Drill string will sustain large uplift force during the shut-in period after gas overflow in an ultra-deep well, and in serious case, it will run out of the wellhead. A calculation model of uplift force was establishe...Drill string will sustain large uplift force during the shut-in period after gas overflow in an ultra-deep well, and in serious case, it will run out of the wellhead. A calculation model of uplift force was established to analyze dynamic change characteristics of the uplift force of drill string during the shut-in period, and then a management procedure for the uplift risk during the shut-in period after gas overflow in the ultra-deep well was formed. Cross section method and pressure area method were used to analyze the force on drill string after shut-in of well, it was found that the source of uplift force was the "fictitious force" caused by the hydrostatic pressure in the well. When the fictitious force is in the opposite direction to the gravity, it is the uplift force. By adopting the theory of annular multiphase flow, considering the effects of wellbore afterflow and gas slippage, the dynamic change of the pressure and fluid in the wellbore and the uplift force of drill string during the shut-in period were analyzed. The magnitude and direction of uplift force are related to the length of drill string in the wellbore and shut-in time, and there is the risk of uplift of drill string when the length of drill string in the wellbore is smaller than the critical drill string length or the shut in time exceeds the critical shut in time. A set of treatment method and process to prevent the uplift of drill string is advanced during the shut-in period after overflow in the ultra-deep well, which makes the risk management of the drill string uplift in the ultra-deep well more rigorous and scientific.展开更多
【目的】通过研究一种基于流量溢出效应的动态负载均衡(Dynamic load balancing based on spillover,D-Spillover)模型与算法,为当前动态负载均衡不能从网络整体资源利用角度将富裕带宽贡献给其他流量,造成资源浪费的问题提供解决方案...【目的】通过研究一种基于流量溢出效应的动态负载均衡(Dynamic load balancing based on spillover,D-Spillover)模型与算法,为当前动态负载均衡不能从网络整体资源利用角度将富裕带宽贡献给其他流量,造成资源浪费的问题提供解决方案。【方法】对网络数据流进行粒子化最优分解,利用粒子群寻优法,以粒子化等比例利用带宽,结合非线性时间序列分析方法,按比例节点数据流溢出后动态调整分发的负载均衡算法和策略,实现每一个时间段、每一个节点上宽带的最大利用化与均衡转发,充分利用网络的带宽,最大化发挥网络设备性能。【结果】D-Spillover负载均衡机制在任何时间段能让流量均匀分配给等比例接口容量,每一个接口都会性价比的利用带宽,流量分布比较均衡。【结论】根据网络的需要,将D-Spillover负载均衡机制运用在网络负载较重的数据中心设备中,有利于整个网络的优化。展开更多
基金Supported by China National Science and Technology Major Project(2016ZX05020-006)
文摘Drill string will sustain large uplift force during the shut-in period after gas overflow in an ultra-deep well, and in serious case, it will run out of the wellhead. A calculation model of uplift force was established to analyze dynamic change characteristics of the uplift force of drill string during the shut-in period, and then a management procedure for the uplift risk during the shut-in period after gas overflow in the ultra-deep well was formed. Cross section method and pressure area method were used to analyze the force on drill string after shut-in of well, it was found that the source of uplift force was the "fictitious force" caused by the hydrostatic pressure in the well. When the fictitious force is in the opposite direction to the gravity, it is the uplift force. By adopting the theory of annular multiphase flow, considering the effects of wellbore afterflow and gas slippage, the dynamic change of the pressure and fluid in the wellbore and the uplift force of drill string during the shut-in period were analyzed. The magnitude and direction of uplift force are related to the length of drill string in the wellbore and shut-in time, and there is the risk of uplift of drill string when the length of drill string in the wellbore is smaller than the critical drill string length or the shut in time exceeds the critical shut in time. A set of treatment method and process to prevent the uplift of drill string is advanced during the shut-in period after overflow in the ultra-deep well, which makes the risk management of the drill string uplift in the ultra-deep well more rigorous and scientific.
文摘【目的】通过研究一种基于流量溢出效应的动态负载均衡(Dynamic load balancing based on spillover,D-Spillover)模型与算法,为当前动态负载均衡不能从网络整体资源利用角度将富裕带宽贡献给其他流量,造成资源浪费的问题提供解决方案。【方法】对网络数据流进行粒子化最优分解,利用粒子群寻优法,以粒子化等比例利用带宽,结合非线性时间序列分析方法,按比例节点数据流溢出后动态调整分发的负载均衡算法和策略,实现每一个时间段、每一个节点上宽带的最大利用化与均衡转发,充分利用网络的带宽,最大化发挥网络设备性能。【结果】D-Spillover负载均衡机制在任何时间段能让流量均匀分配给等比例接口容量,每一个接口都会性价比的利用带宽,流量分布比较均衡。【结论】根据网络的需要,将D-Spillover负载均衡机制运用在网络负载较重的数据中心设备中,有利于整个网络的优化。
