Oil and gas well cement systems using elemental sulfur
A cement composition for cementing an oil or gas well includes Portland cement, water and a sulfur component. The cement composition may be used to cement a well bore by creating a cement slurry including the sulfur component, pumping the slurry into the well bore to a selected location and allowing it to solidify.
1. A cement composition for use in a cementing process of an oil and gas well, said composition comprising elemental sulfur, Portland cement, and sufficient water to create a pumpable slurry, the composition being free of aggregate.
2. The composition of claim 1 further comprising one or more of the following additives: a retarder, a fluid loss control agent, an accelerator, a dispersant, a cementitious material, or a pozzolanic material.
3. The composition of claim 2 further comprising fly ash.
4. The composition of claim 1 wherein the Portland cement is a type A cement or a type G cement.
5. The composition of claim 1 wherein the elemental sulfur is finely divided elemental sulfur.
6. The composition of claim 5 wherein the elemental sulfur has an average particle size less than about 1 mm.
7. The composition of claim 1 wherein the elemental sulfur comprises more than about 0% and less than about 40% by weight of blend of the cement composition.
8. The composition of claim 7 wherein the elemental sulfur comprises more than about 5% and less than about about 30% by weight of blend of the cement composition.
9. The composition of claim 8 wherein the elemental sulfur comprises more than about 10% and less than about about 20% by weight of blend of the cement composition.
10. The composition of claim 1 wherein the elemental sulfur comprises high purity elemental sulfur, with less than about 2% impurities by weight.
11. The composition of claim 1 further comprising a sulfur cross-linking agent.
12. The composition of claim 11 wherein the sulfur cross-linking agent comprises a styrene-butadiene copolymer or a poly-sulfur silane coupling agent.
13. The cement composition of claim 1 , wherein the cement composition shows continuing increases in compressive strength when cured, over a two week period.
14. The cement composition of claim 1 , wherein the cement composition has a higher flexural strength than a similar cement composition not containing the sulfur component.
15. The cement composition of claim 1 , wherein the cement composition has a higher compressive strength when cured under variable temperature conditions than when cured under isothermal conditions.
16. The cement composition of claim 1 , wherein the cement composition has a higher compressive strength to Young's modulus ration than a similar cement composition not containing the elemental sulfur.