Abstract: The mathematical model for commingled production of dual zone reservoir with a crossing flow has been developed by taking variable borehole storage effects as a decay of production, quoting the effective wellbore radius and refering to the relevant references. With Laplace transform for the model, the Laplace's space solutions ate obtained; by utilizing a numerical inversion technique, the draw—down curves at variable parameters are given in this paper. In addition, an analysis of the characteristics is made for the curves.

Key words: Variable borehole storage effect, Production decline, Effective wellbore radius, Crossing flow