The further understand of the reservoir characteristics of the peripheral low permeability blocks in Daqing oilfield provides the theoretical basis for the adjustment of the development measures. Taking the block Mao-503 in Toutai oilfield as an example

and by using the equipment of the mercury injection apparatus

the X-ray energy dispersion spectrometer

the scanning electron microscope and the displacement equipment

we provide the stimulation suggestions of the improving recovery ratio by the imbibi

tion oil recovery

according to the imbibition test and field experiment effects and based on the characters of the pore structure

mineral composition

wettability and reservoir sensitivity. The reservoir physical properties test of the block Mao-503 in Toutai oilfield shows that the main clay minerals of the reservoir rock are the illite

montmorillonite and kaolinite

the main component elements are oxygen（O）

silicon（Si）and aluminium（Al）

and the minor elements are ferrum（Fe）

magnesium（Mg）

natrium（Na）

barium（Ba）and carbon（C）. The target reservoir with the porosity between 10 % and 17 % and the permeability range of（0.40

8

.2）×10

-3

μm

2

belongs to the medium porosity and ultra-low permeability sandstone reservoir. The pore throat size of the rocks is relatively small

and the sorting and connectivity are poor. Furthermore

the rocks show weak hydrophilicity

and the capillary force can be used as power in the process of the production. Meanwhile

the rocks have strong velocity sensitivity

water sensitivity and alkaline sensitivity. The indoor experiment and mineral field experiment show that the similar physical block is suitable for the imbibition oil recovery

and adding the surfactant into the water solution is good for improving the imbibition recovery and enhancing the development effects.