深水压井井筒瞬态传热及复杂流动行为研究

在深水压井循环期间,随着压井液的循环,井筒瞬态温度场不断变化,导致环空多相流动行为变化复杂,进而影响压井过程中的井筒压力分布。为快速准确地预测深水压井过程中不同循环时间和压井排量下的井筒瞬态温度分布,基于能量守恒原理,综合考虑压井液、钻杆、环空、地层、海水以及隔水管之间的热传递,建立了深水压井过程中井筒瞬态温度场解析模型。结合深水压井井筒瞬态传热特征,模拟分析了深水工程师法压井循环期间的井筒压力演变规律以及环空多相流动行为。分析结果表明:深水压井工况下,环空压井液循环温度与静温剖面相差较大,随着循环时间的延长和排量的增加,环空压井液循环温度逐渐偏离静温剖面;压井液温度的变化进一步影响环空自由气体体积波动,导致环空多相流动行为复杂多变。研究结果可为深水压井设计和现场作业提供理论支撑。

Study on Wellbore Transient Heat Transfer and Complex Flow Behavior during Deepwater Well Killing

During the circulation of deepwater well killing,with the circulation of the killing fluid,the transient temperature field of the wellbore changes continuously,which leads to complex changes of the multiphase flow behavior in the annulus,thus affects the wellbore pressure distribution during the well killing process.To predict the transient temperature distribution of the wellbore quickly and accurately under different circulation times and displacements during deepwater well killing,based on the principle of energy conservation and comprehensive consideration of heat transfer among the killing fluid,drill pipe,annulus,formation,seawater and riser,an analytical model of the transient temperature field in the wellbore during deep water well killing is established.Combining with the transient heat transfer characteristics of the wellbore during deepwater well killing,the wellbore pressure evolution and the annulus multiphase flow behavior during the deepwater well killing circulation by engineer’s method are simulated and analyzed.The analysis results show that under deepwater well killing conditions,the circulation temperature of the annulus killing fluid differs greatly from the static temperature profile.As the circulation time and the displacement increases,the circulation temperature of the annulus killing fluid gradually deviates from the static temperature profile.The change of well fluid temperature affects the fluctuation of free gas volume in the annulus,resulting in complex and changeable multiphase flow behavior in the annulus.The research results can provide theoretical support for deepwater well killing design and field operations.