稠油非牛顿渗流规律及挖潜策略研究

Research on Non-Newtonian flow seepage pattern of heavy oil and potential tapping strategy

稠油因其高黏度特性,导致水驱过程中在多孔介质中流动表现为非牛顿流体渗流规律。为理清稠油启动压力梯度和黏度变化及对渗流特征和水驱规律的影响,利用原油地层黏度24~452 mPa·s、平均150 mPa·s的S油田稠油流变性实验数据,确定了稠油启动压力梯度与油相流度的关系和稠油黏度与驱替压力梯度关系,并建立了考虑非牛顿渗流规律的渗流数学模型,对S油田进行数值模拟研究。结果表明:当考虑启动压力梯度和变黏度的非牛顿渗流规律,水驱波及面积缩小,非活塞现象加剧;水平井的驱替压力梯度大,能够有效克服启动压力并且降低原油黏度,波及范围明显大于定向井波及范围。在数值模拟研究结果的基础上建立了考虑稠油非牛顿渗流特征、不同黏度下的定向井、水平井动用范围图版。以此为指导优化了侧钻井,产量由25 m^(3)/d增加到70 m^(3)/d,含水率由88%降低到4%,效果良好。研究成果对稠油油田调整挖潜工作具有较好指导意义。

Due to its high viscosity characteristics,the heavy flow exhibits non-Newtonian fluid flow behavior during water flooding in porous media,deviating from the Darcy seepage law.To elucidate the effects of the starting pressure gradient and viscosity variations of heavy oil on its seepage characteristics and water flooding patterns,rheological experimental data from the S Oilfield,where the crude oil has a formation viscosity ranging from 24 to 452 mPa·s,with an average of 150 mPa·s,were utilized.This analysis established the relationship between the starting pressure gradient and the mobility of the oil phase,as well as the relationship between the oil viscosity and the displacement pressure gradient.Based on the simulation results,a seepage mathematical model considering non-Newtonian seepage law is developed,and the numerical simulations are conducted for S oilfield.The results show,when considering the non-Newtonian seepage law of starting pressure gradient and variable viscosity,the water flooding swept area will be reduced and non-piston effect intensifies.The horizontal wells,with their larger displacement pressure gradient,effectively overcome the starting pressure,and reduce the viscosity,resulting in a significantly larger sweep area compared to directional well.Based on this,a chart was developed to quantitatively characterize the production range of directional and horizontal wells under different viscosities,providing guidance for the potential tapping strategy in heavy oil fields.Guided by this research,which integrated the study of non-Newtonian seepage characteristics and production range,the well location optimization for adjustment wells was carried out,leading to notable improvements:production increased from 25 m^(3)/d to 70 m^(3)/d,and the water cut decreased from 88%to 4%.The results provide valuable reference for the potential tapping in heavy oilfields.