Abstract: The nonlinear filtering flow model considering binary pressure gradient is much more accurate than that of linear in reflecting the filtering flow laws of the formation oil in the reservoir.In terms of the two section composite reservoir,combining the state equation and based on the Darcy law and mass conservation law,we develop the filtering flow equation.Taking the effects of the binary pressure gradient into account,we have established the well testing model in the binary pressure gradient two section composite reservoir whose filtering flow principle is nonlinear.By means of variable alternation,we linearize the filtering flow equation,and get its analytic solution in Laplace domain space and the solution in the actual space utilizing the numerical inversion method.Consequently,we draw the chart curves in two section composite reservoir with influences of the binary pressure gradient,which lead to the results of sensitivity analysis of various parameters.Error analysis shows that the effects of binary pressure gradient shouldn′t be ignored.

Key words: composite reservoir, binary pressure gradient, nonlinear filtering flow, effect hole diameter, well test