Enhanced permeability estimation method of oil and gas reservoir rocks
The Kozeny - Carman permeability-porosity dependence has been updated for enhanced prediction of reservoir rocks permeability. The results of the original and modified model were compared based on the core studies data. Conceptually, the Kozeny - Carman equation is based on the concept that a porous space is represented by a bundle of unconnected capillary tubes with defined hydraulic radius taken as <i>r</i>/2. However, the real rocks are composed of different and variously-sized minerals thus influencing the hydraulic radius of the network interrelated pore channels. To adapt the model to filtration conditions of the real nature, the hydraulic radius was taken with account of the residual water film on the capillary surface. Easy assessment of the residual water saturation by the log analysis data makes it possible to apply the method when interpreting log analysis data. Petrophysical core data sets from the fields in the South Caspian Basin (SCB) were used to estimate the permeability obtained from the original and modified Kozeny - Carman equation and to comparatively analyze the permeability measured values. Estimated permeability, obtained due to the updated model application demonstrated a better correlation with measured data. Thus, the modified dependence between the permeability and porosity demonstrated SCB rocks permeability better requiring no special measurements for the method implementation when interpreting log analysis data.