO_(2)as a fracturing fluid in deep shale environments but also provide new insights into its fracture propagation mechanisms.
基金financially supported by the China Postdoctoral Science Foundation(Nos.2021TQ0300 and 2021M702946)Henan Science and Technology Department(Nos.242102231034 and 242301420040)+1 种基金the joint project from Henan Province,the China-National Natural Science Foundation(No.U2004208)the Central Plains Science and Technology Innovation Leading Talent Project(No.234200510008)
文摘Alkaline water electrolysis poses significant potential for large-sc ale indus trial hydrogen generation,but is impeded by the absence of an efficient electrocatalyst capable of operating at high current densities while maintaining with minimal overpotential.Herein,we construct a mechanically stable and highly active RuSe_(2)/MXene heterojunction electrocatalyst.A typical SC-Ti_(3)C_(2)T_(x)MXene substrate was successfully prepared by supercritical CO_(2)(SC-CO_(2))etching,combined by subsequent DMSO intercalation treatment.Further,the RuSe_(2)nanoparticles were uniformly deposited on the surface of SC-Ti_(3)C_(2)T_(x).Theoretical calculations and experimental results demonstrate that fluorine-rich MXene exhibits stable binding with the active 1T phase RuSe_(2).The as-prepared representative RuSe_(2)@SC-Ti_(3)C_(2)T_(x)-3 heterostructure showed exceptional alkaline hydrogen evolution performance,demonstrating an overpotential of 15 mV at 10 mA cm^(-2)and a Tafel slope of 21.84 mV dec^(-1),which presents excellent HER performance and stability at high-current-density conditions.Moreover,the overpotential under the current density of 500 mA cm^(-2)is merely 182 mV,and the HER efficiency remains unaffected even after 5000 cycles and 120 h of continuous testing.
基金Supported by Scientific and Technological Development Project of Tianjin (No. 01310861111)
文摘Extraction of the Ligusticum Chuanxiong oil with supercritical CO2 （SC-CO2） was investigated at the temperatures ranging from 55℃ to 70℃ and pressure from 25 MPa to 35 MPa. The mass of Ligusticum Chuanxiong oil extracted increased with pressure at constant temperature. The initial slope of the extraction was considered as the solubility of oil in SC-CO2. Chrastil equation was used to correlate the solubility data of Ligusticum Chuanxiong oil. An improved Chrastil equation was also presented and was employed to correlate the solubility data, The correlation results show that the values of the average absolute relative deviation are 5.94% and 3.33% respectively, indicating the improved version has better correlation accuracy than that of Chrastil equation.
基金supported by the National Natural Science Foundation of China (20506014)
文摘Direct extraction of metals from solids with complexing agents in supercritical CO2(SC-CO2) has recently attracted interests in separation,purification,recovery,and analysis of metals.In the present study,the static/dynamic extraction of rare earth elements(Nd,Ce) from their oxides(Nd2O3,CeO2) with organophosphorus complexes with HNO3 and H2O in SC-CO2 was investigated.The static extraction efficiency of Nd from Nd2O3 with the tri-n-butylphosphate(TBP)-HNO3 complex could reach 95% under optimized experiment...
文摘The feasibility of removal of the organochlorine pesticides residues of hexachlorocyclohexane(BHC) from radix ginseng with supercritical CO2 was explored. Some factors, such as extraction pressure, extraction temperature, and kinds of co-solvents were investigated. The experimental results indicate that it is possible to reduce BHC residues in radix ginseng to the level of 0.1 × 10^-6 with supercritical CO2 in the presence of suitable amount of co-solvent, such as water.
文摘An experimental setup for separating ginger essential oil by supercritical fluid extraction is established. The effects of the extraction pressure, temperature, CO2 flow rate and particle size of raw material on the extraction rate are investigated, and the optimum process conditions of supercritical CO2 extraction are determined. A mathematical simulation model is established based on the mass conservation in differential units of extraction bed. The total mass transfer driving force and the equilibrium absorption constant are evaluated by the linear driving force theory. The results from numerical simulation agree well with the experimental data.
基金This work was financially supported by the China Postdoctoral Science Foundation(No.20060400436)the National Nature Foundation of China(No. 50433010)the National 973 Foundation of China(No.2003CB615705).
文摘Microporous poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)membranes following supercritical CO_2 induced phase separation process were prepared using four solvents.The solid electrolytes of PVDF-HFP were formed by microporous PVDF-HFP membranes filled and swollen by a liquid electrolyte.The effect of the solvents on the morphology and structure,electrolyte absorptions and lithium ionic conductivity of the activated membranes were investigated.It was approved that all the membrane had the similar...
文摘The thermal decomposition of 2, 2'-azobis (isobutyronitrile) (AIBN) in supercritical CO2 with cosolvent methanol or cyclohexane has been studied by using UV/Vis spectroscopic method at 335.15 K and at 12.0 MPa and 14.0 MPa. Both of the cosolvents can accelerate the decomposition rate, and the effect of methanol is more significant than that of the cyclohexane.
文摘High-pressure phase behavior of supercritical (SC) CO2+ethanol system was investigated at 333.2 K,348.2K, 353.2K, 368.2K, 413.2K and 453.2K and pressure from 2.0MPa to 14.3MPa. The measurement was carried out in a cylindrical autoclave with a moveable piston and a window for adjustment and observation of phase equilibria at given T and p. The samples were taken from two coexisting phases and were analyzed to obtain their compositions. It is shown that the solubility of SC CO2 in ethanol increases drastically with pressures at the given temperature, but the content of ethanol in CO2-rich phase increase faintly.
文摘A series of gluscose derivatives were designed, synthesized, and their structures were confirmed by IR, NMR and elementary analysis. All new compounds are highly soluble in liquid or supercritical carbon dioxide. The compound with electron-withdrawing substituent on benzene ring had even better solubility than the compounds with electron-donating substituent.
文摘The effect of cosolvent on the palladium catalyst which catalyze alkoxycarbonylation of allyl bromide in supercritical CO2 has been investigated. It was found that a small amount of cosolvent such as ethanol, CH2Cl2 and cyclohexane can affect both reaction yields and selectivities largely. Ethanol was the most favorable cosolvent for increasing the total yield of unsaturated esters and the selectivity of 3-butenoic acid ester. Using cosolvent ethanol and cocatalyst FeCl2 Simultaneously can lead to better reaction results.
基金the National Natural Science Foundation of China(Nos.20332030,20572027,20625205 and 20772034)Natural Science Foundation of Guangdong Province,China(No.07118070).
文摘1 Introduction Nowadays, green chemistry has received increased attention. The use of water and scCO2 as a solvent or reagent is an important field for organic reactions and green chemistry both in laboratory and industry.
文摘Polystyrene/Poly(ethylene terephthlate) (PET) blends have been prepared by theheterogeneous free-radical polymerization of styrene within supercritical carbon dioxide-swollenPET substrates. Composition of the blends and the average molecular weight of polystyrene inthe blends can be controlled by equilibration time and reaction condition.
