Complex gas reservoirs are characterized by strong heterogeneity and complex gas-water relationships. These characteristics lead to high testing costs and significant safety risks, making it difficult to conduct large-scale and long-term productivity tests. However, accurately grasping the productivity of gas wells is of great importance for determining the gas production allocation of gas wells, supporting surface construction, and even optimizing productivity. Currently, in the production field, the calculation of the absolute open flow potential mainly relies on the results of single-point productivity tests, and the conventional “one-point method” formula is used to calculate it, so as to roughly evaluate the productivity of a single well. Through practical verification, compared with the results of productivity tests, the error of the productivity calculated by the conventional “one-point method” exceeds 30%. In response to this problem, considering factors such as reservoir heterogeneity and water production characteristics, three new methods suitable for complex gas reservoirs have been established - the modified “one-point method”, the regression “one-point method”, and the improved “one-point method” constrained by formation pressure and permeability. Taking the reef-beach gas reservoir in the LG gas field of the Sichuan Basin as an example for calculation verification, the research results show that - Firstly, in the case where it is difficult to comprehensively carry out productivity tests, the three newly established methods can all reduce the calculation error of the conventional “one-point method”. Secondly, the improved “one-point method” has the smallest calculation error, which is less than 7%. The modified “one-point method” comes second, with an error less than 10%. The calculation result error of the regression “one-point method” is smaller than that of the modified “one-point method”. Thirdly, the improved “one-point method” is mainly applicable to gas wells that have undergone unstable well testing and have accurately obtained the gas well permeability. These three methods can quickly and conveniently evaluate the productivity of gas wells, and can effectively reduce the calculation error of gas well productivity.