Considering the vertical heterogeneity characteristics of multilayer reservoirs and nonlinear seepage regularity for fluid flowing in the ultra-low permeability reservoirs

natural large-scale outcrop model and nonlinear seepage numerical simulation software were adopted to research the development effect of commingled production for ultra-low permeabi-lity reservoirs.Results show that total recovery percent is influenced by permeability ratio

average permeability

layer number and oil viscosity during commingled production.With the increase of permeability ratio

the total recovery percent decreases and the difference between the higher and the lower permeability layers becomes larger;And the higher the average permeability is

the higher total recovery percent is;the more the layer number is and the higher the oil viscosity is

the poorer the develoipment effect is during commingled production.On this basis

a new parameter called “quad-element synthetic influence factor” is proposed to evaluate the development boundary for the commingled production of multilayer reservoir.Analysis indicates that the total recovery percent is in a power function relationship with this new parameter

which could be used as an important indicator for development effect evaluation of ultra-low permeability multilayer reservoir.