Abstract: Besides the advantages such as short test time, relatively simple process and low cost etc., the single-point well test method can not only reduce the amount of released air during test, but also effectively evaluate deliverability, so the method can be widely used in productivity evaluation for gas fields. However, the value of α in the single-point formula is quite different in different gas fields. The single-point deliverability formula is modified for the application in S gas field of the Right Bank Block of Amu Darya and a unique single-point deliverability formula is established for the gas field. According to the deliverability test results from 42 wells in S gas field, an average α value of 0.28 is obtained for the formula. Because the well deliverability varies greatly, α values should be classified and calculated according to different deliverability ranges. The single-point deliverability formula using the average α value of 0.28 and α values for different ranges can verify that the open flow capacities obtained from α values for different deliverability ranges are more accurate