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 method of cementing a subterranean wellbore, comprising the step of creating a pumpable cement slurry, and introducing the slurry into the wellbore, wherein said slurry comprises water and a cement composition comprising a Portland cement and elemental sulfur, the slurry being free of aggregate.
2. The method of claim 1 which is a primary cementing method.
3. The method of claim 1 which is a remedial cementing process.
4. The method of claim 1 wherein the cement composition further comprises 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.
5. The method of claim 1 wherein the Portland cement is a type A or a type G cement.
6. The method of claim 4 wherein the slurry further comprises fly ash.
7. The method of claim 1 wherein the sulfur component comprises finely divided elemental sulfur, or its reaction products, or both.
8. The method of claim 7 wherein the elemental sulfur has an average particle size less than about 1 mm in size.
9. The method of claim 1 wherein the sulfur component comprises more than 0% and less than about 40% by weight of blend of the cement composition.
10. The method of claim 9 wherein the sulfur component comprises more than about 5% and less than about 30% by weight of blend of the cement composition.
11. The method of claim 10 wherein the sulfur component comprises more than about 10% and less than about 20% by weight of blend of the cement composition.
12. The method of claim 7 wherein the elemental sulfur comprises high purity sulfur, with less than about 2% impurities by weight.
13. The method of claim 1 wherein the cement composition further comprises a sulfur cross-linking agent.
14. The method of claim 13 wherein the sulfur cross-linking agent comprises a styrene-butadiene copolymer or a poly-sulfur silane coupling agent.