Study and Application of Ultra-high Density Cement Slurry

An ultra-high density cement slurry was formulated with iron powder (density 7.0 g/cm³) of different particle sizes 0.154 mm, 0.076 mm and 0.03 mm in a ratio of 3:2:1, and latex suspending agent and liquid additives. This cement slurry has density of 2.82 g/cm³ and good suspending capacity, with density difference between the top and the bottom slurry of equal to or less than 0.028 g/cm³. At 30℃ and ambient pressure, the set cement has compressive strength of 14 MPa after aging for 48 h. API filter loss can be controlled to less than 50 mL. SPN of the cement slurry is equal to or less than 3. This high density cement slurry was used successfully in the cementing operation of well Wen72-421, in combination with a special cementing technology for high density cement slurry.