Nanoclay-enhanced cement composition for deep well treatment

18:

• A dry cement blend composition, comprising:
• silica, a dispersant, a hydraulic cement and an organically modified nanoclay, wherein the organically modified nanoclay is present in an amount of from 1% to less than 4% by weight of the hydraulic cement,
• wherein the organically modified nanoclay is a montmorillonite nanoclay formed from chlorite clay mineral having octahedral sheets, where Fe or Mg is a central cation, wherein the organically modified nanoclay is modified by a quaternary organo-ammonium salt and comprises nanolayers of less than 1 nm in thickness and about 2-10 microns in width or length.

19:

• The composition of claim 18, further comprising at least one additive selected from the group consisting of silica flour, an expanding agent, a dispersant, a fluid loss control agent, a retarder, a defoamer, a density reducing additive, a density enhancing weighting agent, a foaming agent, and a friction reducing agent.

20:

• The composition of claim 18, wherein the hydraulic cement is at least one selected from the group consisting of an API class A Portland cement, an API class H Portland cement, and an API class G Portland cement.

21:

• The composition of claim 18, wherein the hydraulic cement is a Saudi Type G hydraulic cement.

22:

• The composition of claim 18, wherein the organically modified nanoclay has a mean particle size of 6 to 10 microns.

23:

• A wet cement slurry composition, comprising water and the composition of claim 18, wherein a weight ratio of the water:the hydraulic cement is 0.4-0.5.

24:

• The composition of claim 23, which has a density of 8-20 lb/gal.

25:

• The composition of claim 23, which has a plastic viscosity of 131-245 CP.

26:

• The composition of claim 23, wherein the water is fresh water or salt water.

27:

• A cured cement obtained by curing the composition of claim 23.