Dynamic capillarity during displacement process in fractured tight reservoirs with multiple fluid viscosities
Dynamic capillarity during displacement process in fractured tight reservoirs with multiple fluid viscosities
复制标题
多种流体粘度的裂缝性致密油藏驱替过程中的动态毛细管作用（开放获取）
DOI：
10.1002/ese3.558
复制
发表时间：
2019-12-08
影响因子：
3.8
通讯作者：
Li, Jingfa
中科院分区：
文献类型：
--
作者：
Li, Ying;Luo, Hongwen;Li, Jingfa
多孔介质中多相流普遍存在动态毛细现象，在动态毛细过程中，流体粘度发生变化，对动态毛细现象的影响很大。在现场压力和温度条件下，利用专门设计的驱替装置，对亲水性、裂缝性致密岩石进行驱替实验，研究流体粘度对动态毛细作用的影响。通过对毛管压力、动力系数和流体流动行为的测量和计算，考察了基质中的动力效应。结果表明，随着原油粘度的增大，（a）稳态和动态毛管压力的反向速度加快，表现为基质阻力增大，（B）稳态毛管压力与动态毛管压力之差增大约5%~ 19%;（c）水饱和度变化较慢，对应于较低的水相对渗透率，而原油相对渗透率则迅速降低到基本驱替阶段的水平;和（d）动态系数变得高2-3倍，动态接触角变得大10%-25%，显示出更可变的界面。提出了接触角推进系数来识别接触角推进的重要性以及毛细压力和粘性力之间的竞争。研究结果有助于更好地理解致密油藏多相流的规律，提高原油采收率。
Dynamic capillarity commonly exists for multiphase flow in porous media, during which fluid viscosity varies and has strong influence. Displacement experiments are conducted on water-wet, fractured tight rock at in situ pressure and temperature of an oil reservoir via a specially designed apparatus to investigate the effects of fluid viscosity on the dynamic capillarity. The dynamic effect in the matrix is examined through the measurement and calculation of capillary pressure, the dynamic coefficient, and the fluid flow behavior. The results show that with a higher oil viscosity: (a) both the steady and the dynamic capillary pressures reverse their directions more quickly and behave as larger resistances in the matrix; (b) the difference between the steady and the dynamic capillary pressures becomes around 5%-19% more significant; (c) water saturation changes more slowly corresponding to the lower water relative permeability, while oil relative permeability quickly becomes lower than that during the basic displacement process; and (d) the dynamic coefficient becomes 2-3 times higher, and the dynamic contact angle becomes 10%-25% larger, showing a more variable interface. A contact angle advancement coefficient is proposed to identify the significance of contact angle advancement and the competition between capillary pressure and viscous force. The findings of this study can help for better understanding of multiphase flow in tight reservoirs and enhancing oil recovery.