Factors affecting gaseous agricultural wells used in the North plains of Hamedan province and corrosion of their equipments

In Lalejin, Ghahavand-Famenin and Chardoli areas located in the north of Hamedan province, some of agricultural water wells produce gas and their equipments are corrodes in a short period, so the farmers are incurring a large financial loss. Therefore, recognition of sources and effective factors of corrosion are important. For this purpose, using G.P.S, thermometer and questionnaires, temperature, depth of wells, period of corrosion and Geographical characteristics of 36 rings gaseous wells were recorded. Furthermore, 16 water samples from the wells were analyzed in the laboratory. Then, the amount of free carbon dioxide was estimated using Standard Nomographs. Also, data of temperature, depth, free carbon dioxide and period of corrosion were evaluated by using the SPSS program. High amount of free carbon dioxide (more than 100 mg/L) and significant difference between average of water temperature in the wells show that the presence of gas in the water is the result of gaseous hydrothermal solutions with the earth internal provenance that entered into groundwater of these area. In this study, differentstatistical tests show that high amount of free carbon dioxide and sulfate-chloride ions, high temperature and high salinity are the effective factors of the corrosion of the wells’ equipments.Therefore, it is recommended that the metallic equipments of wells be replaced with U.P.V.C equipments.