| Popis: |
We use nuclear magnetic resonance (NMR) imaging to determine spatial distributions of properties used to describe flow in heterogeneous porous media. The methods are demonstrated on sandstone samples, which are characteristic of underground formations. Static imaging experiments conducted on fluid-saturated samples are used to determine porosity distributions. Cars-Purcell-Meiboom-Gill (CPMG) imaging is used to evaluate the .spin density. The local relaxation is modeled in order to estimate the intrinsic magnetization intensity, which is proportional to the amount of saturating fluid. To determine permeability distributions, experiments are conducted whereby fluid is injected into saturated samples. A pulsed-field-gradient stimulated-echo technique is used to resolve the velocity field within the sample. An inverse problem is formulated and solved to determine the permeability distribution. |
