In order to study displacement characteristics and development effect of tight oil reservoir

this paper analyzed the sensitivity

fluid percolation and water-driving displacement characteristics of Chang7 oil layer of the Triassic Yanchang Formation in Shangliyuan area

Ordos Basin.The results show that Chang7 oil layer has weak velocity sensitivity

weak acid sensitivity

no water sensitivity and no salt sensitivity.The starting pressure gradient of single-phase flow is up to 2.0 MPa/cm

and negatively correlates with permeability.The saturation of irreducible water and residual oil is high

the oil-water simultaneous vadose region is narrow

and the isoperm point is low

thus the increasing of water saturation can cause the rapidly decreasing of oil phase permeability.According to the changes of WC(water cut)and oil displacement efficiency in different displacement period

the water-driving in the Chang 7 oil layer can be divided into three different periods including no water period

WC-increasing-rapidly period

and high WC period.The oil displacement efficiency in no water period is 18.1%

and the final oil displacement efficiency is as low as 31.7%.In addition

the weak oil wettability of the oil layer will have a profound impact on later waterflooding.