Abstract: The resistivity response of the deep heavy oil reservoirs in the Third Member of the Shahejie Formation in the Sanhe Village Block, Zhanhua Sag, is complex, characterized by both high and low logging resistivity curves. The influencing factors are unclear, which severely affects the logging discrimination of fluid properties and saturation evaluation. Using data such as lithological descriptions, physical properties, X-ray diffraction, production tests, and well logs, this study investigates the “four-property” characteristics and their interrelationships in the heavy oil reservoirs of the Third Member of the Shahejie Formation, and thoroughly explores the resistivity differences and their influencing factors. The results show that the heavy oil reservoirs are predominantly composed of fine sandstone, with mineral composition mainly quartz, along with small amounts of feldspar and clay, classifying them as medium-high porosity and medium-high permeability reservoirs. Among these, gravelly coarse sandstone and gravelly medium sandstone exhibit the best physical properties, followed by gravelly fine sandstone and fine sandstone, while conglomerate shows the poorest. Samples rich in oil and those that are oil-soaked have better physical properties, whereas samples with oil stains and oil traces have poor physical properties. Oil-rich samples are mainly distributed in gravelly fine sandstone, while oil-soaked and oil-stained samples are primarily developed in fine sandstone and medium conglomerate. The resistivity differences are mainly reflected in different lithologies: the resistivity value of gravel-bearing heavy oil layers is generally higher than 40 Ω·m, whereas that of fine sandstone heavy oil layers is usually below 30 Ω·m. The resistivity response is comprehensively influenced by lithology, physical properties, oil-bearing property, and the occurrence state of oil and water. Particularly, the resistivity differences observed within the same lithology, influenced by the mutual occurrence of heavy oil and water, cannot be ignored. Based on the above analysis of reservoir characteristics and factors influencing resistivity, this study provides a certain basis and implications for determining the lower limit of effective reservoir resistivity in heavy oil reservoirs, saturation logging evaluation, and even the development of similar heavy oil reservoirs.