聚合物微球调剖剂流变性实验研究

Experimental Study on Rheological Properties of Polymer Microsphere Profile Modifier

利用HAAKE流变仪测定了聚合物微球调剖剂在地层温度下不同养护时间的流变性,并基于环境扫描电镜测试的微观形貌阐述流变性变化的机理。研究结果表明:聚合物微球溶液在较低剪切速率(0~200 s-1)下,非牛顿指数n小于1,表现为假塑性流体,随着养护时间增加,n逐渐减小,非牛顿性越来越强;在较高剪切速率(200~1 000 s-1)下,随着养护时间增加,非牛顿指数n由大于1逐渐减小到小于1,流体由弱胀流性逐渐变化为假塑性流体。从微观角度分析,聚合物微球调剖剂在地层温度下养护,微球开始膨胀,边缘逐渐出现水化现象,形成网状结构。在较低的剪切速率下,网状结构发生整体移动,溶液黏度降低,表现为假塑性流体性质;在较高的剪切速率下,初始微球的运动状态从有序变为无序,聚合物微球短暂聚集,黏度增加,表现为弱胀流性流体,养护时间增加,聚合物微球网状结构被破坏,黏度降低,又表现为假塑性流体。

The rheological properties of polymer microsphere profile modifier with different curing time at formation temperature were measured by HAAKE rheometer, and the mechanism of rheological change was explained based on the microscopic morphology of environmental scanning electron microscopy. The results showed that the non-Newtonian exponent n of polymer microsphere solution was less than 1 at low shear rate(0^-200 s-1), which was a pseudoplastic fluid. With the increase of curing time, the non-Newtonian exponent n decreased gradually and non-Newtonian properties became stronger. At high shear rate(200~1 000 s-1), with the increase of curing time, the non-Newtonian exponent n decreased gradually from greater than 1 to less than 1, and the fluid changed from weak swelling fluid to pseudoplastic fluid. From the microscopic point of view, the polymer microsphere cured at formation temperature, the microsphere began to expand, the edge hydration phenomenon gradually appeared, forming a network structure. At lower shear rates, the reticular structure moved as a whole and the solution viscosity decreased, showing pseudoplastic fluid properties;at higher shear rates, the initial microsphere motion state changed from ordered state to disordered state, the polymer microspheres aggregated and the viscosity increased, showing a weak swelling fluid, the curing time increased, the reticular structure of the polymer microspheres was destroyed, and the viscosity decreased. It also behaved as pseudoplastic fluid.