Conn Charles A, Ma Kun, Hirasaki George J, Biswal Sibani Lisa
Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX, USA.
Lab Chip. 2014 Oct 21;14(20):3968-77. doi: 10.1039/c4lc00620h.
Foam mobility control and novel oil displacement mechanisms were observed in a microfluidic device representing a porous media system with layered permeability. Foam was pre-generated using a flow-focusing microfluidic device and injected into an oil-wet, oil-saturated 2-D PDMS microfluidic device. The device is designed with a central fracture flanked by high-permeability and low-permeability zones stratified in the direction of injection. A 1 : 1, 1% blend of alpha olefin sulfonate 14-16 (AOS) and lauryl betaine (LB) surfactants produced stable foam in the presence of paraffin oil. The oil saturation and pressure drop across the microfluidic device were measured as a function of time and the injected pore volume, indicating an increase in apparent viscosity for foam with an accompanying decrease in oil saturation. In contrast to the control experiments, foam was shown to more effectively mobilize trapped oil by increasing the flow resistance in the fracture and high-permeability zones and by diverting the surfactant solution into adjacent low-permeability zones. The foam was observed to separate into gas-rich and aqueous-rich phases depending on matrix permeability, suggesting that it is not appropriate to treat foam as a homogeneous dispersion of gas and liquid.
在一个代表具有分层渗透率的多孔介质系统的微流控装置中，观察到了泡沫流动性控制和新型驱油机制。泡沫是使用流动聚焦微流控装置预先生成的，并注入到油湿、油饱和的二维聚二甲基硅氧烷（PDMS）微流控装置中。该装置设计为在注入方向上，中央裂缝两侧为高渗透率和低渗透率区域分层。1:1的1%α-烯烃磺酸盐14 - 16（AOS）和月桂基甜菜碱（LB）表面活性剂混合物在石蜡油存在下产生了稳定的泡沫。测量了微流控装置中的油饱和度和压降随时间和注入孔隙体积的变化，表明泡沫的表观粘度增加，同时油饱和度降低。与对照实验相比，泡沫通过增加裂缝和高渗透率区域的流动阻力以及将表面活性剂溶液转向相邻的低渗透率区域，更有效地驱替了被困油。观察到泡沫根据基质渗透率分离为富气和富水相，这表明将泡沫视为气体和液体的均匀分散体是不合适的。
