Inversion Method Of Non-darcy Percolation Law In Low Permeability Reservoirs

The percolation curves of low permeability reservoirs show the non-Darcy characteristics.The percolation velocity and pressure gradient are not a simple linear relationship,so they can be represented by the dynamic permeability model.The percolation law is taken into the percolation equations,and the pressure solution can be obtained through the numerical solutions.In this paper,the mathematical models of the low permeability non-Darcy homogeneous reservoir and dual-porosity medium reservoir based on the dynamic permeability model with infinite boundary were established.On the basis of these two models,the following well test interpretation model with adjacent well interference were established then.The dynamic permeability model should be solved through the implicit difference method.Finally,the typical well test curves are obtained under the four mathematical models.By analyzing the flow stages of the typical curves,it can be found that for low permeability non-Darcy reservoir.Through the sensitivity analysis of the typical curves,the effects of the parameters on well test curves were obtained,such as storage coefficient,skin factor,inter-porosity flow coefficient,storativity ratio,and the curves of permeability,the flow rate of interference wells,and the distance between the observation well and the interference well,and also the pressure distribution after disturbance.Finally,this method is applied to the well test interpretation of the data of the oilfield.The explanation includes the important parameters of the reservoir and the the curves of the permeability in the reservoirs,which has achieved good results.