| It have characteristics of tight stratum,deep bury,high pressure,complex trap,difficult exploration in Xujiahe Reservoir of west Sichuan. All of these bring much more requests for fracture technology. Among operating 5 wells, 3 wells fracture operation have failed because of high wells pressure. Their pressure are 128MPa,159.6MPa,135.1MPa. So it is possible that there is a high fracture pressure area in Xujiahe Reservoir. It is the key factor to study of high fracture pressure for fracturing success in the deep Xujiahe Reservoir.On the basis of fractured modeling test, it is studied in detail on geology factors and engineering factors by means of knowledge about geology characteristics in Xujiahe Reservoir. It have been get some results here:(1)It is affected in the rock mechanics test that rock tensile strength exponential declines with porosity increasing. Rock tensile strength of Xujiahe reserveoir is higher 1 twice than Jurassic reservoir. This will make fracture pressure too high.(2)The big fracture modeling test has been done in Xujiahe Reservoir. Horizontal stress will increase after rocks are soaked in mud. This will make fracture pressure too high.(3)11 wells stress section have been interpretation by well log method and fracture method with differential stress test. Min horizontal stress is so high to make fracture pressure too high.(4)Geology factors and reservoir factors have been studied in detail here. Tight stratum,high pressure,high stress are important factors to increase fracture pressure.(5) Engineering factors have been studied in detail here. Stress of well bore distortion,fissure frictional resistance made by bending are the key factors for high fracture pressure.(6)The formula of fracture pressure has been brought out here based on rock bending distortion and stress of well bore distortion, etc.(7)Well fracture pressure has been demonstrated and evaluated with fracture operating well.
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