Well cementing process and gasified cements useful therein
AssigneeHalliburton Company
InventorDavid L. Sutton
Life of this patent
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Abstract
A process for cementing adjacent a subterranean gas-containing zone, in which process a cement slurry containing a stabilized, dispersed gas is placed adjacent the zone. Sufficient gas is present in the cement slurry or is capable of being generated within the slurry to prevent the connate formation gas under pressure from passing into or around the cement prior to the time the cement has set up.
Claims20
An increased compressibility cement composition for sealing a subterranean zone penetrated by a bore hole having a portion pressurized by an adjacent gas source comprising an aqueous hydraulic cement, an effective amount of a gas generating agent for generating a stable volume of gas sufficient to increase the compressibility under such downhole conditions by at least 25% in relation to the initial compressibility of the same composition not containing said gas generating agent and at least 0.05 weight percent, based on dry cement, of a chemical fluid loss control additive.
In an oil well hydraulic cement slurry composition of the type containing hydraulic cement and water, the improvement comprising increasing compressibility of said slurry by at least 25% in relation to the initial compressibility of the unimproved slurry via the inclusion in the cement of an effective amount of an entrained, stable volume of gas, such amount equivalent to at least 0.1 volume percent of the total volume of the slurry, and from about 0.05 to about 3.0 weight percent of a fluid loss control additive, based on the weight of the dry cement, said volume percent being based on the total slurry volume when the cement is in place in the well.
An increased compressibility well cementing composition comprising:
- a hydraulic cement;
- water in an amount from about 20 to about 135 percent by weight of the dry hydraulic cement;
- a fluid loss control additive in an amount of about 0.05 to about 3.0 percent by weight of the dry cement;
- an accelerator gel-preventing material in an amount of from about 0.1 to about 10 percent by weight of the dry cement;
- and
- from about at least 0.1 volume percent of a stable volume of gas under actual downhole conditions, such amount effective to increase the compressibility under such downhole conditions by at least 25% in relation to the initial compressibility of the same composition not containing said gas and accelerator gel-preventing material, and where said gas is dispersed in the composition and is compatible with the remaining components of the composition.
A compressible well cement composition for cementing an oil and gas well comprising:
- a hydraulic cement:
- water in an amount of from about 35 to about 50 percent by weight of the cement;
- a fluid loss control additive in an effective amount to reduce the amount of fluid lost from the cement composition while in its sealing position and prior to set by at least 25 percent in comparison to the fluid lost when the composition does not contain said fluid loss control additive of from about 0.05 to about 2.0 percent by weight of the dry cement;
- and
- aluminum powder in an effective amount to generate a stable volume of a cement compatible gas under actual downhole conditions of from about 0.1 to about 5.0 percent by weight of cement.
Dependencies are inferred from the claim text.