CO2 foam fracturing fluids with gelled methanol as the external phase have been developed. These CO2 foams are generated on the surface by a patented CO2 heating process. Field applications of these fluids demonstrate that they are effective well stimulation fluids for hydrocarbon bearing formations that exhibit low permeability, low reservoir pressure or water sensitivity.

With this system water can be completely eliminated from the treatment fluid while the CO2 provides a gas drive to assist in returning load fluid to the wellbore. Since the density of these fluids is near that of water, they can be utilized to fracture stimulate deep formations without experiencing excessive wellhead pressures. Some CO2 dissolves in the methanol to yield a non-damaging low "pH" methanol fluid system that exhibits extremely low surface tensions which also assists in load fluid recovery. Additionally, these fluids exhibit near perfect proppant support and very high fluid effeciencies.

A comparison of these surface generated methanol/CO2 foam fracture treatments with other stimulation methods in the Morrow formation in the Texas Panhandle and Western Oklahoma and in several other formations in Texas, Oklahoma and Colorado illustrates their success.

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