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Objective Aiming at the corrosion problem of carbon steel weld in the produced water environment of a gas field, trace metal elements such as Mo, Cr, Ni and Cu were added to microalloying the electrode. Method The corrosion resistances of five kinds of carbon steel weld metals with different structures were systematically evaluated by immersion corrosion method at 60 ℃ in the produced water of gas field. Result The addition of Mo and Cr elements can refine the grains and improve the corrosion resistance. Conclusions By adding 12 wt% Cr, 1.5 wt% Ni, 1.6 wt% Mo and 0.8 wt% Cr, 0.3 wt% Ni, 0.3 wt% Cu into the electrode, the electrochemical corrosion resistance of the weld structure can be improved. The corrosion products are mainly composed of FeCO3, and some samples also contain a small amount of FeS or FeS2 and CaCO3. [ABSTRACT FROM AUTHOR]

The produced water, generated from the exploitation of tight gas, is characterized by complex composition, high salinity, and high treatment cost. The treatment and disposal methods of the produced water were analyzed and compared. Among those methods, the dispose of high-salinity produced water by reinjection formation is generally accepted by the industry. The problems of corrosion and scaling which may occurred in the process of produced water reinjection were analyzed, and the anti.corrosion and scaling strategies of reinjection treatment in recent years were summarized. Finally, the development trend of the reinjection formation disposal of the produced water was prospected. [ABSTRACT FROM AUTHOR]

At present, the downhole technology of water reinjection wells in central Sichuan area can meet the requirement of produced water reinjection, but the phenomena of tube bundle break down, corrosion perforation and channeling leakage were exposed in the process of reinjection. The reinjection \veils that have been shut down due to corrosion accounted for more than 35 % of the shutdown wells. The corrosion evaluation result showed that the reinjection well casing in service in sulfur-containing block of central Sichuan was in moderate and serious corrosion, and the corrosion was intensified with the increase of temperature, showing local corrosion characteristics. Through the evaluation of corrosion inhibitor slubility and inhibition effect, the inhibitor CT2-19C was s elected and suitable for reinjection \veils in sulfur-containing blocks of central Sichuan area, the liquid-phase corrosion inhibition rate was more than 80%. [ABSTRACT FROM AUTHOR]