Estimating Permeability in Uncored Wells Using Modified Flow Zone Index

Abstract Permeability estimation for un-cored wells is a classic issue. A simple model that widely used is using core porosity-core permeability cross plot to determine the linier regression. Then we estimate permeability in un-cored well after making adjustment for porosity log to porosity core. The difficulties using that method is most of cross plot did not show clear relationship (scatter data) due to effect of rock heterogeneity. Therefore another effort is needed by separate it based on rock type to get better relationship. Permeability itself is not depend only on porosity but also other properties like clay content, grain size, tortuosity and etc. Part of this phenomenon had been modeled by Carmen-Kozeny which illustrates strong dependency of permeability on average grain size, tortuosity and flow zone index. The conventional way to reduce data scatter is by using additional correlation parameters. Commonly shale content (Vsh) and reservoir facies are used to give reliable transform or regression analysis for estimating the permeability. Start with this concept; we try to simplify the correlation by modified the Carmen Kozeny eq. (used flow zone index term) using clay content as another parameter that influences permeability value. Because we assume that porosity and clay content are the most important properties that have significant effect on permeability. In this paper, we will describe permeability estimation for un-cored well as function of porosity and clay content using modified flow zone index-permeability cross plot. This cross plot has been test in three clastic reservoirs in Lower Sihapas formation either for consolidated or unconsolidated sandstone. The result shows this cross plot give better relationship compare to conventional cross plot and more simple transform to estimate permeability in un-cored well for input to geologic and reservoir simulation models.