Abstract: The sulfur content in the crude oil from some heavy oil blocks in Gudao Oilfeld is higher than 2%. The organic sulfur compounds in crude oil are decomposed during thermal recovery. The enrichment of H₂S in the casing is harmful to the safety of production and operation. Engineers and researchers from the Oil Production Plant and the Petroleum Engineering Technology Research Institute jointly developed an effcient desulfurizer system to convert the hydrogen sulfde into sulfur. Together with the development of a portable skid-mounted desulfurization device, the effcient absorption of hydrogen sulfde gas in the casing is realized, the H₂S content of casing gas after treatment is lower than the maximum allowable concentration. The treatment of sour oil wells in different blocks becomes easy and hence for, the problem of safe operation of heavy oil thermal recovery well due to hydrogen sulfde is solved.