The J oilfield in the Bohai has a long development history and has undergone comprehensive adjustment measures,including water injection and polymer injection.Following these adjustments,the injection and production w...The J oilfield in the Bohai has a long development history and has undergone comprehensive adjustment measures,including water injection and polymer injection.Following these adjustments,the injection and production well network now features coexistence of both polymer injection wells and water injection wells,which has negatively impacted production dynamics.Firstly,based on the adjusted reservoir well network in the J oilfield,a representative water-polymer co-injection well network was established.Subsequently,a numerical simulation model of this typical reservoir unit was developed using reservoir numerical simulation methods to confirm the interference issues associated with water-polymer co-injection.Multiple reservoir numerical simulation models were designed to investigate various factors influencing water-polymer interference,resulting in graphical representations of each factor’s impact under different conditions.Finally,gray relational analysis was employed to rank the influence of these factors,yielding the following order of significance:polymer concentration,the ratio of drainage distance to well spacing,horizontal permeability variation,interlayer permeability variation,and intralayer permeability variation.This understanding provides robust guidance for future adjustments in the oilfield.展开更多
The seismic disaster presents a zonal distribution along the fault strike.In this paper,rupture zone of ground surface soil caused by the uniform dislocation,inclined dislocation and warped dislocation of buried norma...The seismic disaster presents a zonal distribution along the fault strike.In this paper,rupture zone of ground surface soil caused by the uniform dislocation,inclined dislocation and warped dislocation of buried normal fault are studied by constituting a three-dimensional finite element model in Automatic Dynamic Incremental Nonlinear Analysis(ADINA).According to the critical value of surface rupture,the variational features and influencing factors of width and starting position of the"avoiding zone"in engineering construction are analyzed by using 96 model calculations.The main results are as follows:(1)Since the rupture zone of the ground surface soil from the point of mechanics is different from the"avoidance zone"from the point of engineering safety,the equivalent plastic strain and the total displacement ratio should be considered to evaluate the effect of the seismic ground movement on buildings.(2)During fault dislocation,plastic failure firstly occurred on the ground surface soil of the footwall side,and then the larger deformation gradually moved to the side of the hanging wall of the fault with the increase of fault displacement.(3)When the vertical displacement of buried fault reaches 3 m,the width of"avoiding zone"in engineering construction varies within the range of 10-90 m,which is most affected by the thickness of overlying soil and the dip angle of the fault.展开更多
Directional expansion of blast-induced crack is always the common purpose for directional controlled blasting. As it has been demonstrated that slot which located at the side of blasthole can function as a guidance fo...Directional expansion of blast-induced crack is always the common purpose for directional controlled blasting. As it has been demonstrated that slot which located at the side of blasthole can function as a guidance for blast energy, let the stress concentration at the direction of water jet slot. Therefore, it is meaningful to investigate the influence factors of directional controlled blasting with water jet assistance. In this paper, the influence on the guiding characteristics of the water jet slot during the propagation of blast-induced crack by the change of length-width of slot was simulated by ANSYS/LS-DYNA. The results indicate that if the distance from blasthole exceeds the limit, the influence on the guiding characteristics by the change length-width of the slot will get smaller and smaller, and when the width of water jet slot remains the same, the stress shows a monotonic increasing trend with the increase of the length of water jet slot, and the stress reaches its maximum value when the length-width of water jet slot is 0.075m×0.0070m. Moreover, based on stress wave theory and rock fracture theory, the influential mechanism for both the law of transmission of stress wave and of crack propagation by natural fracture and water jet slot were analyzed. The criteria for blast-induced crack propagation were established.展开更多
The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, i...The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, in previous investigation, the analysis on the measurement error was qualitative and only focused on the total effects on the measurement without decoupling the influencing factors. This paper discusses the effects of influencing factors on the measurement results for the interface propagation-based method. Numerical simulations were performed to explore the influencing factors, namely model simplification, subcooling and natural convection, along with their impact on the measurement process and corresponding measurement results. The numerical solutions were provided in terms of moving curves of the solid-liquid interface and the predicted values of thermal conductivity. Results indicated that the impact of simplified model was strongly dependent on Stefan number of the melting process. The degree of subcooling would lead to underestimated values for thermal conductivity prediction. The natural convection would intensify the heat transfer rate in the liquid region, thereby overestimating the obtained results of thermal conductivity. Correlations and experimental guidelines are provided. The relative errors are limited in ±1.5%,±3%and ±2% corresponding to the impact of simplified model, subcooling and natural convection, respectively.展开更多
Frontal upwelling is an important phenomenon in summer in the Yellow Sea(YS)and plays an essential role in the distribution of nutrients and biological species.In this paper,a three-dimensional hydrodynamic model is a...Frontal upwelling is an important phenomenon in summer in the Yellow Sea(YS)and plays an essential role in the distribution of nutrients and biological species.In this paper,a three-dimensional hydrodynamic model is applied to investigate the characteristics and influencing factors of frontal upwelling in the YS.The results show that the strength and distribution of frontal upwelling are largely dependent on the topography and bottom temperature fronts.The frontal upwelling in the YS is stronger and narrower near the eastern coast than near the western coast due to the steeper shelf slope.Moreover,external forcings,such as the meridional wind speed and air temperature in summer and the air temperature in the preceding winter and spring,have certain influences on the strength of frontal upwelling.An increase in air temperature in the previous winter and spring weakens the frontal upwelling in summer;in contrast,an increase in air temperature in summer strengthens the frontal upwelling.When the southerly wind in summer increases,the upwelling intensifies in the western YS and weakens in the eastern YS.The air temperature influences the strength of upwelling by changing the baroclinicity in the frontal region.Furthermore,the meridional wind speed in summer affects frontal upwelling via Ekman pumping.展开更多
Air-layer drag reduction (ALDR) technology for ship energy saving is getting more and more attention in recent years because of the outstanding drag reduction effect. In order to promote practical application, it is n...Air-layer drag reduction (ALDR) technology for ship energy saving is getting more and more attention in recent years because of the outstanding drag reduction effect. In order to promote practical application, it is necessary to fully understand the two phase flow characteristics of the air layer. Recent experimental studies have shown that the surface of the air layer presents wave pattern, which has an important influence on its damage risk. However, it is difficult to measure the wave pattern quantificationally due to the interference of equipment. The main goal of the present paper is to investigate the wave pattern characteristic of air layer in cavity using numerical simulation method. On this basis, the effect of flow and geometric influence factors are discussed to understand the key control conditions. A computational fluid dynamics (CFD) numerical method based on Reynolds averaged Navier-Stokes (RANS) equations and volume of fluid (VOF) interface capturing method is established, and has been successfully applied in the simulation of air layer wave pattern. Both 2-D and 3-D simulations are carried out, aiming at analyzing air-water interface flow and vortex flow directly. Based on the simulation results, several important conclusions about the mechanism of air layer wave pattern can be obtained. Firstly, it is found to be an inherent characteristic that the wave height of the upstream air layer is higher than that of the downstream. The extremely high wave peak is easy to contact with the flat plate, leading to the breakup of air layer and a “central blank area” phenomenon. With the help of flow analysis, it is found that this characteristic is mainly caused by the strong counterclockwise vortex behind the bow wedge block. Secondly, the air layer stability is reduced with the increase of water flow velocity by affecting the wave height. There is a saturation point of air flow rate to reach maximum thickness of air layer. Thirdly, cavity configuration has obvious influence on air layer stability by influencing vortex flow field. The increase of cavity depth and width can aggravate the unsteady and nonlinear characteristics of air layer. Finally, comprehensive design criteria are concluded from the view of geometrical configuration and flow conditions. A cavity with the moderate depth and width can avoid the upstream damage of air layer. Longitudinal position of air nozzles should be set within the low pressure zone behind the wedge block for stable air layer formation.展开更多
基金supported by National Science and Technology Major Project of China(2016ZX05025-001)the Major Science and Technology Project of CNOOC(KJGG2021-0501).
文摘The J oilfield in the Bohai has a long development history and has undergone comprehensive adjustment measures,including water injection and polymer injection.Following these adjustments,the injection and production well network now features coexistence of both polymer injection wells and water injection wells,which has negatively impacted production dynamics.Firstly,based on the adjusted reservoir well network in the J oilfield,a representative water-polymer co-injection well network was established.Subsequently,a numerical simulation model of this typical reservoir unit was developed using reservoir numerical simulation methods to confirm the interference issues associated with water-polymer co-injection.Multiple reservoir numerical simulation models were designed to investigate various factors influencing water-polymer interference,resulting in graphical representations of each factor’s impact under different conditions.Finally,gray relational analysis was employed to rank the influence of these factors,yielding the following order of significance:polymer concentration,the ratio of drainage distance to well spacing,horizontal permeability variation,interlayer permeability variation,and intralayer permeability variation.This understanding provides robust guidance for future adjustments in the oilfield.
基金This research was supported by National Natural Science Foundation of China(Nos.41877294 and 51421005)Hebei Natural Science Foundation(No.D2017403020).
文摘The seismic disaster presents a zonal distribution along the fault strike.In this paper,rupture zone of ground surface soil caused by the uniform dislocation,inclined dislocation and warped dislocation of buried normal fault are studied by constituting a three-dimensional finite element model in Automatic Dynamic Incremental Nonlinear Analysis(ADINA).According to the critical value of surface rupture,the variational features and influencing factors of width and starting position of the"avoiding zone"in engineering construction are analyzed by using 96 model calculations.The main results are as follows:(1)Since the rupture zone of the ground surface soil from the point of mechanics is different from the"avoidance zone"from the point of engineering safety,the equivalent plastic strain and the total displacement ratio should be considered to evaluate the effect of the seismic ground movement on buildings.(2)During fault dislocation,plastic failure firstly occurred on the ground surface soil of the footwall side,and then the larger deformation gradually moved to the side of the hanging wall of the fault with the increase of fault displacement.(3)When the vertical displacement of buried fault reaches 3 m,the width of"avoiding zone"in engineering construction varies within the range of 10-90 m,which is most affected by the thickness of overlying soil and the dip angle of the fault.
基金Natural Science Foundation of Southwest University of Science and Technology (18zx7124).
文摘Directional expansion of blast-induced crack is always the common purpose for directional controlled blasting. As it has been demonstrated that slot which located at the side of blasthole can function as a guidance for blast energy, let the stress concentration at the direction of water jet slot. Therefore, it is meaningful to investigate the influence factors of directional controlled blasting with water jet assistance. In this paper, the influence on the guiding characteristics of the water jet slot during the propagation of blast-induced crack by the change of length-width of slot was simulated by ANSYS/LS-DYNA. The results indicate that if the distance from blasthole exceeds the limit, the influence on the guiding characteristics by the change length-width of the slot will get smaller and smaller, and when the width of water jet slot remains the same, the stress shows a monotonic increasing trend with the increase of the length of water jet slot, and the stress reaches its maximum value when the length-width of water jet slot is 0.075m×0.0070m. Moreover, based on stress wave theory and rock fracture theory, the influential mechanism for both the law of transmission of stress wave and of crack propagation by natural fracture and water jet slot were analyzed. The criteria for blast-induced crack propagation were established.
基金Project(51606224) supported by the National Natural Science Foundation of China
文摘The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, in previous investigation, the analysis on the measurement error was qualitative and only focused on the total effects on the measurement without decoupling the influencing factors. This paper discusses the effects of influencing factors on the measurement results for the interface propagation-based method. Numerical simulations were performed to explore the influencing factors, namely model simplification, subcooling and natural convection, along with their impact on the measurement process and corresponding measurement results. The numerical solutions were provided in terms of moving curves of the solid-liquid interface and the predicted values of thermal conductivity. Results indicated that the impact of simplified model was strongly dependent on Stefan number of the melting process. The degree of subcooling would lead to underestimated values for thermal conductivity prediction. The natural convection would intensify the heat transfer rate in the liquid region, thereby overestimating the obtained results of thermal conductivity. Correlations and experimental guidelines are provided. The relative errors are limited in ±1.5%,±3%and ±2% corresponding to the impact of simplified model, subcooling and natural convection, respectively.
基金The National Key Research and Development Project under contract No.2017YFC1403400the National Key Research and Development Program of China under contract No.2016YFC1402501+2 种基金the National Natural Science Foundation of China under contract No.41806164the Open Fund Project of Key Laboratory of Marine Environmental Information Technology,Ministry of Natural Resourcesthe Shandong Joint Fund for Marine Science Research Centers under contract No.U1406401.
文摘Frontal upwelling is an important phenomenon in summer in the Yellow Sea(YS)and plays an essential role in the distribution of nutrients and biological species.In this paper,a three-dimensional hydrodynamic model is applied to investigate the characteristics and influencing factors of frontal upwelling in the YS.The results show that the strength and distribution of frontal upwelling are largely dependent on the topography and bottom temperature fronts.The frontal upwelling in the YS is stronger and narrower near the eastern coast than near the western coast due to the steeper shelf slope.Moreover,external forcings,such as the meridional wind speed and air temperature in summer and the air temperature in the preceding winter and spring,have certain influences on the strength of frontal upwelling.An increase in air temperature in the previous winter and spring weakens the frontal upwelling in summer;in contrast,an increase in air temperature in summer strengthens the frontal upwelling.When the southerly wind in summer increases,the upwelling intensifies in the western YS and weakens in the eastern YS.The air temperature influences the strength of upwelling by changing the baroclinicity in the frontal region.Furthermore,the meridional wind speed in summer affects frontal upwelling via Ekman pumping.
基金Project supported by the Ministry of Industry and Information Technology of China(Project No.CB01N20-05).
文摘Air-layer drag reduction (ALDR) technology for ship energy saving is getting more and more attention in recent years because of the outstanding drag reduction effect. In order to promote practical application, it is necessary to fully understand the two phase flow characteristics of the air layer. Recent experimental studies have shown that the surface of the air layer presents wave pattern, which has an important influence on its damage risk. However, it is difficult to measure the wave pattern quantificationally due to the interference of equipment. The main goal of the present paper is to investigate the wave pattern characteristic of air layer in cavity using numerical simulation method. On this basis, the effect of flow and geometric influence factors are discussed to understand the key control conditions. A computational fluid dynamics (CFD) numerical method based on Reynolds averaged Navier-Stokes (RANS) equations and volume of fluid (VOF) interface capturing method is established, and has been successfully applied in the simulation of air layer wave pattern. Both 2-D and 3-D simulations are carried out, aiming at analyzing air-water interface flow and vortex flow directly. Based on the simulation results, several important conclusions about the mechanism of air layer wave pattern can be obtained. Firstly, it is found to be an inherent characteristic that the wave height of the upstream air layer is higher than that of the downstream. The extremely high wave peak is easy to contact with the flat plate, leading to the breakup of air layer and a “central blank area” phenomenon. With the help of flow analysis, it is found that this characteristic is mainly caused by the strong counterclockwise vortex behind the bow wedge block. Secondly, the air layer stability is reduced with the increase of water flow velocity by affecting the wave height. There is a saturation point of air flow rate to reach maximum thickness of air layer. Thirdly, cavity configuration has obvious influence on air layer stability by influencing vortex flow field. The increase of cavity depth and width can aggravate the unsteady and nonlinear characteristics of air layer. Finally, comprehensive design criteria are concluded from the view of geometrical configuration and flow conditions. A cavity with the moderate depth and width can avoid the upstream damage of air layer. Longitudinal position of air nozzles should be set within the low pressure zone behind the wedge block for stable air layer formation.
