Shengli Oilfield is a typical continental compound oil and gas area with various reservoir types， many oil-bearing strata，and complex fault systems. It entered the extra-high water cut development stage with a water cut of more than 90% in the early 90s of the 20th century. The basis for enhanced oil recovery in mature oilfields with high water cuts is how to accurately characterize the changes of underground reservoirs and accurately recognize the remaining oil according to different types of reservoirs and development stages. To this end， the oilfield has carried out the fine reservoir description for the remaining oil potential in mature oilfields since 1996. A set of fine reservoir description technologies aligning with Shengli Oilfield characteristics has been formed through breakthroughs in critical technologies such as the fine characterization of reservoir architectures，fine description of low-sequence faults， phase division and connectivity evaluation of glutenites，prediction of thin beach dam sand reservoirs， three-dimensional geological modeling， and the fine description of the remaining oil，as well as multiple rounds of iterations of reservoir description technologies， and the technical specifications of fine reservoir description have been compiled. As of 2023，more than 600 development units have been described，covering 43.6 × 10⁸t of original oil in place. The modeling technology has been widely used in the adjustment of mature areas and the scheme preparation of new areas，which effectively supports the large-scale production of oilfields and stable production with benefits. This paper systematically analyzed the development process of reservoir description technologies in Shengli Oilfield， summarized the characteristic technologies of different types of reservoirs，analyzed five challenges faced by fine reservoir description in mature oilfields in the late stage of extra-high water cut，and expounded on five development directions of reservoir description technologies in the next step， which had guiding and reference significance for promoting fine reservoir description technologies in continental oilfields.