Surge pressure caused by pipe moving through the wellbore full of drilling.fluid is the main factor affecting wellbore stability,on which the additional mud density isdesigned.Thus if is desired to predict the surge p...Surge pressure caused by pipe moving through the wellbore full of drilling.fluid is the main factor affecting wellbore stability,on which the additional mud density isdesigned.Thus if is desired to predict the surge pressure with high accuracy.While this is closely,related with the selection of mud rheological models.Yield-Pseudoplastic model which has three parameters and is.famous for its higher accuracy has been used to describe the mud rheological properties in recent years.Based on this model the paper presents a new theoretical model for calculating surge pressure caused by mud viscosity during tripping or casing in a concentric annulus of directional wells under steady laminar situation.For convenience,the paper plots the distribution of the coefficients of surge pressure for different conditions.An example is given.These results provide the basis for controlling pressure surges and tripping velocity.展开更多
Most of existing methods for the safety assessment of the primary cooling loop of nuclear reactors in conditions of reactor coolant pump(RCP)failure(rotor seizure accident)essentially rely on the combination of one-di...Most of existing methods for the safety assessment of the primary cooling loop of nuclear reactors in conditions of reactor coolant pump(RCP)failure(rotor seizure accident)essentially rely on the combination of one-dimensional theory and experience.This study introduces a novel three-dimensional model of the‘Hualong-1’(HPR1000)primary loop and uses the method of matching the resistance characteristics of the tube to ensure that the main pump operates at the rated operating condition.In particular,the three-dimensional unsteady numerical calculation of the RCP behavior in the rotor-seizure accident condition is carried out in the framework of the RNG k-εturbulence model.The related transient pressure surge law and hydraulic load response are obtained accordingly.展开更多
文摘Surge pressure caused by pipe moving through the wellbore full of drilling.fluid is the main factor affecting wellbore stability,on which the additional mud density isdesigned.Thus if is desired to predict the surge pressure with high accuracy.While this is closely,related with the selection of mud rheological models.Yield-Pseudoplastic model which has three parameters and is.famous for its higher accuracy has been used to describe the mud rheological properties in recent years.Based on this model the paper presents a new theoretical model for calculating surge pressure caused by mud viscosity during tripping or casing in a concentric annulus of directional wells under steady laminar situation.For convenience,the paper plots the distribution of the coefficients of surge pressure for different conditions.An example is given.These results provide the basis for controlling pressure surges and tripping velocity.
文摘Most of existing methods for the safety assessment of the primary cooling loop of nuclear reactors in conditions of reactor coolant pump(RCP)failure(rotor seizure accident)essentially rely on the combination of one-dimensional theory and experience.This study introduces a novel three-dimensional model of the‘Hualong-1’(HPR1000)primary loop and uses the method of matching the resistance characteristics of the tube to ensure that the main pump operates at the rated operating condition.In particular,the three-dimensional unsteady numerical calculation of the RCP behavior in the rotor-seizure accident condition is carried out in the framework of the RNG k-εturbulence model.The related transient pressure surge law and hydraulic load response are obtained accordingly.
