This paper details the application of limited single-well reservoir modeling to predict infill-drilling potential in tight gas fields. Distributions of ultimate recovery and drainage area were developed from a small sample set to estimate incremental reserves. A case history from the Ozona gas field, Crockett County, TX, illustrates this technique. Fifty-one wells were randomly selected from more than 1,500 producing wells to estimate the potential of 40-acre infill drilling. The distributions of production characteristics from the modeled wells reproduced those of the ＇＇full field.＇＇ Calculated drainage area ranged from less than 10 acres to more than 320 acres, with a median drainage area of 36 acres. Approximately 75% of Ozona Canyon wells drain less than 80 acres (current spacing), with 52% draining less than 40 acres. The statistical drainage area and estimated ultimate recovery (EUR) data were combined to estimate the potential reserve growth with 40-acre development. Approximately 1,125 locations, adding 400 Bcf of incremental reserves were identified. The average EUR for 40-acre infill wells is 353 MMcf of gas.