Hua Zhao, Lin Meiqin, Dong Zhaoxia, Li Mingyuan, Zhang Guiqing, Yang Jie
Research Institute of Enhanced Oil Recovery, China University of Petroleum, Beijing, China.
Research Institute of Enhanced Oil Recovery, China University of Petroleum, Beijing, China.
J Colloid Interface Sci. 2014 Jun 15;424:67-74. doi: 10.1016/j.jcis.2014.03.019. Epub 2014 Mar 17.
Scanning electron microscopy (SEM), dynamic lighting scattering (DLS) and HAAKE rheometer experiments were adopted to investigate the shape, size and rheological properties of nanoscale polymer microspheres. Moreover, nuclear-pore film filtration, sand packed tube displacement, core displacement, micro-visual model and capillary flow experiments were used to study the mechanisms of deep profile control and oil displacement of nanoscale polymer microspheres. The results demonstrated that the original shape of the nanoscale polymer microspheres were typically spherical, ranging in size from 30 to 60 nm. When the microspheres were dispersed in water, their size increased by 3-6 times due to swelling and a poly-dispersed system appeared; however, the spherical conformation remained. Within a certain range of shear rates, a 100-900 mg/L microsphere dispersed system exhibited shear thickening behaviour, making it favourable for increasing the flow resistance of a displacement fluid. These polymer microspheres dispersed systems exhibited effective plugging on a nuclear pore film with 0.4-μm pores with deep plugging in the core; these systems also tended to plug the high permeability layer and drive crude oil from the low permeability layer in parallel sand packed tubes. Cross-linked polymer microspheres could reduce water permeability because the microspheres adsorbed, accumulated and bridged in the pore-throat, and the adsorbed layers would be collapsed under the pressure, entering deep into the reservoir due to the good deformation properties of the microspheres. Meanwhile these microspheres would drive crude oil on and in the pores/throats while they are transported in porous media, achieving deep profile control and oil displacement with the ultimate purpose of improving oil recovery.
采用扫描电子显微镜（SEM）、动态光散射（DLS）和哈克流变仪实验来研究纳米级聚合物微球的形状、尺寸和流变性能。此外，利用核孔膜过滤、填砂管驱替、岩心驱替、微观可视化模型和毛细管流动实验来研究纳米级聚合物微球的深部调剖和驱油机理。结果表明，纳米级聚合物微球的原始形状通常为球形，尺寸范围为30至60纳米。当微球分散在水中时，由于溶胀其尺寸增大3至6倍，并且出现多分散体系；然而，球形构象保持不变。在一定的剪切速率范围内，100 - 900 mg/L的微球分散体系表现出剪切增稠行为，这有利于增加驱替流体的流动阻力。这些聚合物微球分散体系在孔径为0.4μm的核孔膜上表现出有效的封堵作用，在岩心中具有深部封堵效果；在平行填砂管中，这些体系还倾向于封堵高渗透层并将原油从低渗透层驱替出来。交联聚合物微球能够降低水渗透率，因为微球在孔喉处吸附、聚集和架桥，并且吸附层在压力下会塌陷，由于微球良好的变形性能而深入储层。同时，这些微球在多孔介质中运移时会在孔隙/孔喉上和内部驱替原油，实现深部调剖和驱油，最终目的是提高原油采收率。
