Hydrothermal ore zoning is a transport-reaction problem in which infiltration is the principal Prcness of transport and dissolution/Precipitation is the Principal process of chemical reactions.Neglecting diffusion an...Hydrothermal ore zoning is a transport-reaction problem in which infiltration is the principal Prcness of transport and dissolution/Precipitation is the Principal process of chemical reactions.Neglecting diffusion and ion exchange/adsorption would not affect the basic attributes of hydrothermal ore zoning. Hydrothermal ore zoning belongs essentially to infiltration metasomatic zoning, it results from the formation and propagation of dissolution/precipitation waves through Permeable media. The authors apply the theory of coupled infiltration and dissolution/precipitation reactions in Physicochemical hydrodynamics to studying the structural characteristics of dissolution/precipitation waves, and apply furthermore the coherence principle in dynamic theory of multicomponent coupled systems to revealing the dynamic mechanisms of their formation. The results of investigation verify and develop . C. 's theory of infiltration metasomatic zoning,on the one hand, raising it from the qualitative, equilibrium thermodynamic basis to the quantitative dynamic level;on the other hand, and more importantly, applying theories of Physicochemical hydrodynamics and dynamics of multicomponent coupled systems to bringing to light the dynamic mechanisms of formation of the structure of hydrothermal ore zoning, and advancing a theory of hydrothermal ore zoning, putting forward new ideas on the nature of the problem of hydrothermal ore zoning, the essence of hydrothermal ore zoning and the structural characteristics and mechanisms of formation of hydrothermal ore zoning.展开更多
The exploitation of thermal water and the mix of cold water changed the properties of geofluid in shallow reservoir,which altered the concentration of the chemical constitutes and continuously built new water-rock rea...The exploitation of thermal water and the mix of cold water changed the properties of geofluid in shallow reservoir,which altered the concentration of the chemical constitutes and continuously built new water-rock reaction. This paper deduced reservoir pressure and temperature variation tendency from 2004 to 2013,analyzed the change of some components in the shallow reservoir water,and finally obtained the evolution of the shallow geothermal water with hydrogeochemical model. The results show the reservoir pressure decreased significantly compared with the slight decline of reservoir temperature,and much cold groundwater infiltrated into the shallow reservoir,which affected the solubility of SiO2 and led to precipitation,the increased CO2 in shallow reservoir promoted the dissolution of aluminosilicate. Calcite and kaolinite precipitation zone has extended to the north in the field,which influenced the porosity of the reservoir rock.展开更多
The models of stress corrosion, pressure solution and flee-face dissolution/precipitation were introduced. Taking a hypothetical nuclear waste repository in an unsaturated dual-porosity rock mass as the calculation ob...The models of stress corrosion, pressure solution and flee-face dissolution/precipitation were introduced. Taking a hypothetical nuclear waste repository in an unsaturated dual-porosity rock mass as the calculation objective, four cases were designed 1） the fracture aperture is a function of stress corrosion, pressure solution and free-face dissolution/precipitation; 2） the fracture aperture changes with stress corrosion and pressure solution; 3） the fracture aperture changes with pressure solution and free-face dissolution/precipitation; 4） the fracture aperture is only a function of pressure solution, and the matrix porosity is also a function of stress in these four cases. Then, the corresponding two-dimensional FEM analyses for the coupled thermo-hydro-mechanical processes were carried out. The results show that the effects of stress corrosion are more prominent than those of pressure solution and free-face dissolution/precipitation, and the fracture aperture and relevant permeability caused by the stress corrosion arc only about 1/5 and 1/1000 of the corresponding values created by the pressure solution and free-face dissolution/precipitation, respectively Under the action of temperature field from released heat, the negative pore and fracture pressures in the computation domain rise continuously, and are inversely proportional to the sealing of fracture aperture. The vector fields of flow velocity of fracture water in the cases with and without considering stress corrosion are obviously different. The differences between the magnitudes and distributions of stresses within the rock mass are very small in all cases.展开更多
Highly crystalline β-type strontium hydrogen phosphate （β-SrHPO4） nanosheets were prepared by a hydro- thermal method and used for the immobilization of lead ions （Pb2＋） from acidic aqueous solution. The effect...Highly crystalline β-type strontium hydrogen phosphate （β-SrHPO4） nanosheets were prepared by a hydro- thermal method and used for the immobilization of lead ions （Pb2＋） from acidic aqueous solution. The effects of various parameters on the immobilization process, including solution pH value, contact time, initial ion concentrations, and coexistent competing cations, were studied to optimize the conditions for maximum immobilization. The β-SrHPO4 nanosheets exhibited a capacity of （1,120 ± 22） mg/g toward Pb2＋ in acidic solution （pH value is 3.0）, and the equilibrium was achieved within 8 rain. The competing cations such as Cu2＋, Zn2＋, Cd2＋, and Co2＋ affected slightly on the selective immobilization of Pb2＋. The results revealed that the removal mechanism of Pb2＋ by the β-SrHPO4 nanosheets was the dissolution/precipitation process in the acidic solution.展开更多
In the present work,a new transient calculation method for parameters that can be used to evaluate the ability of oxygen control in a non-isothermal lead-bismuth eutectic(LBE)loop with solid-phase oxygen control was p...In the present work,a new transient calculation method for parameters that can be used to evaluate the ability of oxygen control in a non-isothermal lead-bismuth eutectic(LBE)loop with solid-phase oxygen control was proposed.It incorporates the dissolution process of PbO particles and the oxygen mass transfer process,and an optimized method was used for finding out the optimized oxygen mass transfer coefficient.In numerical terms,three mass transfer models were simultaneously applied,and comparisons of calculated and experimental results from the CRAFT loop indicated that the optimized calculation method and these new oxygen mass transfer models were correct and applicable to other LBE loops.Through this calculation method,we aimed to optimize prediction of the distribution of oxygen and iron concentrations,time taken to establish the steady state of oxygen,and maximum dissolution/precipitation rates of corrosion products and corrosion depth across the entire LBE loop.We hope that this work will provide a potential reference for designing a more intelligent oxygen control system in the future.展开更多
Restricted by the development of the transient flow and solute reactive transport models for unsaturated soil, empirical functions have been used previously to calculate the mass of dissolved or precipitated salt when...Restricted by the development of the transient flow and solute reactive transport models for unsaturated soil, empirical functions have been used previously to calculate the mass of dissolved or precipitated salt when they have to be taken into account. Besides, the solute reactive transport process has often been inferred based on measurements that cost lots of time and manpower. HP1 model coupled with PHREEQC provides a suitable tool to improve the estimation of salt distribution during evaporation in saline soil, where the salt dissolution and precipitation cannot be ignored. In this study, we compare the performance of a standard solute transport(SST) model and the HP1 model to examine the improvement of salt distribution estimation. Model results are compared with experimental data sets from four field lysimeters. These columns were exposed to Na Cl solution with different concentrations(3, 30, 100, and 250 g/L) and were undergoing the same strong evaporation boundary condition. The pre-existing Ca SO_(4), Na Cl and Na2SO_(4)loads were 1.15, 0.47 and 0.23 g/(100 g of soil), respectively. Simulation results show that HP1 ameliorates the overestimation of salt content by SST in deeper soil due to the absence of dissolution of pre-existing soluble salts, and prevents the concentration of the solute from exceeding the solubilities which would occur in SST-result. Additionally, HP1-predicted results can help trace the transport process of each solute. Based on the results, we strongly suggest that the management of fields sensitive to salt content should make use of a coupled flow and chemical reaction model.展开更多
The paper addresses the issues of reducing the concentration of greenhouse gases in the atmosphere through carbon dioxide sequestration by injection to geological formations to enhance oil recovery and underground sto...The paper addresses the issues of reducing the concentration of greenhouse gases in the atmosphere through carbon dioxide sequestration by injection to geological formations to enhance oil recovery and underground storage.Geochemical reactions occurring in a reservoir during CO_(2) injection can affect physical properties of the formation and mechanisms of carbon dioxide capture.The interactions in the“CO_(2)-formation water-rock”system are complex and depends on many factors:mineralogical composition of rock,composition and salinity of formation water,reservoir thermobaric conditions,time.The paper includes a brief review of carbon dioxide interaction studies with formation fluids and reservoir rock minerals.A methodology is presented for studying geochemical processes during interaction of carbon dioxide-saturated formation water with reservoir rock samples.Experimental results for oil-saturated and water-saturated,carbonate and terrigenous reservoir intervals are discussed.The experiments demonstrate complex interactions of CO_(2) with water and rocks under natural conditions.Important aspects are the influence of mineralogical composition on dissolution and secondary precipitation processes as well as changes in aqueous phase composition and pH.Hydrogeochemical modeling workflow for the studied processes is proposed with calibration to experimental data and their appropriate translation to reservoir conditions.The results demonstrate the need for detailed geochemical studies to better assess the effects of CO_(2) on reservoir properties and the risks associated with mineral deposition and dissolution during carbon capture and storage(CCS/CCUS)operations.展开更多
The natural gas from the Triassic Feixianguan Formation of Northeast Sichuan Basin contains high H2S whereas relatively low CO_(2)concentrations and the CO_(2)display highδ13C values(ranging from-5.81‰to 3.3‰(PDB))...The natural gas from the Triassic Feixianguan Formation of Northeast Sichuan Basin contains high H2S whereas relatively low CO_(2)concentrations and the CO_(2)display highδ13C values(ranging from-5.81‰to 3.3‰(PDB)).This seems to contradict the conventional wisdom that TSR should be a primary source of CO_(2)in natural gas from the Feixianguan Formation.In contrast,many authigenic calcite samples from these sites display very lowδ13C values(ranging from-18.4‰to-10.3‰(PDB)).This suggests that the carbon from TSR source dominated the formation of calcite whereas the carbon from inorganic source came into CO_(2)in natural gas.In order to assess the origin of CO_(2)from these H2S-rich sites,we have calculated the relative contributions of organic and inorganic carbon sources to the CO_(2)and authigenic calcite.The organic carbon source possibly originated from TSR,whereas the inorganic one might be generated from marine carbonates dissolution.This calculation is based on the carbon isotopic compositions of CO_(2)and authigenic calcite as well as an isotopic mass balance.The results show that the contribution of organic carbon source to the CO_(2)is only 2%,whereas that to authigenic calcite is as high as 43%on average.Such results combined with thermodynamic evidence indicate that the isotopically light CO_(2)produced by TSR process may contribute to authigenic calcite precipitation during burial diagenesis.Distinguishable from Ordovician reservoir of Tarim Basin,Feixianguan reservoir of Northeast Sichuan Basin experienced rapid tectonic uplift due to Yanshanian movement after TSR occurred.Such tectonic event could induce temperature decrease and further promote carbonates dissolution.During these processes,secondary porosity has developed in Feixianguan carbonate reservoirs.Therefore,much attention should be paid to the structural highs in search of high quality carbonate reservoirs.展开更多
文摘Hydrothermal ore zoning is a transport-reaction problem in which infiltration is the principal Prcness of transport and dissolution/Precipitation is the Principal process of chemical reactions.Neglecting diffusion and ion exchange/adsorption would not affect the basic attributes of hydrothermal ore zoning. Hydrothermal ore zoning belongs essentially to infiltration metasomatic zoning, it results from the formation and propagation of dissolution/precipitation waves through Permeable media. The authors apply the theory of coupled infiltration and dissolution/precipitation reactions in Physicochemical hydrodynamics to studying the structural characteristics of dissolution/precipitation waves, and apply furthermore the coherence principle in dynamic theory of multicomponent coupled systems to revealing the dynamic mechanisms of their formation. The results of investigation verify and develop . C. 's theory of infiltration metasomatic zoning,on the one hand, raising it from the qualitative, equilibrium thermodynamic basis to the quantitative dynamic level;on the other hand, and more importantly, applying theories of Physicochemical hydrodynamics and dynamics of multicomponent coupled systems to bringing to light the dynamic mechanisms of formation of the structure of hydrothermal ore zoning, and advancing a theory of hydrothermal ore zoning, putting forward new ideas on the nature of the problem of hydrothermal ore zoning, the essence of hydrothermal ore zoning and the structural characteristics and mechanisms of formation of hydrothermal ore zoning.
基金supported by the National Natural Science Foundation of China (No. 41572361)the China Geological Survey (No. 121201112006)
文摘The exploitation of thermal water and the mix of cold water changed the properties of geofluid in shallow reservoir,which altered the concentration of the chemical constitutes and continuously built new water-rock reaction. This paper deduced reservoir pressure and temperature variation tendency from 2004 to 2013,analyzed the change of some components in the shallow reservoir water,and finally obtained the evolution of the shallow geothermal water with hydrogeochemical model. The results show the reservoir pressure decreased significantly compared with the slight decline of reservoir temperature,and much cold groundwater infiltrated into the shallow reservoir,which affected the solubility of SiO2 and led to precipitation,the increased CO2 in shallow reservoir promoted the dissolution of aluminosilicate. Calcite and kaolinite precipitation zone has extended to the north in the field,which influenced the porosity of the reservoir rock.
基金Project(2010CB732101) supported by the National Basic Research Program of ChinaProject(51079145) supported by the National Natural Science Foundation of ChinaProject(2009BAK53B03) supported by the National Key Technology R&D Program of China
文摘The models of stress corrosion, pressure solution and flee-face dissolution/precipitation were introduced. Taking a hypothetical nuclear waste repository in an unsaturated dual-porosity rock mass as the calculation objective, four cases were designed 1） the fracture aperture is a function of stress corrosion, pressure solution and free-face dissolution/precipitation; 2） the fracture aperture changes with stress corrosion and pressure solution; 3） the fracture aperture changes with pressure solution and free-face dissolution/precipitation; 4） the fracture aperture is only a function of pressure solution, and the matrix porosity is also a function of stress in these four cases. Then, the corresponding two-dimensional FEM analyses for the coupled thermo-hydro-mechanical processes were carried out. The results show that the effects of stress corrosion are more prominent than those of pressure solution and free-face dissolution/precipitation, and the fracture aperture and relevant permeability caused by the stress corrosion arc only about 1/5 and 1/1000 of the corresponding values created by the pressure solution and free-face dissolution/precipitation, respectively Under the action of temperature field from released heat, the negative pore and fracture pressures in the computation domain rise continuously, and are inversely proportional to the sealing of fracture aperture. The vector fields of flow velocity of fracture water in the cases with and without considering stress corrosion are obviously different. The differences between the magnitudes and distributions of stresses within the rock mass are very small in all cases.
基金financially supported by the National Natural Science Foundation of China (No.21377063)K.C.Wong Magna Fund in Ningbo University
文摘Highly crystalline β-type strontium hydrogen phosphate （β-SrHPO4） nanosheets were prepared by a hydro- thermal method and used for the immobilization of lead ions （Pb2＋） from acidic aqueous solution. The effects of various parameters on the immobilization process, including solution pH value, contact time, initial ion concentrations, and coexistent competing cations, were studied to optimize the conditions for maximum immobilization. The β-SrHPO4 nanosheets exhibited a capacity of （1,120 ± 22） mg/g toward Pb2＋ in acidic solution （pH value is 3.0）, and the equilibrium was achieved within 8 rain. The competing cations such as Cu2＋, Zn2＋, Cd2＋, and Co2＋ affected slightly on the selective immobilization of Pb2＋. The results revealed that the removal mechanism of Pb2＋ by the β-SrHPO4 nanosheets was the dissolution/precipitation process in the acidic solution.
基金supported by the National Natural Science Foundation of China (Nos. 12027813 and 12105101)the Fundamental Research Funds for the National key project (No. 2019YFB1901301)
文摘In the present work,a new transient calculation method for parameters that can be used to evaluate the ability of oxygen control in a non-isothermal lead-bismuth eutectic(LBE)loop with solid-phase oxygen control was proposed.It incorporates the dissolution process of PbO particles and the oxygen mass transfer process,and an optimized method was used for finding out the optimized oxygen mass transfer coefficient.In numerical terms,three mass transfer models were simultaneously applied,and comparisons of calculated and experimental results from the CRAFT loop indicated that the optimized calculation method and these new oxygen mass transfer models were correct and applicable to other LBE loops.Through this calculation method,we aimed to optimize prediction of the distribution of oxygen and iron concentrations,time taken to establish the steady state of oxygen,and maximum dissolution/precipitation rates of corrosion products and corrosion depth across the entire LBE loop.We hope that this work will provide a potential reference for designing a more intelligent oxygen control system in the future.
基金supported by the National Natural Science Foundation of China (Nos.41572224,U1403282,51709232)the Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan) (No.CUG170103)。
文摘Restricted by the development of the transient flow and solute reactive transport models for unsaturated soil, empirical functions have been used previously to calculate the mass of dissolved or precipitated salt when they have to be taken into account. Besides, the solute reactive transport process has often been inferred based on measurements that cost lots of time and manpower. HP1 model coupled with PHREEQC provides a suitable tool to improve the estimation of salt distribution during evaporation in saline soil, where the salt dissolution and precipitation cannot be ignored. In this study, we compare the performance of a standard solute transport(SST) model and the HP1 model to examine the improvement of salt distribution estimation. Model results are compared with experimental data sets from four field lysimeters. These columns were exposed to Na Cl solution with different concentrations(3, 30, 100, and 250 g/L) and were undergoing the same strong evaporation boundary condition. The pre-existing Ca SO_(4), Na Cl and Na2SO_(4)loads were 1.15, 0.47 and 0.23 g/(100 g of soil), respectively. Simulation results show that HP1 ameliorates the overestimation of salt content by SST in deeper soil due to the absence of dissolution of pre-existing soluble salts, and prevents the concentration of the solute from exceeding the solubilities which would occur in SST-result. Additionally, HP1-predicted results can help trace the transport process of each solute. Based on the results, we strongly suggest that the management of fields sensitive to salt content should make use of a coupled flow and chemical reaction model.
基金The results presented in the paper partially represent a contribution to the fulfillment of the state assignment of OGRI RAS(topic 125020501405-1).
文摘The paper addresses the issues of reducing the concentration of greenhouse gases in the atmosphere through carbon dioxide sequestration by injection to geological formations to enhance oil recovery and underground storage.Geochemical reactions occurring in a reservoir during CO_(2) injection can affect physical properties of the formation and mechanisms of carbon dioxide capture.The interactions in the“CO_(2)-formation water-rock”system are complex and depends on many factors:mineralogical composition of rock,composition and salinity of formation water,reservoir thermobaric conditions,time.The paper includes a brief review of carbon dioxide interaction studies with formation fluids and reservoir rock minerals.A methodology is presented for studying geochemical processes during interaction of carbon dioxide-saturated formation water with reservoir rock samples.Experimental results for oil-saturated and water-saturated,carbonate and terrigenous reservoir intervals are discussed.The experiments demonstrate complex interactions of CO_(2) with water and rocks under natural conditions.Important aspects are the influence of mineralogical composition on dissolution and secondary precipitation processes as well as changes in aqueous phase composition and pH.Hydrogeochemical modeling workflow for the studied processes is proposed with calibration to experimental data and their appropriate translation to reservoir conditions.The results demonstrate the need for detailed geochemical studies to better assess the effects of CO_(2) on reservoir properties and the risks associated with mineral deposition and dissolution during carbon capture and storage(CCS/CCUS)operations.
基金supported by National Natural Science Foundation of China(Grant Nos.40839908,40672072)
文摘The natural gas from the Triassic Feixianguan Formation of Northeast Sichuan Basin contains high H2S whereas relatively low CO_(2)concentrations and the CO_(2)display highδ13C values(ranging from-5.81‰to 3.3‰(PDB)).This seems to contradict the conventional wisdom that TSR should be a primary source of CO_(2)in natural gas from the Feixianguan Formation.In contrast,many authigenic calcite samples from these sites display very lowδ13C values(ranging from-18.4‰to-10.3‰(PDB)).This suggests that the carbon from TSR source dominated the formation of calcite whereas the carbon from inorganic source came into CO_(2)in natural gas.In order to assess the origin of CO_(2)from these H2S-rich sites,we have calculated the relative contributions of organic and inorganic carbon sources to the CO_(2)and authigenic calcite.The organic carbon source possibly originated from TSR,whereas the inorganic one might be generated from marine carbonates dissolution.This calculation is based on the carbon isotopic compositions of CO_(2)and authigenic calcite as well as an isotopic mass balance.The results show that the contribution of organic carbon source to the CO_(2)is only 2%,whereas that to authigenic calcite is as high as 43%on average.Such results combined with thermodynamic evidence indicate that the isotopically light CO_(2)produced by TSR process may contribute to authigenic calcite precipitation during burial diagenesis.Distinguishable from Ordovician reservoir of Tarim Basin,Feixianguan reservoir of Northeast Sichuan Basin experienced rapid tectonic uplift due to Yanshanian movement after TSR occurred.Such tectonic event could induce temperature decrease and further promote carbonates dissolution.During these processes,secondary porosity has developed in Feixianguan carbonate reservoirs.Therefore,much attention should be paid to the structural highs in search of high quality carbonate reservoirs.
