Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear streng...Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear strength under varying dissociation conditions have not been thoroughly investigated. To this end,a series of triaxial compression tests were first carried out on sediments with varying initial hydratesaturations along dissociation pathways. Combining measured data with microscale analysis, the underlyingmechanism for the evolution of shear strength in hydrate-bearing sediment was studied undervarying partial dissociation pathways. Moreover, a shear strength model for hydrate-bearing sedimentwas proposed, taking into account the hydrate saturation and the unhydrated water content. Apart fromthe parameters derived from the hydrate characteristic curve, only one additional model parameter isrequired. The proposed model was validated using measured data on hydrate sediments. The resultsindicate that the proposed model can effectively capture the shear strength behavior of hydrate-bearingsediment under varying dissociation paths. Finally, a sensitivity analysis of the model parameters wasconducted to characterize the proposed model.展开更多
Solar-driven interfacial desalination(SID)offers a sustainable route for freshwater production,yet its long-term performance is compromised by salt crystallization and microbial fouling under complex marine conditions...Solar-driven interfacial desalination(SID)offers a sustainable route for freshwater production,yet its long-term performance is compromised by salt crystallization and microbial fouling under complex marine conditions.Zwitterionic polymers offer promising nonfouling capabilities,but current zwitterionic hydrogel-based solar evaporators(HSEs)suffer from inadequate hydration and salt vulnerability.Inspired by the natural marine environmental adaptive characteristics of saltwater fish,we report a superhydrated zwitterionic poly(trimethylamine N-oxide,PTMAO)/polyacrylamide(PAAm)/polypyrrole(PPy)hydrogel(PTAP)with dedicated water channels for efficient,durable,and nonfouling SID.The directly linked N⁺and O⁻groups in PTMAO establish a robust hydration shell that facilitates rapid water transport while resisting salt and microbial adhesion.Integrated PAAm and PPy networks enhance mechanical strength and photothermal conversion.PTAP achieves a high evaporation rate of 2.35 kg m^(−2)h^(−1)under 1 kW m^(–2)in 10 wt%NaCl solution,maintaining stable operation over 100 h without salt accumulation.Furthermore,PTAP effectively resists various foulants including proteins,bacterial,and algal adhesion.Molecular dynamics simulations reveal that the exceptional hydration capacity supports its nonfouling properties.This work advances the development of nonfouling HSEs for sustainable solar desalination in real-world marine environments.展开更多
How natural gas hydrates nucleate and grow is a crucial scientific question.The research on it will help solve practical problems encountered in hydrate accumulation,development,and utilization of hydrate related tech...How natural gas hydrates nucleate and grow is a crucial scientific question.The research on it will help solve practical problems encountered in hydrate accumulation,development,and utilization of hydrate related technology.Due to its limitations on both spatial and temporal dimensions,experiment cannot fully explain this issue on a micro-scale.With the development of computer technology,molecular simulation has been widely used in the study of hydrate formation because it can observe the nucleation and growth process of hydrates at the molecular level.This review will assess the recent progresses in molecular dynamics simulation of hydrate nucleation and growth,as well as the enlightening significance of these developments in hydrate applications.At the same time,combined with the problems encountered in recent hydrate trial mining and applications,some potential directions for molecular simulation in the research of hydrate nucleation and growth are proposed,and the future of molecular simulation research on hydrate nucleation and growth is prospected.展开更多
Natural gas hydrate is a clean energy source with substantial resource potential.In contrast to conventional oil and gas,natural gas hydrate exists as a multi-phase system consisting of solids,liquids,and gases,which ...Natural gas hydrate is a clean energy source with substantial resource potential.In contrast to conventional oil and gas,natural gas hydrate exists as a multi-phase system consisting of solids,liquids,and gases,which presents unique challenges and complicates the mechanisms of seepage and exploitation.Both domestic and international natural gas hydrate production tests typically employ a single-well production model.Although this approach has seen some success,it continues to be hindered by low production rates and short production cycles.Therefore,there is an urgent need to explore a new well network to significantly increase the production of a single well.This paper provides a comprehensive review of the latest advancements in natural gas hydrate research,including both laboratory studies and field tests.It further examines the gas production processes and development outcomes for single wells,dual wells,multi-branch wells,and multi-well systems under conditions of depressurization,thermal injection,and CO_(2) replacement.On this basis,well types and well networks suitable for commercial exploitation of natural gas hydrate were explored,and the technical direction of natural gas hydrate development was proposed.The study shows that fully exploiting the flexibility of complex structural wells and designing a well network compatible with the reservoir is the key to improving production from a single well.Moreover,multi-well joint exploitation is identified as an effective strategy for achieving large-scale,efficient development of natural gas hydrate.展开更多
During the production of natural gas hydrates,micron-sized sand particles coexist with hydrate within the transportation pipeline,posing a significant threat to the safety of pipeline flow.However,the influence of san...During the production of natural gas hydrates,micron-sized sand particles coexist with hydrate within the transportation pipeline,posing a significant threat to the safety of pipeline flow.However,the influence of sand particles on hydrate formation mechanisms and rheological properties remains poorly understood.Consequently,using a high-pressure reactor system,the phase equilibrium conditions,hydrate formation characteristics,hydrate concentration,and the slurry viscosity in micron-sized sand system are investigated in this work.Furthermore,the effects of sand particle size,sand concentration,and initial pressure on these properties are analyzed.The results indicate that a high concentration of micron-sized sand particles enhances the formation of methane hydrates.When the volume fraction of sand particles exceeds or equals 3%,the phase equilibrium conditions of the methane hydrate shift to the left relative to that of the pure water system(lower temperature,higher pressure).This shift becomes more pronounced with smaller particle sizes.Besides,under these sand concentration conditions,methane hydrates exhibit secondary or even multiple formation events,though the formation rate decreases.Additionally,the torque increases significantly and fluctuates considerably.The Roscoe-Brinkman model yields the most accurate slurry viscosity calculations,and as sand concentration increases,both hydrate concentration and slurry viscosity also increase.展开更多
The commercial exploitation of natural gas hydrates is currently facing several challenges,including low production rates,limited recovery areas,and brief periods of continuous production.To address these issues,we pr...The commercial exploitation of natural gas hydrates is currently facing several challenges,including low production rates,limited recovery areas,and brief periods of continuous production.To address these issues,we propose a novel dual-enhanced stimulation(DES)method for marine hydrate reservoirs.This method involves injecting a special slurry that solidifies into porous,high-permeability,and highstrength slurry veins.These veins not only enhance permeability,allowing for faster gas and water flow,but also improve reservoir stability.This study experimentally investigated the split grouting of clayey-silty sediments with dual-enhanced slurry to assess the feasibility of DES and to explo re the slurry diffusion mechanism and micro-pore structure of the veins.The results showed that split grouting with dual-enhanced slurry exhibited frequent fracture initiation with quick pressure spikes and sharp declines,suggesting shorter fractures in clayey-silty sediments.As vertical stress increased,the primary diffusion direction of the dual-enhanced slurry shifted from horizontal to vertical,aligning with fracture propagation patterns observed during fracturing.Unlike hydraulic fracturing in hard rocks,split grouting in clayey-silty sediments encountered more difficult conditions.These veins formed through a recurring cycle of splitting into fractures and filling with slurry,occurring more frequently in weaker sediments with slower injection rates and higher vertical stress.Increased vertical stress hindered slurry vein diffu sion,easily resulting in compaction grouting near the grouting pipe.Additionally,three-dimensional laser scanning of the veins showed that those formed through split grouting were continuous and stable,with their thickness decreasing as diffusion distance increased.The morphology of these veins was shaped by factors such as grouting rate,formation stress,and elastic modulus,with higher rates and elastic moduli facilitating the formation of complex vein networks.Mercury intrusion porosimetry demonstrated that the DES method resulted in veins with consistent effective porosity between 65%and70%and median pore sizes of 11-15μm across different locations.These veins formed a well-connected porous network of smaller pores,significantly enhancing both permeability and sand control.The research findings validate the effectiveness of the DES method for marine hydrate reservoirs,providing a strategy for the safe and efficient exploitation of NGH resources.展开更多
The flow behaviors of gas and water in hydrate-bearing sediments(HBS)are significantly affected by the threshold pressure gradient(TPG).During long-term natural gas hydrates(NGHs)mining,there exists creep deformation ...The flow behaviors of gas and water in hydrate-bearing sediments(HBS)are significantly affected by the threshold pressure gradient(TPG).During long-term natural gas hydrates(NGHs)mining,there exists creep deformation in HBS,which significantly alters pore structures,makes the flow path of fluid more complex,and leads to changes in TPG.Thus,clarifying the evolution of TPG in HBS during creep is essential for NGH production,but it also confronts enormous challenges.In this study,based on the nonlinear creep constitutive model,a novel theoretical TPG model of HBS during creep is proposed that considers pore structures and hydrate pore morphology.The established model is validated against experimental data,demonstrating its ability to capture the evolution of TPG and permeability in HBS during creep.Additionally,the relationship between initial hydrate saturation and TPG of HBS during creep is revealed by sensitivity analysis.The creep strain increases with the decrease in initial hydrate saturation,leading to a greater TPG and a lower permeability.The evolution of TPG at the stable creep stage and the accelerated creep stage is primarily controlled by the Kelvin element and visco-plastic element,respectively.This novel proposed model provides a mechanistic understanding of TPG evolution in HBS during creep,and it is of great significance to optimize the exploitation of NGHs.展开更多
As a kind of novel environmental-friendly surfactant,Gemini surfactant has attracted extensive research interests in its effects on gas hydrate formation.We investigated the effects of dioctyl sodium sulfosuccinate(AO...As a kind of novel environmental-friendly surfactant,Gemini surfactant has attracted extensive research interests in its effects on gas hydrate formation.We investigated the effects of dioctyl sodium sulfosuccinate(AOT)on the formation thermodynamics/kinetics of CH_(4)and CO_(2)hydrates.Experimental results indicate that while AOT does not exhibit significant thermodynamic promotion for hydrate formation,it demonstrates favorable kinetic promotion effects.Its promotion effect surpasses that of the traditional kinetic promoter SDS and can enhance the gas storage capacity of hydrates.Utilizing the Chen-Guo hydrate model and adsorption kinetic model,we established a kinetic model for AOT with a predictive deviation of 7.17%and fitted key parameters accordingly.展开更多
Hydraulic fracturing technology has played an important role in the exploitation of unconventional oil and gas resources,however,its application to gas hydrate reservoirs has been rarely studied.Currently,there is sti...Hydraulic fracturing technology has played an important role in the exploitation of unconventional oil and gas resources,however,its application to gas hydrate reservoirs has been rarely studied.Currently,there is still limited understanding of the propagation and extension of fractures around the wellbore during the fracturing process of horizontal wells in hydrate reservoirs,as well as the stress interference patterns between fractures.This study simulates hydraulic fracturing processes in hydrate reservoirs using a fluidsolid coupling discrete element method(DEM),and analyzes the impacts of hydrate saturation and geological and engineering factors on fracture extension and stress disturbance.The results show that hydraulic fracturing is more effective when hydrate saturation exceeds 30%and that fracture pressure increases with saturation.The increase in horizontal stress differential enhances the directionality of fracture propagation and reduces stress disturbance.The distribution uniformity index(DUI)reveals that injection pressure is directly proportional to the number of main fractures and inversely proportional to fracturing time,with fracturing efficiency depending on the spacing between injection points and the distance between wells.This work may provide reference for the commercial exploitation of natural gas hydrates.展开更多
Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)format...Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)formation and dissociation are still in controversy.In this study,montmorillonite and illite were separately mixed with quartz sand to investigate their effects on MH formation and dissociation.The microstructure of synthesized samples was observed by cryo-SEM innovatively to understand the effects of montmorillonite and illite on MH phase transition in micron scale.Results show that montmorillonite and illite both show the inhibition on MH formation kinetics and water-to-hydrate conversion,and illite shows a stronger inhibition.The 10 wt%montmorillonite addition significantly retards MH formation rate,and the 20 wt%montmorillonite has a less inhibition on the rate.The increase of illite mass ratio(0-20 wt%)retards the rate of MH formation.As the content of clay minerals increase,the water-to-hydrate conversion decreases.Cryo-SEM images presented that montmorillonite aggregates separate as individual clusters while illite particles pack as face-to-face configuration under the interaction with water.The surface-overlapped illite aggregates would make sediments pack tightly,hinder the contact between gas and water,and result in the more significant inhibition on MH formation kinetics.Under the depressurization method,the addition of clay minerals facilitates MH dissociation rate.Physicochemical properties of clay minerals and MH distribution in the pore space lead to the faster dissociation rate in clay-containing sediments.The results of this study would provide beneficial guides on geological investigations and optimizing strategies of natural gas production in marine hydrate-bearing sediments.展开更多
The mechanism of hydrate-based desalination is that water molecules would transfer to the hydrate phase during gas hydrate formation process,while the salt ions would be conversely concentrated in the unreacted saltwa...The mechanism of hydrate-based desalination is that water molecules would transfer to the hydrate phase during gas hydrate formation process,while the salt ions would be conversely concentrated in the unreacted saltwater.However,the salt concentration of hydrate decomposed water and the desalination degree of hydrate phase are still unclear.The biggest challenge is how to effectively separate the hydrate phase and the remaining unreacted salt water,and then decompose the hydrate phase to measure the salt concentration of hydrate melt water.This work developed an apparatus and pressure-driven filtration method to efficiently separate the hydrate phase and the remaining unreacted saltwater.On this basis,the single hydrate phase was obtained,then it was dissociated and the salt concentration of hydrate melt water was measured.The experimental results demonstrate that when the initial salt mass concentration is 0.3% to 8.0%,the salt removal efficiency for NaCl solution is 15.9% to 29.8%by forming CO_(2) hydrate,while for CaCl_(2) solution is 28.9%to 45.5%.The solute CaCl_(2) is easier to be removed than solute NaCl.In addition,the salt removal efficiency for forming CO_(2) hydrate is higher than that for forming methane hydrate.The multi-stage desalination can continuously decrease the salt concentration of hydrate dissociated water,and the salt removal efficiency per stage is around 20%.展开更多
Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-...Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.展开更多
Carbon dioxide(CO_(2))marine sequestration by hydrate method is considered as one of the options to effectively achieve carbon reduction.However,the slow rate of hydrate formation becomes a major limiting factor.In vi...Carbon dioxide(CO_(2))marine sequestration by hydrate method is considered as one of the options to effectively achieve carbon reduction.However,the slow rate of hydrate formation becomes a major limiting factor.In view of the gas-water mass transfer problem which is the main obstacle,this paper explored the amphiphilic amino acids to promote the formation of CO_(2)hydrate and used low-field nuclear magnetic resonance(LNMR)to conduct an innovative study on its kinetics and spatiotemporal distribution.By comparing the promotion performance of L-methionine(L-met),L-cysteine(L-cys),and L-valine(L-val),the comprehensive kinetic promotion ability of L-met was the highest,reducing the induction time by 60.0%,achieving the maximum water conversion of about 57.0%within only 1 h,and reaching a final CO_(2)storage efficiency of 84.6%.LNMR results showed that hydrates were preferentially formed in large and medium pores in the reservoir region.Interestingly,we found that the combined effect of hydrophilic groups and the hydrophobic side chain of L-met not only promoted the rearrangement of water molecules and provided more nucleation sites,but also created a localized CO_(2)supersaturated environment and facilitated gas-water redistribution.Meanwhile,L-met promoted the formation of a hydrate porous structure to ensure the continuous formation of hydrates.This study innovatively explored CO_(2)hydrate formation behavior in amphiphilic amino acids and laid a theoretical foundation for the realization of CO_(2)marine sequestration by hydrate method.展开更多
Natural gas hydrate(NGH)has a bright future as a clean energy source with huge reserves.Coring is one of the most direct methods for NGH exploration and research.Preserving the in-situ properties of the core as much a...Natural gas hydrate(NGH)has a bright future as a clean energy source with huge reserves.Coring is one of the most direct methods for NGH exploration and research.Preserving the in-situ properties of the core as much as possible during the coring process is crucial for the assessment of NGH resources.However,most existing NGH coring techniques cannot preserve the in-situ temperature of NGH,leading to distortion of the physical properties of the obtained core,which makes it difficult to effectively guide NGH exploration and development.To overcome this limitation,this study introduces an innovative active temperature-preserved coring method for NGH utilizing phase change materials(PCM).An active temperature-preserved corer(ATPC)is designed and developed,and an indoor experimental system is established to investigate the heat transfer during the coring process.Based on the experimental results under different environment temperatures,a heat transfer model for the entire ATPC coring process has been established.The indoor experimental results are consistent with the theoretical predictions of the heat transfer model,confirming its validity.This model has reconstructed the temperature changes of the NGH core during the coring process,demonstrating that compared to the traditional coring method with only passive temperature-preserved measures,ATPC can effectively reduce the core temperature by more than 5.25℃.With ATPC,at environment temperatures of 15,20,25,and 30℃,the duration of low-temperature state for the NGH core is 53.85,32.87,20.32,and 11.83 min,respectively.These findings provide new perspectives on temperature-preserving core sampling in NGH and provide technical support for exploration and development in NGH.展开更多
Natural gas hydrates(hereinafter referred to as hydrates)are a promising clean energy source.However,their current development is far from reaching commercial exploitation.Reservoir stimulation tech-nology provides ne...Natural gas hydrates(hereinafter referred to as hydrates)are a promising clean energy source.However,their current development is far from reaching commercial exploitation.Reservoir stimulation tech-nology provides new approaches to enhance hydrate development effectiveness.Addressing the current lack of quantitative and objective methods for evaluating the fracability of hydrate reservoirs,this study clarifies the relationship between geological and engineering fracability and proposes a comprehensive evaluation model for hydrate reservoir fracability based on grey relational analysis and the criteria importance through intercriteria correlation method.By integrating results from hydraulic fracturing experiments on hydrate sediments,the fracability of hydrate reservoirs is assessed.The concept of critical construction parameter curves for hydrate reservoirs is introduced for the first time.Additionally,two-dimensional fracability index evaluation charts and three-dimensional fracability construction condition discrimination charts are established.The results indicate that as the comprehensive fracability index increases,the feasibility of forming fractures in hydrate reservoirs improves,and the required normalized fracturing construction parameters gradually decrease.The accuracy rate of the charts in judging experimental results reached 89.74%,enabling quick evaluations of whether hydrate reservoirs are worth fracturing,easy to fracture,and capable of being fractured.This has significant engineering implications forthehydraulicfracturingof hydratereservoirs.展开更多
Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the inte...Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the interface,further growth of hydrate due to the suction of water in the capillary system formed between the wall of the cuvette and the end boundary of the hydrate layer occurs.Most probably,substantial effects on the formation of this capillary system may be caused by variations in reactor wall properties,for example,hydrophobic-hydrophilic balance,roughness,etc.We found,that the rate of CO_(2) hydrate film growth on the surface of the humic acid aqueous solution is 4-fold to lower in comparison with the growth rate on the surface of pure water.We suppose that this is caused by the adsorption of humic acid associates on the surface of hydrate particles and,as a consequence,by the deceleration of the diffusion of dissolved carbon dioxide to the growing hydrate particle.展开更多
This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensi...This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensive multiphysics simulations guided by field data from hydrate production tests in the South China Sea,we pinpoint key operational parameters—such as injection rates,depths,and timings—that notably enhance production efficiency.The results indicate that a 3-phase hydrate reservoir transitions from a free-gas-dominated production stage to a hydrate-decomposition-dominated stage.Moderate warm seawater injection supplies additional heat during the hydrate decomposition phase,thereby enhancing stable production;however,excessively high injection rates can impede the depressurization process.Only injection at an appropriate depth simultaneously balances thermal supplementation and the pressure gradient,leading to higher overall productivity.A“depressurization-driven sensible-heat supply window”is introduced,highlighting that timely seawater injection following initial depressurization prolongs reservoir dissociation dynamics.In this study area,commencing seawater injection at 170 d of depressurization proved optimal.This optimized integration leverages clean and renewable thermal energy,providing essential insights into thermal supplementation strategies with significant implications for sustainable,economically feasible,and efficient commercial-scale hydrate production.展开更多
An efficient acetic acid mediated metal-free oxidative C—H cross coupling of imidazo[1,2-a]pyridines with glyoxal hydrates has been developed under air atmosphere.The present protocol exhibits broad substrate scope,g...An efficient acetic acid mediated metal-free oxidative C—H cross coupling of imidazo[1,2-a]pyridines with glyoxal hydrates has been developed under air atmosphere.The present protocol exhibits broad substrate scope,good functional group tolerance,and enables the construction of a series of 1,2-dicarbonyl imidazo[1,2-a]pyridines in good yields.The reaction mechanism studies suggest that the reactions proceed through the electrophilic substitution and subsequent oxidation pathway.展开更多
Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the ...Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the low-permeability characteristics with an average permeability of 5.5 mD and moderate heterogeneity,a 3-D geological model of heterogeneous Class I hydrate reservoirs with three-phase transition layers is established by Kriging interpolation and stochastic modeling method,and a numerical simulation model is used to describe the depressurization production performance of the reservoir.With the development of depressurization,a specific range of complete decomposition zones appear both in the hydrate and transition layers.The entire decomposition zone of the whole reservoir tends to outward and upward diffusion.There is apparent methane escape in the three-phase transition layer.Due to the improvement of local permeability caused by the phase transition of hydrate dissociation,some methane accumulation occurs at the bottom of the hydrate layer,forming a local methane enrichment zone.The methane migration trends in reservoirs are mainly characterized by movement toward production wells and hydrate layers under the influence of gravity.However,due to the permeability limitation of hydrate reservoirs,many fluids have not been effectively produced and remain in the reservoir.Therefore,to improve the effective pressure drop of the reservoir,the perforation method and pressure reduction method were optimized by analyzing the influencing factors based on the gas production rate.The comparative study demonstrates that perforating through the free gas layer combined with one-time depressurization can enhance the effective depressurization and improve production performance.The gas production rate from perforating through the free gas layer can be twice as high as that from perforating through the transition layer.This study can provide theoretical support for the utilization of marine energy.展开更多
A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particl...A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particles,i.e.,LAC-S(silica derived from acid leaching of amorphous C-S-H) and LLC-S(silica derived from acid leaching of low-crystallinity C-S-H) are obtained after calcium ions are removed from both amorphous and low-crystallinity forms of C-S-H through a facile acid leaching process(3 mol/L,25℃,24 h).(29)^Si NMR spectroscopy reveals that the proportion of silicon atoms carrying silanol groups increases from less than 43% to over 80% when silica particles are transferred from a dry state to an aqueous solution.Batch adsorption experiments were conducted to evaluate the sorption performance and selectivity of these silica sorbents toward Sc(Ⅲ).The scandium sorption capacities of LAC-S and LLC-S at an equilibrium pH of 4.2 are 174.45 and 129.57 mg/g,respectively.The separation factors(SFSc/Ln) of both silica particles exceed 1000 in the initial pH range of 3.5-5.The loaded scandium ions are recovered with 3 mol/L hydrochloric acid and the sorbents exhibit good reusability.This strategy provides an efficient and green method for recovering scandium from aqueous solutions.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51939011)the Science and Technology Program of CNOOC Research Institute(Grant No.2023OTKK03)supported by the program of the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2020326).
文摘Shear strength of hydrate-bearing sediment is an essential parameter for assessing landslide potential ofhydrate reservoirs under exploration conditions. However, the characteristics and simulation of thisshear strength under varying dissociation conditions have not been thoroughly investigated. To this end,a series of triaxial compression tests were first carried out on sediments with varying initial hydratesaturations along dissociation pathways. Combining measured data with microscale analysis, the underlyingmechanism for the evolution of shear strength in hydrate-bearing sediment was studied undervarying partial dissociation pathways. Moreover, a shear strength model for hydrate-bearing sedimentwas proposed, taking into account the hydrate saturation and the unhydrated water content. Apart fromthe parameters derived from the hydrate characteristic curve, only one additional model parameter isrequired. The proposed model was validated using measured data on hydrate sediments. The resultsindicate that the proposed model can effectively capture the shear strength behavior of hydrate-bearingsediment under varying dissociation paths. Finally, a sensitivity analysis of the model parameters wasconducted to characterize the proposed model.
基金supported by National Natural Science Foundation of China(22209036,U23A20119)Hebei Provincial Natural Science Foundation,Excellent Youth Project(E2023202069)+1 种基金National Key R&D Program of China(2024YFF0506000,2024YFB4609100)Fundamental Research Foundation from Hebei University of Technology(424132016,282021485).
文摘Solar-driven interfacial desalination(SID)offers a sustainable route for freshwater production,yet its long-term performance is compromised by salt crystallization and microbial fouling under complex marine conditions.Zwitterionic polymers offer promising nonfouling capabilities,but current zwitterionic hydrogel-based solar evaporators(HSEs)suffer from inadequate hydration and salt vulnerability.Inspired by the natural marine environmental adaptive characteristics of saltwater fish,we report a superhydrated zwitterionic poly(trimethylamine N-oxide,PTMAO)/polyacrylamide(PAAm)/polypyrrole(PPy)hydrogel(PTAP)with dedicated water channels for efficient,durable,and nonfouling SID.The directly linked N⁺and O⁻groups in PTMAO establish a robust hydration shell that facilitates rapid water transport while resisting salt and microbial adhesion.Integrated PAAm and PPy networks enhance mechanical strength and photothermal conversion.PTAP achieves a high evaporation rate of 2.35 kg m^(−2)h^(−1)under 1 kW m^(–2)in 10 wt%NaCl solution,maintaining stable operation over 100 h without salt accumulation.Furthermore,PTAP effectively resists various foulants including proteins,bacterial,and algal adhesion.Molecular dynamics simulations reveal that the exceptional hydration capacity supports its nonfouling properties.This work advances the development of nonfouling HSEs for sustainable solar desalination in real-world marine environments.
基金jointly supported by Pilot National Laboratory for Marine Science and Technology (Qingdao)the IGGCAS (IGGCAS-201903 and SZJJ201901)the Chinese Academy of Sciences (ZDBSLY-DQC003)。
文摘How natural gas hydrates nucleate and grow is a crucial scientific question.The research on it will help solve practical problems encountered in hydrate accumulation,development,and utilization of hydrate related technology.Due to its limitations on both spatial and temporal dimensions,experiment cannot fully explain this issue on a micro-scale.With the development of computer technology,molecular simulation has been widely used in the study of hydrate formation because it can observe the nucleation and growth process of hydrates at the molecular level.This review will assess the recent progresses in molecular dynamics simulation of hydrate nucleation and growth,as well as the enlightening significance of these developments in hydrate applications.At the same time,combined with the problems encountered in recent hydrate trial mining and applications,some potential directions for molecular simulation in the research of hydrate nucleation and growth are proposed,and the future of molecular simulation research on hydrate nucleation and growth is prospected.
基金This work was supported by the projects of the China Geological Survey(DD 20221703).
文摘Natural gas hydrate is a clean energy source with substantial resource potential.In contrast to conventional oil and gas,natural gas hydrate exists as a multi-phase system consisting of solids,liquids,and gases,which presents unique challenges and complicates the mechanisms of seepage and exploitation.Both domestic and international natural gas hydrate production tests typically employ a single-well production model.Although this approach has seen some success,it continues to be hindered by low production rates and short production cycles.Therefore,there is an urgent need to explore a new well network to significantly increase the production of a single well.This paper provides a comprehensive review of the latest advancements in natural gas hydrate research,including both laboratory studies and field tests.It further examines the gas production processes and development outcomes for single wells,dual wells,multi-branch wells,and multi-well systems under conditions of depressurization,thermal injection,and CO_(2) replacement.On this basis,well types and well networks suitable for commercial exploitation of natural gas hydrate were explored,and the technical direction of natural gas hydrate development was proposed.The study shows that fully exploiting the flexibility of complex structural wells and designing a well network compatible with the reservoir is the key to improving production from a single well.Moreover,multi-well joint exploitation is identified as an effective strategy for achieving large-scale,efficient development of natural gas hydrate.
基金supported by the Natural Science Starting Project of Sichuan Provincial Youth Foundation Project(2025ZNSFSC1356)Southwest Petroleum University,China(2023QHZ019)+1 种基金General Project of the Sichuan Provincial Natural Science Foundation,China(24NSFSC1295)Open fund of Dazhou Industrial Technology Institute of Intelligent Manufacturing,China(ZNZZ2215).
文摘During the production of natural gas hydrates,micron-sized sand particles coexist with hydrate within the transportation pipeline,posing a significant threat to the safety of pipeline flow.However,the influence of sand particles on hydrate formation mechanisms and rheological properties remains poorly understood.Consequently,using a high-pressure reactor system,the phase equilibrium conditions,hydrate formation characteristics,hydrate concentration,and the slurry viscosity in micron-sized sand system are investigated in this work.Furthermore,the effects of sand particle size,sand concentration,and initial pressure on these properties are analyzed.The results indicate that a high concentration of micron-sized sand particles enhances the formation of methane hydrates.When the volume fraction of sand particles exceeds or equals 3%,the phase equilibrium conditions of the methane hydrate shift to the left relative to that of the pure water system(lower temperature,higher pressure).This shift becomes more pronounced with smaller particle sizes.Besides,under these sand concentration conditions,methane hydrates exhibit secondary or even multiple formation events,though the formation rate decreases.Additionally,the torque increases significantly and fluctuates considerably.The Roscoe-Brinkman model yields the most accurate slurry viscosity calculations,and as sand concentration increases,both hydrate concentration and slurry viscosity also increase.
基金financial support received from the National Natural Science Foundation of China(Nos.51991364,and 42202347)。
文摘The commercial exploitation of natural gas hydrates is currently facing several challenges,including low production rates,limited recovery areas,and brief periods of continuous production.To address these issues,we propose a novel dual-enhanced stimulation(DES)method for marine hydrate reservoirs.This method involves injecting a special slurry that solidifies into porous,high-permeability,and highstrength slurry veins.These veins not only enhance permeability,allowing for faster gas and water flow,but also improve reservoir stability.This study experimentally investigated the split grouting of clayey-silty sediments with dual-enhanced slurry to assess the feasibility of DES and to explo re the slurry diffusion mechanism and micro-pore structure of the veins.The results showed that split grouting with dual-enhanced slurry exhibited frequent fracture initiation with quick pressure spikes and sharp declines,suggesting shorter fractures in clayey-silty sediments.As vertical stress increased,the primary diffusion direction of the dual-enhanced slurry shifted from horizontal to vertical,aligning with fracture propagation patterns observed during fracturing.Unlike hydraulic fracturing in hard rocks,split grouting in clayey-silty sediments encountered more difficult conditions.These veins formed through a recurring cycle of splitting into fractures and filling with slurry,occurring more frequently in weaker sediments with slower injection rates and higher vertical stress.Increased vertical stress hindered slurry vein diffu sion,easily resulting in compaction grouting near the grouting pipe.Additionally,three-dimensional laser scanning of the veins showed that those formed through split grouting were continuous and stable,with their thickness decreasing as diffusion distance increased.The morphology of these veins was shaped by factors such as grouting rate,formation stress,and elastic modulus,with higher rates and elastic moduli facilitating the formation of complex vein networks.Mercury intrusion porosimetry demonstrated that the DES method resulted in veins with consistent effective porosity between 65%and70%and median pore sizes of 11-15μm across different locations.These veins formed a well-connected porous network of smaller pores,significantly enhancing both permeability and sand control.The research findings validate the effectiveness of the DES method for marine hydrate reservoirs,providing a strategy for the safe and efficient exploitation of NGH resources.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515110376)the Open Research Fund of National Center for International Research on Deep Earth Drilling and Resource Development,Ministry of Science and Technology(Grant No.DEDRD-2023-04)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Grant No.107-G1323523046).
文摘The flow behaviors of gas and water in hydrate-bearing sediments(HBS)are significantly affected by the threshold pressure gradient(TPG).During long-term natural gas hydrates(NGHs)mining,there exists creep deformation in HBS,which significantly alters pore structures,makes the flow path of fluid more complex,and leads to changes in TPG.Thus,clarifying the evolution of TPG in HBS during creep is essential for NGH production,but it also confronts enormous challenges.In this study,based on the nonlinear creep constitutive model,a novel theoretical TPG model of HBS during creep is proposed that considers pore structures and hydrate pore morphology.The established model is validated against experimental data,demonstrating its ability to capture the evolution of TPG and permeability in HBS during creep.Additionally,the relationship between initial hydrate saturation and TPG of HBS during creep is revealed by sensitivity analysis.The creep strain increases with the decrease in initial hydrate saturation,leading to a greater TPG and a lower permeability.The evolution of TPG at the stable creep stage and the accelerated creep stage is primarily controlled by the Kelvin element and visco-plastic element,respectively.This novel proposed model provides a mechanistic understanding of TPG evolution in HBS during creep,and it is of great significance to optimize the exploitation of NGHs.
基金supported by National Natural Science Foundation of China(22278424,22127812,22008257).
文摘As a kind of novel environmental-friendly surfactant,Gemini surfactant has attracted extensive research interests in its effects on gas hydrate formation.We investigated the effects of dioctyl sodium sulfosuccinate(AOT)on the formation thermodynamics/kinetics of CH_(4)and CO_(2)hydrates.Experimental results indicate that while AOT does not exhibit significant thermodynamic promotion for hydrate formation,it demonstrates favorable kinetic promotion effects.Its promotion effect surpasses that of the traditional kinetic promoter SDS and can enhance the gas storage capacity of hydrates.Utilizing the Chen-Guo hydrate model and adsorption kinetic model,we established a kinetic model for AOT with a predictive deviation of 7.17%and fitted key parameters accordingly.
基金financially supported by the National Key Research and Development Plan(2023YFC2811001)the National Natural Science Foundation of China(42206233)the Taishan Scholars Program(tsqn202312280,tsqn202306297)。
文摘Hydraulic fracturing technology has played an important role in the exploitation of unconventional oil and gas resources,however,its application to gas hydrate reservoirs has been rarely studied.Currently,there is still limited understanding of the propagation and extension of fractures around the wellbore during the fracturing process of horizontal wells in hydrate reservoirs,as well as the stress interference patterns between fractures.This study simulates hydraulic fracturing processes in hydrate reservoirs using a fluidsolid coupling discrete element method(DEM),and analyzes the impacts of hydrate saturation and geological and engineering factors on fracture extension and stress disturbance.The results show that hydraulic fracturing is more effective when hydrate saturation exceeds 30%and that fracture pressure increases with saturation.The increase in horizontal stress differential enhances the directionality of fracture propagation and reduces stress disturbance.The distribution uniformity index(DUI)reveals that injection pressure is directly proportional to the number of main fractures and inversely proportional to fracturing time,with fracturing efficiency depending on the spacing between injection points and the distance between wells.This work may provide reference for the commercial exploitation of natural gas hydrates.
基金supported by the Key Research Program of the Institute of Geology&Geophysics,CAS(Grant No.IGGCAS-201903).
文摘Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)formation and dissociation are still in controversy.In this study,montmorillonite and illite were separately mixed with quartz sand to investigate their effects on MH formation and dissociation.The microstructure of synthesized samples was observed by cryo-SEM innovatively to understand the effects of montmorillonite and illite on MH phase transition in micron scale.Results show that montmorillonite and illite both show the inhibition on MH formation kinetics and water-to-hydrate conversion,and illite shows a stronger inhibition.The 10 wt%montmorillonite addition significantly retards MH formation rate,and the 20 wt%montmorillonite has a less inhibition on the rate.The increase of illite mass ratio(0-20 wt%)retards the rate of MH formation.As the content of clay minerals increase,the water-to-hydrate conversion decreases.Cryo-SEM images presented that montmorillonite aggregates separate as individual clusters while illite particles pack as face-to-face configuration under the interaction with water.The surface-overlapped illite aggregates would make sediments pack tightly,hinder the contact between gas and water,and result in the more significant inhibition on MH formation kinetics.Under the depressurization method,the addition of clay minerals facilitates MH dissociation rate.Physicochemical properties of clay minerals and MH distribution in the pore space lead to the faster dissociation rate in clay-containing sediments.The results of this study would provide beneficial guides on geological investigations and optimizing strategies of natural gas production in marine hydrate-bearing sediments.
基金The financial support from the National Natural Science Foundation of China(22127812,22278433,22178379)the National Key Research and Development Program of China(2021YFC2800902)are gratefully acknowledged。
文摘The mechanism of hydrate-based desalination is that water molecules would transfer to the hydrate phase during gas hydrate formation process,while the salt ions would be conversely concentrated in the unreacted saltwater.However,the salt concentration of hydrate decomposed water and the desalination degree of hydrate phase are still unclear.The biggest challenge is how to effectively separate the hydrate phase and the remaining unreacted salt water,and then decompose the hydrate phase to measure the salt concentration of hydrate melt water.This work developed an apparatus and pressure-driven filtration method to efficiently separate the hydrate phase and the remaining unreacted saltwater.On this basis,the single hydrate phase was obtained,then it was dissociated and the salt concentration of hydrate melt water was measured.The experimental results demonstrate that when the initial salt mass concentration is 0.3% to 8.0%,the salt removal efficiency for NaCl solution is 15.9% to 29.8%by forming CO_(2) hydrate,while for CaCl_(2) solution is 28.9%to 45.5%.The solute CaCl_(2) is easier to be removed than solute NaCl.In addition,the salt removal efficiency for forming CO_(2) hydrate is higher than that for forming methane hydrate.The multi-stage desalination can continuously decrease the salt concentration of hydrate dissociated water,and the salt removal efficiency per stage is around 20%.
基金supported by the Gas Hydrate R&D Organization and the Korea Institute of Geoscience and Mineral Resources(KIGAM)(GP2021-010)supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2021R1C1C1004460)Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korean government(MOTIE)(20214000000500,Training Program of CCUS for Green Growth).
文摘Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.
基金supported by the National Key Research and Development Program of China for Young Scientists(Grant No.2023YFB4104100)the National Natural Science Foundation of China(Grant 52176057)+3 种基金the National Key Research and Development Program of China(Grant No.2023YFB4104201)supported by the Unveiling and Commanding Foundation of Liaoning Province(Grant 2023JH1/10400003)the Shenzhen Science and Technology Program(No.JCYJ20220818095605012)supported by the Young Changjiang Scholars programme of China。
文摘Carbon dioxide(CO_(2))marine sequestration by hydrate method is considered as one of the options to effectively achieve carbon reduction.However,the slow rate of hydrate formation becomes a major limiting factor.In view of the gas-water mass transfer problem which is the main obstacle,this paper explored the amphiphilic amino acids to promote the formation of CO_(2)hydrate and used low-field nuclear magnetic resonance(LNMR)to conduct an innovative study on its kinetics and spatiotemporal distribution.By comparing the promotion performance of L-methionine(L-met),L-cysteine(L-cys),and L-valine(L-val),the comprehensive kinetic promotion ability of L-met was the highest,reducing the induction time by 60.0%,achieving the maximum water conversion of about 57.0%within only 1 h,and reaching a final CO_(2)storage efficiency of 84.6%.LNMR results showed that hydrates were preferentially formed in large and medium pores in the reservoir region.Interestingly,we found that the combined effect of hydrophilic groups and the hydrophobic side chain of L-met not only promoted the rearrangement of water molecules and provided more nucleation sites,but also created a localized CO_(2)supersaturated environment and facilitated gas-water redistribution.Meanwhile,L-met promoted the formation of a hydrate porous structure to ensure the continuous formation of hydrates.This study innovatively explored CO_(2)hydrate formation behavior in amphiphilic amino acids and laid a theoretical foundation for the realization of CO_(2)marine sequestration by hydrate method.
基金financially supported by Shenzhen Science and Technology Program(Nos.JSGG20220831105002005 and KJZD20231025152759002)the National Natural Science Foundation of China(Nos.52274133 and 523B2101).
文摘Natural gas hydrate(NGH)has a bright future as a clean energy source with huge reserves.Coring is one of the most direct methods for NGH exploration and research.Preserving the in-situ properties of the core as much as possible during the coring process is crucial for the assessment of NGH resources.However,most existing NGH coring techniques cannot preserve the in-situ temperature of NGH,leading to distortion of the physical properties of the obtained core,which makes it difficult to effectively guide NGH exploration and development.To overcome this limitation,this study introduces an innovative active temperature-preserved coring method for NGH utilizing phase change materials(PCM).An active temperature-preserved corer(ATPC)is designed and developed,and an indoor experimental system is established to investigate the heat transfer during the coring process.Based on the experimental results under different environment temperatures,a heat transfer model for the entire ATPC coring process has been established.The indoor experimental results are consistent with the theoretical predictions of the heat transfer model,confirming its validity.This model has reconstructed the temperature changes of the NGH core during the coring process,demonstrating that compared to the traditional coring method with only passive temperature-preserved measures,ATPC can effectively reduce the core temperature by more than 5.25℃.With ATPC,at environment temperatures of 15,20,25,and 30℃,the duration of low-temperature state for the NGH core is 53.85,32.87,20.32,and 11.83 min,respectively.These findings provide new perspectives on temperature-preserving core sampling in NGH and provide technical support for exploration and development in NGH.
基金support of the National Natural Science Foundation of China(Grant No.52074332).
文摘Natural gas hydrates(hereinafter referred to as hydrates)are a promising clean energy source.However,their current development is far from reaching commercial exploitation.Reservoir stimulation tech-nology provides new approaches to enhance hydrate development effectiveness.Addressing the current lack of quantitative and objective methods for evaluating the fracability of hydrate reservoirs,this study clarifies the relationship between geological and engineering fracability and proposes a comprehensive evaluation model for hydrate reservoir fracability based on grey relational analysis and the criteria importance through intercriteria correlation method.By integrating results from hydraulic fracturing experiments on hydrate sediments,the fracability of hydrate reservoirs is assessed.The concept of critical construction parameter curves for hydrate reservoirs is introduced for the first time.Additionally,two-dimensional fracability index evaluation charts and three-dimensional fracability construction condition discrimination charts are established.The results indicate that as the comprehensive fracability index increases,the feasibility of forming fractures in hydrate reservoirs improves,and the required normalized fracturing construction parameters gradually decrease.The accuracy rate of the charts in judging experimental results reached 89.74%,enabling quick evaluations of whether hydrate reservoirs are worth fracturing,easy to fracture,and capable of being fractured.This has significant engineering implications forthehydraulicfracturingof hydratereservoirs.
基金supported by the Russian Science Foundation(23-29-00830).
文摘Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the interface,further growth of hydrate due to the suction of water in the capillary system formed between the wall of the cuvette and the end boundary of the hydrate layer occurs.Most probably,substantial effects on the formation of this capillary system may be caused by variations in reactor wall properties,for example,hydrophobic-hydrophilic balance,roughness,etc.We found,that the rate of CO_(2) hydrate film growth on the surface of the humic acid aqueous solution is 4-fold to lower in comparison with the growth rate on the surface of pure water.We suppose that this is caused by the adsorption of humic acid associates on the surface of hydrate particles and,as a consequence,by the deceleration of the diffusion of dissolved carbon dioxide to the growing hydrate particle.
基金supported by the National Key R&D Program of China(No.2024YFB4206700)the Joint Geological Funds of the National Natural Science Foundation of China(No.U2244223)+5 种基金the China Scholarship Council Program(No.202404910533)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030003)the China Geological Survey Project(No.DD20211350)the Key Deployment Program of Chinese Academy of Sciences(Nos.YJKYYQ20190043,ZDBS-LY-DQC003,KFZD-SW-422,and ZDRW-ZS-2021-3-1)the Scientific Research and Technology Development Project of China National Petroleum Corporation(No.2022DJ5503)the Supercomputing Laboratory,IGGCAS.
文摘This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensive multiphysics simulations guided by field data from hydrate production tests in the South China Sea,we pinpoint key operational parameters—such as injection rates,depths,and timings—that notably enhance production efficiency.The results indicate that a 3-phase hydrate reservoir transitions from a free-gas-dominated production stage to a hydrate-decomposition-dominated stage.Moderate warm seawater injection supplies additional heat during the hydrate decomposition phase,thereby enhancing stable production;however,excessively high injection rates can impede the depressurization process.Only injection at an appropriate depth simultaneously balances thermal supplementation and the pressure gradient,leading to higher overall productivity.A“depressurization-driven sensible-heat supply window”is introduced,highlighting that timely seawater injection following initial depressurization prolongs reservoir dissociation dynamics.In this study area,commencing seawater injection at 170 d of depressurization proved optimal.This optimized integration leverages clean and renewable thermal energy,providing essential insights into thermal supplementation strategies with significant implications for sustainable,economically feasible,and efficient commercial-scale hydrate production.
文摘An efficient acetic acid mediated metal-free oxidative C—H cross coupling of imidazo[1,2-a]pyridines with glyoxal hydrates has been developed under air atmosphere.The present protocol exhibits broad substrate scope,good functional group tolerance,and enables the construction of a series of 1,2-dicarbonyl imidazo[1,2-a]pyridines in good yields.The reaction mechanism studies suggest that the reactions proceed through the electrophilic substitution and subsequent oxidation pathway.
基金supported by the Sinopec Technology Research and Development Project(No.30000000-22-ZC0607-0235,No.33550000-22-ZC0607-0009)the National Natural Science Foundation of China(No.52334002).
文摘Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the low-permeability characteristics with an average permeability of 5.5 mD and moderate heterogeneity,a 3-D geological model of heterogeneous Class I hydrate reservoirs with three-phase transition layers is established by Kriging interpolation and stochastic modeling method,and a numerical simulation model is used to describe the depressurization production performance of the reservoir.With the development of depressurization,a specific range of complete decomposition zones appear both in the hydrate and transition layers.The entire decomposition zone of the whole reservoir tends to outward and upward diffusion.There is apparent methane escape in the three-phase transition layer.Due to the improvement of local permeability caused by the phase transition of hydrate dissociation,some methane accumulation occurs at the bottom of the hydrate layer,forming a local methane enrichment zone.The methane migration trends in reservoirs are mainly characterized by movement toward production wells and hydrate layers under the influence of gravity.However,due to the permeability limitation of hydrate reservoirs,many fluids have not been effectively produced and remain in the reservoir.Therefore,to improve the effective pressure drop of the reservoir,the perforation method and pressure reduction method were optimized by analyzing the influencing factors based on the gas production rate.The comparative study demonstrates that perforating through the free gas layer combined with one-time depressurization can enhance the effective depressurization and improve production performance.The gas production rate from perforating through the free gas layer can be twice as high as that from perforating through the transition layer.This study can provide theoretical support for the utilization of marine energy.
基金Project supported by the National Natural Science Foundation of China (52064002)Guangxi Science and Technology Major Project(AA23073018)。
文摘A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particles,i.e.,LAC-S(silica derived from acid leaching of amorphous C-S-H) and LLC-S(silica derived from acid leaching of low-crystallinity C-S-H) are obtained after calcium ions are removed from both amorphous and low-crystallinity forms of C-S-H through a facile acid leaching process(3 mol/L,25℃,24 h).(29)^Si NMR spectroscopy reveals that the proportion of silicon atoms carrying silanol groups increases from less than 43% to over 80% when silica particles are transferred from a dry state to an aqueous solution.Batch adsorption experiments were conducted to evaluate the sorption performance and selectivity of these silica sorbents toward Sc(Ⅲ).The scandium sorption capacities of LAC-S and LLC-S at an equilibrium pH of 4.2 are 174.45 and 129.57 mg/g,respectively.The separation factors(SFSc/Ln) of both silica particles exceed 1000 in the initial pH range of 3.5-5.The loaded scandium ions are recovered with 3 mol/L hydrochloric acid and the sorbents exhibit good reusability.This strategy provides an efficient and green method for recovering scandium from aqueous solutions.
