The channel sandstones in the first member of Shaximiao Formation (J2s1) in the Shunqing Oilfield show promising exploration and development prospects. Defining their reservoir characteristics and effective petrophysical cutoffs is of great significance for predicting genetic sweet spots. Reservoir evaluation was conducted by integrating core, experimental, and logging data through six methods: oil-bearing grade method, statistical method, porosity-permeability crossplot method, mercury injection capillary pressure method, productivity simulation method, and 2D NMR method. Results indicate that the target sand unit 2 is primarily composed of medium to fine-grained feldspathic litharenite, with an average porosity of 6.63% and an average permeability of 0.25 mD, classifying it as a typical tight sandstone reservoir. The determined cutoffs for the effective reservoir are a porosity of 3.93% and a permeability of 0.099 mD. The lithological cutoff is fine-grained sandstone, and the oil-bearing cutoff is oil stain. This effective reservoir exhibits a distinct well-logging response characterized by "high acoustic interval transit time (57.45 μs/m), low bulk density (2.57 g/cm3), low resistivity (83.74 Ω·m), and low natural gamma ray (243.98 API)". The comprehensive cutoff criteria established in this study provide a critical geological basis for the precise evaluation of regional tight sandstone reservoirs and the optimization of favorable targets.