Abstract:

The fractures in Upper Triassic sandstones in middle west ares of Sichuan Basin has controlled the reservoiring and penetration of fluids.The fracture forming mechanism in Upper Triassic of the area is mainly nontectonic origin,including differential compaction,corrossion,karst collapse and gravity sliding.The top and upper parts of paleo unaka are favourable places for nontectonic fracture system,thus they are perfect places for both test wells and development wells.