致密砂岩储层渗吸数学模型及应用研究

摘要

Based on saturation equation,Corey relative-permeability curve and J finction,a semi-analytical model of imbibition replacement between fracturing fluid and oil is established to evaluate the imbibition perforance in tight sandstone reservoir.The gravity and capillary force are considered to the on-way distribution of saturation under different parameter values and oil replacement rate under different imbibition times.The sensitivity analysis of the relevant parameters is provided and compared with the experimental results of core samples from Heshui and Dingbian in Changqing Oilfield.Research demonstrates that the parameters from high to low sensitivity are wetting phase coefficient,maximum relative-permeability of wetting phase,oil-water viscosity ratio,non-wetting phase coefficient and maximum relative-permeability of non-wetting phase.Increasing fluid mobility and reducing oil-water viscosity ratio could improve the imbibition replacement rate of core sample.The imbibition performance is more dependent on wetting phase properties rather than non-wetting phase properties.The fitting rate between imbibition model calculation and experimeut test is 85.7％,which indicates favorable model applicability.This research could provide certain theoretical reference for the further study on imbibition replacement between fracturing fluid and oil.%针对致密砂岩储层渗吸效果评价的问题,基于饱和度方程、corey相渗曲线及J函数,建立了适用于致密砂岩储层压裂液-原油渗吸置换半解析模型,模型考虑了重力及毛管力作用,能够获取不同参数影响下的饱和度沿程分布及不同渗吸时间下的原油置换率,并利用建立的模型分析了相关参数敏感性,同时与长庆油田合水、定边2个区块致密砂岩岩心渗吸实验结果做了对比分析.研究结果表明:参数敏感性从大到小排序为润湿相系数、润湿相最大相渗值、油水黏度比、非润湿相系数、非润湿相最大相渗值;增加流体流动性、减小油水黏度比有助于提高岩心渗吸置换率;改变润湿相参数比改变非润湿相参数对渗吸作用影响更为显著;模型渗吸稳定置换率计算值与岩心实验计量值拟合率为85.7％,验证了模型具有较好的适用性.研究成果对压裂液-原油渗吸置换研究提供了一定的理论依据.