Abstract: After a long periled of waterflooding, the Wei 95 block of Mazhai Oilfield has entered into an ultra-high water cut period, with the water cut higher than 95%. According to the development state of the Wei 95 block, the HSG-1 reservoir fluid flow control technology is employed. Deep profile control and water shutoff within small sections of reservoirs are conducted, based on using a kind of flow control agent for channeling sealing featuring in small dose, high intensity, and big depth. On the basis of laboratory test, field application of the technology was launched in 8 wells at the end of 2007, 1768 t of crude increment was fulfilled, and the natural decline dropped to 11.2% in 2008 from 16.8% in 2007. The success presents a novel thought and approach to the development of similar reservoirs.