Abstract: The distribution of remaining oil in Tahe oilfield during the middle and later stages of development is not well understood, mainly due to highly complex fracture-cavity structure of carbonate reservoirs. This study starts from the practical situation of oil reservoirs and lays an emphasis on detailed reservoir description and testing and dynamic production data analysis. Seven types and thirteen sub-types of remaining oil distribution patterns are put forward. These include three types and eight sub-types of wellhole-adjacent remaining oil, i.e., attic type, screened dense layer type, and blocked type due to rise of bottom water. Additionally, there are four types and five sub-types of interwell remaining oil, i.e., low-amplitude monadnock type, branch channel type, separated fracture-cave type, and pore-fracture type near the high diversion channel. Combined with production practices, potential-tapping countermeasures are proposed for different remaining oil distribution patterns. On the one hand, drilling new wells or sidetracking from the existing wells are recommended for all kinds of remaining oil existing in non-well-controlled fractured-cave with relatively large well spacing. On the other hand, routine targeted potential-tapping measures are chosen for those with relatively small well spacing. Large-scale acid fracturing-hydraulic dilation and drainage process-displacing oil with gas are unique and effective measures for separated fracture-cave and attic patterns, respectively. Good results of increasing production have been gained by tapping the potential of all kinds of remaining oil during the development of Tahe oilfield. This study provides new thinking and reference measures for remaining oil digging in similar oil reservoirs.