The injection method of a hydrophobic associated polymer with evident salt thickening property

Abstract

A comb like micro-blocked hydrophobic association polymer (CBHAP) with evident thickening property in high salinity and weak thickening property in fresh water was developed. Based on the unique property, we designed the injection strategy that polymer in fresh water with low viscosity was injected into the cores to improve injectivity and high salinity water was used to perform subsequent water flooding to improve mobility control ability. The factors influencing on the injectivity as well as mobility control ability were researched by the core flooding experiments. As a result, pressure fluctuation was found in the subsequent water flooding from 0.7 PV to 1.5 PV, showing obvious variation of viscosity in the cores. The phenomenon was believed to improve mobility control ability. In addition, the positive correlation between polymer concentration, salinity, injected volume and the fluctuation was found. The designed injection method for the polymer can be used to solve injectivity issue as well as improve mobility control ability in high salinity reservoir.