Abstract: The Chang reservoir 8 in Baima area of Xifeng oilfield is the lowpermeability reservoir with average permeability of 0.77×10^-3μm², the wettability of reservoir rock is normally neutralpartial oil. For improving cruel oil recovery, the experiment of wettability reversal agent displacing in lab and numerical simulation were conducted on the basis of reservoir conditions. The optimal displacing plan that slug size is 0.1 times larger than pore space volume, and the slug combination is 1000mg/L(0.05PV)＋200mg/L(0.05PV). The oil recovery expected with wettability reversal model can be 36.75％,which increases by 9% compared to water injection production, the agent replacing oil ratio is 538ton/ton. The conclusion is that the development plan which the wettability reversal agent is injected to displacing oil in the low permeability reservoir should be reasonable.

Key words: lowpermeability, wettability reversal agent displacing, effect factor