低张力体系油水相渗特征的研究  

Oil-water relative permeabilities of low-tension system

作　　者：李贤兵[1] 刘莉[1] 朱斌 

机构地区：[1]中国石油勘探开发研究院

出　　处：《石油勘探与开发》2004年第B11期44-51,共8页Petroleum Exploration and Development

基　　金：国家基础研究发展规划(973)项目(G199022510)

摘　　要：油水相对渗透率曲线是对油藏油水两相渗流过程的综合描述。建立了常温、常压下的稳态相渗曲线测定方法，实现了对低张力体系(油水界面张力最低达到10^-3mN／m)油水相对渗透率曲线的直接测量。用此实验方法研究的结果表明：①随着总驱替速率的提高，油水相渗曲线形态没有显著变化。②在水相黏度为0．8～10mPa．s的条件下，无论水相中是否存在表面活性剂，油相的相对渗透率没有显著变化，水相的相对渗透率明显下降。③存在2个临界界面张力σC1和σC2，对应2个临界毛细管准数NC1和NC2，对于所研究的岩石-流体系统．σC1为3mN／m(对应NC1为5×10^4)，σC2为10^-2mN／m(对应NC2为0．1)。④临界界面张力(或临界毛细管准数)将体系划分为3个渗流规律不同的区间，对于油水界面张力大于σC1(或毛细管准数低于NC1)的体系，其油水两相渗流特征可用常规理论描述；而对于油水界面张力小于σC1(或毛细管准数高于NC1)的低张力体系，两相渗流特征已显著改变，必须对相渗模型进行必要的修正。⑤油水相对渗透率是饱和度、油水间界面张力对数及孔隙结构参数的函数，根据实验数据建立的低张力体系油水相渗模型与实验测量结果符合得很好。建立低张力体系油水相对渗透率曲线的直接测定方法以及相渗模型，对于化学复合驱过程中预测水驱规律以及相关的数值模拟研究均具有非常重要的意义。Water-oil relative permeability, related to all two-phase flow properties, characterizes two-phase flow and displacement processes in porous media. The relative permeability is inherently complicated, and its functional form is difficult to be determined in a particular reservoir study. The adding of various chemical agents into the displacing aqueous phase during alkaline-surfactant-polymer combination chemical flooding significantly changes interfacial tension (σ) of water-oil interfaces, and also increases the degree of difficulty in measuring such changes in the laboratory. To overcome the limitations of the existing laboratory measurements of relative permeability, which are applicable only for high ranges of interfacial tension (e.g., σ> 10-2 mN/m), a comprehensive experiment of two-phase relative-permeability functions in much lower, realistic interfacial tension water-oil systems is presented, including an improved steady-state method of measuring water-oil relative permeability curves; a critical interfacial tension value σc (or the critical capillary number AC1 and NC2) exists such that interfacial tension has little impact on relative permeability for σ > σC1 , while if σ< σC1, relative permeability to both water and oil phases will increase with decreasing interfacial tension; a logarithmic relation exists between water-oil two-phase relative permeability and interfacial tensions. The experiment and proposed conceptual models should be useful for feasibility studies, optimal designs, and numerical simulations of different chemical flooding operations in oil reservoirs.

关 键 词：毛细管准数 油水相对渗透率 低张力体系 相渗模型 稳态实验法 

分 类 号：TE357.46[石油与天然气工程—油气田开发工程]