Logging evaluation method of Penglaizhen formation reservoir at Baimamiao region in West Sichuan

Penglaizhen Formation reservoir at Baimamiao region in West Sichuan is mainly composed of fine lithic arkoses and feldspathic litharenites. Their resistivities are commonly low, being 4 [similar to] 10 Ω·m in general and the difference between deep and shallow laterologs is unclear. In Penglaizhen Formation, the resistivity property of porous sandstone reservoir is hardly differentiated from that of mudstone, thus causing difficulties in identifying reservoir and in discriminating fluid property. On the basis of analyzing the logging response property of the reservoir, a reservoir identification technique being composed of three porosity log overlay method and array neutron log method, a reservoir fluid property judgement and analysis technique being composed of porosity intersection method, compressional velocity-shear velocity ratio method and Schlumberger formation fluid type identification (FTI) method and a permeability evaluation technique by use of Stoneley wave and nuclear magnetic resonance were developed by fully applying the modern logging techniques as FMI, DSI and IPL, etc. Through research it is considered that the porosity intersection method, compressional velocity-shear velocity ratio and neutron porosity log data are the major measures of identifying fluid property in Penglaizhen Formation reservoir in this region; and the magnitude of permeability is both controlled by porosity and directly proportional to feldspar content.