Abstract: Yacheng13-1 Gas Field has characters of long logging time intervals,slow replacement of logging devices and complex borehole environment.So there is great error in reservoir description when well log data used for example well quake mismatch.The single well evaluation method in ERR research often causes disagreement between interwell physical property distribution and sedimentary microfacies because of the man-made factors.Multiwell formation evaluation technique has been applied to petrophysical study of Economic Recoverable Reserve in yacheng13-1 gas field.Strict workflow and Quality Control,such as log data environmental correction and normalization,key well evaluation model study and multiwell optimization processing,ensured the methodology and procedure to be correct.The study results show good accordance with core petrophysical parameters at the whole research region and provide higher accurate logging data for ERR evaluation.