Abstract: Due to the high temperature deep well slurry has the characteristic of high viscosity, high density and complex component, the slurry dispersant has little dispersing effect in Mud to Cement(MTC)mud body and cannot make the slurry. A dispersant SSOB which contains various modified polyethylene gly-
col substance with nonionic groups has been developed. The SSOB dispersant has the character of low dosage, good dispersing properties, and no influence on the performance such as the thickening time, the compression strength etc. Moreover, the dispersant is compatible with other additional chemicals (activa-
tor, retarder etc.), makes slurry the excellent comprehensive properties, improves the cementing quality of the deep well and complication well, supplies the guarantee for the exploitation of hydrocarbon reservoir in the high temperature deep well and has wide prospect of development and application.

Key words: slag, MTC, dispersant, slurry, cement slurry