Study on Rapid Screening Method for Different Chemical Flooding Methods in Heavy-Oil Reservoirs

Heavy-oil reservoirs exhibit a high water–oil mobility ratio. During cyclic steam stimulation or water flooding in the later stages, severe fingering occurs, making it difficult to produce the remaining oil. Chemical flooding methods such as polymer flooding, surfactant–polymer flooding, weak gel flooding, and gel flooding have achieved significant enhanced oil recovery (EOR) effects in the development of high-water-cut oilfields in China. However, the reservoir applicability conditions for each chemical flooding method differ. How to quickly select the appropriate chemical flooding method based on reservoir conditions remains a challenge. This paper uses the basic parameters of a heavy-oil reservoir in Shengli Oilfield as a reference and establishes numerical simulation models for different chemical flooding methods. Then, using the permeability variation coefficient as an indicator to evaluate reservoir heterogeneity, the suitable permeability variation coefficient ranges for different chemical flooding methods are obtained and used as the first-level decision method. Subsequently, based on the differences in temperature and salt tolerance of each chemical flooding method, the applicable ranges for different chemical flooding methods are determined and used as the second-level decision method. Through this two-level decision-making process, the suitable chemical flooding development method for a target reservoir can be rapidly identified, providing support for the efficient development of heavy-oil reservoirs using chemical flooding. The findings are based on a typical heavy-oil reservoir model from Shengli Oilfield; the specific thresholds presented should be calibrated accordingly when applied to reservoirs with different characteristics.