Abstract: Based on gas percolation mechanics theory and general binomial productivity equation, the expression of binomial coefficient A and B as function of Kh is deduced, then the observed parameters, the parameters given by gas reservoir engineering computation (especially by well test interpretation) and data from empirical analogy method are used to establish the binomial equation for solving Kh as an unknown function for the purpose of deducing the stable productivity equation for gas well, obtaining the open-flow capacity. The case study shows that this method is practical, simple and reliable for application.

Key words: gas well, binomial, open-flow capacity, well test, formation factor