The fracture volume is gradually changed with the depletion of fracture pressure during the production process.However,there are few flowback models available so far that can estimate the fracture volume loss using pr...The fracture volume is gradually changed with the depletion of fracture pressure during the production process.However,there are few flowback models available so far that can estimate the fracture volume loss using pressure transient and rate transient data.The initial flowback involves producing back the fracturing fuid after hydraulic fracturing,while the second flowback involves producing back the preloading fluid injected into the parent wells before fracturing of child wells.The main objective of this research is to compare the initial and second flowback data to capture the changes in fracture volume after production and preload processes.Such a comparison is useful for evaluating well performance and optimizing frac-turing operations.We construct rate-normalized pressure(RNP)versus material balance time(MBT)diagnostic plots using both initial and second flowback data(FB;and FBs,respectively)of six multi-fractured horizontal wells completed in Niobrara and Codell formations in DJ Basin.In general,the slope of RNP plot during the FB,period is higher than that during the FB;period,indicating a potential loss of fracture volume from the FB;to the FB,period.We estimate the changes in effective fracture volume(Ver)by analyzing the changes in the RNP slope and total compressibility between these two flowback periods.Ver during FB,is in general 3%-45%lower than that during FB:.We also compare the drive mechanisms for the two flowback periods by calculating the compaction-drive index(CDI),hydrocarbon-drive index(HDI),and water-drive index(WDI).The dominant drive mechanism during both flowback periods is CDI,but its contribution is reduced by 16%in the FB,period.This drop is generally compensated by a relatively higher HDI during this period.The loss of effective fracture volume might be attributed to the pressure depletion in fractures,which occurs during the production period and can extend 800 days.展开更多
新能源随机性使得电力系统潮流复杂多变,加之大量新能源需要远距离输送消纳,输电阻塞问题日益严重。动态热定值(dynamic line rating,DTR)技术能够提升既有架空线路的输电能力,充分发挥系统的灵活调节能力。特别是在N-1事故场景下,采用...新能源随机性使得电力系统潮流复杂多变,加之大量新能源需要远距离输送消纳,输电阻塞问题日益严重。动态热定值(dynamic line rating,DTR)技术能够提升既有架空线路的输电能力,充分发挥系统的灵活调节能力。特别是在N-1事故场景下,采用DTR技术提升线路输送能力,能够缓解严重输电阻塞。然而,传统方法在考虑N-1事故时存在维数灾难问题,因此应用DTR技术仍然存在挑战性。为此,提出了一种两阶段分布鲁棒优化(distributionally robust optimization,DRO)方法以提升架空线路的输电能力。首先,构建了架空线路暂态温度计算模型并做适当简化处理,从而保证后续优化模型的凸性。随后,建立了考虑DTR和N-1安全准则的两阶段DRO模型以避免N-1事故下的持续停电,考虑无功与网损的线性化交流潮流模型能够更准确地计算线路潮流。最后,使用IEEE-24节点系统和IEEE-118节点系统验证了所提方法的有效性。展开更多
瞬时γ辐射会引起系统级封装(system-in-package,SiP)中的瞬时剂量率效应(transient dose rate effect,TDRE),在SiP内部产生闩锁光电流和瞬态光电流,对SiP的正常工作产生影响。本文以国产SZ0501型SiP作为研究对象,提出了一种基于电源分...瞬时γ辐射会引起系统级封装(system-in-package,SiP)中的瞬时剂量率效应(transient dose rate effect,TDRE),在SiP内部产生闩锁光电流和瞬态光电流,对SiP的正常工作产生影响。本文以国产SZ0501型SiP作为研究对象,提出了一种基于电源分布网络(power distribution network,PDN)模型的SiP瞬时剂量率效应的瞬态仿真方法。该方法基于电源完整性和信号完整性(power integrity and signal integrity,PI-SI)仿真方法,对闩锁光电流在SiP内部电源网络引起的直流压降和瞬态光电流引发的瞬时电源噪声进行了仿真分析,定性评估了二者的影响。仿真结果表明,闩锁光电流在SiP中引起的直流压降可以忽略不计,而瞬态光电流导致的电源噪声则显著降低了电源稳定性。与SiP中的共享电源网络相比,PCB测试板中的独立电源网络在瞬时剂量率效应中具有更高的稳定性。最后,通过结合以往的SiP和PCB测试板的瞬时γ射线辐照实验结果对仿真结果进行了验证,实验结果同样表明独立电源网络具有更高的稳定性。研究结果为分析电源分布网络对电子系统瞬时剂量率效应的影响提供了指导意义。展开更多
文摘The fracture volume is gradually changed with the depletion of fracture pressure during the production process.However,there are few flowback models available so far that can estimate the fracture volume loss using pressure transient and rate transient data.The initial flowback involves producing back the fracturing fuid after hydraulic fracturing,while the second flowback involves producing back the preloading fluid injected into the parent wells before fracturing of child wells.The main objective of this research is to compare the initial and second flowback data to capture the changes in fracture volume after production and preload processes.Such a comparison is useful for evaluating well performance and optimizing frac-turing operations.We construct rate-normalized pressure(RNP)versus material balance time(MBT)diagnostic plots using both initial and second flowback data(FB;and FBs,respectively)of six multi-fractured horizontal wells completed in Niobrara and Codell formations in DJ Basin.In general,the slope of RNP plot during the FB,period is higher than that during the FB;period,indicating a potential loss of fracture volume from the FB;to the FB,period.We estimate the changes in effective fracture volume(Ver)by analyzing the changes in the RNP slope and total compressibility between these two flowback periods.Ver during FB,is in general 3%-45%lower than that during FB:.We also compare the drive mechanisms for the two flowback periods by calculating the compaction-drive index(CDI),hydrocarbon-drive index(HDI),and water-drive index(WDI).The dominant drive mechanism during both flowback periods is CDI,but its contribution is reduced by 16%in the FB,period.This drop is generally compensated by a relatively higher HDI during this period.The loss of effective fracture volume might be attributed to the pressure depletion in fractures,which occurs during the production period and can extend 800 days.
文摘新能源随机性使得电力系统潮流复杂多变,加之大量新能源需要远距离输送消纳,输电阻塞问题日益严重。动态热定值(dynamic line rating,DTR)技术能够提升既有架空线路的输电能力,充分发挥系统的灵活调节能力。特别是在N-1事故场景下,采用DTR技术提升线路输送能力,能够缓解严重输电阻塞。然而,传统方法在考虑N-1事故时存在维数灾难问题,因此应用DTR技术仍然存在挑战性。为此,提出了一种两阶段分布鲁棒优化(distributionally robust optimization,DRO)方法以提升架空线路的输电能力。首先,构建了架空线路暂态温度计算模型并做适当简化处理,从而保证后续优化模型的凸性。随后,建立了考虑DTR和N-1安全准则的两阶段DRO模型以避免N-1事故下的持续停电,考虑无功与网损的线性化交流潮流模型能够更准确地计算线路潮流。最后,使用IEEE-24节点系统和IEEE-118节点系统验证了所提方法的有效性。
文摘瞬时γ辐射会引起系统级封装(system-in-package,SiP)中的瞬时剂量率效应(transient dose rate effect,TDRE),在SiP内部产生闩锁光电流和瞬态光电流,对SiP的正常工作产生影响。本文以国产SZ0501型SiP作为研究对象,提出了一种基于电源分布网络(power distribution network,PDN)模型的SiP瞬时剂量率效应的瞬态仿真方法。该方法基于电源完整性和信号完整性(power integrity and signal integrity,PI-SI)仿真方法,对闩锁光电流在SiP内部电源网络引起的直流压降和瞬态光电流引发的瞬时电源噪声进行了仿真分析,定性评估了二者的影响。仿真结果表明,闩锁光电流在SiP中引起的直流压降可以忽略不计,而瞬态光电流导致的电源噪声则显著降低了电源稳定性。与SiP中的共享电源网络相比,PCB测试板中的独立电源网络在瞬时剂量率效应中具有更高的稳定性。最后,通过结合以往的SiP和PCB测试板的瞬时γ射线辐照实验结果对仿真结果进行了验证,实验结果同样表明独立电源网络具有更高的稳定性。研究结果为分析电源分布网络对电子系统瞬时剂量率效应的影响提供了指导意义。
