The liquid carbon dioxide (CO2) fracturing process was studied recentl
y during the completion of a 19-well shallow gas project for Crestar E
nergy Inc. in southeastern Alberta. The project involved mini fracture
treatments that used special tools to record bottomhole pressure, tem
perature, and density conditions at the perforations. The analysis of
the data gathered during this study has shown some surprising results,
and has led to the development of a new technique that may enhance th
e characteristics of the liquid CO2 fracturing process, and lower the
overall costs associated with this type of treatment. This paper discu
sses the uses of low-viscosity, low-temperature fracturing fluids, and
the ways in which they differ from conventional fracturing fluids. Ca
se studies from the Crestar Energy shallow gas project are used to dem
onstrate the cost savings realized by combining liquid CO2( )with nitr
ogen (N-2) during the fracturing process.