Аңдатпа
Background: Conventional waterflooding typically achieves an oil recovery factor of no more than 35–40%, leaving a significant portion of the oil in place within the pore space of the reservoir rock, where it is retained by capillary forces. The application of chemical enhanced oil recovery methods, particularly Alkaline–Surfactant–Polymer (ASP) flooding, is a promising approach for high-viscosity oil reservoirs, where conventional waterflooding is characterized by a highly unfavorable mobility ratio between the displacing fluid and the oil. Aim: Systematic laboratory evaluation of ASP flooding effectiveness for the productive horizons of Field X (Western Kazakhstan),, based on real core samples from borehole K-2524, with the development development of recommendations for optimising the chemical slug formulation. Materials and Methods: The study employed methods such as incoming quality control of commercial surfactant samples, compatibility testing at a specified reservoir temperature over a defined period, phase behaviour screening of lauryl sulfate / sodium hydroxide systems with crude oil from two horizons, and filtration experiments conducted using the PLS-200 petrophysical laboratory setup. Results: ASP flooding with 0.02% sodium dodecyl sulfate (SDS) + 0.6–0.8% NaOH + 2,500–3,000 ppm hydrolyzed polyacrylamide (HPAM) achieved an incremental oil recovery factor of 19.0–19.2% for the Cretaceous chalk horizon (total RF of 68.5–68.9%) and 17.7% for the Jurassic horizon at 3,000 ppm HPAM. The HPAM concentration is a critical design parameter: deviation from the required mobility ratio condition (M ≤ 1.0) reduces the incremental oil recovery by nearly half. Conclusion: ASP flooding demonstrated high efficiency for both horizons when the formulation parameters were properly optimized. The optimal formulation (0.02% SDS + 0.8% NaOH + 2,500 ppm HPAM) is recommended as providing the best balance between incremental oil recovery factor and reagent cost.