Reservoir Characteristics of the Xujiahe Formation in Central-west Sichuan Analogous Foreland Basin
四川类前陆盆地中西部须家河组储层特征

Reservoirs of the upper Triassic Xujiahe Formation has characteristics of low compositional maturity, low cement content and medium maturity in Sichuan analogous foreland basin. Lithology is regularly distributed in plane, dominated by lithic sandstone in the northwest region. lithic sandstone and feldspathic sandstone mixed in central west region, lithic feldspathic sandstones in southwest region, feldspathic lithic and lithic quartz sandstone mixed in central-south region. Reservoir has poor physical properties in general, which are mainly low porosity and permeability reservoir. Only a few reservoirs with middle porosity and low permeability develop in some regions. Because of the sedimentation, diagenesis and tectonic difference in thrust belt, foredeep depression zone, foreland slope and foreland uplift, of the reservoir porosity has zoning characteristics. Reservoir space in Longmen Mountain thrust belt are mainly fracture with small amount of emposieu and original intergranular pore. The pore type in foredeep depression zone is fracture-secondary dissolved pore, dominated by secondary dissolved pore with little primary pore. In foreland slope, the pore type is mainly secondary dissolved pore and primary pore. While in foreland uplift, the pore is mainly dissolved pore and primary pore. The development of reservoirs is controlled by deposition, diagenesis and tectonic disruption.