Effect of pore-throat structure on air-foam flooding performance in a low-permeability reservoir

•Effect of pore-throat structure on air-foam flooding performance in a low-permeability reservoir is examined.•Thin-section analysis, x-ray diffraction analysis, HMI and RMI tests, and NMR technique are integrated.•Appropriate timing for converting water injection to air-foam flooding is beneficial to improve recovery performance.•Concentrated/dispersed throat distribution improves oil washing/microscopic sweep efficiency differently.