Cased-well Formation Resistivity logging is one of the new well- logging methods which was proposed during the later 90\'s, because of its capability of measuring the formation resistivity in cased borehole, which is very different from the traditional open-hole well logging, it can be used in different stage in oil and gas development.

In waterflood-production oilfields, formation water resistivity of water-flooded zone is not only the basic parameter for water-flooded zone evaluation but also the "bottle neck" which restrict water-flooded zone evaluation.

Based on large number of core experiment data, a method for quantitatively deriving formation water salinity (formation water resistivity) and capacity of cation exchange of the theoretical model of spontaneous potential and induced polarization potential is established.

In view of the situation that the spontaneous potential (SP) abnormality in some wells of Shengli Oilfield at high resistivity zones, such as Dongying group and membersⅠ,Ⅱ and Ⅲ of Shahejie group resulted in disunity of rock feature with wireline logging data and errors in interpretation, combining with on-site samples, the paper made analysis of SP abnormality of high resistivity pay zones.