| 摘要 |
<p>METHOD OF CEMENTING WELLS To cement the annulus around a casing string in a well penetrating an underground formation, a column of a gas-con-taining foam cement slurry is placed in the annulus, whereafter the column of cement slurry is allowed to set. The hydrostatic pressure at the bottom of the cement slurry column prior to setting thereof is less than the fracturing pressure of the formation at the level of the bottom of the slurry column. The amount of gas contained in the slurry and the set cement is such that the density of the cement column in the annulus in the lower region of the column is higher than the density of the cement column in the higher region thereof.</p> |
