Revealing Absolute Pore Size Distributions in Clay-Rich and Tight Reservoirs by Means of Low-Field Nuclear Magnetic Resonance

Precise evaluation of rock filtration and capacity properties is challenging, particularly in unconventional reservoir formations with high clay content. This data set contains T2 relaxation time distributions of two different Low-Field Nuclear Magnetic resonance (LF-NMR) approaches, standard and modified differential, along with the Mercury Injection Capillary Pressure (MICP) Pore throat size distribution. The modified differential approach employs the subtraction of the dried sample signal from the signal of the 100 % water-saturated sample before taking the Laplace transform, giving a differential distribution devoid of the unwanted signals from rock matrix, closed porosity and clay-bound water. In the proposed PSD conversion workflow based on the percolation theory, a power function relationship between differential LF-NMR transverse relaxation time T2 and MICP pore-throat diameter can be established, enabling the determination of LF-NMR absolute pore size distribution and pseudo capillary pressure (Pc) curves for clay-rich samples.