割缝筛管水平井注蒸汽热力参数分布规律数值模拟研究

Numerical Simulation in Steam Injection Wells for Optimizing the Distribution of Thermal Parameters in Horizontal Wells with Slotted Liners

为了清楚认识割缝筛管完井水平井注蒸汽过程中热力参数的分布规律,为水平井割缝筛管完井优化提供理论依据,根据质量守恒、动量守恒和能量守恒原理,建立了注蒸汽过程中蒸汽压力、蒸汽温度和蒸汽干度沿水平井筒分布的数学模型,并采用压力增量和干度增量双重迭代方法对其进行求解。以此为基础,通过实例分析了蒸汽热力参数沿水平井筒的分布规律及割缝筛管参数对其分布规律的影响。结果表明:蒸汽通过300m长的水平井段后,其压力、温度和干度分别下降5.8kPa、0.035℃和0.128;割缝宽度、长度及密度分别由0.2 mm增至0.4mm、100m增至140m、200条/m增至360条/m时,水平段吸汽长度分别缩短90,100和70m,在水平段吸汽长度范围内,蒸汽压力下降幅度分别减小1.50,1.74和1.38kPa,蒸汽干度下降幅度分别增加0.03、0.06和0.056。蒸汽压力、蒸汽温度和蒸汽干度沿水平井筒呈二次多项式的非线性下降关系,且增大割缝的宽度、长度和密度,可使蒸汽压力的下降幅度减缓、蒸汽干度的下降幅度增大、水平井段吸汽长度变短。

To clearly understand the distribution patterns of thermal parameters during steam injection in horizontal wells completed with slotted liners and to establish a theoretical basis for the optimization of completion processes,a numerical model for the distribution of steam pressure,temperature and dryness in horizontal well while steam injection was developed according to the law of conservation of mass,momentum and energy.Next,the model was solved by iterating both steam pressure and dryness increments.On this basis,the case analysis was made to identify the distribution of thermal parameters of steam along horizontal wellbore and the impacts of slotted liner parameters on the patterns of distribution.The results show that after passing through a horizontal section of 300 m,the steam pressure,temperature and dryness were reduced by 5.8kPa,0.035 ℃ and 0.128,respectively.When the width,length and density of slot were increased respectively from 0.2mm to 0.4mm,100 mto 140m,and 200slots/m to 360slots/m,the steam absorption length would be reduced by 90 m,100mand 70 m.Within the steam absorption length in the horizontal section,the steam pressures were decreased by 1.5kPa,1.74 kPa and 1.38 kPa,whereas steam dryness increased by 0.03,0.06 and 0.056,respectively.Steam pressure,temperature and dryness display non-linear reduction in quadratic polynomial relationsalong the horizontal wellbore.Therefore,the increase in slot width,length and density will reduce the drop rate of steam pressures,increase the drop amplitude of steam dryness,and shorten the length of steam-absorption in horizontal section.