The redevelopment evaluation of old gas fields often faces problems such as inaccurate data and irregular original records, which makes it difficult to evaluate the oil and gas geology of these fields. The uncertainty of gas field exploration and development increases the risk of exploration and development. In this paper, taking the A gas field in the east of the right bank of the Amu Darya river in Turkmenistan as an example, by referring to the logging interpretation models of different adjacent areas, the fluctuation range of the parameters of the logging interpretation model of the gas field is established, and the fluctuation range of the key parameters such as porosity and saturation of the logging interpretation of the gas field is obtained. At the same time, the error of seismic inversion data in adjacent areas is counted, and the variation range of different parameters such as gas-bearing area and reservoir thickness in A gas field is counted. The distribution table of different parameters is established, and all parameters are sampled and calculated 150 times by Latin hypercube sampling. The results show that under the premise of considering the variation range of different parameters, the reserves of P90, P50 and P10 in A gas field of Turkmenistan are 4.573 × 109 m3, 5.539 × 109 m3 and 6.580 × 109 m3, respectively, which provides a geological basis for economic evaluation and risk prediction.