The transientflow testing of ultra-deepwater gas wells is greatly impacted by the low temperatures of seawater encountered over extended distances.This leads to a redistribution of temperature within the wellbore,whic...The transientflow testing of ultra-deepwater gas wells is greatly impacted by the low temperatures of seawater encountered over extended distances.This leads to a redistribution of temperature within the wellbore,which in turn influences theflow behavior.To accurately predict such a temperature distribution,in this study a comprehensive model of theflowing temperature and pressurefields is developed.This model is based on principles offluid mechanics,heat transfer,mass conservation,and energy conservation and relies on the Runge-Kutta method for accurate integration in time of the resulting equations.The analysis includes the examination of the influence of various factors,such as gasflow production rate,thermal diffusivity of the formation,and thermal diffusivity of seawater,on the temperature and pressure profiles of the wellbore.The keyfindings can be summarized as follows:1.Higher production rates during testing lead to increasedflowing temperatures and decreased pressures within the wellbore.However,in the presence of a seawater thermocline,a crossover inflowing temperature is observed.2.An increase in wellbore pressure is associated with larger pipe diameters.3.Greater thermal diffusivity of the formation results in more rapid heat transfer from the wellbore to the formation,which causes lowerflowing temperatures within the wellbore.4.In an isothermal layer,higher thermal diffusivity of seawater leads to increased wellboreflowing temperatures.Conversely,in thermocline and mixed layer segments,lower temperatures are noted.5.Production test data from a representative deep-water gas well in the South China Sea,used to calculate the bottom-seafloor-wellhead temperature and pressurefields across three operating modes,indicate that the average error in temperature prediction is 2.18%,while the average error in pressure prediction is 5.26%,thereby confirming the reliability of the theoretical model.展开更多
Inserting light element atoms into a transition metal host matrix simultaneously produces high hardness and high superconductivity transition temperature.Here,we report the synthesis of a polycrystalline‘covalent me...Inserting light element atoms into a transition metal host matrix simultaneously produces high hardness and high superconductivity transition temperature.Here,we report the synthesis of a polycrystalline‘covalent metal’–Mo_(3)C_(2)(with space group:P63/mmc)with the high pressure and high temperature(HPHT)method.Direct magnetic susceptibility and electrical resistivity measurements show that Mo_(3)C_(2)is a typical weakly coupled type-II superconductor with a high critical magnetic field and a superconductive temperature of 8.2 K.Moreover,compared with traditional superconductive materials,the asymptotic Vickers hardness value of Mo_(3)C_(2)shows impressive high hardness.Its high superconductive temperature originates from its high Debye temperature and high density of states at the Fermi energy level.The high Debye temperature is closely correlated with the hybridization between Mo-4d orbitals and C-2p orbitals,and the metallic feature leads to the high density of states at the Fermi energy level N(EF).The advent of this class of high hardness superconductive materials bridges the gap between high hardness and superconductivity communities.展开更多
文摘The transientflow testing of ultra-deepwater gas wells is greatly impacted by the low temperatures of seawater encountered over extended distances.This leads to a redistribution of temperature within the wellbore,which in turn influences theflow behavior.To accurately predict such a temperature distribution,in this study a comprehensive model of theflowing temperature and pressurefields is developed.This model is based on principles offluid mechanics,heat transfer,mass conservation,and energy conservation and relies on the Runge-Kutta method for accurate integration in time of the resulting equations.The analysis includes the examination of the influence of various factors,such as gasflow production rate,thermal diffusivity of the formation,and thermal diffusivity of seawater,on the temperature and pressure profiles of the wellbore.The keyfindings can be summarized as follows:1.Higher production rates during testing lead to increasedflowing temperatures and decreased pressures within the wellbore.However,in the presence of a seawater thermocline,a crossover inflowing temperature is observed.2.An increase in wellbore pressure is associated with larger pipe diameters.3.Greater thermal diffusivity of the formation results in more rapid heat transfer from the wellbore to the formation,which causes lowerflowing temperatures within the wellbore.4.In an isothermal layer,higher thermal diffusivity of seawater leads to increased wellboreflowing temperatures.Conversely,in thermocline and mixed layer segments,lower temperatures are noted.5.Production test data from a representative deep-water gas well in the South China Sea,used to calculate the bottom-seafloor-wellhead temperature and pressurefields across three operating modes,indicate that the average error in temperature prediction is 2.18%,while the average error in pressure prediction is 5.26%,thereby confirming the reliability of the theoretical model.
基金supported by the National Key R&D Program of China(No.2018YFA0305900)the National Natural Science Foundation of China(No.11774121,51632002,11674122,51572108,11634004,11504127,11574109,11704143,and 11404134)+4 种基金the National Key Research and Development Program of China(2016YFB0201204)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT_15R23)the National Fund for Fostering Talents of Basic Science(No.J1103202)the 111 Project(No.B12011)the Jilin Provincial Science and Technology Development Project of China(20170520116JH).
文摘Inserting light element atoms into a transition metal host matrix simultaneously produces high hardness and high superconductivity transition temperature.Here,we report the synthesis of a polycrystalline‘covalent metal’–Mo_(3)C_(2)(with space group:P63/mmc)with the high pressure and high temperature(HPHT)method.Direct magnetic susceptibility and electrical resistivity measurements show that Mo_(3)C_(2)is a typical weakly coupled type-II superconductor with a high critical magnetic field and a superconductive temperature of 8.2 K.Moreover,compared with traditional superconductive materials,the asymptotic Vickers hardness value of Mo_(3)C_(2)shows impressive high hardness.Its high superconductive temperature originates from its high Debye temperature and high density of states at the Fermi energy level.The high Debye temperature is closely correlated with the hybridization between Mo-4d orbitals and C-2p orbitals,and the metallic feature leads to the high density of states at the Fermi energy level N(EF).The advent of this class of high hardness superconductive materials bridges the gap between high hardness and superconductivity communities.
