Wells drilled in the Erlian Basin penetrate coal beds with developed fractures, and some of the formations have low strength, resulting in severe lost circulation during well cementing with low density cement slurries, and the cement slurries generally didn’t return to the designed heights. An ultra-low density cement slurry was developed to address these problems. A stability enhancement additive was used in the cement to prevent the separation of micro beads and cement. The minimum density of this cement slurry obtained in field application was 1.06 g/cm^3. Other properties of the cement slurry were as follows: mobility controlled within 19-20 cm, free water 0 mL, 30 ℃ thickening time controlled within 1.5-4.5 h, API filter loss less than 50 mL, 24 h compressive strength greater than 3.5 MPa, 72 h compressive strength greater than 6.0 MPa. The overall performance of the cement slurry is exchis cement slurry has been used 5 times in Erlian Basin (Huabei Oilfield), with all cement slurry returned to the surface in single-stage well cementing, and the pass rate of cementing job quality was 100%.
Drilling Fluid & Completion Fluid
Job quality of well cementing