Permeability Calculation of Sand Conglomerate Reservoirs Based on Nuclear Magnetic Resonance (NMR)

Abstract

The concept of an intermingled fractal unit (IFU) model was first proposed by Atzeni and Pia in 2008, and their model has since been successfully applied to predict thermal conductivity, electrical conductivity, and the mechanical properties of porous media materials. This paper, based on the Pia IFU model, fits the pore size distribution spectrum to quantitatively characterize the Triassic Karamay Formation conglomerate reservoirs in the Mahu region, in the Junggar Basin of Northwest China, and makes permeability predictions using the free fluid T2 spectrum according to the nuclear magnetic resonance (NMR) experimental data. The results show that the accuracy of the IFU model is significantly higher than that of the classic Coates and SDR models for conglomerate reservoirs with complex pore structures, indicating that this is an effective method to calculate permeability based on NMR. In addition, preliminary discussions are entered into regarding the intermingled fractal expression of the Kozeny-Carman equation and the relative permeability, in order to widen the application of the IFU model in reservoir physics. The derived expressions appear complicated in form but are straightforward to calculate and apply using computer programming since their iteration parameters are definite. The findings set out in this paper provide a valuable reference for further research of the IFU model in reservoir physics.