Liquid CO2 system has been pumped as fracturing fluids in North America since the early 1980s and the liquid CO2/N2 system from 1994. The fluids have been used in over 1000 wells in a variety of formations and in wells of permeabilities from 0.1mD to 10 Darcies, depths in excess of 3000 meters and BHT from 10 to 100 degrees Celsius. The chemistry and physics of these fluids are very intriguing and are described. These include the thermodynamics of the fluids and the physical properties of density and viscosity of these fluids. The effect of compressibility and the transient effects on fluid leak off are discussed. The suggested process for proppant placement with these low viscosity, non-damaging fluids are described. This includes the density and turbulent effects. The design model considerations for the design of the fracturing jobs with these fluids are also summarized. Operational considerations of pumping these low temperature fluids in the field are detailed. A summary of the field use of these fluids is described.

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