Abstract: From 1998 to the present, a key technology research was carried into practice by PetroChina on petrophysics and well logging interpretation fro low-resistivity reservoir in themiddle and upper layer of Bohai Bay basin representatively and severalmature techniques are obtained: the reservoir geological condition of the low-resistivity oil formation distribution; clay additional conductivity - petrophysics experiment research on clay electric-chemical bound water; numerical simulation and time lapse logging research on the dual lateral logging and dual induction logging of different saturation oil-layers when saltwatermud or fresh watermud invasion; the corresponding low-resistivity oil-layer identification and evaluation interpretation methods. The important geological outcome has been achieved in Bohai Bay region and the west of China.