A Multi-Step Petrophysical Workflow using Nuclear Magnetic Response and Conventional Logs for Rock Typing and Relative Permeability Estimation

ABSTRACT

Accurate estimation of relative permeability is essential for dynamic reservoir simulation and development planning. This study presents an integrated approach that utilises Nuclear Magnetic Resonance (NMR) log data to derive relative permeability curves for different rock types in a gas-bearing reservoir. NMR-derived porosity has been corrected for gas effects, and then absolute permeability is computed using Coates method. Flow Zone Indicator (FZI) analysis is performed to classify hydraulic flow units, which aids in identifying distinct rock types. A pseudo-capillary pressure curve is reconstructed from substituted T2 distributions using a method based on the relationship between irreducible water saturation and geometric mean T2. These pseudo-capillary pressure curves are then used to estimate normalised saturation and to compute relative permeability curves using the Corey method. This workflow demonstrates that NMR data, when appropriately processed, can serve as a powerful tool for estimating relative permeability in the absence of extensive laboratory measurements, offering significant value for reservoir characterisation and simulation workflows.