Abstract: Perforation leakage happened to an untreated gas transportation pipeline. By means of macro analysis, SEM and EDS analysis, and XRD analysis, the perforation reasons were determined. The results show that the sand depositing at the bottom of the gas transportation pipeline would adsorb and aggregate the produced water in the gas, and H2S dissolved in the produced water and induced H2S corrosion in wet environment, which was main reason for the perforation. The fouling scale composed of corrosion products and sand and Cl- in the produced water, also promoted local corrosion of the pipeline.