Li Jianbing, Niu Liwei, Wu Wenxiang, Sun Meifeng
Laboratory of Enhanced Oil Recovery of Education Ministry, Northeast Petroleum University, Daqing 163318, China.
No. 8 Production Plant, Daqing Oilfield Company Limited, Daqing 163514, China.
Polymers (Basel). 2020 Apr 11;12(4):885. doi: 10.3390/polym12040885.
Polymer microsphere profile control is a promising approach for the profile control of heterogeneous reservoirs. Matching between polymer microspheres and the reservoir pore throat is crucial for profile control. In this study, the range of the optimal matching factor Ra between polymer microspheres and core porosity was divided through core permeability limit experiments, and the dynamic migration laws and shut-off patterns of microspheres were studied using 9-m-long cores and microscopic models. The oil displacement effect and mechanism of microspheres were analyzed using three cores in parallel. The "injectability limit" and "in-depth migration limit" curves were divided by Ra into three zones: blockage (R < 1.09 ± 0.10), near-well profile control (1.09 ± 0.10 < R < 5.70 ± 0.64), and in-depth fluid diversion (R > 5.70 ± 0.64). During migration in porous media, the microspheres gradually enlarged in size and thus successively shut off in four forms: multi-microsphere bridging shut-off, few-microsphere bridging shut-off, single-microsphere shut-off, and elastic shut-off. Microspheres with a rational combination of sizes versus those with a single particle size further enhanced reservoir oil recovery under certain reservoir conditions. Through "temporary shut-off-breakthrough-temporary shut-off," the polymer microspheres were able to change the fluid flow rate and streamlines, mobilize residual oils, and enhance the oil recovery rates.
聚合物微球调剖是一种很有前景的非均质油藏调剖方法。聚合物微球与油藏孔喉的匹配对于调剖至关重要。本研究通过岩心渗透率极限实验划分了聚合物微球与岩心孔隙度之间最优匹配因子Ra的范围，并利用9米长岩心和微观模型研究了微球的动态运移规律及封堵模式。采用三根岩心并联分析了微球的驱油效果及机理。以Ra为依据，将“注入性极限”和“深部运移极限”曲线划分为三个区域：封堵区（R < 1.09 ± 0.10）、近井调剖区（1.09 ± 0.10 < R < 5.70 ± 0.64）和深部液流转向区（R > 5.70 ± 0.64）。在多孔介质中运移时，微球尺寸逐渐增大，从而依次以四种形式封堵：多微球桥接封堵、少微球桥接封堵、单微球封堵和弹性封堵。在一定油藏条件下，粒径合理组合的微球相对于单一粒径的微球能进一步提高油藏采收率。通过“暂堵-突破-暂堵”，聚合物微球能够改变流体流速和流线，动用残余油，提高采收率。
