Abstract: Due to the limited number of exploration wells and appraisal wells in offshore oil fields, the reserve boundaries of some reservoirs are difficult to prove, which leads to heightened risk in deployment of development appraisal wells or adjustment wells. In order to reduce risk, an evaluation method for progressive development in offshore oilfields, based on dynamic OOIP calculations, is proposed. The method is to calculate dynamic OOIP based on production data, re-check static OOIP, re-define reserves boundaries, and then guide the re-calculation of reserves and the deployment and drilling of development appraisal wells and adjustment wells. In order to improve the accuracy of dynamic OOIP calculations, according to the different parameters and the adaptability of the methods, the material balance method, the modern production decline method, and the water drive curve method are all selected to establish the method system for dynamic OOIP calculation. The linear material balance method for apparent reserves combined with water influx calculation has been introduced, and the modern production decline method, with consideration of limited enclosed water bodies, has been proposed. Referring to the "7.5 rule", the regional formula for dynamic OOIP calculation with Type A water drive curves in the western South China Sea has been established. The Yu Qitai Type water drive curve has also been selected to calculate movable OOIP and technical recoverable reserves in the western South China Sea. This evaluation method has achieved good practical performance in the western South China Sea, guiding the OOIP re-calculation of this kind of reservoir, promoting progressive development and adjustment of tapping potential, and reducing the risk associated with development appraisal wells and adjustment wells.