Abstract: Block A of Chengbei Low Uplift is a key development block in the Bohai Bay Basin. Since its commencement of production, it has achieved a considerable scale of oil and gas output. However, challenges such as unclear reservoir characteristics, rapid water-cut rise in water-cut development, and ambiguous distribution of residual oil, which seriously hindered the efficient exploitation of oil and gas in this area. By combining seismic, logging, coring, and dynamic development performance, the reservoir characteristics and water-driven residual oil distribution law in Block A were studied. Results show that the reservoirs of the 9th sand unit (Ed₉) and the 8th sand unit (Ed₈) of the Dongying Formation, the main oil-bearing units in the study area, are turbidite channel sand bodies of deep lake-semi-deep lake facies. The reservoir lithology is mainly medium-fine-grained lithic arkose, with mainly medium-porosity, medium-low permeability, and high heterogeneity. The Ed₈ reservoir was mainly developed in the 6th subunit (Ed₈⁶), and the Ed₉ reservoir is mainly developed in the 5th subunit (Ed₉⁵). These sandbodies have good continuity, distribute widely, and thin out from southwest to northeast. The development of the study area can be divided into four stages: natural energy development, enhanced water injection, sparse-well water-driving, and overall adjustment. In the first stage, natural energy was produced with largely no water; subsequent enhanced water injection supplemented the energy build-up in the reservoir but became watery rapidly, resulting in serious water flooding in the eastern wells. Horizontally, the residual oil in Ed₉−Ed₈ is mainly distributed in the southwest of the study area; and vertically, the residual oil is mainly distributed in the 1st single sandbody unit of Ed₈ (Ed₈^6-1), the 1st single sandbody unit of Ed₉⁵ (Ed₉^5-1) and the 2nd single sandbody unit of Ed₉⁵ (Ed₉^5-2). The sandbody thickness is the main factor on the distribution of residual oil, while the areas with thick sandbody tend to be rich in residual oil. The structural shape played a role in controlling the distribution of the residual oil. The southern part of the production block often has a higher residual-oil abundance due to its high structural position. This study provided a basis for adjusting the development plan and improving the recovery rate in this area as a valuable reference for the development of similar oil and gas reservoirs in the Bohai Bay Basin.