Abstract:

A cement slurry, whose density was 1.5 g/cm3, had been prepared using class-G oil-well cement with silica fume as a thermo stabilizer and microsphere as light-weight admixture. After curing at 45℃and atmospheric pressure for 48 hours, the cement slurry displayed a compressive strength of 15 MPa; the water loss ( at 7 MPa for 30 min. ) was less then 250 ml and no free water was observed. After curing at 350℃and 20 MPa for 3 days, the cement slurry had a compressive strength of more than 10 MPa. Such a temperature-resistant, lightweight cement slurry can be used for well cementing in low-pressure, viscous oil reservoirs planned for thermal recovery to considerably reduce the high temperature-induced strength decline of the cement and prolong the life span of the producing well.

Key words: Viscous oil recovery, Thermal recovery, Lightweight mud, Thermal stability, Well cementing