High temperature cement system
AssigneeUnion Oil Company of California
InventorJulius P. Gallus
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Abstract
A high temperature cement system including a carbon-containing, low volatile material additive admixed with cement in proportions sufficient to provide a fixed carbon content of at least 0.02 weight percent. Additives include anthracite, calcined coke, uncalcined coke, burned oil shale and raw oil shale.
Claims21
A cement system which upon hydration and curing forms a hardened cement mass, said cement system consisting essentially of cement and an effective amount, less than 20 weight percent of said cement system, of a carbon-containing cement additive selected from the group consisting of anthracite, calcined coke, uncalcined coke, raw oil shale and burned oil shale, said cement additive having between about 1 and about 15 weight percent volatile material, said amount being effective to impart to said cement mass an ultimate compressive strength of at least about 1000 p.s.i. and an ultimate permeability less than about 1 millidarcy when exposed to high temperatures.
A cement system consisting essentially of oil well cement and from about 6 to about weight percent of a carbon-containing cement additive selected from the group consisting of anthracite, calcined coke, uncalcined coke, raw oil shale and burned oil shale, said cement additive having a volatile material content of between about 2 and about 10 weight percent.
A cement system consisting essentially of an oil well cement selected from the group consisting of API Class G cement and API Class J cement, and from about 6 to about 15 weight percent of a carbon-containing cement additive selected from the group consisting of anthracite, calcined coke, uncalcined coke, raw oil shale and burned oil shale, said cement additive having a volatile material content of between about 2 and about 10 weight percent.
A hardened cement mass having improved resistance to degradation of its ultimate permeability and compressive strength when exposed to high temperatures, which cement mass is prepared by the method comprising:
- forming a hardenable slurry consisting essentially of a cement system and a water-containing liquid vehicle, said cement system consisting essentially of cement and from about 6 to about 15 weight percent of a carbon-containing cement additive selected from the group consisting of anthracite, calcined coke, uncalcined coke, raw oil shale and burned oil shale, said cement additive having a volatile material content of between about 1 and about 15 weight percent;
- and
- curing said hardenable slurry to form said cement mass.
Dependencies are inferred from the claim text.