考虑微观界面力学效应的低矿化度水驱渗流特征模型

A low⁃salinity water flooding flow characteristics model considering micro interfacial mechanical effect

为更好地描述低矿化度水驱的渗流特征,首先通过岩心驱替实验,验证了低矿化度水驱提高采收率的潜力。在此基础上,建立不同离子类型与矿物间微观界面作用的毛管束数学模型来模拟低矿化度水驱过程,通过岩心驱替实验进行模型验证,在相渗曲线拟合成功后,使用模型分析特征管径、离子价态与浓度对渗流的影响。结果表明:随着特征管径的减小,界面作用对采出程度的影响增加,当特征管径从20μm减小到5μm时,采出程度从2.9%扩大到30.5%,当毛管阻力较大时,常规水驱提高采收率效果有限,孔隙中存在大量残余油;低矿化度水驱可有效提高采收率,且离子价态是影响低矿化度水驱效果的主控因素,使用Na+的低矿化度水驱采出程度提高7.85百分点,而Ca2+则为4.83百分点。建立的毛管束模型可模拟不同离子类型与矿物间的低矿化度水驱效果,为油田现场的低矿化度水驱开发提供更好的理论指导。

In order to better describe flow characteristics of low-salinity water flooding,firstly,the potential of lowsalinity water flooding to improve oil recovery is verified through core displacement experiment.On this basis,a capillary bundle mathematical model considering micro interfacial interaction between different ion types and minerals is established to simulate low-salinity water flooding process,and the model is verified by core displacement experiment.After successful fitting of relative permeability curve,the model is used to analyze the influence of characteristics caliber radius,ion valence and concentration on fluid flow.The results show that,as characteristics caliber radius decreases,the influence of interfacial interaction on recovery of OOIP increases.When characteristics caliber radius decreases from 20μm to 5μm,the difference in recovery of OOIP increases from 2.9%to 30.5%.When capillary resistance is high,conventional water flooding has limited improving recovery effect,with a large amount of residual oil in the pores.Low salinity water flooding effectively improves oil recovery,and ion valence is the main controlling factor affecting the effectiveness of low-salinity water flooding.Using Na+in low-salinity water flooding increases recovery by 7.85 percentage points,while Ca2+increases by 4.83 percentage points.The established capillary bundle model can simulate the effect of low-salinity water flooding between different ion types and minerals,providing better theoretical guidance for field development of low-salinity water flooding.