The newly formulated non-Newtonian rivulet flows streaming down an inclined planar surface,with additional periodic perturbations arising from the application of the 2nd Stokes problem to the investigation of rivulet ...The newly formulated non-Newtonian rivulet flows streaming down an inclined planar surface,with additional periodic perturbations arising from the application of the 2nd Stokes problem to the investigation of rivulet dynamics,are demonstrated in the current research.Hereby,the 2nd Stokes problem assumes that the surface,with a thin shared layer of the fluid on it,oscillates in a harmonic manner along the x-axis of the rivulet flow,which coincides with the main flow direction streaming down the underlying surface.We obtain the exact extension of the rivulet flow family,clarifying the structure of the pressure field,which fully absorbs the arising perturbation.The profile of the velocity field is assumed to be Gaussian-type with a non-zero level of plasticity.Hence,the absolutely non-Newtonian case of the viscoplastic flow solution,which satisfies the motion and continuity equations,is considered(with particular cases of exact solutions for pressure).The perturbed governing equations of motion for rivulet flows then result in the Riccati-type ordinary differential equation(ODE),describing the dynamics of the coordinate x(t).The approximated schematic dynamics are presented in graphical plots.展开更多
The coupled chemo-mechanical impact of supercritical CO_(2)-H_(2)O(ScCO_(2)-H_(2)O)reactions on fracture geometry and nonlinear flow regimes in deep shale under confining pressures remains inadequately quantified.This...The coupled chemo-mechanical impact of supercritical CO_(2)-H_(2)O(ScCO_(2)-H_(2)O)reactions on fracture geometry and nonlinear flow regimes in deep shale under confining pressures remains inadequately quantified.This study systematically investigates the effects of ScCO_(2)-H_(2)O-shale interactions on fracture morphology and flow properties under confining pressures from 15 MPa to 40 MPa by integrating XRD(X-ray diffraction),micro-CT,3D surface profilometry,and multistage steady-state flow experiments.The results demonstrate that ScCO_(2)-H_(2)O exposure drives pyrite/feldspar dissolution and localized clay precipitation,resulting in fracture branching and macroscopic aperture regularization.Critically,confining pressure dictates the net hydraulic response:under low confining pressure(15-25 MPa),dissolution dominates,enhancing permeability,flow efficiency(Q/VP),and pre-linear flow behavior(n<1).At high confining pressures(30-40 MPa)mechanical compaction and mineral precipitation amplify flow resistance,shifting the flow regime toward quasi-linear behavior,as inertial effects become negligible compared to dominant viscous forces and increased flow resistance.Confining pressure thus critically mediates the dissolution-precipitation balance during ScCO_(2)-H_(2)O treatment,with an optimal window of 15-25 MPa identified for enhancing conductivity while minimizing clogging risk.These findings provide a quantitative framework for predicting stress-dependent flow evolution in chemically altered shale fractures.展开更多
管道输送CO_(2)作为碳捕集、利用与封存(Carbon Capture,Utilization and Storage,CCUS)产业链的关键环节之一,在海上CCUS发展中发挥着越来越重要的作用。高压密相CO_(2)管道泄压所造成的管道低温脆性断裂、干冰堵塞等问题,严重影响海...管道输送CO_(2)作为碳捕集、利用与封存(Carbon Capture,Utilization and Storage,CCUS)产业链的关键环节之一,在海上CCUS发展中发挥着越来越重要的作用。高压密相CO_(2)管道泄压所造成的管道低温脆性断裂、干冰堵塞等问题,严重影响海上平台CO_(2)输送管道的安全运行。针对海上平台间高压密相CO_(2)管道,采用LedaFlow动态模拟软件建立CO_(2)输送管道泄压模型,分析海上冬季和夏季环境条件下管道沿程温度、压力和泄压量的变化趋势,并对比管道不同初始输送压力、初始输量和泄压对管道流体低温的影响情况。结果表明,冬季泄压造成的海底管道低温要比夏季泄压时低,故推荐在夏季进行泄压操作。在冬季最低环境温度条件下,适当减小泄压口径能够有效避免沿程温度、压力的大幅变化而导致的管道低温情况。研究成果可为实际海上高压密相CO_(2)输送管道的泄压操作提供参考。展开更多
A radical C−C-coupling reaction of acetonitrile into succinonitrile over hydrophobic TiO_(2) photocatalyst with enhanced catalytic activity was developed.In addition,the usage of a flow reactor further improved the ph...A radical C−C-coupling reaction of acetonitrile into succinonitrile over hydrophobic TiO_(2) photocatalyst with enhanced catalytic activity was developed.In addition,the usage of a flow reactor further improved the photon utilization efficiency for succinonitrile synthesis at room temperature.The space time yield of succinonitrile reached 55.59μmol/(g·h)over hydrophobic TiO_(2) catalyst,which was much higher than that of pristine TiO_(2)(4.23μmol/(g·h)).Mechanistic studies revealed that the hydrophobic modification of TiO_(2) promoted the separation and transfer of photogenerated carriers,as well as suppressed their recombination.Hydrophobic TiO_(2) also enhanced the adsorption of−CH3 of acetonitrile,thus facilitating the activation of C−H bond and the utilization efficiency of photocarriers.展开更多
Global investment in ethylene(C_(2)H_(4))production via nonpetroleum pathways is rising,highlighting its growing importance in the energy and environmental sectors.The electroreduction of carbon dioxide(CO_(2))to C_(2...Global investment in ethylene(C_(2)H_(4))production via nonpetroleum pathways is rising,highlighting its growing importance in the energy and environmental sectors.The electroreduction of carbon dioxide(CO_(2))to C_(2)H_(4) inflow cells is emerging as a promising technology with broad practical applications.Direct delivery of gaseous CO_(2) to the cathode catalyst layer overcomes mass transfer limitations,enhancing reaction rates and enabling high current density.This review summarizes recent research progress in the electrocatalytic CO_(2) reduction reaction(eCO_(2)RR)for selective C_(2)H_(4) production inflow cells.It outlines the principles of eCO_(2)RR to C_(2)H_(4) and discusses the influence of copper-based catalyst morphology,crystal facet,oxidation state,surface modification strategy,and synergistic effects on catalytic performance.In addition,it highlights the compositional structure of theflow cell,and the selection and optimization of operating conditions,including gas diffusion electrodes,electrolytes,ion exchange membranes,and alternative anode reaction types beyond the oxygen evolution reaction.Finally,advances in machine learning are presented for accelerating catalyst screening and predicting dynamic changes in catalysts during reduction.This comprehensive review serves as a valuable reference for the development of efficient catalysts and the construction of electrolytic devices for the electrocatalytic reduction of CO_(2) to C_(2)H_(4).展开更多
Geological CO_(2) storage is a promising strategy for reducing greenhouse gas emissions;however,its underlying multiphase reactive flow mechanisms remain poorly understood.We conducted steady-state imbibition relative...Geological CO_(2) storage is a promising strategy for reducing greenhouse gas emissions;however,its underlying multiphase reactive flow mechanisms remain poorly understood.We conducted steady-state imbibition relative permeability experiments on sandstone from a proposed storage site,comple-mented by in situ X-ray imaging and ex situ analyses using scanning electron microscopy(SEM)and energy-dispersive X-ray spectroscopy(EDS).Despite our use of a brine that was pre-equilibrated with CO_(2),there was a significant reduction in both CO_(2) relative permeability and absolute permeability during multiphase flow due to chemical reactions.This reduction was driven by decreased pore and throat sizes,diminished connectivity,and increased irregularity of pore and throat shapes,as revealed by in situ pore-scale imaging.Mineral dissolution,primarily of feldspar,albite,and calcite,along with precipitation resulting from feldspar-to-kaolinite transformation and fines migration,were identified as contributing factors through SEM-EDS analysis.This work provides a benchmark for storage in mineralogically complex sandstones,for which the impact of chemical reactions on multiphase flow properties has been measured.展开更多
The two-phase flow in porous media is affected by multiple factors.In the present study,a two-dimensional numerical model of porous media was developed using the actual pore structure of the core sample.The phase fiel...The two-phase flow in porous media is affected by multiple factors.In the present study,a two-dimensional numerical model of porous media was developed using the actual pore structure of the core sample.The phase field method was utilized to simulate the impact of displacement velocity,the water-gas viscosity ratio,and the density ratio on the flow behavior of two-phase fluids in porous media.The effectiveness of displacement was evaluated by analyzing CO_(2)saturation levels.The results indicate that the saturation of CO_(2)in porous media increased as the displacement velocity increased.When the displacement velocity exceeded 0.01 m/s,there was a corresponding increase in CO_(2)saturation.Conversely,when the displacement velocity was below this threshold,the impact on CO_(2)saturation was minimal.An“inflection point,”M3,was present in the viscosity ratio.When the viscosity of CO_(2)is less than 8.937×10^(-5)Pa·s(viscosity ratio below M3),variations in the viscosity of CO_(2)had little impact on its saturation.Conversely,when the viscosity of CO_(2)exceeded 8.937×10^(-5)Pa·s(viscosity ratio greater than M3),saturation increased with an increase in the viscosity ratio.In terms of the density ratio,the saturation of CO_(2)increased monotonically with an increase in the density ratio.Similarly,increasing density ratios resulted in a monotonic increase in CO_(2)saturation,though this trend was less pronounced in numerical simulations.Analysis results of displacement within dead-end pores using pressure and velocity diagrams reveal eddy currents as contributing factors.Finally,the impact of pore throat structure on the formation of dominant channels was examined.展开更多
This study introduces a Transformer-based multimodal fusion framework for simulating multiphase flow and heat transfer in carbon dioxide(CO_(2))–water enhanced geothermal systems(EGS).The model integrates geological ...This study introduces a Transformer-based multimodal fusion framework for simulating multiphase flow and heat transfer in carbon dioxide(CO_(2))–water enhanced geothermal systems(EGS).The model integrates geological parameters,thermal gradients,and control schedules to enable fast and accurate prediction of complex reservoir dynamics.The main contributions are:(i)development of a workflow that couples physics-based reservoir simulation with a Transformer neural network architecture,(ii)design of physics-guided loss functions to enforce conservation of mass and energy,(iii)application of the surrogate model to closed-loop optimization using a differential evolution(DE)algorithm,and(iv)incorporation of economic performance metrics,such as net present value(NPV),into decision support.The proposed framework achieves root mean square error(RMSE)of 3–5%,mean absolute error(MAE)below 4%,and coefficients of determination greater than 0.95 across multiple prediction targets,including production rates,pressure distributions,and temperature fields.When compared with recurrent neural network(RNN)baselines such as gated recurrent units(GRU)and long short-term memory networks(LSTM),as well as a physics-informed reduced-order model,the Transformer-based approach demonstrates superior accuracy and computational efficiency.Optimization experiments further show a 15–20%improvement in NPV,highlighting the framework’s potential for real-time forecasting,optimization,and decision-making in geothermal reservoir engineering.展开更多
The increase in CO_(2)injectivity and shifting of CO_(2)-absorbing layers in multilayered geological CO_(2)sequestration(GCS)reservoirs in Ordos,China indicate significantpermeability variations in certain layers.To c...The increase in CO_(2)injectivity and shifting of CO_(2)-absorbing layers in multilayered geological CO_(2)sequestration(GCS)reservoirs in Ordos,China indicate significantpermeability variations in certain layers.To capture these system changes,a numerical model incorporating all 21 aquifers and internal aquitards was developed.The monitored pressure was well matched through multiphase and thermalhydraulic-mechanical(THM)coupling numerical simulations by introducing permeability variations.The results revealed that the permeability in the second layer increased on approximately day 13 due to the abrupt pressure buildup and temperature decrease.Even such a low rate of CO_(2)(2.8 kg/s)injected into the low permeability system initiated some fractures and the permeability in the second layer around the wellbore increased by 722 times.The second critical system change occurred on approximately day 386.As demonstrated in the numerical simulation,the substantial injection of cold CO_(2)induced strong thermal stress,leading to rock contraction and the initiation of several cracks.The permeability of the firstlayer around the wellbore unexpectedly increased by 4 orders of magnitude.Since no additional pressure could drive the CO_(2)into the remaining 17 layers,the total storage capability of the multilayered system was reduced.A whole picture of the system variation is fully presented and the underlying mechanisms are analyzed.It is believed that the phenomenon of thermal-hydraulic fracturing observed in this fieldand the simulation procedures will benefitother fluidinjection and production works in various geotechnical settings.展开更多
CO_(2)capture and storage technology is favorable for the reduction of CO_(2)emissions.In recent years,a great number of research achievements have been obtained on CO_(2)geological storage from nano scale to oil/gas ...CO_(2)capture and storage technology is favorable for the reduction of CO_(2)emissions.In recent years,a great number of research achievements have been obtained on CO_(2)geological storage from nano scale to oil/gas reservoir scale,but most studies only focus on theflow behaviors in single-dimension porous media.Besides,the physical experiment method is influenced by many uncertain factors and consumes a lot of time and cost.In order to deeply understand theflow behaviors in the process of CO_(2)geological storage in microscopic view and increase the volume of CO_(2)geological storage,this paper established 2D and 3D models by using VOF(Volume of Fluid)method which can track the dynamic change of two-phase interface,to numerically simulate supercritical CO_(2)-brine two-phaseflow.Then,the distribution characteristics of CO_(2)clusters and the variation laws of CO_(2)saturation under different wettability,capillary number and viscosity ratio conditions were compared,and the intrinsic mechanisms of CO_(2)storage at pore scale were revealed.And the following research results were obtained.First,with the increase of rock wettability to CO_(2),the sweep range of CO_(2)enlarged,and the disconnection frequency of CO_(2)clusters deceased,and thus the volume of CO_(2)storage increased.Second,with the increase of capillary number,the displacement mode transformed from capillaryfingering to stable displacement,and thus the volume of CO_(2)storage increased.Third,as the viscosity of injected supercritical CO_(2)gradually approached that of brine,theflow resistance between two-phasefluids decreased,promoting the"lubricating effect".As a result,theflow capacity of CO_(2)phase was improved,and thus the volume of CO_(2)storage was increased.Fourth,the influence degrees of wettability,capillary number and viscosity ratio on CO_(2)saturation were different in multi-dimensional porous media models.In conclusion,the CO_(2)-brine two-phaseflow simulation based on VOF method revealed theflow mechanisms in the process of CO_(2)geological storage at pore scale,which is of guiding significance to the development of CCUS technology and provides theoretical guidance and technical support for the study of CO_(2)geological storage in a larger scale.展开更多
Numerical simulation has been widely applied to the assessment of debris flow hazards. In East Asia and especially Taiwan, the most widely used numerical programs are FLO-2D and Debris-aD. Although these two programs ...Numerical simulation has been widely applied to the assessment of debris flow hazards. In East Asia and especially Taiwan, the most widely used numerical programs are FLO-2D and Debris-aD. Although these two programs are applied to the same engineering tasks, they are different in many aspects. These two programs were compared according to their fundamental theories, input and output data, computational algorithms and results. Using both programs, the simulations of a real debris flow with abundant granular material induced by landslides at Xinfa village in southern Taiwan are performed for comparison. The simulation results show that Debris- 2D gives better assessment in hazard area delineating and flow depth predicting. Therefore, Debris-2D is better for simulation of granular debris flows.展开更多
文摘The newly formulated non-Newtonian rivulet flows streaming down an inclined planar surface,with additional periodic perturbations arising from the application of the 2nd Stokes problem to the investigation of rivulet dynamics,are demonstrated in the current research.Hereby,the 2nd Stokes problem assumes that the surface,with a thin shared layer of the fluid on it,oscillates in a harmonic manner along the x-axis of the rivulet flow,which coincides with the main flow direction streaming down the underlying surface.We obtain the exact extension of the rivulet flow family,clarifying the structure of the pressure field,which fully absorbs the arising perturbation.The profile of the velocity field is assumed to be Gaussian-type with a non-zero level of plasticity.Hence,the absolutely non-Newtonian case of the viscoplastic flow solution,which satisfies the motion and continuity equations,is considered(with particular cases of exact solutions for pressure).The perturbed governing equations of motion for rivulet flows then result in the Riccati-type ordinary differential equation(ODE),describing the dynamics of the coordinate x(t).The approximated schematic dynamics are presented in graphical plots.
基金support from the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC1021)the Natural Science Foundation of Sichuan Province(Grant No.2025YFHZ0323).-。
文摘The coupled chemo-mechanical impact of supercritical CO_(2)-H_(2)O(ScCO_(2)-H_(2)O)reactions on fracture geometry and nonlinear flow regimes in deep shale under confining pressures remains inadequately quantified.This study systematically investigates the effects of ScCO_(2)-H_(2)O-shale interactions on fracture morphology and flow properties under confining pressures from 15 MPa to 40 MPa by integrating XRD(X-ray diffraction),micro-CT,3D surface profilometry,and multistage steady-state flow experiments.The results demonstrate that ScCO_(2)-H_(2)O exposure drives pyrite/feldspar dissolution and localized clay precipitation,resulting in fracture branching and macroscopic aperture regularization.Critically,confining pressure dictates the net hydraulic response:under low confining pressure(15-25 MPa),dissolution dominates,enhancing permeability,flow efficiency(Q/VP),and pre-linear flow behavior(n<1).At high confining pressures(30-40 MPa)mechanical compaction and mineral precipitation amplify flow resistance,shifting the flow regime toward quasi-linear behavior,as inertial effects become negligible compared to dominant viscous forces and increased flow resistance.Confining pressure thus critically mediates the dissolution-precipitation balance during ScCO_(2)-H_(2)O treatment,with an optimal window of 15-25 MPa identified for enhancing conductivity while minimizing clogging risk.These findings provide a quantitative framework for predicting stress-dependent flow evolution in chemically altered shale fractures.
文摘管道输送CO_(2)作为碳捕集、利用与封存(Carbon Capture,Utilization and Storage,CCUS)产业链的关键环节之一,在海上CCUS发展中发挥着越来越重要的作用。高压密相CO_(2)管道泄压所造成的管道低温脆性断裂、干冰堵塞等问题,严重影响海上平台CO_(2)输送管道的安全运行。针对海上平台间高压密相CO_(2)管道,采用LedaFlow动态模拟软件建立CO_(2)输送管道泄压模型,分析海上冬季和夏季环境条件下管道沿程温度、压力和泄压量的变化趋势,并对比管道不同初始输送压力、初始输量和泄压对管道流体低温的影响情况。结果表明,冬季泄压造成的海底管道低温要比夏季泄压时低,故推荐在夏季进行泄压操作。在冬季最低环境温度条件下,适当减小泄压口径能够有效避免沿程温度、压力的大幅变化而导致的管道低温情况。研究成果可为实际海上高压密相CO_(2)输送管道的泄压操作提供参考。
基金supported by the National Key R&D Program of China(2021YFF0500703)Natural Science Foundation of Shanghai(22JC1404200)+3 种基金Program of Shanghai Academic/Technology Research Leader(20XD1404000)Natural Science Foundation of China(U22B20136,22293023)Science and Technology Major Project of Inner Mongolia(2021ZD0042)the Youth Innovation Promotion Association of CAS。
文摘A radical C−C-coupling reaction of acetonitrile into succinonitrile over hydrophobic TiO_(2) photocatalyst with enhanced catalytic activity was developed.In addition,the usage of a flow reactor further improved the photon utilization efficiency for succinonitrile synthesis at room temperature.The space time yield of succinonitrile reached 55.59μmol/(g·h)over hydrophobic TiO_(2) catalyst,which was much higher than that of pristine TiO_(2)(4.23μmol/(g·h)).Mechanistic studies revealed that the hydrophobic modification of TiO_(2) promoted the separation and transfer of photogenerated carriers,as well as suppressed their recombination.Hydrophobic TiO_(2) also enhanced the adsorption of−CH3 of acetonitrile,thus facilitating the activation of C−H bond and the utilization efficiency of photocarriers.
基金supported by the National Natural Science Foundation of China(22272081 and 51802160)the Startup Foundation for Introducing Talent of NUIST(S8113082001).
文摘Global investment in ethylene(C_(2)H_(4))production via nonpetroleum pathways is rising,highlighting its growing importance in the energy and environmental sectors.The electroreduction of carbon dioxide(CO_(2))to C_(2)H_(4) inflow cells is emerging as a promising technology with broad practical applications.Direct delivery of gaseous CO_(2) to the cathode catalyst layer overcomes mass transfer limitations,enhancing reaction rates and enabling high current density.This review summarizes recent research progress in the electrocatalytic CO_(2) reduction reaction(eCO_(2)RR)for selective C_(2)H_(4) production inflow cells.It outlines the principles of eCO_(2)RR to C_(2)H_(4) and discusses the influence of copper-based catalyst morphology,crystal facet,oxidation state,surface modification strategy,and synergistic effects on catalytic performance.In addition,it highlights the compositional structure of theflow cell,and the selection and optimization of operating conditions,including gas diffusion electrodes,electrolytes,ion exchange membranes,and alternative anode reaction types beyond the oxygen evolution reaction.Finally,advances in machine learning are presented for accelerating catalyst screening and predicting dynamic changes in catalysts during reduction.This comprehensive review serves as a valuable reference for the development of efficient catalysts and the construction of electrolytic devices for the electrocatalytic reduction of CO_(2) to C_(2)H_(4).
文摘Geological CO_(2) storage is a promising strategy for reducing greenhouse gas emissions;however,its underlying multiphase reactive flow mechanisms remain poorly understood.We conducted steady-state imbibition relative permeability experiments on sandstone from a proposed storage site,comple-mented by in situ X-ray imaging and ex situ analyses using scanning electron microscopy(SEM)and energy-dispersive X-ray spectroscopy(EDS).Despite our use of a brine that was pre-equilibrated with CO_(2),there was a significant reduction in both CO_(2) relative permeability and absolute permeability during multiphase flow due to chemical reactions.This reduction was driven by decreased pore and throat sizes,diminished connectivity,and increased irregularity of pore and throat shapes,as revealed by in situ pore-scale imaging.Mineral dissolution,primarily of feldspar,albite,and calcite,along with precipitation resulting from feldspar-to-kaolinite transformation and fines migration,were identified as contributing factors through SEM-EDS analysis.This work provides a benchmark for storage in mineralogically complex sandstones,for which the impact of chemical reactions on multiphase flow properties has been measured.
基金National Science Foundation of China,Grant/Award Number:5227090113Shenzhen Science and Technology Program,Grant/Award Numbers:KCXFZ20230731093901003,KCXFZ20211020163816023The Project of Hetao Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone,Grant/Award Number:HZQB-KCZYB-2020083。
文摘The two-phase flow in porous media is affected by multiple factors.In the present study,a two-dimensional numerical model of porous media was developed using the actual pore structure of the core sample.The phase field method was utilized to simulate the impact of displacement velocity,the water-gas viscosity ratio,and the density ratio on the flow behavior of two-phase fluids in porous media.The effectiveness of displacement was evaluated by analyzing CO_(2)saturation levels.The results indicate that the saturation of CO_(2)in porous media increased as the displacement velocity increased.When the displacement velocity exceeded 0.01 m/s,there was a corresponding increase in CO_(2)saturation.Conversely,when the displacement velocity was below this threshold,the impact on CO_(2)saturation was minimal.An“inflection point,”M3,was present in the viscosity ratio.When the viscosity of CO_(2)is less than 8.937×10^(-5)Pa·s(viscosity ratio below M3),variations in the viscosity of CO_(2)had little impact on its saturation.Conversely,when the viscosity of CO_(2)exceeded 8.937×10^(-5)Pa·s(viscosity ratio greater than M3),saturation increased with an increase in the viscosity ratio.In terms of the density ratio,the saturation of CO_(2)increased monotonically with an increase in the density ratio.Similarly,increasing density ratios resulted in a monotonic increase in CO_(2)saturation,though this trend was less pronounced in numerical simulations.Analysis results of displacement within dead-end pores using pressure and velocity diagrams reveal eddy currents as contributing factors.Finally,the impact of pore throat structure on the formation of dominant channels was examined.
文摘This study introduces a Transformer-based multimodal fusion framework for simulating multiphase flow and heat transfer in carbon dioxide(CO_(2))–water enhanced geothermal systems(EGS).The model integrates geological parameters,thermal gradients,and control schedules to enable fast and accurate prediction of complex reservoir dynamics.The main contributions are:(i)development of a workflow that couples physics-based reservoir simulation with a Transformer neural network architecture,(ii)design of physics-guided loss functions to enforce conservation of mass and energy,(iii)application of the surrogate model to closed-loop optimization using a differential evolution(DE)algorithm,and(iv)incorporation of economic performance metrics,such as net present value(NPV),into decision support.The proposed framework achieves root mean square error(RMSE)of 3–5%,mean absolute error(MAE)below 4%,and coefficients of determination greater than 0.95 across multiple prediction targets,including production rates,pressure distributions,and temperature fields.When compared with recurrent neural network(RNN)baselines such as gated recurrent units(GRU)and long short-term memory networks(LSTM),as well as a physics-informed reduced-order model,the Transformer-based approach demonstrates superior accuracy and computational efficiency.Optimization experiments further show a 15–20%improvement in NPV,highlighting the framework’s potential for real-time forecasting,optimization,and decision-making in geothermal reservoir engineering.
基金supports from the National Natural Science Foundation of China(Grant Nos.52179095,52378323,and 42407216)are gratefully acknowledged.
文摘The increase in CO_(2)injectivity and shifting of CO_(2)-absorbing layers in multilayered geological CO_(2)sequestration(GCS)reservoirs in Ordos,China indicate significantpermeability variations in certain layers.To capture these system changes,a numerical model incorporating all 21 aquifers and internal aquitards was developed.The monitored pressure was well matched through multiphase and thermalhydraulic-mechanical(THM)coupling numerical simulations by introducing permeability variations.The results revealed that the permeability in the second layer increased on approximately day 13 due to the abrupt pressure buildup and temperature decrease.Even such a low rate of CO_(2)(2.8 kg/s)injected into the low permeability system initiated some fractures and the permeability in the second layer around the wellbore increased by 722 times.The second critical system change occurred on approximately day 386.As demonstrated in the numerical simulation,the substantial injection of cold CO_(2)induced strong thermal stress,leading to rock contraction and the initiation of several cracks.The permeability of the firstlayer around the wellbore unexpectedly increased by 4 orders of magnitude.Since no additional pressure could drive the CO_(2)into the remaining 17 layers,the total storage capability of the multilayered system was reduced.A whole picture of the system variation is fully presented and the underlying mechanisms are analyzed.It is believed that the phenomenon of thermal-hydraulic fracturing observed in this fieldand the simulation procedures will benefitother fluidinjection and production works in various geotechnical settings.
基金supported by the National Natural Science Foun-dation of China“Research on basic theory for development of deep and ultra-deep reservoirs”(No.52034010)“Flow control during drilling/production of ultra-deep oil and gas wells”(No.52288101).
文摘CO_(2)capture and storage technology is favorable for the reduction of CO_(2)emissions.In recent years,a great number of research achievements have been obtained on CO_(2)geological storage from nano scale to oil/gas reservoir scale,but most studies only focus on theflow behaviors in single-dimension porous media.Besides,the physical experiment method is influenced by many uncertain factors and consumes a lot of time and cost.In order to deeply understand theflow behaviors in the process of CO_(2)geological storage in microscopic view and increase the volume of CO_(2)geological storage,this paper established 2D and 3D models by using VOF(Volume of Fluid)method which can track the dynamic change of two-phase interface,to numerically simulate supercritical CO_(2)-brine two-phaseflow.Then,the distribution characteristics of CO_(2)clusters and the variation laws of CO_(2)saturation under different wettability,capillary number and viscosity ratio conditions were compared,and the intrinsic mechanisms of CO_(2)storage at pore scale were revealed.And the following research results were obtained.First,with the increase of rock wettability to CO_(2),the sweep range of CO_(2)enlarged,and the disconnection frequency of CO_(2)clusters deceased,and thus the volume of CO_(2)storage increased.Second,with the increase of capillary number,the displacement mode transformed from capillaryfingering to stable displacement,and thus the volume of CO_(2)storage increased.Third,as the viscosity of injected supercritical CO_(2)gradually approached that of brine,theflow resistance between two-phasefluids decreased,promoting the"lubricating effect".As a result,theflow capacity of CO_(2)phase was improved,and thus the volume of CO_(2)storage was increased.Fourth,the influence degrees of wettability,capillary number and viscosity ratio on CO_(2)saturation were different in multi-dimensional porous media models.In conclusion,the CO_(2)-brine two-phaseflow simulation based on VOF method revealed theflow mechanisms in the process of CO_(2)geological storage at pore scale,which is of guiding significance to the development of CCUS technology and provides theoretical guidance and technical support for the study of CO_(2)geological storage in a larger scale.
基金support from National Science Council of Chinese Taipei(Grant No.NSC 96-2625-Z-002-006-MY3)
文摘Numerical simulation has been widely applied to the assessment of debris flow hazards. In East Asia and especially Taiwan, the most widely used numerical programs are FLO-2D and Debris-aD. Although these two programs are applied to the same engineering tasks, they are different in many aspects. These two programs were compared according to their fundamental theories, input and output data, computational algorithms and results. Using both programs, the simulations of a real debris flow with abundant granular material induced by landslides at Xinfa village in southern Taiwan are performed for comparison. The simulation results show that Debris- 2D gives better assessment in hazard area delineating and flow depth predicting. Therefore, Debris-2D is better for simulation of granular debris flows.
