Abstract: Block D has maintained low-efficiency and low-rate development for more than 30 years, with an oil recovery factor of merely 8.4%. It is urgent to tap the production potential of this mature oilfield. Centered on detailed analysis of production and injection wells, this study achieves breakthroughs via refined sedimentary cognition, clarifies the distribution rules of oil-water contact, accurately characterizes faults to identify reservoir space, predicts remaining oil potential to define development directions, and finally realizes the deployment of profitable well locations. The integrated evaluation and overall edge potential tapping methodology for mature blocks proposed in this paper boasts broad application prospects, which can be extended to 14 mature oilfields including Shuguang Oilfield and Xinglongtai Oilfield.