Abstract: Because the percolation flow pattern in low permeability porous medium does not follow the Darcy Law, previous models were either too simple or too complicated. This paper studies and establishes a simple form tri-parameters Percolation model to approach the actual flow occurring in permeable porous medium. Series of analysis for radial steady-state flow and unsteady-state flow were conducted. Through the analysis, in boundary water reservoir, for relation between the production pressure difference and production rate,it has demonstrated that the models established on the basis of Darcy law do not apply to low permeable reservoirs. Under identical conditions, it gives an unreasonable large calculated production rate. Through the analysis of unsteady-state percolation flow and based on the tri-parameters models, the well-testing equation and typical well-testing curve have been established. The well-testing curve for low permeable reservoir is characterized by the trial-section of radial flow in middle-late period and disappeared, both the pressure and pressure derivative curves going upward.

Key words: low permeability reservoir, non-linear, non- Darcy now, well testing