The Influence of Water-Polymer Co-Flooding on the Development Effect of Oil Reservoirs

The J oilfield in the Bohai has a long development history and has undergone comprehensive adjustment measures, including water injection and polymer injection. Following these adjustments, the injection and production well network now features coexistence of both polymer injection wells and water injection wells, which has negatively impacted production dynamics. Firstly, based on the adjusted reservoir well network in the J oilfield, a representative water-polymer co-injection well network was established. Subsequently, a numerical simulation model of this typical reservoir unit was developed using reservoir numerical simulation methods to confirm the interference issues associated with water-polymer co-injection. Multiple reservoir numerical simulation models were designed to investigate various factors influencing water-polymer interference, resulting in graphical representations of each factor’s impact under different conditions. Finally, gray relational analysis was employed to rank the influence of these factors, yielding the following order of significance: polymer concentration, the ratio of drainage distance to well spacing, horizontal permeability variation, interlayer permeability variation, and intralayer permeability variation. This understanding provides robust guidance for future adjustments in the oilfield.