When studying oil reservoirs, we have the problem of identification of the preferred seepage channel. Conventional methods evaluate the influence of individual factors. The proposed Deng's relational analysis method lets us evaluate the influence of several parameters, their relative weight and correlation. In this paper, we present the basic principles for application of Deng's relational analysis as applied to liquid and gas flow processes. We have calculated the correlation degree and the weighting factors for different geological parameters, production parameters, and seepage directions, and have proposed a mathematical model for identifying the preferred seepage channel and we verify the model using a type A water drive curve.