割缝衬管完井渗流场的有限元分析

Finite Element Analysis of Seepage Field for Slotted Liner Completion

为了得出元坝地区海相碳酸盐岩气藏割缝衬管完井渗流规律,在充分考虑真实天然气的偏差因子、密度以及黏度随压力变化的基础上,建立了渗流数学模型,并利用Comsol Multiphysics软件对该模型进行求解计算,得到衬管完井方式下近井壁的渗流场分布。通过从X平面提取若干条割线,进一步分析各割线处压力的分布特点;最后对裸眼完井渗流场进行对比,计算出衬管完井的产能比。研究得出:在割缝衬管完井渗流场中从供给边界到井底之间的压力表现为明显的"压降漏斗"趋势,与常规解析解趋势相一致。当气体在远离井筒位置时渗流速度很小并且流速接近稳定,在井筒附近区域渗流速度分布呈波浪式,其中两端的渗流速度最大,为速度敏感性分析的重点。定量分析了割缝衬管完井的产能比,结果表明割缝衬管完井的产能比裸眼完井的产能下降了2/3。

To obtain seepage law of slotted liner completion in the marine carbonate gas reservoirs of Yuanba Area,based on the consideration of real gas deviation factor,density,and viscosity changing with pressure,a mathematical model of seepage flow was established,and it was solved by using Comsol Multiphysics software,the distribution of near well seepage field for perforated liner completion was obtained.Several secant lines were extracted from X plane to further analyze the pressure distribution characteristics of the secant lines.Finally the productivity ratio of liner completions was calculated by comparing with the seepage field of openhole completion.The results show that the pressure change presents obviously as the cone of depression from supply boundary to well bottom in the slotted liner completion,it was consistent with the trend of conventional analytical solution.When the gas far away from wellbore location the flow rate of the flow velocity is small and close to stable,near-wellbore region,seepage velocity distribution is wavy flow,in which the maximum flow velocity is at both ends,it is the focus point of the speed sensitivity analysis.The productivity ratio of the slotted liner completion is quantitatively analyzed,the results show that the productivity ratio of slotted liner completion is 2/3lower than that of openhole completion.