A Block has currently entered the high water-cut development stage, undergoing a series of transformation processes including scattered injection-production system adjustments, local well pattern adjustments, and measures to increase production and injection. Currently, the block faces issues such as low oil recovery rate, declining water retention rate year by year, a large proportion of low-yielding wells and long-term shut-in wells, difficulty in effectively utilizing remaining oil in the old areas under the current well pattern conditions, inability to utilize uncontrolled remaining oil reserves, and poor conventional potential tapping results. Therefore, based on detailed reservoir description, through the tertiary decomposition of remaining oil, six types of remaining oil are precisely classified, and targeted potential tapping is carried out for the three major types of remaining oil. A Block will tap into the remaining oil through comprehensive methods such as drilling supplementary wells, directional fracturing, sidetracking of old wells, injection conversion, adjustment of injection production systems, and recovery of long shut in wells. After analyzing the development effect of residual oil tapping, it has been confirmed that the residual oil tapping method is feasible and effective. This article clarifies the utilization status of remaining oil in A Block, forming a three-level classification method of three major categories and six sub categories of remaining oil. It qualitatively and quantitatively describes the distribution of remaining oil, clarifies the comprehensive tapping methods of different types of remaining oil, and achieves good development adjustment effects, compensating for the decline in production and accumulating experience for improving the development effect of similar blocks.