Subterranean oil and gas producing formations are fractured by filling a well casing with a compressible hydraulic fracturing fluid comprising a mixture of liquid, compressed gas, and propant material and precompressed to a pressure of about 1,000 psi or more greater than the fracture extension pressure at the depth of the zone to be fractured. A perforator is provided in the casing to form fluid exit perforations at the selected depth of the fracture zone. Following perforation the perforated zone is fractured by the precompressed fracturing fluid laden with propant material that is discharged into the formation until the hydraulic extension pressure is reached and the perforations are eventually sanded off. Optionally, filling of the well bore is maintained continuously through the filling and perforation of the casing until after decompression of the fracturing fluid is completed.