动态接触角研究

动态接触角研究是研究流体渗流微观规律的基础,在选择提高采收率的方法及模拟油藏动态试验等方面具有重要意义.国外从分子理论和动力学角度对动态接触角与驱替速率、液体的毛细管数、黏度比之间的关系进行理论研究,实验研究结论为较低驱替速率时,动态接触角的余弦差与驱替速率呈线性关系;较高驱替速率时,动态接触角的正切与驱替速率的对数呈线性关系;表面活性剂使液-液界面的动态接触角变小,滞后接触角增大;固体表面粗糙度对动态接触角的影响不大.国内目前主要采用实验方法研究动态接触角,根据插板法实验得出中性玻璃片在气/水和气/油系统中前进接触角的余弦与驱替速率呈线性关系;后退接触角的余弦与驱替速率呈两段线性关系,驱替速率高时的斜率比驱替速度低时的斜率大.图5参17

Studies of dynamic contact angle

Study of dynamic contact angle is the fundament of per-colation law research, and is important for choosing the method of FOR and reservoir modeling. The domestic and overseas researches of dynamic contact angle are summarized. The relationships between contact angle and displacing velocity, liquid capillary number, and viscous ratio are studied overseas based on molecular theory and dynamics. The experiment reveals that the cosin difference of the dynamic contact angles is linear to the displacing velocity in lower displacing velocity; and the tan dynamic contact angles is linear to the displacing velocity in higher velocity. Surfactant could decrease the contact angle of liquid-liquid interface and increase the hyster- esis of contact angle. The roughness of the solid surface has little influence on the dynamic contact angle. In China, most investigators study dynamic contact angles by experiment, in which wettability dashboard experiments in gas-water and gas-oil system show linear relation between cosin advancing contact angle and displacing velocity, two-segment linear relationship between cosin receding con- tact angle and displacing velocity and the line slop ofhigher displac- ing velocity is bigger than the lower displacing velocity.