Resistivity Modeling of Shaly Sand Formation in High Water Salinity

The evaluation of shaly sand formation has a very close relationship with the
study of electrical properties exhibits by the formation itself. The project done is
based on the earliest resistivity model which proposed by Archie in 1942. Since this
equation is only valid for clean sand, the model was modified by Patnode and Wyllie
in 1950 to encounter the shale conductivity effect in shaly sand formation. However,
this resistivity model contains limitation which is in high salinity of water, the shale
conductivity will not able to significantly affect the total conductivity of the
formation. In other words, when the water salinity is sufficiently high, the resistivity
model of shaly sand formation will reduced closely to Archie‟s equation. Based on
this hypothesis, the theory is brought into laboratory work where shaly sand core
sample is tested for its resistivity in high salinity of water. Three types of core
sample were being prepared by varying the shale content. The general properties of
the samples were recorded as references. The result of core sample resistivity
measurement will be able to describe concisely the accuracy of this model and
generally draw its limitation or exception to be made for the model especially when
the shaly sand formation encounters high water salinity.