Carbon Dioxide (CO2)
CO2 is used to energize a stimulation fluid in both fracturing and acidizing
applications. CO2 is pumped as a liquid at –18°C (0°F),
and expands to a gas as the well is flowed back. After the treatment is completed
and the pressure decreases, the liquid CO2 expands significantly to lift
fluids to the surface. This is known as the “pop bottle effect”. Liquid
CO2 is also an excellent stimulation fluid that is used when formation
damage due to fluid retention is suspected.