在利用期间近海油和气体,形成严重猛击是容易的哪个能在连接水源的起床人引起大伤害并且近海平台预处理系统。严重猛击的流动模式和压力变化与 0.051 m 的内部直径在一个试验性的模拟系统被学习。严重猛击能被划分成三严重猛击政体,...在利用期间近海油和气体,形成严重猛击是容易的哪个能在连接水源的起床人引起大伤害并且近海平台预处理系统。严重猛击的流动模式和压力变化与 0.051 m 的内部直径在一个试验性的模拟系统被学习。严重猛击能被划分成三严重猛击政体,这被发现:我与大压力变化,在起床人的液体和气体的断断续续的流动,和液体阶段的明显的截止在低气体和液体流动评估的政体,以有非周期性的变化和不连续的液体流出和没有煤气的截止的高煤气的流动率的政体 II ,以有退化压力变化处于良好的竟技状态的高液体流动率的政体 III 相对冒泡的马厩或塞子流动。当管道的偏斜角度是 0 时。展开更多
The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved ...The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved riser model and the response displacements of the riser were simultaneously recorded by high speed cameras. The gas superficial velocity ranges from 0.1 m/s to 0.6 m/s while the liquid superficial velocity from 0.06 m/s to 0.3 m/s.Severe slugging type 3, unstable oscillation flow and relatively stable slug flow were observed in the considered flow rates. Severe slugging type 3 characterized by premature gas penetration occurs at relatively low flow rates. Both the cycle time and slug length become shorter as the gas flow rate increases. The pressure at the riser base undergoes a longer period and larger amplitude of fluctuation as compared with the other two flow regimes. Additionally, severe slugging leads to the most vigorous in-plane vibration. However, the responses in the vertical and horizontal directions are not synchronized. The vertical vibration is dominated by the second mode while the horizontal vibration is dominated by the first mode. Similar to the vortex-induced vibration, three branches are identified as initial branch, build-up branch and descending branch for the response versus the mixture velocity of gas-liquid flow.展开更多
Severe slugging can occur in a pipeline-riser system at relatively low liquid and gas flow rates during gas-oil transportation, possibly causing unexpected damage to the production facilities. Experiments with air and...Severe slugging can occur in a pipeline-riser system at relatively low liquid and gas flow rates during gas-oil transportation, possibly causing unexpected damage to the production facilities. Experiments with air and water are conducted in a horizontal and downward inclined pipeline followed by a catenary riser in order to investigate the mechanism and characteristics of severe slugging. A theoretical model is introduced to compare with the experiments. The results show that the formation mechanism of severe slugging in a catenary riser is different from that in a vertical riser due to the riser geometry and five flow patterns are obtained and analyzed. A gas-liquid mixture slug stage is observed at the beginning of one cycle of severe slugging, which is seldom noticed in previous studies. Based on both experiments and computations, the time period and variation of pressure amplitude of severe slugging are found closely related to the superficial gas velocity, implying that the gas velocity significantly influences the flow patterns in our experiments. Moreover, good agreements between the experimental data and the numerical results are shown in the stability curve and flow regime map, which can be a possible reference for design in an offshore oil-production system.展开更多
A mathematical model is presented to study the main characteristics of severe slugging in a downward inclined pipeline followed by a catenary riser. In this model, both simplified transient model and phase distributio...A mathematical model is presented to study the main characteristics of severe slugging in a downward inclined pipeline followed by a catenary riser. In this model, both simplified transient model and phase distribution model are included so that the flow characteristics of each stage for severe slugging can be accurately reproduced, especially for blowout stage. The results show that the flow features of severe slugging can be simulated by the proposed mathematical model. A good agreement between the experimental data and the numerical results is observed. The model can predict the transient fluctuation of many respects, such as the superficial gas velocity at the bottom of the riser and the average velocity at the outlet of the riser.展开更多
Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main ...Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main characteristics of severe slugging, leading to the risk of serious damage. In this paper, the separator control is adopted to accurately control the separator liquid level and pressure under severe slugging flow conditions. This indicates that the separator liquid level control alone does not have a significant impact on the upstream flow, but it is beneficial for normal operation and pressure control of the separator. As the separator pressure increases, the peak pressure in the riser apparently diminishes, and the amplitude of pressure fluctuation gradually decreases, which means that severe slugging is inhibited. During the slug blowing out, the gas/liquid slipping in the riser intensifies. The long gas plug quickly flows through the riser, and then tends to morph into short and slowly flowing gas bubbles. The elimination effect of the pressure control strategy on severe slugging is related to the relative rate of the superficial gas/liquid flow.展开更多
利用CFD软件Fluent建立二维全尺寸仿真模型,对立管实验装置中的严重段塞流现象进行数值模拟研究。模拟方法中,采用液体体积函数(volume of fluid,VOF)法追踪气液界面;将长距离海底管道等效为箱体,以提高计算效率。模拟出了立管系统中的...利用CFD软件Fluent建立二维全尺寸仿真模型,对立管实验装置中的严重段塞流现象进行数值模拟研究。模拟方法中,采用液体体积函数(volume of fluid,VOF)法追踪气液界面;将长距离海底管道等效为箱体,以提高计算效率。模拟出了立管系统中的四种流型:典型严重段塞流(SSI)、严重段塞流II(SSII)、过渡流型(SST)和稳定流动;并对这四种流型的模拟结果进行了实验验证。最后,对典型严重段塞流的瞬态流动特性进行了深入分析。结果表明:采用数值模拟方法计算效率高,可准确模拟严重段塞流现象,为长距离立管系统中严重段塞流研究提供了切实可行的模拟方法。模拟工况下,气液喷发的瞬时质量流量可达入口的2.5倍以上,气液平均流速可达入口的4.5倍以上,其瞬态流动特性的分析对严重段塞流危害的准确评估有重要意义。展开更多
During the exploitation of offshore oil,it is easy to form severe slugging in the riser system at a low gas-liquid velocity.The magnitude of the pressure fluctuation can be significantly high,causing dramatic change o...During the exploitation of offshore oil,it is easy to form severe slugging in the riser system at a low gas-liquid velocity.The magnitude of the pressure fluctuation can be significantly high,causing dramatic change of flow rate and leading to other damages.In this paper,the characteristics of slug velocity during the four stages of severe slugging in the pipeline-riser system were studied.It was found that the slug head rose in the riser at a constant velocity in the slug formation stage.At the same time,the direction of slug tail movement was opposite to the flow direction,and the tail velocity kept constant when flowing through the inclined pipe.In the process of blowout,the liquid velocity in the pipeline-riser system increased and reached a maximum value when the slug tail reached the top of the pipeline-riser.At this moment,the instantaneous flow rate was much larger than that in the slug production stage.展开更多
基金Supported by the National High Technology Research and Development Program of China(2006AA09Z302)
文摘在利用期间近海油和气体,形成严重猛击是容易的哪个能在连接水源的起床人引起大伤害并且近海平台预处理系统。严重猛击的流动模式和压力变化与 0.051 m 的内部直径在一个试验性的模拟系统被学习。严重猛击能被划分成三严重猛击政体,这被发现:我与大压力变化,在起床人的液体和气体的断断续续的流动,和液体阶段的明显的截止在低气体和液体流动评估的政体,以有非周期性的变化和不连续的液体流出和没有煤气的截止的高煤气的流动率的政体 II ,以有退化压力变化处于良好的竟技状态的高液体流动率的政体 III 相对冒泡的马厩或塞子流动。当管道的偏斜角度是 0 时。
基金financially supported by the National Natural Science Foundation of China(Grant No.11502220)the Youth Science&Technology Foundation of Sichuan Province(Grant No.2017JQ0055)the Youth Scientific and Technological Innovation Team of the Safety of Deep-Water Pipe Strings of Southwest Petroleum University(Grant No.2017CXTD06)
文摘The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved riser model and the response displacements of the riser were simultaneously recorded by high speed cameras. The gas superficial velocity ranges from 0.1 m/s to 0.6 m/s while the liquid superficial velocity from 0.06 m/s to 0.3 m/s.Severe slugging type 3, unstable oscillation flow and relatively stable slug flow were observed in the considered flow rates. Severe slugging type 3 characterized by premature gas penetration occurs at relatively low flow rates. Both the cycle time and slug length become shorter as the gas flow rate increases. The pressure at the riser base undergoes a longer period and larger amplitude of fluctuation as compared with the other two flow regimes. Additionally, severe slugging leads to the most vigorous in-plane vibration. However, the responses in the vertical and horizontal directions are not synchronized. The vertical vibration is dominated by the second mode while the horizontal vibration is dominated by the first mode. Similar to the vortex-induced vibration, three branches are identified as initial branch, build-up branch and descending branch for the response versus the mixture velocity of gas-liquid flow.
基金financially supported by the National Natural Science Foundation of China(Grant No.11272211)the National Program on Key Basic Research Project of China(973 Program,Grant No.2015CB251203)
文摘Severe slugging can occur in a pipeline-riser system at relatively low liquid and gas flow rates during gas-oil transportation, possibly causing unexpected damage to the production facilities. Experiments with air and water are conducted in a horizontal and downward inclined pipeline followed by a catenary riser in order to investigate the mechanism and characteristics of severe slugging. A theoretical model is introduced to compare with the experiments. The results show that the formation mechanism of severe slugging in a catenary riser is different from that in a vertical riser due to the riser geometry and five flow patterns are obtained and analyzed. A gas-liquid mixture slug stage is observed at the beginning of one cycle of severe slugging, which is seldom noticed in previous studies. Based on both experiments and computations, the time period and variation of pressure amplitude of severe slugging are found closely related to the superficial gas velocity, implying that the gas velocity significantly influences the flow patterns in our experiments. Moreover, good agreements between the experimental data and the numerical results are shown in the stability curve and flow regime map, which can be a possible reference for design in an offshore oil-production system.
基金financially supported by the National Natural Science Foundation of China(Grant No.51979257)the Key Research and Development Program of Shandong Province(Grant No.2018GHY115045)
文摘A mathematical model is presented to study the main characteristics of severe slugging in a downward inclined pipeline followed by a catenary riser. In this model, both simplified transient model and phase distribution model are included so that the flow characteristics of each stage for severe slugging can be accurately reproduced, especially for blowout stage. The results show that the flow features of severe slugging can be simulated by the proposed mathematical model. A good agreement between the experimental data and the numerical results is observed. The model can predict the transient fluctuation of many respects, such as the superficial gas velocity at the bottom of the riser and the average velocity at the outlet of the riser.
文摘Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main characteristics of severe slugging, leading to the risk of serious damage. In this paper, the separator control is adopted to accurately control the separator liquid level and pressure under severe slugging flow conditions. This indicates that the separator liquid level control alone does not have a significant impact on the upstream flow, but it is beneficial for normal operation and pressure control of the separator. As the separator pressure increases, the peak pressure in the riser apparently diminishes, and the amplitude of pressure fluctuation gradually decreases, which means that severe slugging is inhibited. During the slug blowing out, the gas/liquid slipping in the riser intensifies. The long gas plug quickly flows through the riser, and then tends to morph into short and slowly flowing gas bubbles. The elimination effect of the pressure control strategy on severe slugging is related to the relative rate of the superficial gas/liquid flow.
文摘利用CFD软件Fluent建立二维全尺寸仿真模型,对立管实验装置中的严重段塞流现象进行数值模拟研究。模拟方法中,采用液体体积函数(volume of fluid,VOF)法追踪气液界面;将长距离海底管道等效为箱体,以提高计算效率。模拟出了立管系统中的四种流型:典型严重段塞流(SSI)、严重段塞流II(SSII)、过渡流型(SST)和稳定流动;并对这四种流型的模拟结果进行了实验验证。最后,对典型严重段塞流的瞬态流动特性进行了深入分析。结果表明:采用数值模拟方法计算效率高,可准确模拟严重段塞流现象,为长距离立管系统中严重段塞流研究提供了切实可行的模拟方法。模拟工况下,气液喷发的瞬时质量流量可达入口的2.5倍以上,气液平均流速可达入口的4.5倍以上,其瞬态流动特性的分析对严重段塞流危害的准确评估有重要意义。
文摘During the exploitation of offshore oil,it is easy to form severe slugging in the riser system at a low gas-liquid velocity.The magnitude of the pressure fluctuation can be significantly high,causing dramatic change of flow rate and leading to other damages.In this paper,the characteristics of slug velocity during the four stages of severe slugging in the pipeline-riser system were studied.It was found that the slug head rose in the riser at a constant velocity in the slug formation stage.At the same time,the direction of slug tail movement was opposite to the flow direction,and the tail velocity kept constant when flowing through the inclined pipe.In the process of blowout,the liquid velocity in the pipeline-riser system increased and reached a maximum value when the slug tail reached the top of the pipeline-riser.At this moment,the instantaneous flow rate was much larger than that in the slug production stage.