Modeling two-dimensional magnetic resonance measurements in coupled pore systems

We present numerical simulations of a two-dimensional (2D) nuclear magnetic resonance process, T_{2}-storage-T_{2}, on a simple mixed porosity system, the micrograin consolidation (μGC) model. The results of these calculations are compared with predictions based on the analytic two-site exchange model, for which we have independently established numerical values for all the input parameters. Although there is qualitative and semiquantitative agreement between the two models, we identify specific instances where the two-site model fails to properly describe the combined effects of relaxation and diffusion. Generally, these instances occur when a gradient in magnetization within the large pores of the μGC model is established during the initial phase of the 2D process. The two-site model assumes that the magnetization is spatially uniform within each of its subpore systems and thus cannot describe such effects.