Abstract: The available classical decline equations can't be used for effectively explaining the production decline curves protruding rightwardslightly and the declining rate curves being convex early and concave later. From fluid mechanics in porous medium, this paper educes a newgeneralized production decline equation for dealing with these problems. Also, it can be used for interpreting both why the monotone decreasingappears in production decline curves and the monotone increasing early and monotone decreasing later in them. Based on these, the paper stud-ies and analyses the decline equation and corresponding relative permeability to oil and production decline rate vary ing with the characteristicparameters. These can prov ide theoretical ground to select and apply the decline equation. This decline equation is directive significance theo-reilkl)y4at0 lslialyAcademic Journal Electronic Publishing House. All rights reserved.

Key words: production decline, percolation, relative permeability curve, distribution, characteristic