During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtr...During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a challenge.Herein,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,DADC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether crosslinker.Due to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the DADC copolymer exhibited outstanding temperature-and salt-resistance.The rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing performance.The DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling fluids.Moreover,the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)environments.Therefore,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.展开更多
In this study,the pressure compensation mechanism of a reducer bellows is analyzed.This device is typically used to reduce the size of undersea instruments and improve related pressure resistance and sealing capabilit...In this study,the pressure compensation mechanism of a reducer bellows is analyzed.This device is typically used to reduce the size of undersea instruments and improve related pressure resistance and sealing capabilities.Here,its axial stiffness is studied through a multi-fold approach based on theory,simulations and experiments.The results indicate that the mechanical strength of the reducer bellows,together with the oil volume and temperature are the main factors influencing its performances.In particular,the wall thickness,wave number,middle distance,and wave height are the most influential parameters.For a certain type of reducer bellows,the compensation capacity attains a maximum when the wave number ratio is between 6:6 and 8:4,the wall thickness is 0.3 mm,and the wave height is between 4–5 mm and 5–6 mm.Moreover,the maximum allowable ambient pres-sure of the optimized reducer bellows can reach 62.6 MPa without failure,and the maximum working water depth is 6284 m.展开更多
对于熔盐堆全堆高保真流体动力学计算,即使借助超级计算机的并行计算能力在面对快速甚至实时求解的问题仍然面临效率的巨大挑战,引入和采用模型降阶(Reduced Order Modeling,ROM)方法,将能够有效解决这类问题。基于本征正交分解(Proper ...对于熔盐堆全堆高保真流体动力学计算,即使借助超级计算机的并行计算能力在面对快速甚至实时求解的问题仍然面临效率的巨大挑战,引入和采用模型降阶(Reduced Order Modeling,ROM)方法,将能够有效解决这类问题。基于本征正交分解(Proper Orthogonal Decomposition,POD)方法与Galerkin投影法,引入基于有限体积的模型降阶(ROM based on Finite Volume approximation,FV-ROM)方法和上确界稳定模型降阶(ROM with supremizer stabilization,SUP-ROM)方法,针对液态燃料熔盐堆(Liquid Fuel Molten Salt Reactor,LFMSR)层流和湍流瞬态工况开展适用性分析。结果表明:FV-ROM方法在速度误差和计算效率方面占有明显优势,层流和湍流瞬态速度平均L^(2)相对误差低于0.5%和0.6%,且单步长的加速比分别为1500和1000倍左右;相比之下,SUP-ROM方法在压力预测方面表现出显著的优势,层流和湍流瞬态压力平均L^(2)相对误差低至0.20%和0.38%。因此,通过FV-ROM和SUP-ROM两种方法相结合的方式进行熔盐堆流体动力学速度场和压力场预测,能够更加有效地提高流体动力学仿真的效率,并确保瞬态模拟过程计算可靠性和精确度。展开更多
基金the National Natural Science Foundation of China(No.52204023)China Postdoctoral Science Foundation(2022M713465)Postdoctoral Innovation Talent Support of Shandong Province(SDBX2022033)。
文摘During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a challenge.Herein,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,DADC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether crosslinker.Due to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the DADC copolymer exhibited outstanding temperature-and salt-resistance.The rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing performance.The DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling fluids.Moreover,the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)environments.Therefore,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.
基金Key Laboratory of Petroleum and Natural Gas Equipment of Ministry of Education.
文摘In this study,the pressure compensation mechanism of a reducer bellows is analyzed.This device is typically used to reduce the size of undersea instruments and improve related pressure resistance and sealing capabilities.Here,its axial stiffness is studied through a multi-fold approach based on theory,simulations and experiments.The results indicate that the mechanical strength of the reducer bellows,together with the oil volume and temperature are the main factors influencing its performances.In particular,the wall thickness,wave number,middle distance,and wave height are the most influential parameters.For a certain type of reducer bellows,the compensation capacity attains a maximum when the wave number ratio is between 6:6 and 8:4,the wall thickness is 0.3 mm,and the wave height is between 4–5 mm and 5–6 mm.Moreover,the maximum allowable ambient pres-sure of the optimized reducer bellows can reach 62.6 MPa without failure,and the maximum working water depth is 6284 m.
文摘对于熔盐堆全堆高保真流体动力学计算,即使借助超级计算机的并行计算能力在面对快速甚至实时求解的问题仍然面临效率的巨大挑战,引入和采用模型降阶(Reduced Order Modeling,ROM)方法,将能够有效解决这类问题。基于本征正交分解(Proper Orthogonal Decomposition,POD)方法与Galerkin投影法,引入基于有限体积的模型降阶(ROM based on Finite Volume approximation,FV-ROM)方法和上确界稳定模型降阶(ROM with supremizer stabilization,SUP-ROM)方法,针对液态燃料熔盐堆(Liquid Fuel Molten Salt Reactor,LFMSR)层流和湍流瞬态工况开展适用性分析。结果表明:FV-ROM方法在速度误差和计算效率方面占有明显优势,层流和湍流瞬态速度平均L^(2)相对误差低于0.5%和0.6%,且单步长的加速比分别为1500和1000倍左右;相比之下,SUP-ROM方法在压力预测方面表现出显著的优势,层流和湍流瞬态压力平均L^(2)相对误差低至0.20%和0.38%。因此,通过FV-ROM和SUP-ROM两种方法相结合的方式进行熔盐堆流体动力学速度场和压力场预测,能够更加有效地提高流体动力学仿真的效率,并确保瞬态模拟过程计算可靠性和精确度。
