Synthesis and rheological properties of high performance HPAM for polymer EOR

Abstract

The polymer enhanced oil recovery (EOR) has drawn a lot of attentions as one of three major EOR technologies (Thermal/Gas/Chemical). It has been required to have superior rheological properties of the pol-ymer to apply the polymer EOR to more oil fields. The objective of this study is to synthesize a novel partially hydrolyzed polyacrylamide polymer (HPAM) and explore its effect of the rheological properties of new HPAM on the performance of the EOR during flow in the reservoir rocks.

This study aimed to determine the molecular weight of a novel polymer, partially hydrolyzed poly-acrylamide (HPAM), and to explore the effects of rheological properties of the polymer solution on its per-formance in EOR. The polymer was synthesized through vinyl polymerization using acrylic acid and acryl amide. To evaluate HPAM, several methods are used in this study. Field flow fractionation revealed that it had ultrahigh molecular weight (UHMW

7.330 $\times$ 106 Da absolute weight-average molecular weight).

Most studies on the use of HPAM as polymer flooding material focused on enhancing the rheological properties of the polymer, which is essential for recovering large quantities of crude oil. The rheological prop-erties of HPAM in polymer flooding in EOR are strongly influenced by the injection flow rate, molecular weight of polymer, reservoir temperature, salinity of brine, and geological properties of reservoir. The rheology test results showed that UHMW-HPAM solution with low concentration (1000 ppm) was applicable to pol-ymer flooding in EOR at high temperature (70 $^\circ C$) and high salt concentration (3.0 wt%). The polymer exhib-ited remarkable performance in EOR, with 4% more oil recovery than that attained with water flooding due to its high molecular weight and high viscosifying characteristic. This potentially makes it applicable to polymer flooding as well as utilizing in its related EOR technologies such as polymer surfactant and alkaline surfactant polymer flooding in oil fields.