Derivation of fluid transport properties in porous media from NMR flow velocity spectrum measurements

摘要

The effective porosity and tortuosity of e.g. oil-bearing rocks is derived from NMR flow velocity spectrum measurements on samples having an imposed pressure gradient. The fluid in closed-off pores gives a subsidiary peak at zero velocity. Tortuosity is derived from the velocity spectrum transverse to the pressure gradient (fig. 7). Stimulated echoes are used to allow greater transit times. The method may be applied in well-logging by the use of pressure pulses. Conventional magnetic field imaging gradients may be applied in addition to the flow encoding gradients. IMAGE