Abstract: In deliverability evaluation of a gas well, the single point deliverability test is widely applied to gas field with simple and easy operation as well as short test time. However, the calculation results tend to be in large deviation when it is applied to low-permeability gas reservoir. Starting from the theory which derives the single point deliverability formula and the low-permeability gas reservoir characteristics, and based on the trinomial deliverability equation considering the threshold pressure gradient, a single point deliverability formula for gas well in low-permeability gas reservoir has been deduced, and a method for calculating deliverability factors by a single point test data has been established. It is shown that compared with conventional single point formula, the number of the empirical parameter in the single point formula for low-permeability gas well has become two from one, and empirical parameters α, δ are also related with threshold pressure gradient. The case study indicates that this method presented in this paper is feasible.

Key words: low permeability, gas well, one point method, threshold pressure gradient, deliverability, productivity