复配聚合物对驱油效果影响的核磁共振实验研究

Experimental study on displacement effect of compound of different molecular weight polymers by NMR

为研究不同相对分子质量聚合物复配对驱油效果的影响,基于在线核磁共振成像技术,对相对分子质量为1 000×104的单一聚合物及复配聚合物开展岩心驱替实验。根据水驱阶段结束、聚合物驱阶段结束的核磁共振T2谱信号对不同尺寸孔喉的氟油动用程度占总动用程度的比例进行定量表征及分析。结果表明:在2种聚合物粘度基本相同、岩心孔喉结构相近的情况下,使用复配聚合物的岩心采出程度和中、小尺寸孔喉中氟油采出量占总油量的比例分别比使用单一聚合物高1.5%和7.1%。复配聚合物中的小相对分子质量聚合物由于具有较小的尺寸,可以有效驱替出中、小尺寸孔喉中的氟油,而大相对分子质量聚合物对大尺寸孔喉中的氟油驱油效果也较好,与单一聚合物相比,复配聚合物可以动用更宽尺寸孔喉范围内的氟油,从而扩大波及体积,取得更好的驱油效果。

In order to study the oil displacement effect of compound of different molecular weight polymers,core flooding experiments were carried out by using on-line nuclear magnetic resonance(NMR)imaging technology with 10 million sin-gle molecular weight polymer and compounded polymer.According to the NMR T2 spectrum signal after water flooding stage and polymer flooding stage,the quantitative characterization of the recovery proportion in pore throats of different siz-es was performed and analyzed.The results show that by using polymers with same viscosity and cores having similar pore structure,the recovery and the proportion of fluorine oil recovered from the medium-and small-sized pore throats to total oil by compounded polymer are respectively 1.5%and 7.1%higher than those by single molecular weight polymer.The small molecular weight polymer in the compounded polymer has a small volume and can effectively displace the fluorine oil in the medium-and small-sized pore throats,while the large molecular weight polymer also has good displacement effect in large pores.Therefore,compared with the single molecular weight polymers,the compounded polymer can drive oil in a wid-er pore throat size range,and ultimately achieve better displacement effect.