Improvement of low density Cement slurry

摘要

A 9 to 12 ppg (1.08 to 1.4 kg/litre) cement slurry for use in oil well type completions which comprises hydraulic cement about 8 to about 50 weight percent hollow glass microspheres based on the weight of the cement and sufficient water to form a pumpable slurry with an API free water content of no more than about 2 volume percent. The microspheres have ANSI/ASTM D2840-69 true particle densities of about 0.2 to about 0.5 gm/cm3, ANSI/ASTM D3102-73 hydrostatic collapse strengths of at least 500 psi (3447 kPa) and average particle diameters of less than about 500 microns.