A reservoir in a certain block has medium porosity and low permeability, with a single effective thickness of 0.8 m. It has been developed using a combined vertical and horizontal well network, achieving economic and effective utilization of difficult to recover reserves. Currently, the block has entered the stage of ultra-high water cut development, with a high proportion of low production wells and measured wells. Under the current well network conditions, it is difficult to tap the remaining oil potential. However, there is a loss of reserves in the front distance of the horizontal well target and the undeveloped layer, and residual oil is enriched at the fault edge. Therefore, this article aims to improve the control level of reserves in the vertical and fault edges of the horizontal well plane. Based on the determination of remaining potential in different zones, and according to the principle of “distinguishing types of wells, considering both vertical and horizontal well networks, and controlling reserves through sand chasing bodies”, the first supplementary on-site test for adjusting the vertical and horizontal joint development zone during the ultra-high water cut period is carried out, A characteristic adjustment and supplementation method is formed for the deployment of horizontal well areas, toe ends, complementary layers, sand chasing bodies, and top oil areas in vertical well areas, to improve the control of block reserves and improve development effectiveness. Deploy and adjust 30 additional wells, with a production capacity of 14,500 tons, to provide guidance and reference for the densification adjustment of the same type of oilfield's direct leveling joint zone.