Compositions and Methods for Well Completions
AssigneeSchlumberger Technology Corporation
InventorsAnthony Loiseau, Alice Chougnet-Sirapian, Elena Tomilina, Simon Gareth James
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Abstract
Incorporation of carbonaceous materials in a cement slurry increases the linear thermal-expansion coefficient of the set cement. When placed in a subterranean well having at least one casing string, cement sheaths with linear thermal-expansion coefficients similar to that of the casing will be subjected to lower compressive and tensile stresses during downhole-temperature changes. Such cement slurries are particularly advantageous in the context of thermal-recovery wells.
Claims20
A method for adjusting the linear thermal-expansion properties of a cement slurry for placement in a subterranean well having at least one casing string, comprising:
- incorporating a carbonaceous material in the cement slurry, such that the linear thermal-expansion coefficient of the set cement is higher than that of a set cement not containing the carbonaceous material.
A method comprising, adjusting linear thermal-expansion properties of a set cement placed in a subterranean well having at least one casing string with a carbonaceous material, and controlling thermal and mechanical stresses exerted upon the cement sheath in the well.
A method for controlling thermal and mechanical stresses in a cement sheath in a subterranean well, comprising:
- i. installing at least one casing string in the well,
- ii. forming a cement slurry containing at least one carbonaceous material in a quantity sufficient such that the set cement has a linear thermal-expansion coefficient higher than that of a set cement not containing the carbonaceous material, and lower than or equal to about 50·10−6/° C.;
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- iii. placing the cement slurry in the well, adjacent to the casing string, and allowing it to set.
Dependencies are inferred from the claim text.