The Oman D field is a typical porosity-type carbonate reservoir in the Middle East. The field employs a closely spaced, long horizontal well pattern with bottom-water injection and top-oil production for overall waterflood development. After more than 20 years of water injection, the reservoir has entered a high water-cut stage, facing challenges such as difficulty in water injection, severe ineffective water cycling, uneven reserve mobilization, and complex remaining oil distribution. The situation of stabilizing oil production and controlling water is becoming increasingly severe, urgently requiring effective strategies to reduce water cut and improve recovery. This study takes the Cretaceous USH reservoir in the Oman D field as an example to conduct a detailed analysis of waterflood development performance and remaining oil distribution characteristics. Based on this analysis, three optimization strategies focused on injection-production structure adjustments are proposed: a well pattern optimization strategy for fault-block reservoirs tailored to different types and distributions of remaining oil; mechanical water plugging measures for production wells to address uneven water channeling caused by microfractures or high-permeability streaks; and a refined adjustment strategy for injection-production parameters to address unreasonable injection-production indices during the high water-cut period. Through dynamic management of refined injection-production parameters, significant incremental oil production has been achieved. The comprehensive strategies presented in this study provide effective references and practical approaches for stabilizing oil production, controlling water, and enhancing development efficiency in similar high water-cut carbonate reservoirs.