Lightweight composite cement compositions and methods of cementing wells with said compositions

Abstract

Composite cement compositions and pumpable slurries for cementing well or at least one zone of the wells are provided and comprise cementitious material that forms calcium silicate hydrates upon exposure to water, inert filler material, nano-sized calcium carbonate particles, and water, wherein the cementitious material has a mean particle size of at least about 0.5 micron and no more than about 20 microns, the inert filler material has particle sizes of at least about 25 microns and no more than about 2 millimeters (mm), and the compositions and slurries have densities of at least about 9.5 pounds per gallon (ppg) and no more than about 12.5 ppg and solid volume fractions of at least about 50%. Methods of cementing the wells or the at least one zone of the wells are also provided and comprise pumping the compositions and slurries into the well and allowing the compositions and slurries to set or cure to form or produce lightweight composite cements having compressive strengths of greater than 400 pounds per square inch.

Dependencies are inferred from the claim text.