Azman Munthoha Maula et al. 2026. Impact of Reservoir Horizontal Permeability Vertical Distribution on Recovery Efficiency Based on Deepwater Massive Sands. Journal of Petroleum and Geothermal Technology. 7, 1 (May 2026), 37–46. DOI:https://doi.org/10.31315/jpgt.v7i1.16798.