Real-time quantitative PCR of pmoA genes encoding methane monooxygenase of methanotrophs was performed in this study to investigate whether air-dried soil could be used for microbial prospecting for oil and gas resources. Soil samples were collected from the depths of 0-30, 30-60, 60-100 and 100-150 cm from oil and gas fields and from two control fields where no oil and gas reservoirs were observed. The copy number of pmoA genes was determined by qPCR in soil samples under fresh, air-dried and lyophilized conditions. The amount of DNA extract was apparently lower in air-dried and lyophilized soils than that in fresh soils, and the copy number of pmoA genes decreased by 90.7% and 77.5%, respectively. Considerable amount of pmoA genes was detected at soil depth down to 100 cm from oil and gas reservoirs, while pmoA gene was below detection limit in soils samples at depth lower than 30 cm soil samples from control fields. The results of this study suggest that air-dried or lyophilized soils could be used for microbial prospecting for oil and gas reservoirs in the field.