Abstract
Petrophysical log analyses were performed on the 3 different types of reservoirs and different permeability estimation methods were applied as 3 case studies.
In the case 1, based on the clear positive correlation between core porosity and core permeability, Coates equation was successfully applied. This case is an example where permeability is mainly controlled by porosity (pore volume).
In the case 2, positive correlation between core porosity and core permeability are observed but there is a strong dependency on lithofacies. In order to accurately estimate permeability, facies log is required prior to log analysis and facies-dependent log analysis was performed. This case is an example where permeability is controlled by porosity but the relationship is different from facies to facies.
In the case 3, there is no obvious correlation observed between core porosity and core permeability, and any facies/rock type information can not explain the scatter in porosity vs. permeability crossplot. However, there is a systematic relationship between, water saturation, capillary pressure and permeability. By generating a regression surface among these three parameters, permeability was estimated with fair accuracy. This is an example where permeability is strongly controlled by pore geometry. In this case capillary pressure vs. water saturation curve, which is strongly related to pore size distribution and possibly pore geometry, can help to estimate permeability.
