Expandable cement composition

摘要: Particulate magnesium oxide prepared by calcining at between about 1100°C and 1500°C. At least 80% of the particles are 150 microns to 400 in diamater. This is capable producing expansion set cements when temeperature thereof 60°C. Preferably has been calcined 1300°C for 1 3 hours, 200 325 microns. Further, BET surface area preferably 0.8 1.8 m²/g, acid neutralization time (using method described) 15 20 minutes, further 17 25 minutes. Expandable cement compositions using such oxide, a them cementing wells, also disclosed.