Eroding Processes And Preveting Methods Of Well Equipment In Qijia Well Fidld Of Daqing

This thesis, aiming at the corrosion and clogging of well facilities at Qijia water supply base, makes deep studies of the hydrogeochemical environment o f the base and the mechanism of the corrosion and clogging, makes experiments on preventing the problem, and discusses how to put the experiments into practice ?Studies of the hydrogochemical environment indicate that the groundwater in Taikang group aquifer is under a weakly acidic and reductive conditions with relatively high Pco2(>10-1atm), low pH(<6.7) and Eh(-185--168mV) values, which give rise to high contents of Fe2+, Ca2+, Mg2+ and weak reduction of SO42- in groundwater. The corrosion of well facilities has close relation with that hydrogeochemical environment and H2S and CO2 are the main corrosion factors. The clogging of well screen is caused by three kinds o f substances: (1) grains coming from the aquifer: (2) corrosion products falling from casing wall, mainly FeS and FeCO3; (3) precipitates from groundwater, such as FeCO3, FeS, CaCO3 caused by degassing of CO2 and H2S because of pressure drop, when the groundwater comes near the screen from aquifer. Owing to the hydrogeochemical environment and mechanism of corrosion and clogging stated above, Vyredox method is chosen to be used for removing iron and HiS from groundwater in-situ. Experiments indicate that the method is of effect for thepurpose, and subsequently can abate the corrosion and clogging of well facilities and is practicable for Qijia water supply base.