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Cementitious compositions are provided that can be use in drilling oil and gas well applications. The compositions include a source of hydraulically settable cement, calcium carbonate, free lime and alkali ions, calcium sulfate and an organic component. Methods for cementing a casing and liners and

Cementitious compositions are provided that can be use in drilling oil and gas well applications. The compositions include a source of hydraulically settable cement, calcium carbonate, free lime and alkali ions, calcium sulfate and an organic component. Methods for cementing a casing and liners and for remedial operations such as plugging back and squeeze cementing are also provided.

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What is claimed is: 1. An oil and/or gas well cementitious composition comprising: a hydraulic cement; a source of free lime and alkali ions; a source of calcium carbonate; a source of calcium sulfate; and an organic component, wherein when the composition is mixed with water, the composition has a

What is claimed is: 1. An oil and/or gas well cementitious composition comprising: a hydraulic cement; a source of free lime and alkali ions; a source of calcium carbonate; a source of calcium sulfate; and an organic component, wherein when the composition is mixed with water, the composition has a minimum thickening time of at least about 90 minutes and an eight-hour compressive strength of at least about 200 psi (about 1.4 MPa). 2. The composition of claim 1, wherein the hydraulic cement is present in an amount of greater than or equal to about 50% by weight of the composition. 3. The composition of claim 1, wherein the source of free lime and alkali ions is present in an amount of less than about 25% by weight of the composition. 4. The composition of claim 1, wherein the source of free lime and alkali ions comprises cement kiln dust. 5. The composition of claim 1, wherein the organic component is present in the composition in an amount of less than or equal to about 3% by weight of the composition. 6. The composition of claim 1, wherein the organic component comprises one or more of: polyhydric alcohols, alkanolamines, amine acetates, salts and equivalents thereof. 7. The composition of claim 1, wherein the source of calcium carbonate is present in an amount of about 3 to about 25% by weight of the composition. 8. The composition of claim 1, wherein the source of calcium carbonate comprises one or more of: calcium carbonate, limestone, dolomite, calcite and aragonite. 9. The composition of claim 1, wherein the source of calcium carbonate comprises limestone. 10. The composition of claim 1, wherein the source of calcium sulfate is present in an amount of about 3 to about 10% by weight of the composition. 11. The composition of claim 1, wherein the source of calcium sulfate comprises gypsum. 12. The composition of claim 1, wherein the hydraulic cement comprises one or more of Portland cements of Type I, Type II, Type III and Type V, modified Portland cements, performance hydraulic cement, blended hydraulic cements and alumina cements. 13. The composition of claim 1, wherein the cementitious composition has a Blaine surface area of greater than about 220 m2/kg. 14. The composition of claim 1, wherein the cementitious composition has greater than or equal to about 65% passing on a 325 mesh screen. 15. The composition of claim 1, wherein the composition comprises: about 50% to about 90% by weight of the composition of the hydraulic cement, about 1% to about 25% by weight of the composition of the free lime and alkali ions; about 3% to about 25% by weight of the composition of the calcium carbonate; about 3% to about 10% by weight of the composition of the calcium sulfate; and less than or equal to about 3% of the organic component. 16. A wellbore cementitious composition comprising: a hydraulic cement present at greater than or equal to about 50% by weight of the composition; a source of free lime and alkali ions present at greater than or equal to about 1% by weight of the composition; a source of calcium carbonate present at greater than or equal to about 3% by weight of the composition; a source of calcium sulfate present at greater than or equal to about 3% by weight of the composition; and an organic component present at less than or equal to about 3% by weight of the composition. 17. The composition of claim 16, wherein the hydraulic cement comprises Portland cement, the source of free lime and alkali ions comprises cement kiln dust; the source of calcium carbonate comprises one or more of: calcium carbonate, limestone, dolomite, calcite and aragonite; the source of calcium sulfate comprises gypsum; and the organic component comprises one or more of: polyhydric alcohols, alkanolamines, amine acetates, salts and equivalents thereof. 18. The composition of claim 16, wherein the cementitious composition has a Blaine surface area of greater than or equal to about 220 m2/kg. 19. The composition of claim 16, wherein the cementitious composition has greater than or equal to about 65% passing on a 325 mesh screen. 20. The composition of claim 16, wherein in the presence of water, the cementitious composition forms a slurry that has a minimum thickening time of about 90 minutes and wherein the cementitious composition forms a solid set cement that has an eight-hour compressive strength of about 200 psi (about 1.4 MPa) to about 4,400 psi (about 30 MPa). 21. The composition of claim 16, wherein the hydraulic cement is present at about 50% to about 90% by weight of the composition, the source of free lime and alkali ions is present at about 1% to about 25% by weight of the composition and the source of free lime and alkali ions comprises cement kiln dust, the source of calcium carbonate is present at about 3% to about 25% by weight of the composition, the source of calcium sulfate is present at about 3% to about 10% by weight of the composition, and the organic component is present at less than or equal to about 3% by weight of the composition. 22. A wellbore cementitious composition comprising: a hydraulic cement present at about 50% to about 90% by weight of the composition, wherein the hydraulic cement comprises Portland cement; a source of free lime and alkali ions present at about 1% to about 25% by weight of the composition, wherein the source of free lime and alkali ions comprises cement kiln dust; a source of calcium carbonate present at about 3% to about 25% by weight of the composition, wherein the source of calcium carbonate comprises limestone; a source of calcium sulfate present at about 3% to about 10% by weight of the composition, wherein the source of calcium sulfate comprises gypsum; and an organic component present at less than or equal to about 3% by weight of the composition. 23. The composition of claim 21, wherein in the presence of water, the cementitious composition forms a slurry that has a minimum thickening time of about 90 minutes and wherein the cementitious composition forms a solid set cement that has an eight-hour compressive strength of about 200 psi (about 1.4 MPa) to about 4,400 psi (about 30 MPa).