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