6l.eblane D P, Martel T, Graves I) G, el al. Application of propane (LPG) based hydraulic fracturing in the McCully gas field, New Brunswick,Canada[R]. SPE 144093,2011.
7Campbell S M, Fairchild Jr. N R, Arnold D L. Liquid CO2 and sand stimulations in the lewis shale, San Juan Basin. New Mexico:a case study[R]. SPE 60317,2000.
8Stidham J E, Tetrick t. T, Glenn S A. Nilrogen coiled-tubing fracturing in the Appalachian Basin[R]. SPE 72382,2001.
9Gottschling J C,Royce T N. Nitrogen gas and sand:a new tech- nique for stimulation of Devonian shale[J]. Journal of Petroleum Technology,1985,37(5) :901-907.
10Ishida T, Aoyagi K, Niwa T, et al. Acoustic emission monitoring of hydi'aulie fracturing laboratory experiment with supercritieal and liquid CO2 [ J]. Geophysical Research Letters, 2012,39 (16) 1-6.