Reservoir characteristics and controlling factors of the 6th member of the Xujiahe Formation in the Guanyinchang-Washi region, southern Sichuan

The petrology, porosity, permeability and controlling factors are explored on the basis of the field investigation, core observation, microscopic examination and well logs from the 6th member of the Xujiahe Formation in the Guanyinchang-Washi region, southern Sichuan. The lithology in the study area mainly consists of medium-to fine-grained feldspathic litharenite and lithic quartz sandstone, with the porosity ranging between 6% and 10% and an average of 7.3%, and with the permeability ranging between 0.03×10^-3μm² and 0.9×10^-3μm² and an average of 0.177×10^-3μm². The reservoirs cited above belong to the typical low-porosity and lowpermeability reservoirs with intergranular and intragranular solution openings. In a planar view, the physical properties of the reservoirs tend to be controlled by sedimentary facies,and vertically, they become sharply poorer due to compaction and cementation with the increase of depths. On the whole, the physical properties of the reservoirs tend to be improved by the rim cementation of chlorite, dissolution of feldspar and tectonism in the study area.