Numerical simulation of rock pore-throat structure effects on NMR T2 distribution

We built a three-dimensional irregular network model which can adequately describe reservoir rock pore-throat structures. We carried out numerical simulations to study the NMR T(2) distribution of water-saturated rocks. The results indicate that there is a good correlation between T(2) distribution and the pore radius frequency histogram. The total T(2) distribution can be partitioned into pore body and pore throat parts. The effect of parameters including throat radius, pore-throat ratio, and coordination number of the micropore structure on the T(2) distribution can be evaluated individually. The result indicates that: 1) with the increase of the pore throat radius, the T(2) distribution moves toward longer relaxation times and its peak intensity increases; 2) with the increase of the pore-throat ratio, the T(2) distribution moves towards longer T(2) with the peak intensity increasing and the overlap between pore body T(2) and pore throat T(2) decreasing; 3) With the increase of connectivity, the short T(2) component increases and peak signal intensity decreases slightly.