High-Sulfate-Resistance Cement for Heavy Oil Wells

In this study, high-sulfate-resistance
G-class oil well cement (G cement), produced according to the API-10A
standard,⁴³ was provided by Xinjiang Tianshan
Cement Co., Ltd. Quartz and metakaolin were used to control the high-temperature
resistance of the cement paste. The stability and rheological properties
of the cement slurry were controlled by fluid-loss additives and dispersants,
to meet the requirements for cement slurry properties in cementing
engineering of a heavy oil well.⁴⁴ The
chemical compositions of G cement, metakaolin, and quartz were tested
using X-ray fluorescence. Before sample testing, all samples were
dried at 105 °C for 2 h, and the loss on ignition (LOI) was recorded. Table 1 shows the chemical
composition of the G cement, quartz, and metakaolin. In this experiment,
the cement paste consisted of G cement, 25 wt % quartz, 10 wt % metakaolin,
2 wt % fluid-loss additive, 0.8 wt % dispersant, and 54 wt % water.
This cement formulation has been used in the cementing operation of
heavy oil wells by the Xinjiang Oilfield Company.