Polyrotaxane-reinforced settable fluids with entrapped gas phase under high pressure
AssigneeSaudi Arabian Oil Company
InventorsAshok Santra, Hasmukh A. Patel
Life of this patent
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Abstract
This document relates to methods for preventing or inhibiting the cracking or explosion of cement in an oil well using cement compositions that contain polyrotaxane additives. The cement compositions containing the polyrotaxane additives exhibit increased resiliency to cracking as compared to the same cement without the polyrotaxane additive.
Claims14
A cement composition comprising:
- cement;
- and
- a slurry comprising:
- about 2% to about 8% by weight of the slurry a cross-linked polyrotaxane additive selected from the group consisting of γ-CD-PS-NH-CC, α-CD-PEG-NH-CC, and β-CD-PPG-NH-CC;
- and
- a gas-generating compound.
A method of preparing a foamed cement composition, comprising:
- preparing a slurry comprising a gas-generating compound and about 2% to about 8% by weight of the slurry a cross-linked polyrotaxane additive selected from the group consisting of γ-CD-PS-NH-CC, α-CD-PEG-NH-CC, and β-CD-PPG-NH-CC;
- and
- mixing the slurry with cement and a foaming agent.
A method for preventing cracking in cement with entrapped gas of an oil well when the gas is subjected to a negative change in pressure, the method comprising:
- providing to the oil well a cement composition comprising cement and a slurry comprising a gas-generating compound and about 2% to about 8% by weight of the slurry a cross-linked polyrotaxane additive selected from the group consisting of γ-CD-PS-NH-CC, α-CD-PEG-NH-CC, and β-CD-PPG-NH-CC.
A method of improving the resiliency of a foamed cement composition to cracking, comprising adding a slurry comprising a gas-generating compound and about 2% to about 8% by weight of the slurry a cross-linked polyrotaxane additive selected from the group consisting of γ-CD-PS-NH-CC, α-CD-PEG-NH-CC, and β-CD-PPG-NH-CC to a cement composition, wherein the resiliency of the foamed cement composition to cracking is greater than the resiliency of the same cement composition to cracking without the polyrotaxane additive.
Dependencies are inferred from the claim text.