VELOCITY DISTRIBUTION OF SLOW FLUID-FLOWS IN BENTHEIMER SANDSTONE - AN NMRI AND PROPAGATOR STUDY

This work addresses the special problems of measuring flow velocity di stributions in rock by NMR methods, Specifically, these problems are t o measure very slow bows as well as flows in the presence of backgroun d magnetic field gradients caused by heterogeneities of the rock, We m odify a stimulated echo sequence for use in diffusion measurements, in order to maximize velocity sensitivity and minimize background gradie nt effects. Accurate velocity images of Soltrol 220 oil in sandstone w ere made for flow velocities up to around 0.04 mm/s with an imager tha t does not have echo-planar capability. Accurate velocity distribution s by the propagator method can be obtained even with stimulated echo d elays of 1.9 T-1 by phase cycling combined with suitable crusher gradi ents. Copyright (C) 1996 Elsevier Science Inc.