Abstract: Abundant OOIP is discovered in the low-quality reservoirs of Tahe oilfield. But this kind of reservoirs can’t be economically developed because of low well productivity after preflush acid-fracturing and high cost of staged acid fracturing with tools in horizontal wells. Tool-free, temporary-plugging staged acid fracturing method is used in fracture-cave carbonate reservoirs, that is using steering acid and degradable fiber at fissure vents as barriers, which could force fracture initiation from the next section and then the reservoirs could be connected with each other. Thus the single fracture-cave pattern of preflush acid-fracturing is changed and several reservoirs in a single well can be produced effectively through one-time acid fracturing. Field application result shows that the average acid fracturing cost for a single section in one well can be reduced by 47.8% and well productivity can be increased to 1.8 times of that in neighboring wells. Consequently, the development benefit is significantly improved