Method for improving cement toughness
This document relates to methods for providing long-term zonal isolation in oil wells using cement compositions that contain triazine-based polymeric additives. The cement compositions containing the polymeric additives exhibit increased tensile strength, elastic strength, or both, without suffering a decrease in compressive strength, as compared to the same cement without the polymeric additive.
1. A cement composition for providing long-term zonal isolation in oil wells, comprising:
cement; and
a triazine polymeric additive selected from a polymer having repeat units of structure A and structure B:
wherein R 1 is selected from the group consisting of a cyclic aliphatic secondary amine, an aromatic diamine, an aromatic diol, an aliphatic diamine, and an aliphatic diol; and
n is about 10 to about 1000.
2. The composition of claim 1 , wherein R 1 is selected from the group consisting of:
wherein:
R 2 and R 3 are each independently selected from the group consisting of C 1 -C 6 alkyl, C(═O), SO 2 , and O;
m is 0 to 6;
p is 0 to 8; and
q is 0 to 8.
3. The composition of claim 2 , wherein R 1 is
4. The composition of claim 3 , wherein the polymeric additive is a polymer having repeat units of structure A and has the structure:
5. The composition of claim 3 , wherein the polymeric additive is a polymer having repeat units of structure B and has the structure:
6. The composition of claim 1 , wherein the amount of polymeric additive in the cement composition is between about 0.1% to about 10% by weight of the cement.
7. The composition of claim 6 , wherein the amount of polymeric additive in the cement composition is about 3% by weight of the cement.
8. The composition of claim 1 , wherein the cement composition further comprises one or more of a suspending agent, a neutralizing agent, and a reaction propagating agent.
9. The composition of claim 8 , wherein the one or more suspending agent, neutralizing agent, and reaction propagating agent are selected from the group consisting of N,N-diisopropylethylamine, triethylamine, trimethylamine, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.
10. The composition of claim 1 , wherein the cement composition further comprises water.
11. The composition of claim 1 , wherein the cement composition has a Young's modulus of about 0.1 GPa to about 40 GPa, about 3 GPa to about 25 GPa, or about 5 GPa to about 20 GPa at a pressure of about 0.1 MPa to about 150 MPa, about 10 MPa to about 100 MPa, or about 20 MPa to about 40 MPa, at a temperature of about 77° F. to about 450° F., about 125° F. to about 350° F., or about 150° F. to about 200° F.
12. The composition of claim 11 , wherein the cement composition has a Young's modulus of about 5 GPa to about 10 GPa at a pressure of about 20 MPa and a temperature of about 180° F.
13. The composition of claim 1 , wherein the cement composition has a compressive strength of about 1000 psi to about 10,000 psi, about 2000 psi to about 8000 psi, or about 3500 psi to about 6500 psi, at a pressure of about 0.1 MPa to about 150 MPa, about 10 MPa to about 100 MPa, or about 20 MPa to about 40 MPa, at a temperature of about 77° F. to about 450° F., about 125° F. to about 350° F., or about 150° F. to about 200° F.
14. The composition of claim 13 , wherein the cement composition has a compressive strength of about 5500 psi to about 6500 psi at a pressure of about 20 MPa and a temperature of about 180° F.