Abstract: In Daniudi gas field, the overall unit decline method has been used to evaluate SEC reserves, with the development of gas field, the reasonable overall unit decline rate cannot be determined due to the influence of flowing well numbers, measures, production limit and other factors, and the result of SEC reserves evaluation is distorted. By dividing the development wells of assessment units into different production components according to the production time and well types, including stable existing wells, unstable existing wells and new wells, natural gas production is predicted respectively, and the overall output of assessment units is finally obtained by superposition. This method can eliminate the adverse factors of selecting reasonable decline rate.The SEC reserves in block DK13 of Daniudi gas field are reevaluated by using the yield composition method,which fully reflects the influence of well types, production life, production limit and other factors, and makes the calibration result more timely reflect the actual development status of the units.