Liu Zheyu, Mendiratta Shruti, Chen Xin, Zhang Jian, Li Yiqiang
College of Petroleum Engineering, China University of Petroleum (Beijing) Beijing 102249 PR China
Chemical and Petroleum Engineering, University of Calgary Calgary AB T2N 1N4 Canada.
RSC Adv. 2019 Apr 16;9(21):11968-11977. doi: 10.1039/c9ra00465c. eCollection 2019 Apr 12.
Conventional polymer flooding ( using polyacrylamide) has been widely used in the oil fields as an economical means for enhanced oil recovery. However, its efficacy is affected by the polymer properties and increasingly harsh reservoir conditions. In this study, a high-molecular-weight modified polyacrylamide polymer (GF-1) encapsulated in a water-in-oil emulsion is proposed for controlled polymer release towards enhanced oil recovery. It is compared with the conventional polyacrylamide in terms of their microscopic morphology, dissolving capacity, concentration-viscosity relationship, and rheological properties. It contained swollen polymer micelles and gradually released the polymer after phase inversion, which caused its viscosity, viscoelasticity, and plugging capacity to increase with aging time. The plugging analysis surprisingly showed a four-fold increase in the dimensionless breakthrough pressure of the emulsion polymer and five-fold increase in the residual resistance factor after five days of aging, confirming the significant increase in viscosity in confined spaces. The most interesting results were obtained by parallel core flooding experiments, where a higher recovery factor of 2.7% more than the conventional polymer was observed for GF-1 and GF-1 outperformed the conventional polymer by 6.9% in the low permeability zone. This emulsion polymer is a promising material to achieve enhanced oil recovery using in-depth profile modification in future oilfield related efforts.
传统的聚合物驱油法（使用聚丙烯酰胺）已作为一种提高采收率的经济方法在油田中广泛应用。然而，其效果受聚合物性质及日益恶劣的储层条件影响。在本研究中，提出了一种封装在油包水乳液中的高分子量改性聚丙烯酰胺聚合物（GF-1），用于可控聚合物释放以提高采收率。将其与传统聚丙烯酰胺在微观形态、溶解能力、浓度-粘度关系及流变性质方面进行了比较。它含有溶胀的聚合物胶束，在相转变后逐渐释放聚合物，这使其粘度、粘弹性和封堵能力随老化时间增加。封堵分析令人惊讶地表明，老化五天后，乳液聚合物的无因次突破压力增加了四倍，残余阻力系数增加了五倍，证实了在受限空间内粘度显著增加。通过平行岩心驱替实验获得了最有趣的结果，其中观察到GF-1的采收率比传统聚合物高2.7%，且在低渗透区GF-1比传统聚合物高出6.9%。这种乳液聚合物是未来油田相关工作中通过深度调剖实现提高采收率的一种有前景的材料。
