Abstract: It is difficult to properly determine the percolation and variation of low permeability and heterogeneous reservoir that has been developed by water flood process for many years and especially conducting several stimulations. Applying the well test technique can effectively identify such percolation and variation, and provide basis for the reservoir management and reformation. The case study from Shanan reservoir in eastern Junggar basin shows that the feature of such a reservoir has been changed a lot by many-year waterflooding and stimulations, effective analysis of these variations can help to correctly recognize and evaluate this reservoir, thus guide the stable and high production of it.

Key words: Junggar basin, Shanan oil field, pressure transient testing, low permeability reservoir, percolation