A new nmr-based permeability model based on two-pore structure characterization methods for complex pore structure rocks: permeability assessment in nanpu sag, china

The NMR estimate of permeability is one of the fundamental methods and have numerous applications in reservoir engineering and petrophysics. To improve the accuracy of NMR-based permeability model, many variables are introduced into NMR-based permeability prediction models due to geometrical complexity and pore structure heterogeneity. In the paper, two pore structure characterization methods are investigated based on Kozeny-Carman model and equivalent component model. Furthermore, a NMR-based permeability model accounting for the effect of pore structure is proposed based on the analysis of the relationship between two pore structure parameters, and it is applied to practically predict permeability. Results show that the new model calculated permeability has good agreement with experimental data, moreover, the adaptability of the new NMR-based permeability prediction model is highly improved through reducing undetermined variables, and key parameters can be measured directly using NMR. The new model provides a valuable scientific resource and assists in the evaluation of hydrocarbon-bearing reservoirs with complex pore structure, such as tight sandstone, shale and carbonate rock.