Optimization of polymer flooding in medium viscosity oil reservoir

Abstract

Polymer flooding is an alternative improved oil recovery (IOR) technique to improve volumetric sweep efficiency, slow down water breakthrough time and increase amount of oil recovery by decreasing water/oil mobility ratio. Two types of polymers commonly used for polymer flooding are partially hydrolyzed polyacrylamide (HPAM) and xanthan polymers. In this study, we propose polymer flooding by using commercial HPAM (Flopaam 3330S) which has an appropriate in-situ polymer viscosity at reservoir conditions. A hypothetical reservoir simulation model was constructed based on a quarter five-spot flooding pattern with reservoir and fluid properties from an onshore oilfield in Thailand. The proposed technique is divided into three main scenarios. First, single polymer slug in various concentration is injected till breakthrough. Second, two slugs of polymer with progressively decreasing polymer concentration is injected till breakthrough. Third, two slugs of polymer is chased by water till breakthrough. Then, the results were compared with the ones from water flooding. Moreover, sensitivity analysis was conducted to study the impact of polymer flood’s uncertain parameters. Injection of two polymer slugs with drive water can help to increase polymer utilization than injecting only a single slug of polymer but the oil recovery factor (RF) is slightly lower due to less areal sweep efficiency. However, decrease in RF can be compensated by lower amount of polymer and shorter production time.